Onboard Motor Controller Collision Failsafe Switching
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Solution Overview
Problem
Existing onboard motor controllers for electric vehicles take too long to initiate a failsafe process during a collision due to the time required to switch control modes and respond to current sensors, potentially leading to delayed motor shutdown and safety risks.
Innovation Solution
An onboard motor controller with a control circuit that includes a collision detecting unit and a control mode switching unit, allowing immediate switching from voltage phase control to current vector control upon collision detection, independent of current sensor response, and utilizing a power supply relay to quickly terminate electricity supply to the motor drive circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control mode switching is performed based on current sensor response, then control precision is improved, but response time increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple control modes (voltage phase control and current vector control) in advance within the control circuit. When a collision is detected, the system can immediately switch between pre-programmed control modes without requiring real-time current sensor processing, thus reducing response time while maintaining control precision through the use of pre-calculated control parameters
Solution Approach 2:
The patent implements the skipping principle by bypassing the normal current sensor response and processing chain during collision events. The collision detecting unit triggers an immediate control mode switch that skips the time-consuming current detection and calculation steps, rushing through the critical safety response phase to stop the motor quickly
2Adaptability or versatility
If voltage phase control by rectangular wave driving is used, then driving range at high rotational speed is improved, but failsafe response time deteriorates
Solution Approach 1:
The patent applies dynamics by making the control mode adaptive and changeable based on operating conditions. The system dynamically switches between voltage phase control (for high-speed driving range) and current vector control (for safety-critical situations) based on collision detection, allowing the control strategy to be flexible and situation-dependent rather than fixed
Solution Approach 2:
The patent implements parameter changes by altering the fundamental control parameters (switching from voltage-based rectangular wave control to current-based sinusoidal PWM control) when a collision is detected. This parameter change enables the system to prioritize safety response time over driving range performance during emergency conditions
3Duration of action of stationary object
If electricity supply is maintained to motor controller, then motor driving continuity is improved, but safety risk increases
Solution Approach 1:
The patent introduces an intermediary mechanism (the control circuit with collision detecting unit and control mode switching unit) that mediates between the high-voltage power source and the motor drive circuit. This intermediary can detect collisions and interrupt electricity supply as needed, providing safety protection while maintaining normal operation during non-critical conditions
Data Source
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AI summary
There is provided an onboard motor controller (1) that makes it possible to shorten the time until a failsafe process is executed at the time of a collision of a vehicle. A control circuit (15) in the motor controller (1) acquires an acceleration (G) detected by an acceleration sensor (8). When the acceleration (G) is equal to or higher than a prescribed value, the control circuit (15) determines that a collision of the vehicle has occurred, and executes a switching process of a control mode of a motor. The control circuit (15) immediately switches the control mode of a motor from voltage phase control by rectangular wave driving to current vector control based on sinusoidal PWM control when the collision is detected. The control circuit (15) reads current values from current detectors (14a, 14b, 14c). When an overcurrent is detected, the control circuit (15) executes a failsafe process to turn off the MOSFETs (Q1, Q2, Q3, Q4, Q5, Q6) of an inverter (13). The control circuit (15) stops a supply of electricity to the inverter (13) by turning off a power supply relay (11), thereby stopping the rotation of the electric motor (10).