PWM Frequency Limiting in Switching Power Converters Under Variable Load
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Solution Overview
Problem
Existing switching power converting apparatuses have a fixed operating frequency, which leads to inefficiencies at light loads (low efficiency) and heavy loads (magnetic component saturation).
Innovation Solution
The improved switching power converting apparatus includes a power converting circuit, a sampling circuit, a signal gain adjustment circuit, a frequency limiting circuit, and a pulse width modulation controller. The sampling circuit detects the power converting circuit to obtain a sampled signal, which is adjusted by the signal gain adjustment circuit to generate a control signal. This control signal is used by the frequency limiting circuit to dynamically adjust the operating frequency based on the load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the operating frequency is fixed at a high value, then the switching speed is improved, but the efficiency deteriorates at light load
Solution Approach 1:
The patent applies dynamics by making the operating frequency adjustable rather than fixed. The frequency limiting circuit dynamically changes the operating frequency based on load conditions, allowing the system to adapt between high frequency (for switching speed) and low frequency (for efficiency at light load)
Solution Approach 2:
The patent changes the frequency parameter based on operating conditions. The frequency limiting circuit modifies the operating frequency parameter according to load status, transitioning between fixed high frequency and variable frequency modes to optimize performance
2Loss of energy
If the operating frequency is fixed at a low value, then the efficiency is improved at light load, but the magnetic component saturates at heavy load
Solution Approach 1:
The frequency limiting circuit enables dynamic frequency adjustment, allowing the system to operate at low frequency for efficiency at light load, and automatically switch to high frequency when heavy load is detected to prevent magnetic component saturation
Solution Approach 2:
The patent uses feedback through the frequency limiting circuit that monitors operating conditions and adjusts frequency accordingly. When heavy load is detected, the circuit provides feedback to increase frequency, preventing magnetic component saturation
3Reliability
If the operating frequency is dynamically adjusted, then the efficiency and reliability are improved, but the device complexity increases
Solution Approach 1:
The frequency limiting circuit serves multiple functions: it limits maximum frequency, adjusts frequency based on load, and protects against magnetic component saturation. This multi-functionality reduces the need for separate control circuits, thereby limiting the increase in device complexity
Data Source
AI summary
An improved switching power converting apparatus (10) includes a power converting circuit (102), a sampling circuit (104), a signal gain adjustment circuit (106), a frequency limiting circuit (108) and a pulse width modulation controller (110). The sampling circuit (104) is configured to detect the power converting circuit (102) to obtain a sampled signal (Vs) and transmit the sampled signal (Vs) to the signal gain adjustment circuit (106). The signal gain adjustment circuit (106) is configured to adjust the sampled signal (Vs) to obtain a control signal (Vcon) and transmit the control signal (Vcon) to the frequency limiting circuit (108). The pulse width modulation controller (110) is configured to control an operating frequency of the pulse width modulation controller (110) based on the control signal (Vcon).