Dual-Source Motor Power Switching Without Isolation Transformers
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Solution Overview
Problem
Existing electronic power equipment that can connect to both AC and DC power sources tends to be bulky due to the need for AC/DC converters with isolation transformers, which increases size and complexity.
Innovation Solution
The design incorporates a switching mechanism with relay switches in both AC and DC circuits, allowing for insulation between the two power sources, eliminating the need for AC/DC converters and enabling a compact structure, with a controller for reliable switching and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an AC/DC converter with isolation transformer is used to convert AC voltage to DC voltage for a DC motor, then the motor can be driven by AC power, but the equipment size increases
Solution Approach 1:
The patent divides the power supply system into separate AC circuit and DC circuit paths with independent switching mechanisms. The AC circuit includes AC switches and AC fuses, while the DC circuit includes DC switches and DC fuses, allowing each circuit to be independently controlled and insulated from the other, eliminating the need for bulky isolation transformers
Solution Approach 2:
The motor is designed as a universal motor that can operate with both AC and DC power sources. The power supply device provides a unified interface that accepts either AC or DC input, and the controller automatically adapts the operating parameters based on the detected power source type, making the motor compatible with both power types without requiring separate motor designs
2Reliability
If multiple switches are arranged in series in both positive and negative lines of AC and DC circuits, then insulation between AC and DC circuits is improved, but device complexity increases
Solution Approach 1:
The patent employs asymmetric switching arrangements where AC switches are positioned in the AC circuit lines and DC switches are positioned in the DC circuit lines, with each switch type optimized for its specific circuit requirements. This asymmetric placement simplifies the overall design by avoiding the need for symmetric dual-switch configurations in both circuits while maintaining insulation integrity
Solution Approach 2:
The controller serves as an intermediary that coordinates the operation of multiple switches across AC and DC circuits. By centralizing the control logic, the system can manage complex switching sequences and insulation requirements through software control rather than requiring additional physical switching components, thereby reducing device complexity while maintaining reliability
Data Source
AI summary
An electronic power equipment, which is configured to be connected to both an AC power source and a DC power source, has a motor 14 configured to be driven by both AC power and DC power, an AC circuit 30 for supplying AC electric power to the motor 14, a DC circuit 40 for supplying DC electric power to the motor 14, switching parts RL1-RL12 for switching between the AC circuit 30 and the DC circuit 40 wherein the AC and DC circuits are insulated relative to each other, and a controller A1 configured to control the switching parts RL1-RL12, the AC circuit 30, and the DC circuit 40.