Sensorless Motor Inverter Control to Prevent Washer Drum Reversal
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Solution Overview
Problem
Laundry treatment machines without position sensors face challenges in accurately estimating the rotor position of the motor, leading to difficulties in preventing reverse rotation phenomena during laundry washing and spinning processes.
Innovation Solution
A sensorless motor driving apparatus that estimates the rotor position using both output current and output voltage detection, employing a PWM-based switching control signal to control the inverter and supply alignment and torque currents to the motor, ensuring accurate rotation and preventing reverse rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is used to accurately sense rotor position, then motor control precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the position sensing function from a dedicated hardware sensor and implements it through software-based estimation algorithms using existing motor phase current and voltage measurements. This eliminates the need for additional position sensor hardware while maintaining control functionality.
Solution Approach 2:
The motor system uses its own operational parameters (phase currents and voltages) to self-determine rotor position information through estimation algorithms, without requiring external sensing devices. The system serves its own positioning needs using internally available data.
2Ease of manufacture
If sensorless motor control is implemented to reduce manufacturing cost, then manufacturing cost decreases, but rotor position estimation accuracy deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where estimated rotor position and speed are continuously fed back to adjust the motor control parameters. The system uses measured phase currents and voltages as feedback signals to refine position estimation and maintain accurate control without sensors.
Solution Approach 2:
The patent employs parameter estimation techniques that dynamically calculate rotor position and speed by analyzing changes in motor electrical parameters (currents and voltages) during operation. This allows accurate sensorless control through mathematical modeling and parameter analysis.
3Stability of the object's composition
If alignment current is supplied during starting operation to align the motor, then motor alignment accuracy is improved, but reverse rotation phenomenon occurs when only torque current is supplied
Solution Approach 1:
The patent applies preliminary alignment current during the starting phase to establish proper motor alignment and rotor position before transitioning to normal torque production. This preliminary action ensures the motor is properly positioned to prevent reverse rotation during subsequent operation.
Solution Approach 2:
The patent dynamically transitions the motor control from alignment current mode to torque current mode, and subsequently to a combined mode where both alignment and torque currents are supplied together. This dynamic control strategy maintains alignment stability while preventing reverse rotation during load variations.
4Reliability
If alignment current and torque current are supplied together after motor alignment, then reverse rotation phenomenon is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent makes the motor control system multi-functional by enabling it to perform both alignment and torque production simultaneously through combined current supply. This universal approach allows the same control system to handle multiple functions (alignment maintenance and reverse rotation prevention) without requiring separate dedicated systems.
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 stable and accurate motor control in a sensorless mode, effectively preventing reverse rotation of the drum during laundry treatment, enhancing operational reliability and reducing manufacturing costs by eliminating the need for position sensors.
Implementation Method 1
an inverter to convert DC voltage into AC voltage and to output the AC voltage to the motor
Data Source
AI summary
A laundry treatment machine includes a drum, a motor to rotate the drum, and a driving unit to drive the motor, wherein the driving unit includes an inverter to convert direct current (DC) voltage into alternating current (AC) voltage and to output the AC voltage to the motor and an inverter controller to control the inverter to supply an alignment current to the motor so as to align the motor during a starting operation of the motor and to supply a torque current for rotating the motor to the motor together with the alignment current after the motor is aligned. Such a laundry treatment apparatus prevents a reverse rotation phenomenon of the drum due to load.