SMPS Load Detection via Measurement Pulses
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Solution Overview
Problem
Switch mode power supplies (SMPS) face challenges in minimizing no-load power consumption, which leads to increased output voltage fluctuations and delayed load response due to low energy transfer per pulse and high switching frequencies.
Innovation Solution
A power converter circuit with a transformer and main switch, utilizing controlled driving circuits to generate measurement, reference, and detection pulses, allowing for accurate output voltage detection and minimizing energy transfer during no-load conditions to maintain low no-load power consumption while enabling timely load response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switching frequency is increased to improve response time, then load response speed is improved, but no-load power consumption increases
Solution Approach 1:
The patent implements periodic measurement pulses at reduced frequency during no-load conditions to detect output voltage while minimizing switching losses. The controller alternates between measurement mode (periodic pulses) and normal operation mode, achieving both low power consumption and adequate monitoring capability.
Solution Approach 2:
The switching frequency is dynamically adjusted based on load conditions. During no-load conditions, the frequency is reduced to minimize power consumption, while under load conditions, the frequency increases to improve response speed. This dynamic adaptation resolves the contradiction between speed and energy consumption.
2Use of energy by moving object
If energy transfer per pulse is decreased to reduce no-load power, then no-load power consumption is reduced, but output voltage detection precision deteriorates
Solution Approach 1:
Before normal operation, the system performs preliminary measurement pulses with sufficient energy transfer to accurately detect the output voltage and establish a reference value. This preliminary action ensures detection precision while keeping subsequent operational power consumption low.
Solution Approach 2:
The system uses measurement pulses that replicate the essential characteristics of full-power pulses but at reduced energy levels. These copied pulses are sufficient for voltage detection purposes while consuming minimal power, resolving the contradiction between detection precision and power consumption.
3Use of energy by moving object
If measurement pulse frequency is reduced to minimize power transfer, then no-load power consumption is minimized, but response time to load changes increases
Solution Approach 1:
The measurement pulse frequency is dynamically adjusted based on detected conditions. During stable no-load conditions, frequency is reduced to minimize power consumption. When load changes are detected, the frequency increases automatically to improve response time, thus resolving the time-power tradeoff.
Solution Approach 2:
The system continuously monitors output voltage and provides feedback to the controller. When voltage changes indicate a load condition, the feedback triggers an increase in measurement pulse frequency, ensuring rapid response while maintaining low power consumption during stable conditions.
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 reduces no-load power consumption and maintains responsive load detection, ensuring stable output voltage by optimizing pulse energy transfer and frequency, thereby addressing the limitations of existing SMPS technologies.
Implementation Method 1
a transformer (14) having a primary winding (P1) coupled to an input supply voltage (Vin) and a secondary winding (S1) coupled to an output (Vout)
Implementation Method 2
a main switch (16) coupled to the primary winding (P1). The main switch (16) is turned ON and OFF by a controlled driving circuit (20)
Data Source
AI summary
A pulse scheme is used for load change detection in a switching mode power supply with low no-load power consumption. The pulse scheme includes a measurement pulse for determining a load condition or a no-load condition at the output. Generation of the measurement pulse results in sufficient energy transfer to the secondary side to accurately measure the output voltage via a reflected voltage on the primary side. Once in no-load operation mode, a reference pulse having a lower energy transfer than the measurement pulse is used to determine a baseline reflected voltage value that corresponds to a no-load condition. Successive detection pulses are then generated and corresponding reflected voltage measured and compared to the baseline reflected voltage. A change in the reflected value that exceeds a threshold value is indicative of a change in the no-load condition.