Synchronous Machine Stator Current Vector Startup Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the optimum stator current vector direction in synchronous machines, particularly in passenger transportation apparatuses like elevators, are unreliable during startup due to limited rotor movement and high costs associated with extensive sensor systems required for linear drives.
Innovation Solution
A method involving the imposition of different stator current vectors with the same amplitude but varying directions to identify a minimum stator current vector, which is then used to determine the starting stator current vector, allowing for efficient operation without precise movement or torque measurement, utilizing a single acceleration sensor for direction detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If test excitations are used to determine the optimum stator current vector direction, then the starting operation can be initiated, but the method is unreliable when rotor movement is limited (e.g., in elevator systems with activated brakes)
Solution Approach 1:
The patent replaces mechanical sensor systems (incremental transducers requiring rotor movement) with an electrical field-based measurement approach. By injecting test current vectors and measuring the resulting back-EMF voltages, the system determines rotor position and optimum current vector direction without requiring mechanical rotor movement, thus resolving the contradiction between reliability and ease of operation in systems with limited movement capability
Solution Approach 2:
The patent introduces back-EMF voltage measurements as an intermediary parameter to indirectly determine rotor position and optimum current vector direction. Instead of directly measuring mechanical position (which requires movement), the system uses electrical voltage measurements as a mediator that can be obtained even when the rotor is constrained, thereby maintaining reliability without requiring rotor movement
2Measurement precision
If incremental transducers are used to determine rotor orientation, then precise orientation information can be obtained, but a number of electrical rotations or significant rotor movement are required to detect the reference signal
Solution Approach 1:
The patent performs preliminary action by determining the optimum stator current vector direction through back-EMF measurements before actual motor operation begins. This allows the system to pre-calculate the correct current vector direction without requiring the rotor to complete electrical rotations to find a reference marker, thus eliminating the time loss associated with reference detection while maintaining precise orientation information
3Measurement precision
If extensive sensor systems are deployed for linear drives, then accurate position and torque measurement can be achieved, but the costs increase significantly
Solution Approach 1:
The patent makes the existing acceleration sensor serve multiple functions: it detects both the direction of rotor movement and the magnitude of driving torque. By utilizing the sensor's output signal for dual purposes (movement detection and torque measurement), the system achieves accurate position and torque measurement without adding extensive sensor systems, thereby reducing device complexity and cost while maintaining measurement precision
Solution Approach 2:
The patent enables the existing acceleration sensor to self-serve by processing its own output signals to determine both movement direction and torque magnitude. The control unit evaluates the sensor signal to extract multiple pieces of information without requiring additional dedicated sensors, allowing the single sensor to perform the work of what would traditionally require multiple sensors, thus reducing system complexity and cost
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
Enables reliable and cost-effective determination of the starting stator current vector for synchronous machines, facilitating optimal startup and operation without requiring extensive sensor systems or significant rotor movement, thus improving efficiency and reducing costs.
Implementation Method 1
A stator current vector with a specific stator current vector direction can be imposed upon the stator winding. A stator current vector of this type is characteristic of the energization of the stator winding.
Implementation Method 2
different stator current vectors with the same amplitude but with different directions are imposed upon the stator winding in the course of a plurality of current application operations, at which a minimum stator current vector is determined from the different stator current vectors, at which no driving torque acting on the rotor is generated
Data Source
AI summary
A method for determining a stator current vector for starting a synchronous machine of a drive of a passenger transportation apparatus having a rotor and a stator with a stator winding may involve imposing different stator current vectors with different stator current vector directions on the stator winding over the course of a plurality of current application operations, determining from the different stator current vectors a minimum stator current vector with a minimum stator current vector direction at which a minimum driving torque acting on the rotor is generated in the synchronous machine, determining a starting stator current vector with a starting stator current vector direction from the minimum stator current vector, and imposing the starting stator current vector on the stator winding for starting the synchronous machine.