Drive Controller Rotor Position Tracking Using Single Edge Signal Averaging
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Solution Overview
Problem
Small electric machines and those requiring high efficiency face issues due to variance in the duty cycle of position sensors, leading to phase differences between detected and actual rotor positions, which can reduce power and efficiency.
Innovation Solution
A control system that generates control signals for electric machines in response to a single edge of a position-sensor signal, averaging the interval between edges to obtain a half-cycle time insensitive to duty cycle imbalances, thereby ensuring more efficient and powerful operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control signals are generated in response to each edge of the position-sensor signal, then the control system can accurately track rotor position, but duty cycle variance causes phase differences that reduce power and efficiency
Solution Approach 1:
The patent segments the position sensor signal processing by using only a single edge (either rising or falling) of the signal for control, rather than responding to both edges. This segmentation isolates the control trigger from the problematic duty cycle variations present in the full signal waveform, eliminating phase differences while maintaining accurate rotor position tracking.
Solution Approach 2:
The patent changes the parameter used for control triggering from responding to signal edges (which are affected by duty cycle) to responding to a fixed time interval (half-cycle time) derived from averaging multiple edges. This parameter change transforms the control system from being sensitive to duty cycle variations to being insensitive, thereby eliminating power losses.
2Device complexity
If the position sensor duty cycle varies, then the system can operate with simple sensor timing, but phase differences between detected and actual rotor positions reduce machine efficiency
Solution Approach 1:
The patent performs preliminary action by averaging the interval between successive edges of the position sensor signal over at least one mechanical cycle to obtain a half-cycle time before using it for control. This pre-calculated half-cycle time is then used to generate control signals, ensuring that the control system is prepared with accurate timing information that is insensitive to duty cycle imbalances, thereby maintaining high machine efficiency.
3Reliability
If control signals are generated for each electrical half-cycle in response to a single edge, then phase synchronization is improved, but the system requires additional processing to determine half-cycle time
Solution Approach 1:
The control system performs self-service by using the position sensor signal itself to determine the half-cycle time through averaging the interval between successive edges. The system extracts the necessary timing information from its own input signal without requiring external timing sources or complex synchronization mechanisms, thereby achieving reliable phase synchronization while keeping the control processing relatively simple.
Data Source
AI summary
A control system for an electric machine, the control system including a position sensor and a drive controller. The drive controller generates one or more control signals for use in exciting a winding of the electric machine. Control signals for each electrical half-cycle of one mechanical cycle are generated by the drive controller in response to a single edge of a signal output by the position-sensor.