Method for Sensorless Operation of a Power Converter-Fed Permanently Excited Synchronous Machine with a Test Signal

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This patent describes a method for operating a permanent magnet synchronous motor (PMSM) without the need for physical position sensors. The invention continuously corrects the estimated rotor position and speed by superimposing a time-discrete pseudo-noise test signal onto the reference current or voltage. Unlike traditional sinusoidal test signals, this pseudo-noise signal has a longer base period, which significantly reduces tonal motor noise during operation.

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• Electric vehicles and railway traction systems, where maintenance-free and reliable motor control is desirable
• Industrial automation applications where noise reduction and sensorless PMSM drives are required
• Home appliances or HVAC systems using sensorless motors for quieter operation
• Robotics or medical devices where precise, low-noise, and robust sensorless motor drives are needed
• Renewable energy systems like wind turbines using permanent magnet generators without sensors

BenefitsContent extracted from patent full text and abstract with AI.

• Enables sensorless operation of PMSMs, eliminating the need for expensive and failure-prone physical position sensors
• Significantly reduces unpleasant tonal (whistling or humming) noises typically produced by test signals in sensorless drives, leading to a quieter environment
• Improves reliability and reduces maintenance since there are fewer parts subject to wear or misalignment
• Generates less electrical interference and avoids problematic resonances in power networks (beneficial for critical applications like railway traction)
• The pseudo-noise signal can be tailored offline, allowing for optimization in noise performance and system integration
• Minimizes additional current and voltage requirements, enhancing system efficiency

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Patent Abstract

The invention relates to a method for field-oriented operation of a sensorless, permanently -energised synchronous motor (2), wherein an estimated rotor positional angle (?) and an estimated rotor circuit frequency (?) are continuously corrected by mean of a test signal superimposed on a set current sinor (idRef, iqRef). According to the invention, a time-discrete pseudo-noise signal with a relatively long base period duration is provided as test signal. A method for a sensorless operation of a converter-fed, permanently-energised synchronous motor (2) is thus achieved, which causes significantly fewer tonal motor noises.