Motor Activation Circuit With Low-Voltage Relay State Sensing
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Solution Overview
Problem
Existing electric appliance systems face reliability issues due to high power consumption and safety risks from inadequate sensing arrangements for electric motor activation and deactivation, leading to potential failures and increased energy usage.
Innovation Solution
A circuit and method for managing electric motor activation/deactivation in washing and drying appliances, incorporating an inrush current limiting device and a sensing network with a resistive network and filtering arrangement, allowing for low-voltage sensing and reliable operation while preventing safety risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-voltage sensing arrangements are used to detect switching device states, then sensing capability is achieved, but power consumption increases significantly
Solution Approach 1:
The patent introduces a voltage divider circuit as an intermediary between the high-voltage switching device and the low-voltage microcontroller. This intermediary steps down the high voltage to a safe low-voltage level that the microcontroller can sense without excessive power consumption or safety risks
Solution Approach 2:
The patent replaces direct high-voltage electrical sensing with a low-voltage sensing system using a microcontroller. By using a voltage divider to translate high-voltage states into low-voltage signals, the system substitutes a power-intensive direct sensing approach with a low-power microcontroller-based sensing approach
2Use of energy by moving object
If only some switching devices are sensed to reduce power consumption, then power saving is achieved, but reliability decreases due to undetected failures
Solution Approach 1:
The patent implements a sensing system that automatically monitors all switching devices without requiring manual selection or configuration. Each switching device has its own dedicated sensing circuit that continuously monitors its state, enabling the system to self-diagnose failures in any switching device while maintaining low power consumption through the efficient voltage divider design
3Strength
If inrush current limiting devices are used during motor activation, then power conversion system stress is reduced, but device complexity increases
Solution Approach 1:
The patent incorporates an NTC thermistor in series with the power conversion system that automatically limits inrush current during motor startup before the motor reaches full speed. This preliminary current limiting action protects the power conversion components from stress during the critical startup phase
Solution Approach 2:
The patent utilizes the temperature-dependent resistance phase transition of an NTC thermistor. During startup, the thermistor has high resistance to limit inrush current; as current flows and the thermistor heats up, its resistance automatically decreases, allowing full current to pass once the motor is running normally
4Reliability
If comprehensive sensing of all switching devices is implemented, then reliability is improved, but power consumption and device complexity increase
Solution Approach 1:
The patent divides the sensing network into separate, independent voltage divider circuits for each switching device. Each switching device has its own dedicated sensing circuit that operates independently, allowing comprehensive monitoring of all devices while keeping each individual sensing circuit simple and low-power
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
The solution reduces power consumption, enhances reliability, and ensures safe operation by effectively managing electric motor states and door locking mechanisms, addressing the limitations of existing systems.
Implementation Method 1
a limiter circuit configured to temporarily limit a charging current drawn by the inverter supply block during a bulk capacitor charging phase
Implementation Method 2
a sensing network for sensing the first or second states of the switching device and for providing a corresponding state signal
Data Source
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AI summary
A washing and/or drying appliance (100) is proposed. The appliance comprises: an electric load (205), a driving arrangement (210,215,C) for driving the electric load (205), the driving arrangement (210,215,C) having first (T205,IN1) and second (T205,IN2) terminals coupleable, respectively, to a line terminal (TL) and to a neutral terminal (TN) providing a reference voltage (VCC), an inrush current limiting device (RFUSE;RNTC) and a switching device (RL;RL1) between the reference terminal (TN) and the second terminal (T205,IN2) of the driving arrangement (210,215,C), the switching device (RL;RL1) being operable in first or second states preventing or allowing, respectively, an electric current to flow through the inrush current limiting device (RFUSE,RNTC), and a sensing network (RPD) for sensing the first or second states of the switching device (RL;RL1) and for providing a corresponding state signal (SSTATE;S*STATE), the sensing network (RPD) having a first terminal (TRPD,1), and a second terminal (TRPD,2) coupled to a reference terminal providing a further reference voltage (GND) lower than the reference voltage (VCC), wherein, during sensing: in the first state of the switching device (RL;RL1) the reference terminal (TN) and the first terminal (TRPD,1) of the sensing network (RPD) being coupled to each other such that the first terminal (TRPD,1) of the sensing network (RPD) receives the reference voltage (VCC) and the state signal (SSTATE;S*STATE) takes a first level (SSTATE,H) equal to the reference voltage (VCC), in the second state the state signal (SSTATE, S*STATE) taking a second level (SSTATE,I;SSTATE,L) lower than the first level (SSTATE,H).