Switch Control Circuit for Buck Converter Average Current Regulation
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Solution Overview
Problem
Existing switch control technologies for buck converters face challenges in maintaining a stable average current, especially when there are changes in input power, load, or switch off-time, leading to difficulties in controlling the average current accurately and efficiently.
Innovation Solution
A switch control circuit that includes a current measuring unit, a current integral unit, and a control unit, which measures and integrates the current, compares it to a reference value, and controls the current control switch based on the comparison and predefined off-time, ensuring accurate and real-time average current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an intermediate operational circuit is used to determine and store reach time, then the control circuit can regulate current, but a delay time for current control occurs and it becomes difficult to control the average current according to input power and load changes
Solution Approach 1:
The patent extracts the timing measurement function from the intermediate operational circuit and implements it directly in the control unit using a timer that measures the time from when the switch is turned on to when the current reaches the reference value. This eliminates the need for separate intermediate circuits that cause delays, allowing the control unit to directly obtain accurate timing information for real-time average current control.
Solution Approach 2:
The control unit preliminarily sets the reference current value based on the desired average current before the switching operation begins. The timer is also prepared to immediately measure the reach time as soon as the switch is activated. This preliminary preparation eliminates delays that would occur if these parameters needed to be calculated or adjusted during operation, enabling faster and more accurate current control.
2Adaptability or versatility
If a conventional control circuit with intermediate operational circuits is used, then current regulation is possible, but the average current cannot be controlled stably when load or input power changes
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously measures the actual current using a sensing circuit, compares it with the reference current value, and adjusts the switch control accordingly. The timer measures the reach time, and this timing information is fed back to control the switch off-time, creating a closed-loop system that automatically adapts to load and input power changes while maintaining stable average current.
Solution Approach 2:
The control unit dynamically adjusts the switch off-time based on real-time measurements of the reach time and current conditions. Rather than using fixed timing, the system continuously adapts the switching parameters in response to changing load and input power conditions, enabling stable average current control across varying operating conditions.
3Ease of operation
If the load current is assumed to constantly increase, then control is simplified, but accurate average current control becomes difficult when the load current does not constantly change
Solution Approach 1:
The timer automatically measures the reach time without requiring external intervention or complex computational circuits. The control unit directly uses this measured time to determine when to turn off the switch, eliminating the need for intermediate operational circuits that would complicate the system. This self-measuring approach maintains simplicity while accurately handling non-linear current profiles.
Solution Approach 2:
The control unit changes the reference current parameter dynamically based on the measured reach time and desired average current. Rather than assuming a constant current profile, the system adjusts the reference parameter in real-time to match actual current conditions, enabling accurate control whether the current is constantly increasing or varying in other patterns.
Data Source
AI summary
Provided is a switch control circuit for controlling a current control switch of a power supply, the power supply including a load, an inductor and the current control switch that are series-coupled to an input power. The switch control circuit includes a current measuring unit configured to measure a current flowing into the load, a current integral unit configured to integrate the measured current, a comparison unit configured to compare the integrated current value and a reference value and a control unit coupled to the current control switch, the control unit being configured to turn off the current control switch when the integrated current is substantially the same as the reference value and turn on the current control switch when a predefined off-time elapses from a time when the current control switch is turned off. The switch control circuit may quickly and accurately control an average current.