Apparatus for driving a linear ac motor using DC voltage
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Solution Overview
Problem
Existing air mattresses with internal pneumatic components face challenges in safely using mains AC voltage for linear AC pumps, due to shock hazards and the need to minimize circuit components and space within the mattress.
Innovation Solution
An apparatus comprising a power converter to convert AC mains power to DC voltage, a DC motor driver with an H-bridge that generates a square wave to drive a linear AC pump, and a microcontroller for PWM control signals, allowing the linear AC pump to operate safely within the air mattress using DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mains AC voltage is directly coupled to circuitry internal to the air mattress to power linear AC pumps, then the pump can operate effectively, but shock hazards arise due to high voltage levels
Solution Approach 1:
A DC-AC inverter circuit is introduced as an intermediary device between the DC power source (battery or DC adapter) and the linear AC pump. This inverter converts DC voltage to AC voltage, enabling the pump to operate at low voltage without direct coupling to high-voltage mains AC, thereby eliminating shock hazards while maintaining pump functionality.
2Reliability
If a power converter and DC motor driver with H-bridge are added to convert AC to DC and generate square wave, then safety is improved by eliminating shock hazards, but the number of circuit components and space occupied by PCB increases
Solution Approach 1:
The power converter and DC motor driver functions are merged into a single integrated circuit board design. The H-bridge motor driver circuit is implemented on the same PCB that houses the microcontroller, eliminating the need for separate discrete components and reducing overall space requirements while maintaining the safety benefits of DC operation.
3Productivity
If the linear AC pump is driven by AC mains voltage in a housing outside the mattress, then the pump operates effectively, but the circuitry and high voltage components cannot be located inside the mattress
Solution Approach 1:
A DC-AC inverter is introduced as an intermediary that enables the linear AC pump to operate effectively using low-voltage DC power. This allows the entire pump assembly to be relocated inside the mattress without requiring direct connection to AC mains, achieving both effective pump operation and location flexibility within the mattress structure.
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 drives a linear AC motor using DC voltage, minimizing shock hazards and reducing the number of circuit components within the air mattress, thus enhancing safety and efficiency.
Implementation Method 1
a power converter that converts incoming alternating current (AC) mains power into a direct current (DC) voltage
Implementation Method 2
a DC motor driver that includes an H-bridge which receives the DC voltage from the power converter as an input and which generates a square wave as an output that is coupled to the linear pump to drive the arm back and forth
Data Source
AI summary
An apparatus includes a power converter to convert incoming alternating current (AC) mains power into a direct current (DC) voltage. A linear AC pump of the apparatus has an arm that reciprocates linearly back and forth to move a pair of diaphragms to pressurize air that is output from the linear AC pump. The apparatus also includes a DC motor driver having an H-bridge that receives the DC voltage from the power converter as an input and that generates a square wave as an output that is coupled to the linear AC pump to drive the arm back and forth. The pressurized air from the linear AC pump is used to inflate one or more bladders of an air mattress, for example.