DC-DC Power Supply Switch Sequencing for Low-Load Cut-Off
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Solution Overview
Problem
In power supply devices with DC-DC converters, semiconductor switches may be subjected to load when switched off, leading to potential damage and inefficiencies.
Innovation Solution
A power supply device design that includes a controller to switch a first switch into off-state and subsequently switch a second switch into off-state, thereby cutting off electrical connection and reducing load on the switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the second switch is switched off while the first switch is still on, then the cut-off speed is improved, but the switch may be subjected to excessive load and potential damage
Solution Approach 1:
The controller switches the first switch into off-state before switching the second switch into off-state. This preliminary action of turning off the first switch eliminates the potential load path through the power converter circuit, ensuring that when the second switch is turned off, no excessive current or voltage spikes can reach it, thus protecting the second switch while maintaining fast cut-off performance
2Device complexity
If both switches are switched off simultaneously, then the device complexity is reduced, but the load on each switch increases leading to potential damage
Solution Approach 1:
The switch-off operation is segmented into two sequential steps: first switching off the first switch, then switching off the second switch. This segmentation divides the single complex simultaneous operation into two simpler sequential operations, reducing control complexity while effectively distributing and reducing the load on each switch during the transition
3Reliability
If the switching sequence is optimized to reduce load on switches, then the reliability is improved, but the cut-off time increases
Solution Approach 1:
The controller rapidly switches the first switch into off-state and immediately proceeds to switch the second switch into off-state without unnecessary delays. This rushing through the switching sequence minimizes the overall cut-off time while still achieving the protective effect of turning off the first switch before the second, as the sequential operation itself is executed as quickly as possible
Data Source
AI summary
A power supply device includes an input terminal to which a direct-current power supply can be connected, an output terminal, a power converter circuit, a first switch placed between the input terminal and a power converter circuit, a second switch placed between the power converter circuit and the output terminal, and a controller configured to control the first switch and the second switch to switch between an on-state and an off-state. For cutting off an electrical connection between the input terminal and the output terminal, the controller is configured to switch the first switch into an off-state and thereafter switch the second switch into an off-state.