Resolver Direction Detection via Quadrant Transition Synchronization
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Solution Overview
Problem
Conventional methods for determining the rotational direction and speed of a resolver are prone to noise issues due to rate-of-change measurements and require complex trigonometric calculations, which can lead to errors in determining the angular position and direction.
Innovation Solution
A synchronizer circuit with flip flops and comparators is used to detect the quadrant transitions of a resolver, generating a clock signal to synchronize the secondary voltages with the primary voltage, allowing for the determination of rotational direction without relying on rate-of-change information or analog trigonometric calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods use rate-of-change measurements to determine rotational direction and speed, then the measurement can be obtained, but noise issues occur due to the derivative calculations
Solution Approach 1:
The patent segments the continuous rotational measurement into discrete quadrant transitions. Instead of calculating rate-of-change from continuous analog signals, the method divides the rotation into four quadrants and detects transitions between them, converting a continuous measurement problem into a discrete event detection problem that is inherently more noise-resistant.
Solution Approach 2:
The patent replaces the mathematical/mechanical differentiation operation (rate-of-change calculation) with a digital logic-based transition detection system. By using comparators and logic circuits to detect quadrant boundary crossings, the system substitutes noisy analog derivative calculations with clean digital edge detection.
2Measurement precision
If conventional methods use trigonometric calculations on secondary windings to calculate shaft angle, then the angular position can be determined, but the complexity of the system increases
Solution Approach 1:
The patent segments the continuous angular measurement space into four distinct quadrants. Instead of performing trigonometric calculations to determine continuous angle values, the system only needs to detect which quadrant the resolver is in and the direction of transition, dramatically simplifying the computational requirements while maintaining directional accuracy.
Solution Approach 2:
Instead of calculating the angle from the secondary voltages using trigonometry and then differentiating to get speed and direction, the patent inverts the approach by directly detecting quadrant transitions to determine direction and using transition frequency to determine speed. This eliminates the need for complex trigonometric calculations entirely.
3Measurement precision
If conventional methods calculate current angle and subtract from previous angle to determine direction, then the rotational direction can be found, but errors accumulate due to noise in rate-of-change measurements
Solution Approach 1:
The patent applies preliminary action by pre-defining the four quadrants and their boundary conditions before measurement begins. The comparators are configured in advance to detect when secondary voltages cross zero, which corresponds to quadrant boundaries. This pre-configuration eliminates the need for continuous angle calculation and subtraction, preventing error accumulation from the start.
Solution Approach 2:
The patent replaces the error-prone continuous angle calculation and subtraction mechanism with a discrete transition counting system. Each quadrant transition is a clean digital event detected by logic circuits, and direction is determined by the sequence of transitions rather than by subtracting noisy angle measurements, eliminating cumulative errors.
Data Source
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AI summary
Provided are embodiments for a circuit (400) including a resolver (402) having a primary winding and a set of secondary windings, wherein the resolver has a resolver shaft, and a polarity detection circuit coupled to the resolver. The circuit can also include a synchronizer circuit coupled to the polarity detection circuit, wherein the synchronizer circuit synchronizes signals from the positive polarity detection circuit; and a controller configured to determine a direction of the resolver shaft using an output of the synchronizer circuit. Also provided are embodiments of a method for determining the resolver rotation direction using non-analog means.