Hybrid EV Battery Discharge Control During Catalyst Warm-Up
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Solution Overview
Problem
Existing hybrid electric vehicles face issues with voltage drops during catalyst device warm-up, leading to potential component damage and reduced drivability due to increased battery output power, which is not effectively managed by existing control methods.
Innovation Solution
Implementing a control device that adjusts battery discharge control by setting different lower limit voltages and dischargeable power levels based on catalyst warm-up status, allowing for temporary power increases while protecting battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output limit of the battery is increased to enable catalyst device warm-up, then the catalyst device can be warmed up, but the voltage drop increases causing the battery voltage to reach the lower limit voltage earlier and potentially become lower than the lower limit voltage
Solution Approach 1:
The patent applies dynamics by making the lower limit voltage of the battery variable rather than fixed. The control device dynamically adjusts the lower limit voltage based on whether the catalyst device requires warm-up: setting it to a first lower limit value when warm-up is needed (allowing higher dischargeable power) and to a second lower limit value when warm-up is not needed (maintaining normal voltage protection). This dynamic adjustment resolves the contradiction by adapting the voltage threshold to the specific operational context.
Solution Approach 2:
The patent changes the parameter of lower limit voltage based on the operational state. When the catalyst device needs warm-up and the current lower limit voltage would cause excessive voltage drop, the control device changes the lower limit voltage parameter to a higher value, allowing the battery to discharge more power without triggering voltage protection mechanisms that would limit motor torque and affect drivability.
2Power
If the output limit of the battery is increased to enable catalyst device warm-up, then the catalyst device can be warmed up, but the driving force is limited in an early stage causing shock and hesitation
Solution Approach 1:
The patent makes the lower limit voltage dynamic to prevent premature torque limitation. By adjusting the lower limit voltage based on catalyst warm-up requirements, the system ensures that the battery can provide sufficient power during transient conditions without unnecessarily limiting motor torque, thereby maintaining smooth acceleration and drivability.
Solution Approach 2:
The control device uses feedback from the catalyst device's warm-up status to adjust the battery's lower limit voltage. This feedback mechanism ensures that the battery discharge characteristics are optimized for the current operational context, preventing situations where the battery voltage would trigger torque limitation before the catalyst is properly warmed up, thus avoiding shock and hesitation during acceleration.
3Reliability
If the lower limit voltage of the battery is set to a higher value to prevent voltage drop, then component protection is improved, but the dischargeable power of the battery is reduced preventing catalyst device warm-up
Solution Approach 1:
The patent resolves this contradiction by making the lower limit voltage dynamic rather than fixed. The control device sets the lower limit voltage to a first value when catalyst warm-up is required (allowing higher dischargeable power for warm-up) and to a second value when warm-up is not required (providing stronger component protection). This dynamic adjustment allows the system to optimize between component protection and warm-up capability based on real-time operational needs.
Data Source
AI summary
A hybrid electric vehicle includes a control device that performs travel control and battery control. The battery control includes: first discharge control that sets a lower limit voltage of the battery to a first lower limit value when the battery is not in a warm-up state of the catalyst device, and sets battery dischargeable power to a first upper limit value; and second discharge control that sets a lower limit voltage of the battery to a second lower limit value that is smaller than the first lower limit value when the battery is in a warm-up state of the catalyst device, and sets the battery dischargeable power to a second upper limit value that is larger than the first upper limit value. The travel control includes transient control for causing the battery to output power that is a sum of the battery dischargeable power and a temporary increase.