Resolver Reference Signal Circuit for High-Speed Phase Synchronization
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Solution Overview
Problem
Existing reference signal generation methods for synchronous detection in angle calculation sections of motor rotation angle converters fail to maintain accurate phase synchronization at high rotation speeds due to phase difference compensation issues and noise-induced phase shifts, leading to reduced loop gain and distorted waveforms.
Innovation Solution
A reference signal generation circuit that multiplies two-phase resolver detection signals by sine and cosine values of the digital output angle, and uses an adder to generate a reference signal with the same phase as the excitation signal component, along with a tracking loop lock signal generator and switch to ensure phase accuracy, and includes comparators and phase locked loops to mitigate noise effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If zero-crossing edge detection is used to generate the reference signal, then the reference signal can be generated with the correct phase at low rotation speeds, but the amplitude-modulated waveform becomes distorted at high angular velocities causing phase errors
Solution Approach 1:
The patent replaces the mechanical/physical edge detection method with a mathematical calculation method. Instead of detecting zero-crossing edges of the amplitude-modulated signal, the system calculates the reference signal phase using the formula φ_ref = atan2(Vq, Vk), where Vk and Vq are the in-phase and quadrature components obtained from synchronous detection. This mathematical approach eliminates the waveform distortion issues that occur at high rotation speeds.
Solution Approach 2:
The patent introduces intermediate variables (the in-phase component Vk and quadrature component Vq) as mediators to determine the reference signal phase. Rather than directly using the amplitude-modulated waveform edges, the system uses these intermediate detection components to calculate the phase through arctangent function, providing a more robust method that works across all rotation speeds.
2Reliability
If synchronous detection is performed with the excitation signal sin ωt as reference, then the excitation signal component can be removed, but the loop gain is reduced due to phase difference Δω
Solution Approach 1:
The patent implements a feedback mechanism where the detected angle φ is fed back to calculate the reference signal phase. The system continuously adjusts the reference signal phase based on the detected position, creating a closed-loop system that maintains optimal phase alignment between the reference signal and the excitation signal component, thereby maximizing loop gain while ensuring accurate synchronous detection.
Solution Approach 2:
The patent makes the reference signal phase dynamic rather than fixed. Instead of using a static excitation signal phase, the system dynamically adjusts the reference signal phase angle based on the detected angle φ and the phase difference Δω. This dynamic adjustment ensures that the reference signal remains synchronized with the excitation signal component across varying operating conditions, maintaining high loop gain.
3Ease of manufacture
If edge detection signal at zero crossing is used, then the reference signal can be generated, but phase shift occurs due to noise intruding in actual use
Solution Approach 1:
The patent replaces the noisy edge detection method with a mathematical calculation approach. Instead of detecting zero-crossing edges that are susceptible to noise, the system calculates the reference signal phase using the arctangent function of the in-phase and quadrature components. This mathematical method is inherently more robust to noise as it uses the magnitude and phase information from synchronous detection rather than relying on precise edge timing.
Solution Approach 2:
The patent changes the parameter used for phase determination from time-based (edge detection timing) to amplitude-based (ratio of in-phase and quadrature components). By using the arctangent of the voltage components ratio, the system transforms the phase determination problem into a calculation that is less sensitive to noise, thereby improving phase stability while maintaining implementation simplicity.
Data Source
AI summary
A reference signal generation circuit generates a reference signal used in synchronous detection for removing an excitation signal component in an angle calculation section that converts a detection angle θ obtained from two-phase resolver detection signals output from a resolver, to a digital output angle φ. The reference signal generation circuit includes a first multiplier, a second multiplier, and an adder. The first multiplier multiplies one of the resolver detection signals sin θ sin(ωt+Δω) by the sine value sin φ of the digital output angle φ obtained from the angle calculation section. The second multiplier multiplies the other resolver detection signal cos θ sin(ωt+Δω) by the cosine value cos φ of the digital output angle φ obtained from the angle calculation section. The adder adds the output of the first multiplier and the output of the second multiplier to output the sum signal sin(ωt+Δω) as the reference signal.