CN103904894A - Novel wide-range power supply designing method - Google Patents

Abstract

The invention discloses a novel wide-range power supply designing method. According to the designing method, five modules, namely a rectifier module, a relay module, a hysteresis comparator module, a boost module and a flyback module are included. Input voltage reaches a load through the rectifier module, a relay 1, the boost module, a relay 2 and the flyback module. The hysteresis comparator module and the rectifier module are connected in parallel and control the relay 1 and the relay 2 to work. When the input voltage is high, the input voltage directly passes through a rectifier bridge to be used as input voltage of a flyback circuit, the two relays work under a normally-closed state, and a middle boost circuit does not work. When the input voltage is low, by judging of a hysteresis comparator, the two relays are controlled to be sucked, two switches are both turned to the normal-on state, the input voltage becomes V1 after rectification, the voltage is boosted to V2 through the boost circuit, and then the voltage is used as input voltage of the flyback circuit. The alternating-current input voltage range of a power supply can reach 25 V-265 V, and meanwhile a power supply with the direct-current output range of 150 V-400 V is borne.

Description

A New Design Method of Wide Range Power Supply

technical field

The invention relates to a design method of a novel wide-range power supply, in particular to a design method of a switching power supply with a DC voltage input of 150V-400V and compatible with an AC input voltage range of 25V-265V.

technical background

With the large number of applications of switching power supplies, the requirements for them are constantly improving, requiring high efficiency, high power factor, high power density, and high reliability.

When the switching power supply is required to be able to adapt to two voltage specifications of AC 110V and 220V, the switching power supply is generally designed to be 90~265V input. However, under some harsh working conditions, sometimes when the AC input voltage is lower than 90V or higher than 265V, the switching power supply is still required to work normally.

In addition, with the development of servers, the increase in power supply performance requirements, and the use of high-voltage DC power supply technology, the power supply that meets the 240V DC power of telecom has been designed, but the power supply that meets the 336V DC power introduced by the latest mobile is still under development. When analyzing the use of the power supply, we found that if we can make a power supply that can meet the DC input of 240V and 336V at the same time, then the general purpose of the power supply will be stronger, so we propose to design a DC voltage input that can withstand 150V-400V The power supply is also compatible with the power supply whose AC input voltage range can reach 25V-265V.

Contents of the invention

The technical problem to be solved by the present invention is: different from the input voltage range of 240V and 336V DC power supplies, expanding the acceptable input voltage range of the power supply to achieve high compatibility, and at the same time enabling the AC input voltage range to reach a wide range of 25V-265V, Meet the needs of the global market.

The technical scheme adopted in the present invention is:

A design method for a new wide-range power supply. The design method includes five modules: a rectifier module, a relay module, a hysteresis comparator module, a boost module, and a flyback module. The input voltage passes through the rectifier module, relay 1, and boost module. , Relay 2, Flyback module reaches the load, the hysteresis comparator module is connected in parallel with the rectifier module and controls the work of Relay 1 and Relay 2, when the input voltage ratio is high, the input voltage directly passes through the rectifier bridge as the input voltage of the flyback circuit, two The relays all work in the normally closed state, and the boost circuit in the middle does not work. If the input voltage is relatively low, through the judgment of the hysteresis comparator, the two relays are controlled to pull in, and both switches are turned to the normally open state. The input voltage becomes V1 after rectification, and then the voltage is increased by the booster circuit to obtain V2. Then as the input voltage of the flyback circuit. When the hysteresis comparator is used to judge the input voltage level, there is a hysteresis range, which makes the circuit work more stably.

Whether the two relays are normally closed or normally open, there are 4 combined working modes in the entire circuit:

Mode 1 normally open normally open DC-DC after boost first

Mode 2 normally closed normally closed direct DC-DC without boost

Mode 3 normally closed normally open invalid mode

Mode 4 normally open normally closed invalid mode

The working principle of the flyback module is as follows:

When the switch tube is turned on, the inductance current on the primary side of the transformer starts to rise. At this time, due to the relationship between the secondary terminal with the same name, the output diode is cut off, the transformer stores energy, and the load is supplied with energy by the output capacitor. When the switch tube is turned off, the voltage induced by the inductance on the primary side of the transformer is reversed, and the output diode is turned on at this time, and the energy in the transformer supplies power to the load through the output diode, and at the same time charges the capacitor to supplement the energy just lost.

For a wide range of input DC voltage design methods, a high compatibility DC power supply design method is adopted to improve compatibility. The implementation method is as follows:

In the flyback module, a highly compatible voltage-controlled oscillator is used for current control, and a voltage-controlled element is used as a frequency control device in the oscillation circuit. If DC voltage is used as the control voltage, the voltage-controlled oscillator can be made into a very convenient signal source for frequency adjustment.

The traditional flyback switching power supply is designed as follows:

This design can only control the voltage below 264V by controlling the current IC. Due to the difference in input voltage, the linear change rate of the transformer inductor current is different, so the conduction time of the power switch tube is also completely different; The turn-on time of the power MOSFET is very short during input, only 300-600nS, and the instantaneous peak current flowing through the power MOSFET is very large; a saturation state may occur when the power MOSFET is turned off. The result is that the power conversion does not turn on linearly at turn-on, resulting in reduced efficiency and reduced reliability of the converter.

The current control of the high-compatibility voltage-controlled oscillator is to remove the control of the reference voltage to the timing resistor in the design of the traditional flyback switching power supply, and introduce a variable voltage given timing resistor and error amplifier, and the voltage converter is set at the error After the amplifier and the voltage-controlled oscillator (VCO), a simple voltage regulator tube is placed in the error amplifier to accept the change of the entire output voltage. When the input voltage is the lowest and the output power is fully loaded, the duty cycle of the switch tube will exceed 50%, and the input voltage of the VCO will reach the required value.

On the basis of this method, the relevant parameters of the resistance, capacitance and inductance are readjusted accordingly to achieve a wide input voltage standard.

The beneficial effects of the present invention are:

The AC input voltage range of the power supply using the method of the present invention can reach 25V-265V; at the same time, the power supply with a DC voltage input range of 150V-400V can maintain normal operation, and can achieve high efficiency, high power factor, high power density, high reliability, etc. Requirements, with the continuous promotion of this new type of wide-range power supply technology, and the large demand for energy-saving equipment, it will have a broad application prospect in the server market.

Description of drawings

Fig. 1 is a schematic diagram of the circuit structure of the present invention;

2 is a schematic diagram of the basic circuit of the flyback topology of the present invention;

Figure 3 shows the traditional flyback switching power supply design

FIG. 4 is a schematic diagram of current control of a high-compatibility voltage-controlled oscillator.

Detailed ways

Below with reference to accompanying drawing, the present invention is further described by specific embodiment:

A design method for a new type of wide-range power supply. The design method includes five modules: a rectifier module, a relay module, a hysteresis comparator module, a boost module, and a flyback module. The input voltage passes through the rectifier module, relay 1, and boost module. , relay 2, and the flyback module reach the load, and the hysteresis comparator module is connected in parallel with the rectifier module to control the work of relay 1 and relay 2. When the input voltage ratio is high, the input voltage directly passes through the rectifier bridge as the input voltage of the flyback circuit, as shown in the figure 1. The two relays in the figure are both working in the normally closed state, and the boost circuit in the middle does not work. If the input voltage is relatively low, through the judgment of the hysteresis comparator in the figure, the two relays are controlled to pull in, and the two switches are both in the normally open state. Therefore, when the input voltage Vac is rectified and becomes V1, and then boosted The circuit increases the voltage to obtain V2, which is then used as the input voltage of the flyback circuit. When the hysteresis comparator is used to judge the input voltage level, there is a hysteresis range, which makes the circuit work more stably.

Whether the two relays are normally closed or normally open, there are 4 combined working modes in the entire circuit:

Mode 1 normally open normally open DC-DC after boost first

Mode 2 normally closed normally closed direct DC-DC without boost

Mode 3 normally closed normally open invalid mode

Mode 4 normally open normally closed invalid mode

As shown in Figure 2, the working principle of the flyback module is as follows:

When the switch tube is turned on, the inductance current on the primary side of the transformer starts to rise. At this time, due to the relationship between the secondary terminal with the same name, the output diode is cut off, the transformer stores energy, and the load is supplied with energy by the output capacitor. When the switch tube is turned off, the voltage induced by the inductance on the primary side of the transformer is reversed, and the output diode is turned on at this time, and the energy in the transformer supplies power to the load through the output diode, and at the same time charges the capacitor to supplement the energy just lost.

Design method for a wide range of input DC voltages:

This high-compatibility DC power supply design method to improve compatibility is mainly implemented in the flyback module, specifically using a high-compatibility voltage-controlled oscillator current control: the core is to use voltage-controlled components as the frequency in the oscillation circuit control device. If DC voltage is used as the control voltage, the voltage-controlled oscillator can be made into a very convenient signal source for frequency adjustment.

As shown in Figure 3, the traditional flyback switching power supply is designed as follows:

This design can only control the voltage below 264V by controlling the current IC. Due to the difference in input voltage, the linear change rate of the transformer inductor current is different, so the conduction time of the power switch tube is also completely different; The turn-on time of the power MOSFET is very short during input, only 300-600nS, and the instantaneous peak current flowing through the power MOSFET is very large; a saturation state may occur when the power MOSFET is turned off. The result is that the power conversion does not turn on linearly at turn-on, resulting in reduced efficiency and reduced reliability of the converter.

As shown in Figure 4, the current control of the high-compatibility voltage-controlled oscillator, in the traditional flyback switching power supply design, removes the control of the reference voltage on the timing resistor, and introduces a variable voltage to give the timing resistor and error amplifier, the voltage The converter is set between the error amplifier and the voltage-controlled oscillator (VCO). A simple Zener tube is placed behind the error amplifier to accept the change of the entire output voltage. When the input voltage is the lowest and the output power is fully loaded, the switch The duty cycle of the tube will exceed 50%, and the input voltage of the VCO will reach the required value.

On the basis of this method, the relevant parameters of resistance, capacitance and inductance are adjusted accordingly to achieve a wide input voltage standard. At present, the voltage input of 150VDC-400VDC can be realized, which is compatible with the 240VDC of telecom and the 336VDC standard of mobile.

Of course, related parameters can also be changed according to other requirements to achieve higher and wider DC voltage input.

Claims (4)

1. the method for designing of a novel wide-range power, it is characterized in that: affiliated method for designing comprises five modules: rectification module, relay module, hysteresis comparator module, boost module, flyback module, wherein input voltage is through rectification module, relay 1, boost module, relay 2, flyback module arrives load, hysteresis comparator module also control relay 1 in parallel with rectification module and relay 2 are worked, when input voltage is when high, input voltage directly passes through the input voltage of rectifier bridge as circuit of reversed excitation, two relays are all operated in normally off, middle booster circuit is not worked, in the time that input voltage is lower, by the judgement of hysteresis comparator, control two relay adhesives, two switches are all got to normally open, input voltage becomes V1 after over commutation, then improves voltage through booster circuit and obtain V2, then as the input voltage of circuit of reversed excitation.

2. the method for designing of a kind of novel wide-range power according to claim 1, is characterized in that: in flyback module, adopt highly compatible voltage controlled oscillator Current Control, adopt voltage-controlled element as frequency control device in oscillating circuit.

3. the method for designing of a kind of novel wide-range power according to claim 2, it is characterized in that: described highly compatible voltage controlled oscillator Current Control, in the design of classical inverse excitation type switch power-supply, remove the control of reference voltage to timing resistor, introduce a variable voltage to timing resistor and error amplifier, after electric pressure converter is arranged on error amplifier and between voltage controlled oscillator, be placed on error amplifier and accepted afterwards the variation of whole output voltage with a simple voltage-stabiliser tube, when input voltage minimum, and power output full load, the duty ratio of switching tube will exceed 50%, the input voltage of VCO will reach required evaluation.

4. the method for designing of a kind of novel wide-range power according to claim 3, is characterized in that: the relevant parameter of corresponding regulating resistance, electric capacity and inductance, realize wide input voltage standard.

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