Motor driving apparatus and laundry treatment machine including the same
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Solution Overview
Problem
Laundry treatment machines without position sensors face challenges in accurately estimating the rotor position of motors, leading to inefficiencies in washing, rinsing, and spin-drying cycles.
Innovation Solution
A sensorless motor driving apparatus that includes an inverter controller, output current detection unit, and output voltage detection unit, utilizing resistors and a comparator to directly detect PWM-based output voltage, enabling accurate estimation of rotor position and speed without additional analog-to-digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a position sensor is not used in the laundry treatment machine, then the device complexity is reduced, but the measurement precision of rotor position deteriorates
Solution Approach 1:
The patent introduces an intermediary signal processing mechanism that uses the existing PWM output voltage signal as a mediator to infer rotor position. Instead of directly measuring rotor position without a sensor, the system uses the PWM voltage waveform characteristics (which are already present in the motor control circuit) as an intermediary to estimate rotor position and speed, thereby avoiding additional sensors while maintaining measurement capability
Solution Approach 2:
The patent replaces the mechanical/electrical position sensor system with a signal processing-based estimation system. By substituting the physical sensor with a computational approach that analyzes PWM voltage waveforms, the system eliminates the need for additional hardware sensors while achieving rotor position and speed estimation through mathematical processing of existing electrical signals
2Measurement precision
If additional analog-to-digital conversion components are added to detect output voltage, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent applies the self-service principle by utilizing the existing PWM output voltage signal and the already-present analog-to-digital converter in the inverter controller for the intended measurement purpose. The system repurposes existing components (the ADC that was already part of the PWM generation circuitry) to also perform rotor position estimation, eliminating the need for additional dedicated measurement hardware while maintaining high measurement precision
Solution Approach 2:
The patent demonstrates multi-functionality by making the existing analog-to-digital converter serve dual purposes: its original function for PWM signal processing and an additional function for rotor position and speed estimation. This universal use of existing components avoids adding dedicated measurement hardware, thereby maintaining measurement precision without increasing device complexity
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 solution allows for efficient and accurate control of the motor in a sensorless mode, ensuring precise operation of the laundry treatment machine by rapidly detecting output voltage and removing noise components, thereby improving the estimation of rotor position and speed.
Implementation Method 1
a comparator to compare voltage detected by the resistor with reference voltage and to detect PWM-based output voltage
Data Source
AI summary
The laundry treatment machine, absent a position sensor to sense the rotor position of a motor, includes a driving unit having an DC/AC inverter, an voltage detection unit to detect output voltage, and an inverter controller to control the inverter. The output voltage detection unit includes a plurality of resistors connected between the inverter and the motor and a comparator to compare voltage detected by some of the resistors with reference voltage and to detect pulse width modulation (PWM)-based output voltage. The voltage detection unit outputs the PWM-based output voltage output from the comparator to the inverter controller in a first mode in which at least one switching device of the inverter is turned on. The voltage detection unit outputs voltage detected by other some of the resistors to the inverter controller in a second mode in which all switching devices of the inverter are turned off.