Single Inverter Control for Asynchronous Motor Torque Distribution
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Solution Overview
Problem
In electric vehicles with multiple asynchronous machines, the existing control methods require separate inverters for each machine, leading to significant space and weight constraints due to the volume of power electronics, necessitating a more efficient use of installation space and reduction in energy and weight.
Innovation Solution
A method for jointly controlling asynchronous machines using a single inverter by determining a common stator voltage and frequency, allowing for optimal distribution of drive torques based on sensed speeds and slips, eliminating the need for additional inverters and optimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate inverters are used for each asynchronous machine, then each machine can be controlled independently, but the installation space and weight increase significantly
Solution Approach 1:
The patent combines multiple independent inverter systems into a single shared inverter that controls multiple asynchronous machines. The inverter is configured with multiple output channels, each capable of independently controlling a separate asynchronous machine. This merging approach eliminates the need for multiple separate inverter units, reducing overall system weight and installation space while maintaining independent control capability through software-based torque distribution algorithms that allocate power between machines based on driving conditions.
Solution Approach 2:
The single inverter system is designed with multi-functional capability to control multiple asynchronous machines simultaneously. The inverter includes a control unit that can independently manage different output channels, allowing it to function as multiple separate inverters would. The system can dynamically distribute power to different machines based on real-time driving conditions, making the single inverter universal enough to replace multiple specialized inverter units.
2Measurement precision
If separate inverters are used for each asynchronous machine, then control precision is maintained, but the installation space volume increases
Solution Approach 1:
The patent merges multiple inverter functions into a single integrated unit with multiple output channels. The control unit within the inverter uses sensor inputs from each asynchronous machine to independently regulate torque and speed for each machine, maintaining control precision equivalent to separate inverter systems. The physical consolidation into one unit dramatically reduces the installation space volume required compared to multiple separate inverter housings and connections.
3Weight of stationary object
If a single inverter controls multiple asynchronous machines, then space and weight are reduced, but the complexity of torque distribution control increases
Solution Approach 1:
The control system manages the increased complexity by dynamically changing operational parameters such as torque distribution ratios, frequency, and voltage levels for each output channel based on real-time sensor feedback. The control unit adjusts these parameters continuously to optimize performance, handle different driving conditions, and maintain independent control of each asynchronous machine. This parameter-based control approach manages complexity through software algorithms rather than additional hardware components.
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 approach reduces installation space and weight by enabling simultaneous control of multiple asynchronous machines with a single inverter, improving energy efficiency and adaptability to various driving situations while maintaining safety and performance.
Implementation Method 1
an inverter (4) which is designed for supplying the first asynchronous machine (2) and the second asynchronous machine (3) with a common stator voltage (5) at a common stator frequency (6)
Data Source
AI summary
The invention relates to a method for jointly controlling asynchronous machines (2; 3) of a motor vehicle (1) having a first asynchronous machine (2) and a second asynchronous machine (3) for driving the motor vehicle (1); an inverter (4), which is designed to supply the first asynchronous machine (2) and the second asynchronous machine (3) with a common stator voltage (5) at a common stator frequency (6). The method comprises the steps of determining a specified setpoint drive torque (11) of the motor vehicle (1) for a current driving situation of the motor vehicle (1); sensing a first rotational speed (7a) of the first asynchronous machine (2) and a second rotational speed (7b) of the second asynchronous machine (3); determining a common operating strategy of the first asynchronous machine (2) and of the second asynchronous machine (3) according to the specified setpoint torque (11) while taking into account the sensed rotational speeds (7a; 7b); and controlling the stator voltage (5) and the stator frequency (6) in order to set the drive torques (9a; 9b) of the asynchronous machines (2; 3) according to the operating strategy.