Resolver Signal Line Open Fault Detection Circuit
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Solution Overview
Problem
Existing methods for diagnosing open lines in resolver coils, such as sinusoidal and cosinusoidal coils, are not sufficiently reliable as they can incorrectly identify clipping issues, leading to inaccurate fault detection in resolver systems used for motor vehicle control systems.
Innovation Solution
The implementation of pull-up and pull-down resistors connected to different direct voltages at the terminals of the signal lines, allowing for the monitoring of differential voltage between the signal lines at symmetric sampling times to determine an offset value, which can identify an open line fault by comparing it to a threshold value, thereby distinguishing it from other faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clipping is used to diagnose open line faults in resolver coils, then fault detection is achieved, but reliability is insufficient because clipping can also occur for other reasons leading to incorrect diagnosis
Solution Approach 1:
The patent introduces pull-up and pull-down resistors as intermediary components connected to the signal lines of the resolver coils. These resistors create a voltage divider network that produces a characteristic voltage pattern when a line is open, allowing reliable distinction between open line faults and other issues like clipping. The resistors act as mediators that transform the fault condition into a detectable and unambiguous signal.
2Measurement precision
If pull-up and pull-down resistors are added for fault detection, then diagnosis precision is improved, but device complexity increases due to additional hardware components
Solution Approach 1:
The pull-up and pull-down resistors serve multiple functions: they enable fault detection, establish a reference voltage level for the AD converter, and create a detectable voltage pattern for open line identification. By making these components multi-functional, the patent reduces the need for additional dedicated fault detection circuitry, thereby limiting the increase in overall device complexity while maintaining high diagnostic precision.
3Speed
If continuous monitoring of differential voltage is implemented, then fault detection speed is improved, but energy consumption increases due to permanent monitoring requirements
Solution Approach 1:
The patent implements periodic sampling of the differential voltage at specific sampling times during the exciter period, rather than continuous monitoring. The evaluation unit checks the voltage difference at predetermined intervals, which maintains fast fault detection capability while significantly reducing energy consumption compared to continuous analog-to-digital conversion and processing.
Data Source
AI summary
A method for detecting an open line (10) of a receiver coil (17; 18) of a resolver (16) comprises—providing a pull-up resistor (R1; R3) and a pull-down resistor (R2; R4) at the terminals (7a, 7b; 8a, 8b) on a control device (1) for the signal lines (13a, 13b; 14a, 14b) of the receiver coil (17; 18);—measuring the voltage between the two signal line terminals (7a, 7b; 8a, 8b) of the receiver coil at two sampling times provided symmetrically at the middle of the excitation period;—calculating an offset value by calculating an average value that comprises the measured values measured at the two sampling times in an excitation period; and—identifying an open line (10) if the offset value exceeds a threshold value.