DC Bus Voltage Control via Feedforward Torque Prediction
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Solution Overview
Problem
Existing vehicle dc bus voltage control systems face challenges in maintaining stability and response time, particularly during transient voltage drops due to high load demands, which can lead to motor controller failures and limited torque generation capabilities, and require efficient energy recovery during regenerative braking.
Innovation Solution
A controller system that includes a feed forward module and a PI control module to generate torque parameters based on power demand, usage coefficients, and voltage levels, ensuring efficient energy management and voltage regulation by synchronizing torque control loops and using voltage-square error feedback for dynamic load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional voltage control methods are used, then the system is simple to implement, but the response time is slow and voltage stability deteriorates during transient drops
Solution Approach 1:
The feed forward module calculates and applies torque parameters in advance based on power demand signals before voltage deviations occur. By anticipating load changes and pre-adjusting generator torque, the system achieves faster response without waiting for voltage errors to develop, thus improving response time while maintaining manageable complexity through structured prediction algorithms
Solution Approach 2:
The controller is divided into distinct functional modules: a feed forward module for predictive control and a PI control module for reactive correction. This segmentation allows each module to specialize in specific control tasks, with the feed forward module handling transient response and the PI module ensuring steady-state accuracy, thereby achieving fast response time while keeping overall system complexity organized and manageable
2Reliability
If generator torque is increased to maintain voltage during high load demand, then voltage stability improves, but motor torque generation capability deteriorates due to energy depletion
Solution Approach 1:
The PI control module continuously monitors dc bus voltage and adjusts generator torque based on voltage error feedback. This closed-loop feedback ensures voltage stability by automatically increasing generator output when voltage drops, while the proportional-integral control algorithm optimizes the torque adjustment to maintain overall system power balance and prevent motor torque degradation
Solution Approach 2:
The controller dynamically adjusts generator torque parameters based on real-time voltage conditions and power demand. By changing torque magnitude and timing parameters adaptively, the system maintains voltage stability during transient drops while optimizing power distribution to preserve motor torque generation capability, achieving both voltage reliability and power availability through parameter optimization
3Reliability
If energy is dissipated across crow bar resistor during regenerative braking, then voltage overload is prevented, but energy recovery efficiency deteriorates
Solution Approach 1:
The controller implements a dual-mode energy management strategy: during regenerative braking, it first attempts to recover energy by directing it back to the dc bus through the generator, and only when voltage thresholds indicate overload risk does it discard excess energy through the crow bar resistor. This selective discarding and recovering approach maximizes energy recovery efficiency while maintaining voltage overload protection, achieving both energy conservation and system reliability
Data Source
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AI summary
Provided is a method and controller for controlling a vehicle dc bus voltage. The method includes generating a parameter. The parameter is based on a reference dc bus voltage squared. The method includes controlling the vehicle dc bus voltage based on the parameter and a detected dc bus voltage. The method may also include generating another parameter (S705) based on a power demand associated with at least one of a motoring mode operation and a generating mode operation of a. traction motor associated with the vehicle (S710). The power demand is indicated in a message received via a. dedicated high speed data bus. The method includes controlling the vehicle dc bus voltage based on the another parameter (S715).