Sensorless Electric Machine Rotor Positioning and Starting
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Solution Overview
Problem
Sensorless starting of electrical machines with two phases results in increased starting noise and thermal load on power semiconductors due to conventional methods, which are not optimized for efficient torque delivery and rotor positioning.
Innovation Solution
The method involves positioning the rotor in a predetermined rotational angle by energizing one phase for a defined period, then initiating rotation by energizing a second phase while the first is not active, with subsequent phase switching based on commutation times to achieve efficient and quiet start-up, reducing thermal load on control electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sine/cosine starting method is used for sensorless operation, then the rotor can be started without sensors, but starting noise increases and thermal load on power semiconductors increases
Solution Approach 1:
The rotor is first positioned in a predetermined angular position by energizing the first phase before initiating rotation. This preliminary positioning action allows the rotor to start from an optimized position, enabling more efficient torque delivery and reducing the need for high starting currents, thereby decreasing both starting noise and thermal load on power semiconductors
Solution Approach 2:
The method dynamically switches between different phase energizing sequences based on rotor position and speed. By alternating between first-phase energizing (for positioning) and second-phase energizing (for rotation initiation), the system adapts the control strategy to the current operational state, optimizing torque delivery throughout the starting process and reducing harmful effects
2Device complexity
If conventional sensorless starting is used, then no rotational angle detection is needed, but torque delivery efficiency is suboptimal
Solution Approach 1:
The first phase is energized for a predetermined first period of time to position the rotor in an optimal starting angle before rotation begins. This preliminary positioning ensures that when the second phase is energized to initiate rotation, the rotor is already in a favorable position for efficient torque generation, compensating for the lack of sensor feedback
Solution Approach 2:
The system uses the predetermined time periods and phase switching sequence as an open-loop feedback mechanism. By carefully controlling the duration of first-phase energizing followed by second-phase energizing, the system creates an inherent feedback loop that positions the rotor optimally without requiring actual position measurement, thus maintaining torque delivery efficiency without sensors
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 a fast, low-noise start-up of electrical machines with reduced thermal stress on power semiconductors by optimizing torque delivery and rotor positioning, allowing for efficient and reliable sensorless operation.
Implementation Method 1
Positioning a rotor of the electrical machine in a predeterminable rotational angle position (tightening position) by electrically activating the electrical machine, the activating being carried out by energizing at least a first phase of the electrical machine
Implementation Method 2
initiating a rotary movement of the rotor by energizing a second phase for a predefinable second period of time when the first phase is not energized
Data Source
Figure 1~2
Figure 3~6
AI summary
The invention relates to a method for the sensorless operation of an electric, electronically commutating machine (5) having at least two phases (A/B), comprising the following steps: - positioning a rotor (2) of the electric machine (5) at a predetermined rotating angle position (9) (tightening position) by the electric actuation of the electric machine (5), wherein the actuation occurs for a predeterminable first time period (T1) by means of energizing at least one first phase (A) of the electric machine (5), - subsequent initiation of a rotating movement of the rotor (2) by means of energizing a second phase (B) for a predeterminable second time period (T2) at a non-energized first phase (A).