Hybrid Vehicle Battery-Less Travel Control Apparatus
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Solution Overview
Problem
Hybrid vehicles experience instability in motor voltage during battery-less travel control due to poor control precision of inverter output voltage, especially when shifting from PWM to rectangular control at high vehicle speeds, leading to potential power balance collapse and instability.
Innovation Solution
Implementing a control apparatus that switches between pulse width modulation and rectangular control based on vehicle speed, with a vehicle speed limitation during battery-less travel control to prevent instability by maintaining PWM control below a threshold speed and adjusting torque limits, and modifying these limits based on transmission gear settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If rectangular control is used to increase motor output at high vehicle speeds, then motor torque is improved, but control precision deteriorates leading to voltage instability
Solution Approach 1:
The control apparatus dynamically switches between PWM control and rectangular control based on vehicle speed conditions. During normal operation at high speeds, rectangular control is used to maximize motor output. However, during battery-less travel control, the system dynamically adjusts to use only PWM control to maintain stability when the battery cannot provide buffering capability.
Solution Approach 2:
The invention changes the control parameter (control method) based on the operating condition (battery status and vehicle speed). By detecting battery abnormalities and switching control modes, the system adapts the inverter control parameter from rectangular control to PWM control during battery-less travel, ensuring stable voltage output while maintaining acceptable motor performance.
2Reliability
If the battery is disconnected during abnormality, then system reliability is improved by isolating the fault, but power balance stability deteriorates due to loss of buffering capability
Solution Approach 1:
The control apparatus continuously monitors battery status and detects abnormalities through feedback mechanisms. When a battery abnormality is detected, the system switches to battery-less travel control mode, adjusting the operation of the motor and generator accordingly. This feedback-based control ensures that the system maintains stable power balance by preventing conditions that would lead to voltage instability.
Solution Approach 2:
The control apparatus takes preliminary action by switching to a restricted control mode (PWM only) before voltage instability can occur. By proactively limiting the vehicle speed and preventing rectangular control execution during battery-less travel, the system preemptively maintains power balance stability rather than reacting after instability begins.
3Productivity
If vehicle speed increases during battery-less travel control, then productivity is improved, but voltage stability deteriorates due to shift to rectangular control
Solution Approach 1:
The system dynamically adjusts the relationship between vehicle speed and control method during battery-less travel control. Unlike normal operation where high speed enables rectangular control, during battery-less travel the system maintains PWM control across all speeds, effectively creating a dynamic constraint that prioritizes voltage stability over maximum speed capability.
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 the motor voltage during battery-less travel control by maintaining accurate power balance and preventing shifts to rectangular control, ensuring continuous and stable vehicle operation.
Implementation Method 1
a generator that generates electric power using the power of the engine
Implementation Method 2
a motor that causes the output shaft to rotate using electric power
Data Source
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AI summary
In a hybrid vehicle including an engine, a motor, a generator, and a battery that is electrically connected to the motor and the generator, an ECU performs "battery-less travel control" enabling the vehicle to travel when a fault occurs in the battery by disconnecting the battery from an electrical system including the motor and the generator and driving the motor using power that is generated by the generator using the power of the engine. When the battery-less travel control is underway (YES in S20) and a vehicle speed V exceeds a vehicle speed limit Vsh (YES in S21), the ECU implements a vehicle speed limitation (S22). As a result, a control mode of the motor is less likely to shift to a rectangular control mode during the battery-less travel control.