A novel PWM control in the secondary side driven of power supply unit

Abstract

This paper investigates a novel varying-frequency isolated drive power supply method using an isolation method to drive a primary side high-voltage circuit of a power supply by a secondary side PWM, while using a varying-frequency method as a control method to enhance effectiveness and efficiency. The control method mainly focuses on the importance of present power management and energy saving, so that it is necessary to reduce the power consumption while the power supply is working or standby. Therefore, this paper proposed and verified some practical methods to reduce the switching loss or other normal rated losses of a switching power supply at a very light load or no load. In addition, the pros and cons of varying-frequency synchronous rectification and other loss reduction technologies are introduced. The new control method disclosed in this paper also takes the voltage resistance level of the surge protection of electronic products into consideration. In general, a power supply is the electronic device having the most impact on surges. For induced voltages or currents produced by indoor indirect contact surges, European Union CE regulation EN 55024 requires all ITE products should pass and certify the EN61000–4–5 surge test, and adjustments of the design and arrangement for integrated circuit protection structure for the power supply are taken if necessary. Therefore, this paper also emphasizes this specification for the test and shows that the installed secondary side can prevent or reduce the influence of surges. In the meantime, the design method provided by this paper completes the experiments on 5V/8A and 12V/13A power supplies with a total output of 196W, and achieves an excellent energy-saving effect in the condition of a reduced switching loss. Besides the lightning prevention is measured such as a lightning rod or grounded BYPASS method.