Charge Control Circuit for Overcurrent Prevention
Solution Overview
Problem
Charge circuits that generate constant voltage for loads connected to their output terminals, even without a battery, can cause overcurrent when a battery with lower voltage is connected, leading to inefficient charging and potential damage.
Innovation Solution
A charge control circuit that includes a charge/discharge circuit for capacitors, an error amplifier circuit, and a drive circuit to manage inductor current and output voltage, ensuring the error between charging voltage and reference voltage is minimized, thereby preventing overcurrent and optimizing charging modes between constant current and constant voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the charge circuit generates constant voltage to drive the load even without a battery connected, then the load can be powered continuously, but overcurrent flows when a battery with lower voltage is connected to the output terminal
Solution Approach 1:
The patent employs feedback control by detecting the voltage at the output terminal and comparing it with a reference voltage. When a battery with lower voltage is connected, the detection circuit identifies the voltage drop, and the control circuit adjusts the switching element to limit current flow, preventing overcurrent damage while maintaining continuous power supply to the load
Solution Approach 2:
The charge circuit dynamically switches between different operating modes (constant voltage mode for load power supply, constant current mode for battery charging) based on real-time detection of terminal conditions. The switching element's duty cycle is continuously adjusted according to the detected voltage levels, enabling adaptive current control that prevents overcurrent when batteries are connected
2Productivity
If the charge circuit operates in constant current mode to charge the battery, then charging efficiency is improved, but the circuit cannot maintain constant voltage for the load simultaneously
Solution Approach 1:
The patent segments the power delivery function into two independent controllable paths: one path dedicated to constant current charging of the battery through the switching element and inductor, and another path for constant voltage supply to the load through the output terminal. The control circuit independently manages each path's parameters, allowing simultaneous optimization of charging efficiency and voltage stability without mutual interference
3Device complexity
If the charge circuit uses a simple voltage regulation method, then the device complexity is reduced, but the switching time between constant current and constant voltage modes is prolonged
Solution Approach 1:
The patent implements preliminary action by pre-configuring the switching element and control circuitry to enable rapid transition between operating modes. The control circuit continuously monitors voltage conditions and pre-prepares the switching state, so when mode transition is required (from constant voltage to constant current or vice versa), the switching element can be activated or deactivated immediately without delay, reducing mode switching time while maintaining simple circuit architecture
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 limits input current to prevent overcharging, ensures accurate charging of batteries, and reduces the time required to shift between constant current and constant voltage modes, thereby preventing damage and improving charging efficiency.
Implementation Method 1
a booster circuit including an inductor supplied with the input current, including the transistor configured to increase an inductor current flowing through the inductor when the transistor is turned on, and being configured to boost the output voltage by supplying the inductor current to the terminal when the transistor is off
Implementation Method 2
a charge/discharge circuit configured to charge a capacitor when an input current from the input power supply is smaller than a first current, and discharge the capacitor when the input current is greater than the first current
Data Source
AI summary
A charge control circuit includes: a charge/discharge circuit to charge a capacitor when an input current from an input power supply is smaller than a first current, and discharge the capacitor when the input current is greater than the first current; a discharge circuit to discharge the capacitor when the input current becomes greater than a second current greater than the first current; an error amplifier circuit to amplify an error between a lower voltage between a capacitor charging voltage and a reference voltage corresponding to the maximum output voltage, and a feedback voltage corresponding to the output voltage; and a drive circuit to perform switching of a transistor of a booster circuit, including an inductor and the transistor to increase an inductor current, configured to boost the output voltage by supplying the inductor current to the terminal when the transistor is off, so that the error becomes smaller.