Motor Controller Active Short Circuit Control Method
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Solution Overview
Problem
Conventional motor controllers face damage from impulse currents during active short circuit operations in electric vehicles, leading to potential overvoltage and excessive brake torque, which can result in switch transistor damage and increased risk of vehicle turnover.
Innovation Solution
A motor controller method and system that generates an enabling signal to turn on all switch transistors in the upper or lower bridge arm of the inverter, adjusts motor currents to characteristic values, and outputs control signals to safely activate the active short circuit, reducing output torque to zero and preventing excessive impulse currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active short circuit operation is performed directly via microcontroller or redundant circuit, then vehicle safety is improved during collisions or failures, but impulse current damages switch transistors in the inverter
Solution Approach 1:
The patent applies preliminary action by adjusting motor currents to characteristic values before executing the active short circuit operation. The control method first modifies the current state of the motor (reducing direct-axis and quadrature-axis currents to specific values), and only then activates the active short circuit. This preparatory current adjustment prevents the generation of harmful impulse currents that would otherwise damage switch transistors, while still achieving the safety function when collisions or failures occur.
2Speed
If all switch transistors are turned off directly due to high speed operation, then control response is improved, but overvoltage on direct-current bus damages switch transistors
Solution Approach 1:
The patent applies preliminary action by adjusting motor currents to characteristic values before executing the active short circuit operation. The control method first modifies the current state of the motor (reducing direct-axis and quadrature-axis currents to specific values), and only then activates the active short circuit. This preparatory current adjustment prevents the generation of harmful impulse currents that would otherwise damage switch transistors, while still achieving the safety function when collisions or failures occur.
3Strength
If active short circuit is performed after vehicle deceleration, then switch transistor damage is reduced, but vehicle safety response time is increased
Solution Approach 1:
The patent applies preliminary action by adjusting motor currents to characteristic values before executing the active short circuit operation. The control method first modifies the current state of the motor (reducing direct-axis and quadrature-axis currents to specific values), and only then activates the active short circuit. This preparatory current adjustment prevents the generation of harmful impulse currents that would otherwise damage switch transistors, while still achieving the safety function when collisions or failures occur.
Data Source
AI summary
A motor controller, an active short circuit thereof, and a method for controlling active short via the same. An enabling signal is generated and outputted in response to determining that a vehicle is to enter a safe mode and a speed of a motor exceeds a threshold. Currents of a direct-axis and a quadrature-axis of the motor are adjusted to characteristic currents according to the enabling signal. An action flag signal and a control signal that corresponds to the enabling signal are generated and outputted in response to determining that the currents of the direct-axis and the quadrature-axis are adjusted to be the characteristic currents. A driving signal corresponding to the control signal is generated and outputted according to the action flag signal. A driving circuit safely controls a corresponding switch transistor in the inverter to be turned on based on the driving signal.