Power Converter Transistor Control Across Conduction Modes
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Solution Overview
Problem
Existing switch-mode power converters face issues such as high standby power consumption, increased operating current in light load modes, and decreased efficiency due to premature transistor turn-off in continuous conduction modes, particularly at high switching frequencies, leading to increased temperature and electromagnetic interference.
Innovation Solution
A controller with a mode detector that determines the operation mode of the power converter and adjusts the transistor's on/off states based on predetermined conditions, ensuring optimal operation in various modes, including discontinuous conduction, continuous conduction, light load, and high/low AC voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transistor is turned off early in continuous conduction mode to reduce switching losses, then switching losses are reduced, but operating current increases and efficiency decreases
Solution Approach 1:
The patent implements dynamic transistor control by detecting conduction mode (continuous or discontinuous) and adjusting transistor turn-off timing accordingly. The controller dynamically switches between different operating modes: in discontinuous conduction mode, the transistor turns off early to reduce switching losses; in continuous conduction mode, the transistor remains on longer to maintain efficiency, thus adapting the system behavior to current operating conditions rather than using a fixed control strategy
Solution Approach 2:
The patent changes the operating parameters of the transistor based on detected conduction mode. The control signal timing parameters are adjusted: in discontinuous conduction mode, the transistor turn-off time is advanced; in continuous conduction mode, the transistor turn-off time is delayed. This parameter adaptation allows the system to optimize between switching losses and efficiency depending on the actual operating state
2Productivity
If the transistor remains on longer in continuous conduction mode to improve efficiency, then efficiency improves, but temperature increases and electromagnetic interference worsens
Solution Approach 1:
The system dynamically adjusts transistor operation based on conduction mode detection. When continuous conduction mode is detected and efficiency is prioritized, the transistor remains on longer. However, the system also monitors for conditions where temperature or EMI becomes problematic and can switch to discontinuous conduction mode with earlier transistor turn-off, thus dynamically balancing efficiency against temperature and EMI concerns
Solution Approach 2:
The patent converts the potentially harmful effects of extended transistor conduction (increased temperature and EMI) into beneficial efficiency improvements by carefully controlling the timing. The mode detector identifies specific conditions where extended conduction is beneficial, and the controller precisely times the transistor turn-off to capture efficiency gains while limiting temperature rise and EMI through controlled, conditional operation
3Object-generated harmful factors
If the transistor turns off early to reduce electromagnetic interference, then electromagnetic interference improves, but switching losses increase
Solution Approach 1:
The patent changes the transistor turn-off parameter based on detected conduction mode. In discontinuous conduction mode, the turn-off time is advanced to reduce EMI, accepting increased switching losses. In continuous conduction mode, the turn-off time is delayed to reduce switching losses, accepting increased EMI. This parameter adaptation allows the system to optimize for different priorities based on operating conditions
Solution Approach 2:
The system dynamically switches between early and late transistor turn-off strategies based on conduction mode detection. The controller adapts its control signal timing in real-time: generating early turn-off signals when discontinuous conduction is detected (prioritizing EMI reduction), and late turn-off signals when continuous conduction is detected (prioritizing efficiency). This dynamic adaptation resolves the contradiction by making the optimal strategy context-dependent
Data Source
AI summary
Controller and method for a power converter. For example, a controller for a power converter includes: a mode detector configured to determine a mode of operation for the power converter; a first gate driver configured to output a first drive voltage to a first transistor related to a first auxiliary winding coupled to a primary winding, a secondary winding, and a second auxiliary winding; a second gate driver configured to output a second drive voltage to a second transistor related to the primary winding; wherein the first gate driver is further configured to, if the mode of operation satisfies one or more first predetermined conditions, generate the first drive voltage so that the first transistor remains turned off during a switching cycle of the power converter.