Technical methods for reducing power consumption in high-power switching power supplies
With the increasing importance of energy efficiency and environmental protection, people have higher expectations for the standby efficiency of switch mode power supplies. Customers require power supply manufacturers to provide power products that meet green energy standards such as BLUEANGEL, ENERGY STAR, ENERGY 2000, etc. The EU's requirements for switch mode power supplies are that by 2005, the standby power consumption of switch mode power supplies with rated power of 0.3W~15W, 15W~50W, and 50W~75W should be less than 0.3W, 0.5W, and 0.75W, respectively.
At present, when most switching power supplies switch from rated load to light load and standby mode, the power efficiency drops sharply, and the standby efficiency cannot meet the requirements. This presents new challenges for power design engineers.
Analysis of Power Consumption of Switching Power Supply
To reduce standby losses and improve standby efficiency of switch mode power supplies, it is necessary to first analyze the composition of switch mode power supply losses. Taking flyback power supply as an example, its operating losses are mainly manifested as MOSFET conduction loss and MOSFET conduction loss
In standby mode, the main circuit current is low, the MOSFET conduction time ton is small, and the circuit operates in DCM mode, so the related conduction losses, secondary rectifier losses, etc. are small. At this time, the losses are mainly composed of parasitic capacitance losses, switch overlap losses, and starting resistance losses.
Switching overlap loss, PWM controller and its starting resistor loss, output rectifier tube loss, clamp protection circuit loss, feedback circuit loss, etc. The first three losses are directly proportional to frequency, that is, directly proportional to the number of device switches per unit time.
