Sensorless Polyphase Motor Control via Evaluation Signal
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Solution Overview
Problem
Brushless direct current motors face challenges in efficiently starting, rotating slowly, and braking without sensors, as they require precise commutation timing which is difficult to achieve without sensor feedback.
Innovation Solution
A polyphase motor actuating apparatus with five phase terminals, a high terminal for supply voltage, and a low terminal for reference potential, using a control device to generate a pulse-width-modulated voltage pattern in four phase terminals to produce an evaluation signal for determining the rotor's angle of rotation and commutation condition, allowing sensorless operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless operation is used to reduce device complexity, then the number of components is reduced, but precise commutation timing becomes difficult to achieve
Solution Approach 1:
The motor system uses its own phase windings to generate evaluation signals for rotor position detection. By switching off one phase terminal and using the remaining four phase terminals to generate PWM voltage patterns, the system creates self-generated evaluation signals that enable sensorless determination of the rotor's angle of rotation and commutation conditions, making the system self-sufficient without external sensors
Solution Approach 2:
The patent introduces evaluation signals as an intermediary mechanism between the phase windings and the control device. These evaluation signals, generated through the interaction of the PWM voltage pattern with the motor's phase windings, serve as a mediator that carries rotor position information from the motor to the control device, enabling precise commutation timing without direct sensor measurement
2Adaptability or versatility
If evaluation signals are generated through PWM voltage patterns to enable sensorless operation, then sensor feedback is eliminated, but the control complexity increases
Solution Approach 1:
The control device performs multiple functions using the same hardware resources. The phase terminals are used both for applying PWM voltage patterns to drive the motor and for generating evaluation signals for rotor position detection. This multi-functionality allows the control device to handle both motor control and sensorless position sensing without requiring separate dedicated circuits or components
Solution Approach 2:
The patent merges the motor control function and the rotor position detection function into a single integrated process. By combining the PWM voltage pattern application with the evaluation signal generation in the same phase terminals, the control device unifies these two functions, reducing overall system complexity despite the sophisticated control algorithm required
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
Enables efficient operation and precise commutation in brushless direct current motors, facilitating starting, slow rotation, and braking without the need for sensors, by determining the rotor's position and commutation condition through evaluation signals.
Implementation Method 1
the control device is configured to impress a pulse-width-modulated voltage pattern in four of the five phase terminals by connecting the phase terminals to the high terminal or the low terminal so that in the fifth phase terminal, an evaluation signal is generated which depends on the angle of rotation of the polyphase motor
Data Source
AI summary
An actuating apparatus for a polyphase motor includes five phase terminals for connecting of in each case one phase of the polyphase motor, a high terminal for applying a supply voltage (UB), a low terminal for applying a reference potential of the supply voltage (UB), a control device, wherein the control device is adapted, in four of the five phase terminals, to impress a pulse-width-modulated voltage pattern by connecting the phase terminals to the high terminal or the low terminal so that in the first phase terminal, an evaluation signal which is dependent on the angle of rotation of the polyphase motor is produced, and wherein the control device is adapted to determine the angle of rotation and/or a commutation condition of the polyphase motor from the evaluation signal.