Switch Control Circuit for Non-Insulating Power Supply Safety
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Solution Overview
Problem
Non-insulating power supply devices pose safety risks due to exposure to electric shock when handling AC inputs, despite their simpler design and lower production costs compared to insulating power supply devices.
Innovation Solution
A switch control circuit is introduced that includes a protection switch and a switch control method to detect line openings using sense voltage and reference voltage comparisons, automatically turning off the protection switch when a line is determined to be open, thereby preventing electric shock and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a non-insulating power supply device is used, then design simplicity and production cost are improved, but user safety deteriorates due to electric shock exposure
Solution Approach 1:
The control circuit proactively detects line open conditions before they can cause electric shock hazards. By continuously monitoring the output terminal connection status and predicting potential safety issues in advance, the system takes preventive action to disconnect power, thereby maintaining the simple non-insulating structure while eliminating the electric shock risk.
2Ease of manufacture
If a non-insulating power supply device is used, then production cost is reduced, but safety reliability deteriorates
Solution Approach 1:
The power supply device performs self-diagnosis of line open conditions through its own control circuit monitoring the output terminal connection status. This self-monitoring capability enables the system to detect and respond to safety issues autonomously without requiring additional insulating structures or external safety devices, thereby maintaining low production cost while improving safety reliability.
3Object-affected harmful factors
If line open detection is implemented, then safety is improved, but device complexity increases
Solution Approach 1:
The control circuit performs multiple functions using the same hardware resources: it controls the power switch for normal operation, generates reference signals for PWM control, and simultaneously detects line open conditions by monitoring the sense voltage. This multi-functionality allows the circuit to provide electric shock prevention without adding separate dedicated detection hardware, thereby minimizing the increase in device complexity.
4Measurement precision
If continuous monitoring is performed, then detection precision is improved, but energy consumption increases
Solution Approach 1:
The control circuit continuously monitors the sense voltage during normal operation without requiring separate measurement cycles or additional active components. The line open detection utilizes the existing PWM switching signals and sense voltage already present in the circuit, enabling continuous precision monitoring while avoiding extra energy consumption from dedicated measurement circuits.
Data Source
AI summary
Embodiments of the present invention relate to a switch control circuit, a switch control method, and a power supply device using the same.Embodiments generate a reference signal according to a full-wave rectification voltage and control a switching operation of a power switch according to a comparing result of a sense voltage corresponding to a current flowing to the power switch and the reference voltage. Embodiments determine whether a line is opened between a first output terminal and a second output terminal of the power supply device using the sense voltage. When the line is opened, Embodiments turn off the protection switch.