Resolver Signal Detection Circuit for Stationary Disconnection
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Solution Overview
Problem
Existing resolver signal detection circuits cannot detect disconnection of signal wires when the motor is not in rotation, as the sum of squares of COS-phase and SIN-phase signals equals 1 even if a SIN-phase signal is 0, making it impossible to differentiate between a connected and disconnected state.
Innovation Solution
A resolver signal detection circuit with offset power supplies, series resistor circuits, a detection power supply, power supply control, and comparison logic that applies offset voltages and a delay to detect disconnections by comparing voltages during a predetermined time period, allowing detection even when the motor is stationary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sum of squares method is used to detect wire disconnection, then detection is possible during motor rotation, but detection fails when the motor is stationary and SIN-phase signal is 0
Solution Approach 1:
The patent applies preliminary action by introducing a delay circuit that activates offset power supplies before the main detection power supply. This preliminary offset voltage application creates a non-zero baseline state that enables detection to function properly even when the motor is stationary and the SIN-phase signal would otherwise be zero, thus resolving the detection failure in static conditions
2Reliability
If offset voltages are applied to enable stationary detection, then detection works during idle state, but circuit complexity increases
Solution Approach 1:
The patent merges the offset voltage generation function into the existing power supply structure by using delay circuit control to sequentially activate offset power supplies and the main detection power supply. This integration approach enables stationary detection capability while minimizing additional circuit complexity by combining control functions rather than adding completely separate detection circuits
Solution Approach 2:
The delay circuit provides preliminary control action by timing the activation of offset power supplies to occur before the main detection power supply. This preliminary sequencing enables the circuit to establish appropriate voltage baselines before full detection operation begins, achieving reliable stationary detection without requiring continuously active complex circuitry
Data Source
AI summary
A power supply control part supplies offset voltages from power supplies to each of signal wires at start time and then, after a predetermined delay time period, supplies a reference voltage from a power supply. A series resistor circuit of resistor elements is provided in each signal wire and a resistor element is connected between a supply node of the offset voltage and an input terminal of the series resistor circuit. A resistor element is connected between the supply node of reference voltage and the output terminal of the series resistor circuit provided in the signal wire of a high-potential side. A comparison logic part detects a disconnection of the signal wire based on a voltage developed at the input terminal of itself during the delay time.