Power Transfer System Soft-Start Circuit Voltage Control
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Solution Overview
Problem
Conventional power transfer systems face issues such as voltage jumps and large transient currents due to differences in power source voltages, which can cause damage to switches and connectors, and are prone to damage from poor contact voltage spikes and current spikes.
Innovation Solution
A power transfer system with two main switches and control circuitry that selectively transfers power from either a USB connector or an adapter connector to an output terminal, using a soft-start circuit and body control circuit to manage current and voltage, ensuring that the main switch remains off until the output voltage is stable and within a predefined range, thereby preventing voltage jumps and transient currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the main switch is turned on immediately when a power source is connected, then power transfer speed is improved, but voltage jumps and large transient currents occur causing component damage
Solution Approach 1:
The control circuit activates the soft-start circuit before turning on the main switch. The soft-start circuit gradually increases the output voltage from zero to the target voltage over a predetermined time period, preventing sudden voltage jumps and large transient currents when the main switch is activated. This preliminary voltage establishment protects the main switch and other components from damage.
Solution Approach 2:
The soft-start circuit acts as a cushioning mechanism that absorbs and mitigates the harmful effects of sudden power connection. By gradually ramping up the voltage instead of applying full voltage instantaneously, the circuit cushions against voltage spikes and current surges that would otherwise damage components.
2Stability of the object's composition
If the main switch remains off during power source connection, then voltage stability is improved, but power transfer time increases due to delayed main switch activation
Solution Approach 1:
The control circuit performs preliminary voltage establishment through the soft-start circuit before activating the main switch. This preliminary action ensures voltage stability by preventing sudden jumps, while the predetermined time period is optimized to be sufficiently short so as not to cause significant power transfer delay.
Solution Approach 2:
The system dynamically transitions from a soft-start mode to a full power transfer mode. During the predetermined time period, the soft-start circuit gradually increases voltage; after this period, the main switch is activated for efficient power transfer. This dynamic approach balances voltage stability requirements with power transfer speed requirements.
3Productivity
If power transfer occurs without current control, then power transfer efficiency is improved, but component damage occurs due to uncontrolled transient currents
Solution Approach 1:
The soft-start circuit establishes a controlled current path before the main switch is activated. By gradually increasing the output voltage during the predetermined time period, the circuit controls the charging current to the output capacitor, preventing uncontrolled transient currents that would damage components while still enabling efficient power transfer after the soft-start period.
Solution Approach 2:
The soft-start circuit acts as an intermediary between the power source and the main switch. It mediates the power transfer process by controlling the initial current flow and voltage buildup, protecting the main switch and other components from harmful transient currents while enabling subsequent efficient power transfer.
Data Source
AI summary
In a power transfer system, a first main switch can transfer power from a first connector to an output terminal. A first path can deliver a current from the first connector to the output terminal and control the current to be within a predefined ranger. A second main switch can transfer power from a second connector to the output terminal. A second path can deliver a current from the second connector to the output terminal and control the current to be within a predefined range. Control circuitry can turn off the second main switch and the second path and turn on the first path if the first power source is available at the first connector when the second power source is providing power to the output terminal. The control circuitry can turn on the first main switch when a time interval from turning on the first path has elapsed.