Power Conversion Device Collision Residual Charge Discharge
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Solution Overview
Problem
Existing power conversion devices in electric vehicles face challenges in rapidly discharging residual charge from smoothing capacitors during a collision, as normal control operations may be hindered by disconnected power supply lines or battery voltage drops, preventing effective consumption of residual charge.
Innovation Solution
A power conversion device equipped with a collision detection unit, relay for switching DC power, and a control unit that controls a gate driving unit to increase switching losses and alternate between boosting and step-down operations to rapidly consume residual charge in smoothing capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If normal converter control is used to consume residual charge, then residual charge can be discharged, but control cannot be performed when power supply line is disconnected or battery voltage drops due to collision
Solution Approach 1:
The control unit detects collision conditions in advance (through voltage drop or power line disconnection detection) and switches to a special discharge mode before normal control becomes impossible. This preliminary detection and mode switching ensures that residual charge discharge can begin immediately when collision occurs, rather than waiting for complete system failure
Solution Approach 2:
The control unit dynamically adjusts its operation mode based on the detected power supply condition. When normal power supply is detected, standard control is used; when collision is detected (voltage drop or disconnection), the system transitions to a special discharge mode that operates under the degraded power conditions, ensuring continuous adaptability to changing system states
2Reliability
If residual charge is discharged rapidly, then safety is improved, but switching loss increases and may damage switching elements
Solution Approach 1:
The control unit applies partial action by selectively increasing switching loss only to the extent necessary for rapid discharge under collision conditions. The control adjusts the switching frequency and duty cycle to achieve sufficient discharge rate without pushing the switching elements beyond their damage threshold, balancing safety requirements with component protection
Solution Approach 2:
The control unit changes operating parameters (switching frequency, duty cycle, pulse width) dynamically based on the discharge state and detected collision severity. By adjusting these parameters, the system optimizes the discharge rate to be as fast as safety requires while staying within the tolerable switching loss limits of the power semiconductor elements
3Duration of action of moving object
If gate driving voltage is reduced to decrease power consumption, then discharge operation can continue longer, but switching element control precision deteriorates
Solution Approach 1:
The control unit dynamically adjusts the gate driving voltage parameter based on the discharge state and remaining power supply voltage. When power supply is sufficient, higher gate voltage is applied for precise control; as power depletes due to collision damage, the gate voltage is reduced proportionally to extend operation duration while maintaining adequate control precision for the degraded conditions
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
Enables rapid discharge of residual charge in smoothing capacitors during a vehicle collision, ensuring efficient energy consumption and protecting the switching elements from damage.
Implementation Method 1
The control unit controls the gate driving unit to increase a switching loss of the switching element in response to detection of the collision of the vehicle by the collision detection unit
Data Source
AI summary
In a power conversion device of a vehicle, when a collision of a vehicle is detected, the voltage of a gate signal that drive a semiconductor switching element included in the power conversion device is decreased, and residual charge stored in a smoothing capacitor is discharged. Such a configuration increases switching loss when the semiconductor switching element is turned on or off during discharge of the residual charge in the power conversion device, so that discharge of the residual charge can be accomplished in a shorter time.