Current-Excited Synchronous Machine Torque Control
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Solution Overview
Problem
Current electric and hybrid vehicles using permanently excited synchronous machines face challenges in achieving dynamic torque demand due to the sluggish dynamics of the permanent magnetic field, which limits energy and power efficiency and vehicle longitudinal dynamics.
Innovation Solution
Implementing a current-excited synchronous machine with a control unit that strategically sets the exciting current based on the gear selecting position and brake pedal position, allowing for dynamic torque demand by switching the exciting current on and off accordingly, particularly in 'Drive' and 'Reverse' positions, and building up the exciting field during braking phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If permanently excited synchronous machines are used, then energy efficiency is improved, but dynamic response and torque demand capability deteriorate due to sluggish magnetic field dynamics
Solution Approach 1:
The patent applies the Dynamics principle by transitioning from a static permanently excited synchronous machine to a dynamic current-excited synchronous machine where the rotor magnetic field can be actively controlled. The control unit dynamically adjusts the exciting current based on real-time operating conditions (gear selecting position and brake pedal position), enabling the magnetic field to adapt rapidly to changing torque demands and improve dynamic response while maintaining energy efficiency through strategic current management.
2Power
If exciting current is continuously supplied, then torque demand capability is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by strategically switching the exciting current on and off based on operating phases. The control unit supplies exciting current during braking phases when torque demand is low or zero, and switches off the current during coasting or idle periods. This periodic excitation strategy maintains the necessary magnetic field for torque generation while significantly reducing overall energy consumption compared to continuous excitation.
Solution Approach 2:
The patent applies preliminary action by building up the rotor magnetic field during braking phases before torque demand occurs. The control unit anticipates potential torque needs and ensures the magnetic field is already established and ready, reducing latency times when torque demand arises. This preparatory excitation strategy ensures immediate torque response capability while avoiding continuous current supply.
3Speed
If current-excited synchronous machine is used with dynamic control, then vehicle longitudinal dynamics are improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the control unit to handle multiple functions within a single device. The control unit simultaneously manages exciting current regulation, monitors gear selecting position, detects brake pedal position, and coordinates torque demand responses. This multi-functional approach improves vehicle longitudinal dynamics through comprehensive control while minimizing the increase in device complexity by consolidating control functions rather than adding separate dedicated systems for each function.
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
This operating strategy enhances the dynamic and efficient operation of the current-excited synchronous machine, reducing latency times and improving vehicle longitudinal dynamics by aligning the exciting current with torque demands and braking phases.
Implementation Method 1
permanent magnets are used for the rotor, which permanent magnets generate a magnetic field without an external excitation, which magnetic field generates a torque on the rotor axis in an interaction with a 3-phase excitation of the stator
Implementation Method 2
The control unit sets an exciting current of the rotor. The setting of the exciting current takes place as a function of a gear selecting position set at the gear selecting device
Data Source
AI summary
An electrical drive machine for a vehicle includes a brake apparatus and a gear-selection apparatus, such that the electrical machine is designed as a current-powered synchronous machine. The vehicle includes a control unit which is associated with the current-powered synchronous machine, wherein the control unit sets a field current of the rotor based on a gear-selection position set at the gear-selection apparatus and based on a position of a brake pedal of the brake apparatus.