Motor Controller Bypass for Rapid Torque Response
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Solution Overview
Problem
Field-oriented control systems for electric motors in vehicles face computational complexity and slow processing times, which can lead to delayed torque adjustments during sudden changes in driving conditions, such as those required by antilock braking systems (ABS) and electronic stability programs (ESP), resulting in potential bucking in the drivetrain.
Innovation Solution
A motor controller with an exception situation identification device that bypasses the setpoint current value forming unit to adjust torque-forming setpoint currents directly based on present torque values, using a frozen setpoint torque value when exceptions are detected, and adjusts these values via a ratio computation device to maintain dynamic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If field-oriented control with setpoint current value forming unit is used, then optimized operating point is achieved, but computation speed is slow
Solution Approach 1:
The control system is segmented into two paths: a normal path through the setpoint current value forming unit for optimized operating points, and an exception path that bypasses this unit for rapid torque adjustments. This segmentation allows the system to maintain optimization during normal operation while achieving fast response during exception situations.
Solution Approach 2:
The exception situation identification device continuously monitors torque values and computes changes in advance, ready to trigger the bypass path immediately when exception conditions are detected. This preliminary monitoring ensures that when sudden torque changes are needed, the system can switch to the fast path without delay.
2Manufacturing precision
If setpoint current value forming unit processes torque changes, then optimized current values are computed, but response time is delayed
Solution Approach 1:
The exception situation identification device extracts the torque value monitoring and change computation functions from the main control flow. When exceptions occur, the torque-forming setpoint current value is adjusted directly through the bypass path, taking out the time-consuming optimization calculations from the critical response path while maintaining them for normal operation.
Solution Approach 2:
The system dynamically switches between two operational modes: normal mode where the setpoint current value forming unit computes optimized values, and exception mode where direct adjustment occurs. This dynamic adaptation allows the system to optimize for speed when needed and for precision when conditions allow.
3Measurement precision
If torque adjustments are delayed, then computation accuracy is maintained, but drivetrain stability is compromised
Solution Approach 1:
The exception situation identification device acts as an intermediary that continuously monitors torque values and intermediates between the setpoint torque value and the torque-forming setpoint current value. When exception conditions are detected, this intermediary triggers direct adjustment, preventing the drivetrain instability that would result from delayed torque adjustments while maintaining computation accuracy during normal operation.
4Speed
If bypass path is used for torque adjustment, then response speed is improved, but optimization is reduced
Solution Approach 1:
The bypass path provides partial optimization by adjusting the torque-forming setpoint current value directly based on the ratio between frozen and current setpoint torque values. While this doesn't provide full optimization like the setpoint current value forming unit, it provides sufficient action for exception situations where speed is critical, accepting reduced optimization as a necessary trade-off.
Data Source
AI summary
A motor control system is provided for field-oriented control of an electric motor for driving a vehicle. The motor control system includes a current setpoint creator, which is designed to receive a torque setpoint as an input signal and to output a torque-creating current setpoint and at least one field-creating current setpoint as output signals in order to control the electric motor in a field-oriented manner. An exceptional situation detection device detects a present torque setpoint, calculates a change based on the present torque setpoint and an earlier torque setpoint, and detects an exceptional situation if the magnitude of the change exceeds a specified threshold value. The motor control system is designed to adapt the torque-creating current setpoint based on the present torque setpoint when the exceptional situation is detected, thereby bypassing the current setpoint creator.