Control of an electric machine
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Solution Overview
Problem
Existing electric machine control systems lack efficient methods to adjust power in response to varying input signals, such as power-supply identification and user-defined modes, leading to inefficiencies and potential excessive current demand.
Innovation Solution
The method involves storing power maps with control values for different power levels and selecting them based on input signals, including power-supply identification and user-defined modes, to control the electric machine's power by adjusting excitation and freewheeling times of the winding, ensuring efficient operation across a range of voltages and speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single power map is used for all operating conditions, then the control system is simple, but the electric machine cannot adapt to different power supplies and accessories, leading to excessive current demand and reduced efficiency
Solution Approach 1:
The patent segments the control strategy by dividing it into multiple power maps, each optimized for specific operating conditions (different power supplies, accessory configurations). This segmentation allows the system to select the appropriate control parameters for each scenario, achieving adaptability without requiring a completely complex redesign of the control architecture.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing optimal control parameters in multiple power maps before operation. Each power map contains pre-determined duty cycles and timing parameters for different operating conditions. When a specific condition is detected, the corresponding pre-prepared power map is selected, eliminating the need for real-time complex calculations and reducing computational burden.
2Measurement precision
If power maps are selected based on multiple input signals, then precise power control is achieved, but the control logic becomes more complex
Solution Approach 1:
The control logic is segmented into distinct detection stages for different input signals (power supply type, accessory presence, user mode). Each stage independently evaluates its specific condition and contributes to the final power map selection. This modular segmentation of control logic makes it more manageable and easier to implement than a monolithic complex decision-making system.
Solution Approach 2:
The patent introduces an intermediary layer (the power map selection mechanism) that translates multiple input signals into a single selected power map. This intermediary layer simplifies the overall control logic by providing a structured framework for processing multiple inputs, where each input signal is evaluated and combined through the power map selection process rather than requiring direct complex interaction between all control parameters.
3Power
If excitation timing is advanced, then power output increases, but current demand may become excessive
Solution Approach 1:
The patent applies parameter changes by adjusting the excitation timing parameters (advance angle, duty cycle) based on the selected power map. Each power map contains optimized parameter values that achieve the desired power output while maintaining current demand within acceptable limits. The parameters are dynamically changed according to operating conditions, allowing the system to optimize the balance between power output and current consumption for each specific scenario.
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 allows for precise control of power and efficiency, maintaining constant output power and high efficiency (at least 75%) across a broad range of voltages and speeds, preventing excessive current demand and optimizing performance in battery-powered devices.
Implementation Method 1
exciting and freewheeling a winding of the electric machine. The winding is excited in advance of zero-crossings of back emf in the winding
Implementation Method 2
as the back emf in the winding falls, current spikes may arise should the excitation voltage exceed the falling back emf. By freewheeling the winding within the region of falling back emf, current spikes may be avoided
Data Source
AI summary
A method of controlling an electric machine, the method comprising storing a plurality of power maps, each power map comprising control values for driving the electric machine at different power, and selecting a power map in response to an input signal. Additionally, a control system for an electric machine, and a product incorporating the control system and electric machine.