Switching Power Supply Digital Control Circuit Constant Frequency
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Solution Overview
Problem
Existing switching power supplies face inefficiencies and reliability issues due to variable switching frequency and suboptimal dead time settings, leading to noise and potential short-circuit risks.
Innovation Solution
A switching power supply apparatus with a digital control circuit that sets optimal on-times for switching elements based on a clock signal and monitor signals, ensuring constant switching frequency and preventing simultaneous switching element activation, using a configuration that includes a transformer with multiple windings and rectification smoothing circuits for stable output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dead time is provided to prevent simultaneous switching of multiple switching elements, then reliability is improved, but switching frequency varies and switching noise occurs in a wide range
Solution Approach 1:
The patent changes the parameter of dead time from a fixed value to a variable value that is adjusted based on the load current. By dynamically adjusting the dead time duration, the switching frequency is maintained constant, thereby preventing switching noise in a wide range while still preventing simultaneous switching of multiple elements.
Solution Approach 2:
The patent introduces dynamic adjustment of the dead time period based on load conditions. The control circuit dynamically modifies the dead time duration to maintain constant switching frequency, transforming the static dead time into a dynamic parameter that adapts to changing load requirements.
2Reliability
If a long dead time is set in the full load region, then reliability is improved, but efficiency deteriorates in the steady state
Solution Approach 1:
The patent implements dynamic adjustment of dead time based on load conditions. During transient states when reliability is critical, a longer dead time is applied. During steady-state operation, the dead time is reduced to minimize efficiency losses. This dynamic adaptation resolves the contradiction between reliability and efficiency.
Solution Approach 2:
The dead time parameter is changed from a fixed long duration to a variable duration that is optimized for different operating conditions. The control circuit adjusts the dead time length based on whether the system is in transient or steady state, thereby maintaining reliability while improving efficiency.
3Device complexity
If a constant dead time is used in transient and steady states, then simplicity is maintained, but optimum dead time cannot be achieved in steady state
Solution Approach 1:
The patent transitions from a static dead time control to a dynamic control mechanism that detects whether the system is in transient or steady state and adjusts the dead time accordingly. This dynamic approach maintains reliability and optimality without significantly increasing system complexity.
Solution Approach 2:
The patent employs feedback mechanisms to detect the operating state (transient or steady state) and uses this information to adjust the dead time. The control circuit continuously monitors system conditions and modifies the dead time parameter to achieve optimal performance in each state.
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 achieves high reliability and efficiency by maintaining constant switching frequency, reducing noise, and preventing simultaneous switching element activation, thereby enhancing EMI characteristics and output voltage stability.
Implementation Method 1
a transformer T being configured by one magnetic component and including at least a first primary winding np and a first secondary winding ns1, magnetically coupled
Data Source
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AI summary
A resonance-type power supply in which no short circuit occurs and driving can be performed with a constant switching period is realized by performing switching control using the change of magnetic flux of a magnetic component as a trigger When the change of magnetic flux of the transformer T is detected (S102: Yes), the first switching control signal Vgs1 is caused to transit to the Hi level (S103). Next, the detection voltage signal Vo is A/D-converted (S103'), the on-time Ton1 is determined from the level thereof, and the on-time Torn2 is calculated by subtracting the on-time Ton1 from the constant switching period Ts (S104'). When the first switching control signal Vgs1 is caused to transit to the Low level on the basis of the on-time Ton1 (S105), the change of magnetic flux of the transformer T is detected (SI06: Yes), and the second switching control signal Vgs2 is caused to transit to the Hi level (S107) and is caused to transit to the Low level after the on-time Ton2 has elapsed (S108)