Sensorless PMSM Control in Household Appliances at Low Speed
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Solution Overview
Problem
Existing household appliances with speed-controlled electric drives, particularly those using permanently excited three-phase synchronous motors, face challenges in accurately determining the angular position of the rotor at low speeds without sensors, affecting efficient control and energy consumption.
Innovation Solution
The method involves using field-oriented control with high-frequency voltage injection during the braking phase to determine the angular position of the rotor through high-frequency current components, allowing for speed-controlled operation and reducing energy consumption by optimizing the supply voltage and current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If field-oriented control is used for speed control of the three-phase synchronous motor, then speed control performance is improved, but accurate determination of rotor angular position at low speeds becomes difficult without sensors
Solution Approach 1:
The patent introduces high-frequency voltage as an intermediary signal to enable rotor position detection. By superimposing high-frequency voltage on the supply voltage during braking phase, the system generates high-frequency current components that carry rotor position information, allowing accurate angular position determination without sensors even at low speeds
Solution Approach 2:
The patent changes the frequency parameter of the supply voltage by superimposing high-frequency voltage during the braking phase. This parameter change enables the extraction of rotor position information through high-frequency current components, resolving the contradiction between maintaining field-oriented control performance and achieving accurate low-speed position detection
2Measurement precision
If high-frequency voltage is superimposed on supply voltage to determine rotor position, then measurement precision of angular position is improved, but device complexity increases due to additional control signals
Solution Approach 1:
The patent merges the rotor position detection function with the existing field-oriented control system by superimposing high-frequency voltage on the supply voltage. The detection of high-frequency current components and extraction of rotor position information is integrated into the existing control architecture, avoiding the need for separate detection hardware and minimizing additional complexity
Solution Approach 2:
The system uses its own high-frequency voltage injection and the resulting high-frequency current components to automatically determine rotor position. The control system processes the current measurements and extracts position information through mathematical operations already present in the field-oriented control algorithm, enabling self-service position detection without external sensors
3Manufacturing precision
If discrete field-oriented control is used with current controller operating at controller frequency, then control precision is improved, but synchronization with high-frequency voltage injection becomes challenging
Solution Approach 1:
The patent employs periodic high-frequency voltage injection during the braking phase, synchronized with the discrete field-oriented control cycles. The controller frequency is set equal to the high-frequency voltage frequency, creating a periodic pattern where current measurements are taken at specific phases (maximum and minimum) to extract position information, thereby synchronizing the control precision requirements with the injection timing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise control of the three-phase synchronous motor at low speeds without sensors, improving the efficiency and energy consumption of household appliances by accurately determining the rotor position and reducing energy usage.
Implementation Method 1
superimposing a high-frequency voltage on a supply voltage generated by the actuator and intended to operate the three-phase synchronous motor, whereby phase currents and the longitudinal and transverse currents of the three-phase synchronous motor have corresponding high-frequency current components
Implementation Method 2
determining high-frequency current components of the longitudinal and transverse currents, determining the angular position of the rotor relative to the stator as a function of the high-frequency current components of the longitudinal and transverse currents
Data Source
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AI summary
The invention relates to a household appliance (1, 101) and a method for operating a household appliance (1, 101). The household appliance (1, 101) comprises a component (21, 102) and a controlled electric drive (40) which includes a permanent magnet three-phase synchronous motor (36), an actuator, in particular designed as a converter (41), for controlling the three-phase synchronous motor (36), and a field-oriented control (43) for controlling the actuator. The three-phase synchronous motor (36) comprises a stator (37) and a rotor (38) rotatably mounted with respect to the stator (37) and is part of the component (21, 102) or is intended to drive this component (21, 102).