Hybrid Vehicle Inverter Phase Control for Limp Home Mode
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Solution Overview
Problem
In hybrid vehicles, when an abnormality occurs in the voltage sensor, the failure of motor drive control leads to reduced traveling distance and speed due to the inability to maintain limp home mode, as the stepping-up converter and inverter operation are stopped, causing voltage fluctuations that disrupt motor control.
Innovation Solution
The electronic control unit controls the step-up converter to stop stepping up and causes the first inverter's three phases to be in an ON state when an abnormality is detected, allowing the counter-electromotive force from the generator to be supplied to the motor, and when power consumption is lower than the counter-electromotive force, it forms a closed circuit to suppress voltage rise, ensuring continuous motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the voltage sensor detects abnormality and the stepping-up converter is stopped, then the motor drive control fails, but the hybrid vehicle cannot travel in limp home mode
Solution Approach 1:
The patent segments the inverter control into independent phase control (U-phase, V-phase, W-phase) rather than treating it as a unified system. By controlling each phase separately through the inverter, the system can maintain motor operation in limp home mode even when the voltage sensor is abnormal, thus resolving the contradiction between control reliability and operational capability.
Solution Approach 2:
The patent introduces the inverter as an intermediary component between the abnormal voltage sensor and the motor control system. The inverter acts as a mediator that can bypass the abnormal voltage sensor signals and directly control the motor through phase-specific switching, enabling limp home mode operation while maintaining control stability.
2Duration of action of moving object
If the first inverter operation is stopped to supply counter-electromotive force to the motor, then the traveling distance increases, but the voltage of the capacitor rises causing control failure
Solution Approach 1:
The patent dynamically adjusts the inverter phase states based on real-time voltage conditions. When capacitor voltage rises during limp home mode operation, the system dynamically switches specific phases (U-phase, V-phase, or W-phase) to ON state to regulate voltage, and switches them back when voltage stabilizes. This dynamic control enables extended traveling distance while preventing voltage-related control failures.
Solution Approach 2:
The patent changes the operational parameters of the inverter phases (switching between ON and OFF states) to control capacitor voltage during limp home mode. By adjusting which phases are active, the system can regulate voltage levels to prevent overvoltage conditions while maintaining motor operation, thus extending traveling distance without sacrificing control reliability.
3Stability of the object's composition
If three phases of the first inverter are caused to be in ON state to suppress voltage rise, then the voltage stability improves, but the power consumption increases
Solution Approach 1:
The patent applies partial action by activating only the necessary number of phases (one or more of U-phase, V-phase, or W-phase) rather than all three phases simultaneously. This selective phase activation suppresses voltage rise while minimizing power consumption, resolving the contradiction between voltage stability and energy efficiency during limp home mode operation.
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 solution prevents motor drive control failure and allows the hybrid vehicle to maintain limp home mode by stabilizing voltage and ensuring continuous operation, even when the stepping-up converter is stopped, thereby increasing traveling distance and speed.
Implementation Method 1
a generator configured to generate a counter-electromotive force due to rotation of the engine
Implementation Method 2
a smoothing capacitor attached to the second voltage system electric power line
Data Source
AI summary
A hybrid vehicle includes an engine; a generator that generates a counter-electromotive force; a motor; a first inverter for the generator; a second inverter for the motor; a step-up converter that steps up an electric power of a first voltage system electric power line and supplies the electric power to a second voltage system electric power line; and a smoothing capacitor of the second voltage system electric power line. In a case where the hybrid vehicle travels by driving the engine in a state in which the stepping up by the step-up converter and an operation of the first inverter are stopped when an abnormality occurs in a voltage sensor, when an electronic control unit determines that there is an indication that the voltage of the capacitor will rise, the first inverter is controlled to cause three phases of the first inverter to be in an ON state.