Circuit for laundry treating appliance with high power drive
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Solution Overview
Problem
Laundry treating appliances with high load capacity, such as commercial washing machines, require a higher voltage supply than typically available in 120 VAC systems, leading to insufficient operating power for variable frequency drives (VFDs), with existing solutions being either limited in current capacity or requiring large and expensive transformers.
Innovation Solution
A voltage doubling circuit that uses a current-limiting surge suppressor and a MOSFET bypass to charge capacitor banks, allowing for the supply of up to 340 VDC to a VFD, enabling operation with a 120 VAC input and providing sufficient power for larger appliances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a 120 VAC input variable frequency drive is used with an internal doubling circuit, then the voltage is doubled to achieve higher output voltage, but the current capacity is limited to about 4.2 amps which is insufficient for driving larger loads
Solution Approach 1:
The patent segments the voltage doubling function into two distinct circuits: a first voltage doubling circuit for charging capacitor banks during normal operation, and a second voltage doubling circuit activated during high-power demand periods. This segmentation allows each circuit to be optimized for its specific function, with the second circuit providing additional current capacity when needed without limiting the overall system power output.
Solution Approach 2:
The patent implements dynamic switching between different voltage doubling circuits based on power demand. A controller monitors the power requirements and dynamically activates the second voltage doubling circuit when high power is needed, and deactivates it when normal operation suffices. This dynamic approach allows the system to adapt current capacity to actual load requirements, overcoming the static current limitation of single-circuit designs.
2Power
If a very large step-up voltage doubling transformer is used to change from 120 VAC input to 240 VAC output, then sufficient voltage and power are provided for large appliances, but the transformer becomes very large, heavy, and expensive
Solution Approach 1:
The patent employs periodic activation of the second voltage doubling circuit based on detected power demand. Rather than continuously operating a large transformer, the system periodically activates the additional voltage doubling circuit only when high power demand is detected (such as during motor starting or high-speed spin cycles). This periodic action allows the system to provide high power capacity when needed while keeping the average power consumption and component size much smaller than a continuously-operating large transformer would require.
Solution Approach 2:
The patent changes the operational parameters of the voltage doubling system by switching between different circuit configurations. The first voltage doubling circuit operates continuously at lower power levels, while the second circuit is activated to provide additional voltage and current capacity during high-power demands. This parameter changing approach allows the system to achieve high power output capability without requiring a permanently configured large transformer, thereby reducing weight and cost.
3Power
If the second voltage doubling circuit operates continuously, then maximum power output is always available, but energy is wasted during periods when high power is not needed
Solution Approach 1:
The patent implements a feedback control mechanism where a controller continuously monitors the power demand of the connected load. Based on this feedback, the controller dynamically determines when to activate or deactivate the second voltage doubling circuit. When high power demand is detected (such as during motor acceleration or high-speed operation), the controller activates the second circuit to provide additional power capacity. When normal operation levels are detected, the controller deactivates the second circuit, thereby eliminating energy waste while ensuring power is available when needed.
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 effectively doubles the input voltage to the VFD, enabling commercial washing machines to operate with higher power demands during high-speed cycles, such as spin or extraction phases, while maintaining efficient voltage regulation and reducing the need for large transformers.
Implementation Method 1
charging at least one capacitor bank through a current-limiting surge suppressor defining a current-limiting path connected with the voltage supply to a predetermined voltage
Implementation Method 2
charging the at least one capacitor bank through a bypass path operable to bypass the current-limiting path of the current-limiting surge suppressor
Implementation Method 3
disabling, by activation of a current drain, the bypass path of the current-limiting surge suppressor
Data Source
AI summary
A circuit that increases input voltage to higher output voltage connected to a drive. The circuit can include a power input that receives the input voltage from a power source and at least one capacitor bank connected with the power input. A current-limiting surge suppressor is positioned between the power input and the at least one capacitor bank. The current-limiting surge suppressor includes a first current-limiting path and a second bypass path. A drain, when operable, dissipates the charge of the at least one capacitor bank. The drive is operable in response to the higher voltage output from the at least one capacitor bank.