Power Converter Ton-Min Modulation for Low-Load Constant Frequency
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Solution Overview
Problem
Power converters face inefficiencies at low loads due to varying input voltages and load demands, leading to electromagnetic interference and reduced efficiency.
Innovation Solution
A power converter circuit that modulates the minimum on-time (Ton-min) based on input voltage magnitude, allowing operation at a constant frequency across a wide range of conditions, including continuous and discontinuous conduction modes, and adjusts operating mode exit conditions to enhance efficiency at low loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the power converter operates with fixed minimum on-time, then the circuit operation is simple, but the efficiency deteriorates at low loads due to varying input voltages
Solution Approach 1:
The patent implements dynamic adjustment of the minimum on-time parameter based on input voltage magnitude. The modulation circuitry continuously varies Ton-min in response to changing input voltage conditions, allowing the power converter to maintain optimal efficiency across different operating points while managing complexity through automated control
Solution Approach 2:
The patent changes the minimum on-time parameter dynamically based on input voltage magnitude. By modulating Ton-min according to Vin conditions, the system optimizes efficiency at low loads without requiring complete redesign of the power converter architecture
2Loss of energy
If the power converter uses variable frequency operation, then the efficiency improves at low loads, but the electromagnetic interference increases
Solution Approach 1:
The patent modulates the minimum on-time parameter to achieve efficiency improvement while maintaining constant switching frequency. By adjusting Ton-min rather than the frequency itself, the system avoids generating variable frequency electromagnetic interference while still optimizing power conversion efficiency at low loads
3Object-generated harmful factors
If the power converter maintains constant frequency operation, then the electromagnetic interference is reduced, but the efficiency deteriorates at low loads due to fixed minimum on-time
Solution Approach 1:
The patent combines constant frequency operation with dynamic minimum on-time adjustment. The switching frequency remains fixed to minimize electromagnetic interference, while the minimum on-time parameter is dynamically modulated based on input voltage to maintain high efficiency at low loads
Solution Approach 2:
The patent changes the minimum on-time parameter while maintaining constant switching frequency. This selective parameter modulation allows the system to improve efficiency at low loads without introducing variable frequency electromagnetic interference
4Loss of energy
If the power converter enters operating region based on first combination but exits based on second combination, then the efficiency improves at low loads, but the control complexity increases
Solution Approach 1:
The patent implements asymmetric hysteresis control where the operating region exit conditions differ from entry conditions. This feedback mechanism uses different thresholds for entering and exiting low-power modes, improving efficiency while managing control complexity through established control theory principles
Data Source
AI summary
A switching mode power supply that supplies power to a load. The circuitry of the power supply of this disclosure may be configured to operate with a constant switching frequency over a range of input voltages and a range of load power demand. The circuitry of this disclosure may modulate a minimum on-time (Ton-min) for a duty cycle for an operating frequency of the circuit based on the magnitude of the input voltage. The circuitry may also operate in continuous conduction mode (CCM) or in discontinuous conduction mode (DCM) based on an operating region. The operating region is based on a combination of the demand from the load (Iout) and the input voltage (Vin). The circuitry of this disclosure may enter an operating region based on a first combination but exit the operating region under a second and different combination of Iout and Vin.