AC Motor Torque Control via DC Bus Voltage Proportionality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems for controlling motor torque output in heavy-duty machines, such as mining trucks, face inefficiencies due to frequent fluctuations in DC bus voltage during regenerative braking, leading to wasted energy and the need for constant calibration of model perpendicular components in vector control strategies.
Innovation Solution
A system comprising a controller, inverter, and operation status detector that calculates basic voltage vectors proportional to the DC bus voltage, generating a stator field vector by maintaining a constant angle with the rotor field vector and utilizing these vectors to efficiently convert DC bus voltage to AC signals for optimal torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vector control strategy with model perpendicular component is used to control torque output, then torque control capability is improved, but system complexity increases and constant calibration is required
Solution Approach 1:
The patent extracts and eliminates the model perpendicular component from the vector control strategy, retaining only the essential parallel component for torque control. This simplifies the control system by removing the unnecessary calibration process while maintaining torque control capability through direct control of the parallel component based on DC bus voltage
Solution Approach 2:
The patent uses a simplified control approach that copies only the essential functionality of the original vector control strategy - controlling torque through the parallel component - while eliminating the complex model perpendicular component calibration process. This creates a lighter, more efficient control system that achieves the same torque control objective
2Measurement precision
If model perpendicular component calibration is performed to improve torque control accuracy, then torque precision is improved, but time consumption increases
Solution Approach 1:
The patent removes the time-consuming model perpendicular component calibration process entirely from the control strategy. By recognizing that only the parallel component is necessary for torque control, the system eliminates the calibration step that caused time delays while maintaining torque control accuracy through direct parallel component control
Solution Approach 2:
The control system directly uses the measured DC bus voltage to determine the appropriate parallel component value without requiring external calibration data or pre-stored models. This self-service approach eliminates calibration time by allowing the system to adapt automatically to varying DC bus voltage conditions
3Stability of the object's composition
If parallel component is maintained in vector control to improve torque stability, then torque stability is improved, but energy efficiency deteriorates
Solution Approach 1:
The patent implements dynamic control of the parallel component based on real-time DC bus voltage conditions. Rather than maintaining a fixed parallel component that wastes energy at certain voltage levels, the system dynamically adjusts the parallel component magnitude to match the available DC bus voltage, thereby maintaining torque stability while optimizing energy efficiency across varying operating conditions
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 solution enhances the use of DC bus voltage for torque generation, maintaining torque output proportionality with voltage fluctuations and reducing energy wastage, thereby improving fuel efficiency in heavy-duty machines.
Implementation Method 1
The inverter is also configured to convert the DC bus voltage to one or more AC voltage signals according to the voltage command
Data Source
AI summary
Systems and methods are disclosed for controlling a torque output by an AC motor drawing power from a DC bus. According to certain embodiments, the system for controlling the torque output has a controller and an inverter. The controller further has an operation status detector, a basic voltage vector calculator, and a voltage command generator. The operation status detector is configured to determine a DC bus voltage and a rotor field vector. The basic voltage vector calculator is configured to calculate a plurality of basic voltage vectors having a magnitude proportional to the DC bus voltage. The voltage command generator is configured to generate a voltage command for producing a stator field vector. Producing the stator field vector includes at least one of maintaining a constant angle between the stator field vector and the rotor field vector, and setting a magnitude of the stator field vector equal to the magnitude of the plurality of basic voltage vectors. The inverter is electrically connected to the controller and configured to receive the voltage command. The inverter is also configured to convert the DC bus voltage to one or more AC voltage signals according to the voltage command. The inverter is further configured to apply the one or more AC voltage signals to the AC motor to produce the stator field vector.