Resolver Angle Conversion Using In-Loop Correction Angle Data
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Solution Overview
Problem
Conventional RD converters cannot accurately correct angle errors in resolvers that vary with the number of revolutions, and they require high memory capacity for correction data storage.
Innovation Solution
An RD converter with a correction data part that adds a correction angle to the digital output angle in the angle calculation loop, reducing the need to store corrected angles and allowing precise error correction by recording only the error difference, using a configuration with SIN and COS ROMs, multipliers, subtractors, and a synchronous detecting circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction data is stored for each output angle in the correction memory, then angle error correction is achieved, but the memory capacity becomes excessively large
Solution Approach 1:
The invention extracts only the essential correction information (angle error characteristics) from the full correction data table, separating the necessary correction parameters from the redundant data. This allows storing only the critical correction values needed for accurate angle error compensation without requiring the full 49152-bit memory capacity
Solution Approach 2:
Instead of storing corrected angles for each possible output angle value, the invention inverts the approach by storing angle error characteristics that can be used to calculate corrections dynamically. This inversion transforms a large static lookup table into a compact set of characteristic parameters
2Measurement precision
If correction is performed using conventional methods, then some angle errors are corrected, but the correction fails when angle error characteristics vary with the number of revolutions
Solution Approach 1:
The invention makes the correction system dynamic by incorporating the number of revolutions as a variable parameter. The angle error characteristics are measured and stored for multiple different numbers of revolutions, allowing the correction to adapt dynamically based on the actual operating conditions rather than being fixed for a single speed
Solution Approach 2:
The invention changes the parameters used for correction by measuring and storing angle error characteristics at different operating conditions (different numbers of revolutions). This allows the correction system to select appropriate correction data based on the current operational parameters, making it adaptable to varying rotational speeds and conditions
Data Source
AI summary
An RD converter is disclosed that has a first multiplier multiplying a resolver signal S1 by an output of a SIN ROM; a second multiplier multiplying a resolver signal S2 by an output of a COS ROM; a subtractor subtracting an output of the first multiplier from an output of the second multiplier; a synchronous detecting circuit detecting synchronously an output of the subtractor with reference to an excitation signal; a controller controlling an output angle θ′ to make an output of the synchronous detecting circuit equal to zero; a correction data part outputting a correction angle θc for the output angle θ′; an adder adding the output angle θ′ and the correction angle θc; the SIN ROM producing a sine value of a result from the adder; and the COS ROM producing a cosine value of the result.