CN205265546U - Power adapter - Google Patents

Abstract

The utility model relates to a power adapter and aims to solve the problem of low conversion efficiency and high standby power consumption of the existing power adapter. The utility model provides a power adapter, which includes an AC input port, a pre-stage protection circuit connected in series with the AC input port, an EMI filter circuit, an input rectification circuit, an RCD clamp circuit, a PWM circuit, a power conversion circuit, and an output rectification filter The circuit and the branch output port, the voltage and current feedback modulation circuit connected with the PWM circuit and the switch tube current control circuit, the voltage feedback circuit connected with the power conversion circuit, the voltage and current feedback modulation circuit connected with the switch tube current control circuit and the voltage feedback circuit. The utility model is suitable for power supply adapters of household appliances.

Description

Power Adapter

technical field

The utility model relates to a power adapter.

Background technique

Switching power supply, also known as power adapter, broadly speaking, any device that uses a semiconductor power switching device as a switch tube and converts one form of electrical energy into another form of electrical energy through high-frequency on and off control of the switch tube is called a switch. Converter. The power supply with switching converter as the main component, using closed-loop automatic control to stabilize the output voltage, and adding protection links to the circuit is called switching power supply. With the increasing popularity of mobile electronic products, power adapters are increasingly widely used, such as set-top boxes, routers, walkmans, notebooks and other equipment. However, limited by the characteristics and technical level of the current electronic components, the power adapter has the disadvantages of large starting current during operation, high power consumption during standby, and large audio noise during operation, resulting in poor overall performance. At the same time, global concerns about rising energy costs, environmental protection, and energy sustainability are driving relevant agencies in the European Union, California, and other places to successively introduce regulations to reduce energy consumption of electronic equipment. AC input power, whether it is independent or integrated in electronic equipment, will cause a certain amount of energy waste; first, the efficiency of the power supply cannot be 100%, and part of the energy is wasted when the power supply is working under heavy load; secondly, when the A power supply connected to the AC line consumes energy in the form of standby power when the load is not in use. In addition, in recent years, the requirements for power efficiency levels have become increasingly stringent, and meeting CECLever5 has become a basic standard. The energy efficiency standard of the new initiative is DOELot6. Also, the old way of testing efficiency only at full load is obsolete. The current new standard involves the average of the four points of 25%, 50%, 75% and 100% of the rated load. Similarly, the maximum allowable standby power consumption is increasingly restricted. The European Union currently requires that the standby power consumption be less than 0.3W as an acceptable limit for low-power power adapters (output power ≤ 49W). The new standby power consumption standard is even more Less than 0.1W. Therefore, whether it is to maintain the sustainable development of the earth for energy conservation and environmental protection, or to meet the energy standards of various countries, it is of great significance and market prospect to develop green power adapters with high conversion efficiency and low standby power consumption.

Utility model content

The purpose of the utility model is to solve the problem of low conversion efficiency and high standby power consumption of existing power adapters.

In order to achieve the above purpose, the utility model provides a power adapter, including a PCB board and an AC input port installed on the PCB board, a front-stage protection circuit for a DC output port, an EMI filter circuit, an input rectifier circuit, an RCD clamp circuit, a PWM circuit, power conversion circuit, voltage feedback circuit, switching tube current control circuit, voltage and current feedback modulation circuit and output rectification and filtering circuit;

The AC input port is connected to the pre-stage protection circuit, the pre-stage protection circuit is connected to the EMI filter circuit, the EMI filter circuit is connected to the input rectifier circuit, the input rectifier circuit is connected to the RCD clamp circuit, the RCD clamp circuit is connected to the PWM circuit, The PWM circuit is respectively connected with the voltage and current feedback modulation circuit, the switching tube current control circuit and the power conversion circuit, the power conversion circuit is respectively connected with the output rectification filter circuit and the voltage feedback circuit, the output rectification filter circuit is connected with the DC output port, and the voltage and current feedback modulation The circuit is respectively connected with the switch tube current control circuit and the voltage feedback circuit.

Specifically, the pre-stage protection circuit includes a plastic-sealed fuse, a fuse resistor, and a varistor, one end of the fuse resistor is connected to the EMI filter circuit, the other end is connected to one end of the varistor and the live wire, and the other end of the varistor Connect with one end of the plastic-sealed safety tube, and connect the other end of the plastic-sealed safety tube with the zero line.

Specifically, the output rectification and filtering circuit includes a diode, a resistor, a first capacitor, a second capacitor, and a third capacitor. The resistor is connected in series with the first capacitor and then connected in parallel with the diode. The anode of the diode is connected to the power conversion circuit. The cathode of the tube is connected to the second capacitor, the second capacitor is connected in parallel to the third capacitor, and the third capacitor is connected to the DC output port.

Preferably, an adapter housing is also included, and the PCB board is installed in the adapter housing.

Specifically, the adapter housing is a plastic housing.

The beneficial effects of the utility model are: by providing a power adapter convenient for the power supply of household electrical equipment, including a casing and a PCB arranged in the casing, in the limited casing, a reasonable layout design is carried out for the PCB, and the power supply control chip and Reasonable selection of circuit parameters. It can greatly reduce the energy consumption of the designed product, and the average efficiency and standby power consumption of the designed power adapter are far lower than the CECLever5 energy efficiency standard.

Description of drawings

Fig. 1 is a functional block diagram of the power adapter of the present invention.

detailed description

The utility model provides a power adapter for solving the problem of low conversion efficiency of the existing power adapter and high standby power consumption. , the protection of the post-stage circuit under the condition of abnormally large voltage and abnormally large current; the EMI filter circuit is used to shield the external electromagnetic interference, and at the same time, it is also used to shield the electromagnetic interference generated by itself; The input alternating current is rectified into a pulsating direct current, and at the same time, the pulsating direct current is smoothed to become a pure square wave current; the RCD clamp circuit is used to absorb the leakage inductance peak of the switching transformer; the PWM circuit is used for pulse width modulation of the input voltage , the PWM power switch is realized by a triode; power conversion circuit. This circuit mainly relies on a switching transformer to realize step-down and power conversion, which is used to convert the high voltage of about 300V after primary rectification and filtering into a low voltage of 5.2VDC; voltage feedback circuit, this scheme uses primary side feedback, and the sampling voltage is the feedback winding. The voltage; switch tube current control circuit. It is used to sample the current signal flowing through the switch tube; the voltage and current feedback modulation circuit is used to adjust the opening and closing of the switch tube after integrating the voltage and current feedback signals; the output rectification filter circuit. Realize the rectification and smoothing of the pulsating signal after step-down by the transformer into the pure low voltage 5.2VDC required by the terminal equipment.

The AC input port is connected to the pre-stage protection circuit, the pre-stage protection circuit is connected to the EMI filter circuit, the EMI filter circuit is connected to the input rectifier circuit, the input rectifier circuit is connected to the RCD clamp circuit, the RCD clamp circuit is connected to the PWM circuit, and the PWM circuit They are respectively connected to the voltage and current feedback modulation circuit, the switching tube current control circuit and the power conversion circuit. The power conversion circuit is respectively connected to the output rectification filter circuit and the voltage feedback circuit. The output rectification filter circuit is connected to the DC output port. It is connected with the switching tube current control circuit and the voltage feedback circuit.

The PWM circuit of the single output power adapter of the utility model is the used control chip C2174PX8, and the control mode of the C2174 is current type pulse width modulation. The chip is mainly composed of CC control module, CV control module, line compensation module, transient detection module, timing module and PWM/PFM selection module. It is a hybrid switching mode of PWM and PFM during normal operation, while conventional chips are mostly in PWM (pulse width modulation) switching mode during normal operation, thus solving the low power consumption during normal operation from the chip itself. At the same time, the chip has built-in Input undervoltage protection module, output overcurrent protection module, output overvoltage protection module, etc., thus improving the stability and reliability of the system.

The EMI filter circuit of the single output power adapter of the utility model is mainly completed by a Π-type filter circuit composed of a bridge rectifier and two capacitors. The common mode inductor has the characteristics of bidirectional high impedance, which can effectively suppress the electromagnetic interference introduced by the input terminal.

The input rectification circuit of the single output power adapter of the utility model is designed as a complete rectification composed of rectification bridge stacks.

The single-output power supply adapter RCD clamping circuit of the utility model is composed of a resistor, a capacitor and a diode. It is used to absorb and clamp the peak voltage generated by the leakage inductance of the transformer. To achieve the purpose of protecting the reliable operation of the IC.

The PWM circuit of the single output power adapter of the present invention is the used control chip C2174PX8.

The power conversion circuit of the single output power adapter of the utility model mainly includes a switching transformer. It is used to convert the rectified DC power into the voltage required by customers under PWM control. At the same time, when designing the switching transformer, use the safety frame (with primary side and secondary side) instead of the secondary flying lead, which is both Isolation of high and low voltages is possible, allowing compliance with safety regulations and ease of production.

The voltage feedback circuit of the single output power adapter of the utility model divides the voltage on the feedback winding by two series voltage dividing resistors, and the voltage on the voltage dividing resistor is recognized by the PWM controller and compared with the internal reference voltage. The comparison voltage U1 is obtained after the error amplifier.

The switch tube circuit control circuit of the single output power adapter of the utility model is composed of three parallel resistors, which are used to detect the current flowing through the switch tube in the primary winding of the transformer.

Claims (5)

1. power supply adaptor, it is characterized in that, comprise pcb board and be arranged on ac input end mouth, DC output end mouth prime holding circuit, EMI filter circuit, input rectification circuit, RCD clamp circuit, pwm circuit, power conversion circuit, voltage feedback circuit, switching tube current control circuit, feedback of voltage and current modulation circuit and the output rectifier and filter on pcb board;

Described ac input end mouth is connected with prime holding circuit, prime holding circuit is connected with EMI filter circuit, EMI filter circuit is connected with input rectification circuit, input rectification circuit is connected with RCD clamp circuit, RCD clamp circuit is connected with pwm circuit, pwm circuit respectively with feedback of voltage and current modulation circuit, switching tube current control circuit and power conversion circuit connect, power conversion circuit is connected with output rectifier and filter and voltage feedback circuit respectively, output rectifier and filter is connected with DC output end mouth, feedback of voltage and current modulation circuit is connected with switching tube current control circuit and voltage feedback circuit respectively.

2. power supply adaptor as claimed in claim 1; it is characterized in that; described prime holding circuit comprises plastic packaging protective tube, insurance resistance and piezo-resistance; described insurance resistance one end is connected with EMI filter circuit; the other end is connected with one end and the live wire of piezo-resistance; the other end of piezo-resistance is connected with one end of plastic packaging protective tube, and the other end of plastic packaging protective tube is connected with zero line.

3. power supply adaptor as claimed in claim 1, it is characterized in that, described output rectifier and filter comprises diode, resistance, the first electric capacity, the second electric capacity and the 3rd electric capacity, after described resistance and the first capacitances in series with diodes in parallel, the positive pole of diode is connected with power conversion circuit, the negative pole of diode is connected with the second electric capacity, the second electric capacity and the 3rd Capacitance parallel connection, and the 3rd electric capacity is connected with DC output end mouth.

4. power supply adaptor as claimed in claim 1, is characterized in that, also comprises adapter shell, and described pcb board is arranged in adapter shell.

5. power supply adaptor as claimed in claim 1, is characterized in that, described adapter shell is plastic casing.