Boost Chopper Power Supply Circuit Startup Overcurrent Prevention
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Solution Overview
Problem
Conventional power supply circuits using boost chopper circuits face issues with overcurrent during switching operation startup, particularly when the inductance value is low or switching frequency is low, leading to repeated overcurrent protection and potential system operation failures.
Innovation Solution
The solution involves detecting the ripple component of the DC voltage and starting the switching operation when it becomes positive, comparing the input current instantaneous value with a proportional value to determine the start time, and optionally increasing the switching frequency temporarily during startup to prevent overcurrent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the inductance value of the reactor is set to a small value or the switching frequency is set to a low frequency, then the device complexity and energy loss are reduced, but an overcurrent occurs at the time of starting the switching operation
Solution Approach 1:
The control circuit detects the ripple component of the DC voltage before starting the switching operation and determines the optimal start timing based on this detection. By performing this preliminary detection and timing determination, the system ensures that switching starts at the appropriate moment when overcurrent is prevented, allowing the use of small inductance values and low switching frequencies without causing overcurrent issues.
2Device complexity
If the switching operation starts in a period during which no current flows, then the control is simplified, but an overcurrent occurs due to the large duty ratio required at startup
Solution Approach 1:
The control circuit performs preliminary detection of the ripple component of the DC voltage to determine the optimal start timing before initiating the switching operation. This preliminary action allows the system to start switching at the appropriate moment when the duty ratio is naturally limited, preventing overcurrent while maintaining the simplified control structure that does not require complex current detection circuits.
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
This approach effectively prevents overcurrent during startup, ensuring smooth activation of the power supply circuit, reducing stress on switching elements, and enhancing the reliability of the power supply circuit.
Implementation Method 1
a ripple component of a DC voltage is detected and a start timing of the switching operation is determined when the ripple component of the DC voltage becomes 'positive'
Data Source
Figure 1~2
Figure 3(A)~4(b)
Figure 5A~5B
AI summary
A problem of the present invention is to prevent an overcurrent at the time of starting a switching operation in a power supply circuit using a boost chopper circuit (3). In order to solve the above-described problem, the present invention is characterized in that in the power supply circuit using a boost chopper circuit, a switching operation is started in a vicinity of a peak value of an input current once per a half cycle of a power supply cycle. As one of specific arrangement, a ripple component of a DC voltage is detected, and the switching operation is started at a timing when the ripple component of the DC voltage becomes "positive". As another specific arrangement, an input current instantaneous value is compared with a value proportional to the magnitude of the input current (e.g., the effective value or the like), and a switching operation is started in a period during which the input current instantaneous value exceeds the value proportional to the magnitude of the input current.