TW201541839A - A switching power supply circuit - Google Patents

Abstract

A switching power supply circuit includes a primaryside and a secondary side. The primaryside comprises a primary winding to receive an input voltage. The secondary side comprises a first secondary winding, a second secondary winding, an output winding switch and output voltage detection means for detecting a supply voltage signal and controlling the output winding switch. When on the output voltage detection means judge the supply voltage signal as a low voltage state or a high voltage state, the output winding switch will be turned off or turned on, respectively, to adjust the turn of the secondary winding. Whereby, the switching power supply circuit can adjust its turn ratio to fit the different demands of an output supply voltage.

Description

Switching power supply circuit

The invention relates to a switching power supply circuit, in particular to a design of a switching power supply circuit in a Flyback architecture, so that the turns ratio of the transformer can be flexibly adjusted according to practical application.

Flyback Switching Mode Power Supply (SMPS) has the advantages of high efficiency, low loss, small size and light weight, so it has been widely used as a power conversion device for various electronic products, such as Taiwan. The prior art of a flyback switching power supply is disclosed in the patent TW201014139. Please refer to FIG. 1 , which is a schematic diagram of a conventional flyback power supply 100. The rectifier circuit 101 and the filter capacitor 102 are used to rectify and filter the AC input voltage Vac to generate an input voltage Vdc. Input winding 110 (primary winding) is used to receive the input voltage. The output winding 120 (secondary winding), the output switch 121 and the output capacitor 122 are used to generate an output voltage Vout. The output voltage Vout can also be processed by a signal of a feedback circuit (not shown), and the feedback signal Sfb is generated and fed back to the switch control circuit 150. The auxiliary winding 130, the auxiliary voltage output switch 131, and the auxiliary output capacitor 132 are used to generate the auxiliary voltage Vaux, which is supplied to the switch control circuit 150, which is a pulse width modulator (PWM IC), and provides a pulse signal to control the power input switch. 160.

Prior art Flyback design using a single set of output coils, only Detecting the output voltage setting signal and changing the voltage division ratio of the feedback signal. However, electronic products have different voltage requirements. Therefore, a power supply must also provide different voltages according to different output voltage requirements, such as Qualcomm®. The Quick Charge 2.0 (QC2.0) specification requires a voltage of 5/9/12/20V. However, in the case of such a design, if there is a large voltage difference between the lowest and highest output voltages, the design has the following problems:

The amount of change in the auxiliary voltage Vaux voltage is too large. The auxiliary voltage Vaux provides the power required by the switch control circuit 150, which itself is like a flyback line shared by the auxiliary winding 130 and the secondary side (output side) output, so the design of the auxiliary voltage Vaux can be based on the secondary side (output The output voltage Vout of the side is calculated by the auxiliary winding 130 and the secondary winding 120: Where Vout is the output voltage, the number of turns of the Naux auxiliary winding, and Nsec is the number of turns of the output winding (secondary winding). According to the requirements of QC2.0, the minimum output voltage Vout is 5V, and the highest output voltage Vout is 20V. When the demand is brought into the equation (1), it is found that the auxiliary voltage Vaux is four times the output voltage Vout when the output voltage Vout is 20V. According to this situation, the switch control circuit 150 is easily damaged due to insufficient voltage and the primary side. (Input side) Low efficiency, the higher the output voltage Vout voltage, the worse the efficiency.

Duty Cycle limit. In fact, the duty cycle is operated at a specific duty ratio according to the number of turns of the transformer design, and the PWM IC only stably controls the system at this operating point. As shown in Fig. 2, when Vdc is the input DC voltage and Vor is the secondary side conduction, the reflected voltage obtained on the primary side is Faraday's law: Vdc × Ton = Vor × Toff (Formula 2). Equal to the area of B. And the Vor relationship is: Where Np is the number of turns of the primary winding and N is the turn ratio of the transformer. According to the specification of QC2.0, when the output voltage Vout is raised from 5V to 20V, Vout becomes 4 times, and when the number of turns is fixed to N, the reflected voltage Vor is 4 times that of the original according to the formula of Equation 3. '=4Vor), in order to balance the area of A and B, the Ton time must be extended to Ton', so that the duty ratio becomes larger. In general, PWM ICs have a maximum duty cycle limit and cannot be increased indefinitely, so when the output voltage rises, it is usually accompanied by a problem of poor system control stability.

Since the transformer turns ratio is fixed, it will have too high reflected voltage (Vor) and excessive duty cycle (Duty Cycle) at the maximum output voltage, and too low reflected voltage at the lowest output voltage. And the duty cycle makes the actual control quite difficult. In addition, since the auxiliary power supply Vaux is determined by the auxiliary coil, the secondary side (output side) coil and the output voltage Vout in the transformer, when the output voltage Vout is too high, the excessive auxiliary voltage Vaux may be caused once. The side control line is damaged, and at the lowest output voltage, the auxiliary power supply Vaux that is too low may not be able to operate the control line on the primary side.

An exchange power supply circuit includes a primary side and a secondary side, the primary side including an input line including an input winding, wherein the input winding is for receiving an input voltage Vdc. The secondary side includes a first output line and a second output line. A first output line includes a first output winding, a first output switch and a first output capacitor, and the first output switch and the first output capacitor are electrically coupled to the first output winding. a second output line, the package thereof The second output winding, the second output switch and the second output capacitor are electrically coupled to the second output winding. The first output winding is electrically coupled in series with the second output winding. The first output capacitor and the second output capacitor are connected in series at a series of contacts, and an output voltage Vout is transmitted from the series contact. An output winding switch in parallel with the second output capacitor and having a gate. An output voltage detection means is connected in parallel with the first output capacitor and electrically connected to the series connection point for detecting a supply and output voltage signal Vs and controlling the gate end. A power input switch is connected in series with the input winding. An auxiliary circuit includes an auxiliary winding, an auxiliary output switch and an auxiliary output capacitor. The auxiliary output switch 232 is electrically coupled to the auxiliary winding to generate an auxiliary voltage Vaux. A switch control circuit whose operating voltage is supplied by the auxiliary voltage Vaux and generates a pulse output PWM to control whether the power input switch is turned on or off.

When the output voltage detection means detects that the supply and output voltage signal Vs is in a low voltage state, the gate is controlled to open the output winding switch, and the second output winding is in a disabled state. At this time, the output voltage Vout Controlled by the first output winding and the input winding. The auxiliary voltage Vaux is controlled by the auxiliary winding and the first output winding. When the output voltage detection means detects that the supply and output voltage signal Vs is in a high voltage state, controlling the gate end to turn on the output winding switch, and the second output winding is in a state of uniform energy, and the first output winding is The second output winding is electrically connected in series, whereby the output voltage Vout is controlled by the first output winding, the second output winding and the input winding connected in series. The auxiliary voltage Vaux is controlled by the auxiliary winding and the first output winding and the second output winding connected in series.

The power supply circuit of the present invention, wherein the first output line and the second output line are connected in a manner that the first output switch, the first output capacitor and the first output winding are connected in series in an end-to-end manner. a winding point of the second output winding is connected to the first end of the second output switch, and a final winding point of the second output winding is connected to the starting point of the first output winding and the first The first end of the output switch is connected to the second end of the second output capacitor. The second end of the second output capacitor is coupled in series with the first end of the first output capacitor. When the second output winding is in the disabled state, the first output switch is turned on, and the second output switch is turned off by the output winding switch 290. When the second output winding is in the enabled state, the second output switch is turned on, and the first output switch is turned off.

The power supply circuit of the present invention, wherein the first output line and the second output line are connected in a manner that the first output switch, the first output capacitor and the first output winding are connected in series in an end-to-end manner. a first end of the second output switch is connected to a starting point of the first output winding and a first end of the first output switch, and a second end of the second output switch is connected to a final winding point of the second output winding, The winding end of the second output winding is connected to the first end of the second output capacitor, and the second end of the second output capacitor is connected in series with the first end of the first output capacitor. When the second output winding is in the disabled state, the first output switch is turned on, and the second output switch is turned off by the output winding switch 290. When the second output winding is in the enabled state, the second output switch 241 is turned on, and the first output switch is turned off.

The power supply circuit of the present invention, wherein the first output line and the second output line are connected in a manner that the second output switch, the second output capacitor and the second output winding are connected in series in an end-to-end manner. The second end of the first output switch is connected to the final winding point of the second output winding and the first end of the second output switch, and the first end of the first output switch is connected to the starting point of the first output winding, The final winding of the first output winding is connected to the second end of the first output capacitor, and the second end of the second output capacitor is connected in series with the first end of the first output capacitor. When the second output winding is in the disabled state, the first output switch and the second output switch are turned on. When the second output winding is in the enabled state, the second output switch is turned off, and the first output switch is turned on.

The power supply circuit of the present invention, wherein the first output switch, the first output capacitor and the first output winding are connected in series in an end-to-end manner; the final winding point of the second output winding is connected to the second output switch a second end, the winding point of the second output winding is connected to a final winding point of the first output winding and a second end of the first output switch, and the first end of the second output switch is connected to the second end of the second output capacitor a first end of the second output capacitor is connected in series with the second end of the first output capacitor; and when the second output winding is in the disabled state, the first output switch is turned on, the first The two output switches are turned off by the output winding switch 290; when the second output winding is in the enabled state, the second output switch is turned on, and the first output switch is turned off.

The power supply circuit of the present invention, wherein the first output winding is electrically coupled in parallel with the second output winding, and an output voltage is sent from both ends of the first output capacitor; an output winding switch has a gate and is electrically The first output capacitor is coupled between the first output capacitor and the second output capacitor. An output voltage detection means is connected in parallel with the first output capacitor for detecting a supply and output voltage signal and controlling the gate; when the output voltage detection means detects that the supply and output voltage signal is a low voltage In the state, controlling the gate to open the output winding switch, wherein the output voltage is controlled by the first output winding and the input winding, the auxiliary voltage is controlled by the auxiliary winding and the first output winding; When the output voltage detection means detects that the supply and output voltage signal is in a high voltage state, controlling the gate end to turn on the output winding switch, and the output voltage is controlled by the second output winding and the input winding.

The power supply circuit of the present invention, wherein the output voltage detecting means determines whether the supply and output voltage signal Vs is the high voltage state or the low voltage state according to a threshold voltage Vth. The high voltage state is when the voltage supply signal Vs is higher than the threshold voltage, and the low voltage state is when the power supply voltage signal Vs is lower than the threshold voltage, wherein the threshold voltage is not a fixed value, and the output voltage detection means 280 can be used. Change settings. The first output switch and the second output switch include: a power diode and a power MOSFET. The output winding switch, the power input switch includes Power transistor, thyristor component.

100‧‧‧Return-type power supply

10‧‧‧Input line

101 201‧‧‧Rectifier circuit

102 202‧‧‧Filter capacitor

110 210‧‧‧Input winding

120‧‧‧Output winding

121‧‧‧Output switch

122‧‧‧Output capacitor

120‧‧‧Output winding

121‧‧‧Output switch

122‧‧‧Output capacitor

30‧‧‧Auxiliary lines

130 230‧‧‧Auxiliary winding

131 231‧‧‧Auxiliary voltage output switch

132 232‧‧‧Auxiliary output capacitor

150 250‧‧‧Switch Control Circuit (PWM IC)

160 260‧‧‧Power input switch

20‧‧‧First output line

220‧‧‧First output winding

221‧‧‧First output switch

222‧‧‧First output capacitor

40‧‧‧second output line

240‧‧‧second output winding

241‧‧‧Second output switch

242‧‧‧second output capacitor

290‧‧‧Output winding switch

280‧‧‧ Output voltage detection means

Vac‧‧‧AC input voltage

Vdc, Vdc'‧‧‧ input DC voltage

Vin‧‧‧Input voltage

Vaux‧‧‧Auxiliary voltage

Vout‧‧‧ output voltage

Vs‧‧‧ supply voltage signal

Vor, Vor'‧‧·reflection voltage

Vref‧‧‧reference voltage

Vth‧‧‧ threshold voltage

Np‧‧‧Input winding turns

Naux‧‧‧Auxiliary winding turns

Nsec‧‧‧ Output winding turns

N‧‧‧ turns ratio

Vc‧‧‧ control signal

Vref‧‧‧ a reference voltage terminal

Sfb‧‧‧ feedback signal

The first figure is a prior art of a flyback switching power supply circuit.

The second graph shows the effect of the change in the ratio of the ratio between the input side (primary side) and the output side (secondary side) on the duty cycle.

The third figure is an embodiment of the switching power supply circuit of the present invention.

The fourth figure is another embodiment of the switching power supply circuit of the present invention.

The fifth figure is another embodiment of the switching power supply circuit of the present invention.

The sixth drawing is another embodiment of the switching power supply circuit of the present invention.

The seventh figure is another embodiment of the switching power supply circuit of the present invention.

The eighth figure is another embodiment of the switching power supply circuit of the present invention.

In order to make the present invention more comprehensible, the following is a detailed description of the exchange power supply and its control method according to the present invention, with reference to the accompanying drawings, but the embodiments provided are not intended to limit the present invention. The scope covered.

The exchange power supply (transformer) circuit provided by the invention has an output winding (secondary winding) with adjustable number of turns, and adjusts the number of turns of the output winding (Nsec) according to the demand of different output voltages (Vout), thereby correcting The turns ratio (N) is used to reduce the variation of the auxiliary voltage Vaux and the duty ratio. Conceptually, the transformer consists of a single-side winding that is changed from a single single coil to two or more sets of coils in series. The external control circuit detects the actual output voltage requirement: when the output voltage is in the lower output range, only one single coil is turned on by controlling one switching element. When the output voltage is in the higher output range, the switching element is controlled so that the two coils are connected in series to achieve a relatively low coil ratio, so that the previously mentioned problems can be overcome.

The power supply circuit shown in FIG. 3 has an input line 10 on the primary side thereof, and includes a rectifier circuit 201, a filter capacitor 202 and an input winding 210. The rectifier circuit 201 and the filter capacitor 202 are rectified and filtered to generate an input voltage Vdc. Winding 210 receives an input voltage Vdc. The secondary side includes a first output line 20 and a second output line 40. The first output line 20 includes a first output winding 220 (having a number of turns Nsec1), a first output switch 221 and a first output capacitor 222, the first output switch 221, the first output capacitor 222 and the first output winding The electrical coupling is electrically coupled to the first output switch 221, the first output capacitor 222 is connected in series with the first output winding 220, and the first output winding 220 is connected to the first point. The first end (P end) of the output switch 221, the second end (N end) of the first output switch 221 is connected to the first end of the first output capacitor 222 and the positive end (+) of the output voltage Vout, the first output winding The second winding end of 220 connects the second end of the first output capacitor 222 with the negative terminal (-) of the output voltage Vout. a second output line 40 comprising a second output winding 240 (having a number of turns Nsec2), a second output switch 241 and a second output capacitor 242, the second output switch 241, the second output capacitor 242 and the second output winding The electrical coupling of the second output winding 240 is connected to the first end (P end) of the second output switch 241, and the second end (N end) of the second output switch 241 is electrically coupled. The first output capacitor 242 is connected to the first output capacitor 242. The second output capacitor 242 is connected in series with the first output capacitor 222. The second end of the second output capacitor 242 is connected to the first end of the first output capacitor 222. The second output winding 240 is electrically coupled in series with the first output winding 220. The final winding point of the second output winding 240 electrically coupled in series is directly connected to the winding point of the first output winding 220.

The auxiliary circuit 30 includes an auxiliary winding 230 (having a number of turns Naux), an auxiliary output switch 231, and an auxiliary output capacitor 232. The auxiliary output switch 231 and the auxiliary output capacitor 232 are electrically coupled to the auxiliary winding 230. Electrical coupling mode is auxiliary output switch 231, auxiliary The output capacitor 232 is connected in series with the auxiliary winding 230. The auxiliary winding 230 is connected to the first end of the auxiliary output switch 231, and the second end of the auxiliary output switch 231 is connected to the first end of the auxiliary output capacitor 232. And outputting an auxiliary voltage Vaux for providing a voltage source of the switch control circuit 250 (pulse width modulator: PWM IC). A power input switch 260 has a first end connected in series with the input winding 210 (such as a winding point connecting the input winding 210), a second end of the power input switch 260, a final winding point of the auxiliary winding 230, and an auxiliary output capacitor 232. The second end is commonly connected to a reference voltage Vref, and the pulse signal outputted by the switch control circuit 250 controls the gate of the power input switch 260 to control the switch 260 to be turned on or off.

An output winding switch 290 is connected in parallel with the second output capacitor 242. The first end of the output winding switch 290 is connected to the first end of the second output capacitor 242, and the second end of the output winding switch 290 is connected to the second end of the second output capacitor 242. The positive terminal (+) of the terminal and the output voltage Vout, the gate of the output winding switch 290 is controlled by an output voltage detecting means 280, and the output voltage detecting means 280 is connected across the positive terminal (+) of the output voltage Vout. The output voltage detection means 280 can control the conduction or disconnection of the output winding switch 290 between the negative terminals (-) and between the two ends of the first output capacitor 222. The output voltage detection means 280 is for detecting a supply voltage signal Vs. For example, when the output voltage detection means detects that the supply and output voltage signal Vs is in a low voltage state, the control causes the gate of the output winding switch 290 to be disconnected, and the first output switch 221 of the first output line 20 is turned on. The voltage of the first output winding 220 from the winding point transmits the output voltage Vout through the first output switch 221, at which time the second output winding 240 is in a disabled state, and the winding on the output side (secondary side) of the transformer has only the first output winding 220. The output voltage Vout is controlled by the input (primary side) winding 210 of the transformer and the first output winding 220, and the turns ratio between the input winding 210 and the secondary side is N1 (Np/Nsec1). On the other hand, when the output voltage detection means detects 280 that the supply and output voltage signal Vs is in a high voltage state, the control causes the gate of the output winding switch 290 to be turned on, and the second output switch 241 is turned on, and the first output switch is turned on. 221 is disconnected, and the voltage of the second output winding 240 from the winding point transmits the output voltage Vout via the second output switch 241, at this time The second output winding 240 functions (enable state), the secondary winding of the transformer is a series winding of the first output winding 220 and the second output winding 240, and the output voltage Vout is input to the input winding 210 of the transformer. The two output windings 220, 240 are controlled; the turns ratio between the input winding 210 and the secondary side is N2 (Np / (Nsec1 + Nsec2)), where N2 < N1. It can be seen from the above that the number of turns of the secondary winding of the power supply circuit of the present invention is not fixed, and the number of turns of the secondary winding can be changed due to the difference in the output voltage Vout. When the output voltage Vout changes from low to high, The number of turns is adjusted from N1 to N2. It can be seen from the above formulas 1, 2 and 3 that the high and low voltage variations of the auxiliary voltage Vaux are small, and the variation of the duty ratio of the power input switch 260 is also small, so that the switch control circuit (PWM IC) 150 can have good reliability, and the power supply circuit also has better efficiency.

The output voltage detecting means 280 is configured to detect the supply and output voltage signal Vs, determine whether the voltage supplied by the power supply circuit is high voltage or low voltage, and send the control signal Vc to control the gate end of the output winding switch 290. Turn on or off. The supply voltage signal Vs can be an actual analog signal or a digital signal via the code; the output voltage detection means 280 can be a separately designed circuit, or added by a USB chip controller, or mechanically, such as a manual switch. , jumper, manually send the control signal Vc manually. The voltage detecting means 280 determines that the decoded supply and output voltage signal Vs is compared with a threshold voltage Vth, Vs is greater than Vth is a high voltage state, Vs is less than Vth is a low voltage state, and the threshold voltage Vth is a non-fixed value, which can be The requirements are arbitrarily set. The Quick Charge 2.0 (QC2.0) specification is used as an example. QC2.0 needs to provide 5/9/12/20V voltage, so Vth can be set to V1 value, so that the output voltage detection means 280 can determine 5V. For low voltage, 9V or higher (including 9V) is high voltage, or Vth is set to V2 value, so that output voltage detection means 280 determines that 5/9V is low voltage, 12V or higher (including 12V) is high voltage, or Vth is set to The V3 value causes the output voltage detection means 280 to recognize that 5/9/12V is a low voltage, and that 20V or more (including 20V) is a high voltage.

The first output switch 221, the second output switch 241, and the auxiliary output switch 231 shown in the third figure are represented by a diode, but in practical applications, the first and second output switches 221 and 242 and the auxiliary output switch 231 Includes power diodes and power MOSFETs. The power input switch 260 and the output winding switch 290 include a power transistor, a thyristor element.

The fourth figure shows another embodiment of the present invention, illustrating another manner in which the first output winding and the second output winding are electrically coupled in series. The figure is a modification 1 and a third embodiment of the third embodiment. The embodiment of the present embodiment is the same as the first output line 20 and the second output line 40. The first output line 20 also includes a first output winding 220, a first output switch 221 and a first output capacitor 222. The first output switch 221 and the first output capacitor 222 are electrically coupled to the first output winding 220, and are electrically coupled to the first output switch 221, the first output capacitor 222 and the first output winding 220. Connected in series. The second output line 40 also includes a second output winding 240, a second output switch 241 and a second output capacitor 242. The difference between this embodiment and the embodiment of FIG. 3 is only in the second output winding 240 and the second output switch 241. The position of the second output winding 240 and the first output winding 220 are electrically coupled in series, and the second output switch 241 is electrically connected in series, that is, the winding point of the first output winding 220 is connected to the second output. The first end (P end) of the switch 241 is coupled to the first end of the first output switch 221, and the second end (N end) of the second output switch 221 is coupled to the final winding point of the second output winding 240. The second output winding 240 is connected to the first end of the second output capacitor 222. The second end of the second output capacitor 242 is connected in series with the first end of the first output capacitor 222.

When the output voltage detection means detects that the supply and output voltage signal Vs is in a low voltage state, the gate of the output winding switch 290 is controlled to be disconnected, and the first output switch 221 of the first output line 20 is turned on, first The voltage of the output winding 220 from the winding point transmits the output voltage Vout through the first output switch 221; at this time, the second output winding 240 is in a disabled state, and the winding on the output side (secondary side) of the transformer has only the first output winding 220, and the output The voltage Vout is wound by the input of the transformer (primary side) The group 210 is controlled by the first output winding 220, and the turns ratio between the input winding 210 and the secondary side is N1 (Np/Nsec1). On the other hand, when the output voltage detection means detects 280 that the supply and output voltage signal Vs is in a high voltage state, the gate of the output winding switch 290 is controlled to be turned on, and the second output switch 241 is turned on, and the first output switch 221 is turned on. Disconnected, the second output winding 240 functions (enable state), the voltage of the winding point transmits the output voltage Vout, and the secondary winding of the transformer is the series winding of the first output winding 220 and the second output winding 240, The output voltage Vout is controlled by the input winding 210 of the transformer and the first and second output windings 220, 240, and the turns ratio between the input winding 210 and the secondary side is N2 (Np / (Nsec1 + Nsec2)).

The fifth figure shows another embodiment of the present invention, illustrating another manner in which the first output winding and the second output winding are electrically coupled in series. The figure is a second modification and a third embodiment of the third embodiment. The embodiment of the present embodiment is the same as the first output line 20 and the second output line 40. The second output line 40 also includes a second output winding 240, a second output switch 241 and a second output capacitor 242. The second output switch 241, the second output capacitor 242 and the second output winding 240 are electrically coupled in a manner that the second output switch 241 and the second output capacitor 242 are connected in series with each other. The first output line 20 also includes a first output winding 220, a first output switch 221 and a first output capacitor 222. The electrical connection of the first output winding 220 and the second output winding 240 is electrically coupled in series. The first output winding 220 is electrically connected in series with the second output winding 240 via the first output switch 221 . The second end of the first output switch 221 is connected to the first winding end of the second output winding 240 and the first end of the second output switch 241, and the first end of the first output switch 221 is connected to the starting point of the first output winding 220, The second winding end of the first output winding 222 is connected to the second end of the first output capacitor 222. The second end of the second output capacitor 242 is connected in series with the first end of the first output capacitor 222.

When the output voltage detection means detects that the supply and output voltage signal Vs is in a low voltage state, the gate of the output winding switch 290 is controlled to be disconnected, the first output switch 221 and the second output The output switch 241 is turned on, and the voltage of the first output winding 220 from the winding point transmits the output voltage Vout through the first and second output switches 221 and 241; at this time, the second output winding 240 is in a disabled state, and the output side of the transformer (secondary side) The winding has only the first output winding 220, and the output voltage Vout is controlled by the input (primary side) winding 210 of the transformer and the first output winding 220, and the turns ratio between the input winding 210 and the secondary side is N1 ( Np/Nsec1). On the contrary, when the output voltage detection means detects 280 that the supply and output voltage signal Vs is in a high voltage state, the gate of the output winding switch 290 is controlled to be turned on, and the second output switch 241 is turned off, and the first output switch is turned off. 221 is turned on, the second output winding 240 functions (enable state), the secondary winding of the transformer is a series winding of the first output winding 220 and the second output winding 240, and the second output winding 240 is connected to the voltage of the winding point. The output voltage Vout is controlled by the input winding 210 of the transformer and the first and second output windings 220, 240, and the turns ratio between the input winding 210 and the secondary side is N2 (Np/(Nsec1+Nsec2) )).

The sixth figure shows another embodiment of the present invention, and illustrates another manner in which the first output winding and the second output winding are electrically coupled in series. The figure is a modification 3 of the third embodiment. The same as the embodiment of the third embodiment, the embodiment of the figure still has a first output line 20 and a second output line 40. The first output circuit 20 includes a first output winding 220 (having a number of turns Nsec1), a first output switch 221 and a first output capacitor 222. The first output switch 221 is electrically coupled to the first output switch 221 and the first output capacitor 222. The first output winding 220 is connected in series with the end-to-end connection; the first output winding 220 is connected to the first end of the first output capacitor 222 and the positive end (+) of the output voltage Vout, and the first output winding 220 is terminated. Connected to the second end (N terminal) of the first output switch 221 by a wraparound point, the first end (P end) of the first output switch 221 is connected to the second end of the first output capacitor 222 and the negative end of the output voltage Vout (-) . The second output line 40 includes a second output winding 240 (having a number of turns Nsec2), a second output switch 241 and a second output capacitor 242 electrically coupled to the second output winding 240 and the first output winding 220. The series is coupled in series, and the electrical series coupling shown in the figure is a direct connection. As shown, the winding point of the second output winding 240 is connected to the final winding point of the first output winding 220 and the first output. The second end of the second output winding 240 is connected to the second end (N end) of the second output switch 241, and the first end (P end) of the second output switch 241 is connected to the second output capacitor 242. The second end of the second output capacitor 242 is connected in series with the second end of the first output capacitor 222 at a series of contacts.

When the output voltage detection means detects that the supply and output voltage signal Vs is in a low voltage state, the gate of the output winding switch 290 is controlled to be disconnected, and the first output switch 221 of the first output line 20 is turned on, first The voltage of the final winding of the output winding 220 is transmitted through the first output switch 221 to the output voltage Vout(-), and the voltage of the first output winding 220 is connected to the output voltage Vout(+); at this time, the second output winding 240 is lost. In the energy state, the winding on the output side (secondary side) of the transformer has only the first output winding 220, and the output voltage Vout is controlled by the input (primary side) winding 210 of the transformer and the first output winding 220, and the input winding 210 and the secondary side are The turns ratio between the two is N1 (Np/Nsec1). On the other hand, when the output voltage detection means detects 280 that the supply and output voltage signal Vs is in a high voltage state, the gate of the output winding switch 290 is controlled to be turned on, and the second output switch 241 is turned on, and the first output switch 221 is turned on. Disconnected, the second output winding 240 functions (enable state), and the voltage of the second output winding 240 at the final winding point transmits the output voltage Vout(-) through the second output switch and the output winding switch 290, and the secondary winding of the transformer For the series winding of the first output winding 220 and the second output winding 240, the output voltage Vout is controlled by the input winding 210 of the transformer and the first and second output windings 220, 240, between the input winding 210 and the secondary side The turn ratio is N2 (Np/(Nsec1+Nsec2)).

The seventh figure shows another embodiment of the present invention. The figure is the third embodiment. The difference is only in the secondary side. The second output side has the first output line 20 and the second output line 40. The first output is The line 20 also includes a first output winding 220 (having a number of coils Nsec1), a first output switch 221 and a first output capacitor 222, which are connected in series in an end-to-end manner. The first output winding 220 is electrically coupled in parallel with the second output winding 240. An output voltage Vout is sent from the first output capacitor 222. The specific connection is as follows: the first output winding 220 is connected by a wraparound point. First output switch The first end of the first output switch 221 is connected to the first end of the first output capacitor 222, the first end of the output winding switch 290, and the positive end (+) of the output voltage Vout, and the first output capacitor 222 The second end is connected to the final winding point of the first output winding 220 and the negative terminal (-) of the output voltage Vout. The second output line 40 includes a second output winding 240 (having a number of coils Nsec2), and a second output switch 241 and a second output capacitor 242, which are connected in series in an end-to-end manner. The second output winding 240 is connected to the first end of the second output switch 241, and the second end of the second output switch 241 is connected to the first end of the second output capacitor 242 and the second end of the output winding switch 290. The second end of the two output capacitors 242 is connected to the negative terminal (-) of the output voltage Vout. The output voltage detection means 280 is connected in parallel with the first output capacitor 222 for detecting a supply and output voltage signal Vs and controlling the gate of the output winding switch 290.

When the output voltage detection means 280 detects that the supply and output voltage signal Vs is in a low voltage state, the gate is controlled to open the output winding switch 290, and the first output switch 221 is turned on, and the second output switch 241 is turned off. The first output winding 220 transmits the output voltage Vout via the first output switch 221, and the number of coils of the secondary winding is Nsec1, and the output voltage Vout is received by the first output winding 220 and the input winding 210. Control, the ratio of turns between the input winding 210 and the secondary side is N1 (Np/Nsec1). When the output voltage detecting means 280 detects that the supply and output voltage signal Vs is in a high voltage state, the gate terminal is controlled to turn on the output winding switch 290, and the second output switch 241 is turned on, and the first output switch 221 is turned off. The voltage of the second output winding 240 from the winding point transmits the output voltage Vout via the second output switch 241 and the output winding switch 290. At this time, the number of coils of the secondary winding is Nsec2, and the output voltage is received by the second output winding 240. Controlled by the input winding 210, the turns ratio between the input winding 210 and the secondary side is N2 (Np/Nsec2); wherein Nsec2>Nsec1, so N1<N2.

The eighth figure shows another embodiment of the present invention. The figure shows that the difference between the embodiment of the third figure is only the secondary side, and the second output side has the first output line 20 and the second output line 40, and the first output. Line 20 also includes a first output winding 220 (which has a number of coils Nsec1), a first output switch 221 and the first output capacitor 222, which are connected in series in an end-to-end manner. The first output winding 220 is electrically coupled in parallel with the second output winding 240. An output voltage Vout is sent from the first output capacitor 222. The specific connection is as follows: the first output winding 220 is connected to the winding point. The first end of the first output capacitor 222 and the positive end (+) of the output voltage Vout; the second end of the first output capacitor 222 is connected to the first end of the first output switch 221, and the first end of the output winding switch 290 is The negative terminal (-) of the output voltage Vout, the second end of the first output switch 221 is connected to the final winding point of the first output winding 220. The second output line 40 includes a second output winding 240 (having a number of coils Nsec2), and a second output switch 241 and a second output capacitor 242, which are connected in series in an end-to-end manner. The second output winding 240 is connected to the first end of the second output capacitor 242 and the positive end (+) of the output voltage Vout, and the second end of the second output capacitor 242 is connected to the first end of the second output switch 241. The second end of the output winding switch 290 is connected to the second end of the second output winding 240. The output voltage detection means 280 is connected in parallel with the first output capacitor 222 for detecting a supply and output voltage signal Vs and controlling the gate of the output winding switch 290.

When the output voltage detection means 280 detects that the supply and output voltage signal Vs is in a low voltage state, the gate is controlled to open the output winding switch 290, and the first output switch 221 is turned on, and the second output switch 241 is turned off. The voltage of the first winding of the first output winding 220 is transmitted through the first output switch 221, and the number of coils of the secondary winding is Nsec1. The output voltage Vout is received by the first output winding 220 and the input winding 210. Control, the ratio of turns between the input winding 210 and the secondary side is N1 (Np/Nsec1). When the output voltage detecting means 280 detects that the supply and output voltage signal Vs is in a high voltage state, the gate terminal is controlled to turn on the output winding switch 290, and the second output switch 241 is turned on, and the first output switch 221 is turned off. The voltage of the second winding of the second output winding 240 is transmitted to the output voltage Vout via the second output switch 241 and the output winding switch 290. At this time, the number of coils of the secondary winding is Nsec2, and the output voltage is received by the second output winding 240. Controlled by the input winding 210, the ratio of turns between the input winding 210 and the secondary side is N2 (Np/Nsec2); wherein Nsec2> Nsec1, so N1 < N2.

While the present invention has been described above by way of example, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

10‧‧‧Input line

201‧‧‧Rectifier circuit

202‧‧‧Filter capacitor

210‧‧‧Input winding

30‧‧‧Auxiliary lines

230‧‧‧Auxiliary winding

231‧‧‧Auxiliary voltage output switch

232‧‧‧Auxiliary output capacitor

250‧‧‧Switch Control Circuit (PWM IC)

260‧‧‧Power input switch

20‧‧‧First output line

220‧‧‧First output winding

221‧‧‧First output switch

222‧‧‧First output capacitor

40‧‧‧second output line

240‧‧‧second output winding

241‧‧‧Second output switch

242‧‧‧second output capacitor

290‧‧‧Output winding switch

280‧‧‧ Output voltage detection means

Vac‧‧‧AC input voltage

Vdc‧‧‧ input voltage

Vout‧‧‧ output voltage

Vs‧‧‧ supply voltage signal

Vaux‧‧‧Auxiliary voltage

Vc‧‧‧ control signal

Vref‧‧‧ a reference voltage terminal

Claims (12)

An exchange power supply circuit includes: an input line including an input winding, wherein the input winding is for receiving an input voltage; and a first output line including a first output winding and a first output switch And a first output switch, the first output switch is electrically coupled to the first output winding; a second output line includes a second output winding, a second output switch, and a a second output capacitor, the second output switch and the second output capacitor are electrically coupled to the second output winding; the first output winding is electrically coupled in series with the second output winding, the first output capacitor is coupled The second output capacitor is connected in series with a series of contacts, and an output voltage is transmitted from the series of contacts; an output winding switch is connected in parallel with the second output capacitor and has a gate; an output voltage detection means And the first output capacitor is connected in parallel with the first output capacitor, and is electrically connected to the series connection point for detecting a supply and output voltage signal, and controlling the gate end; when the output voltage detection means detects the supply and output voltage signal One In the pressed state, the gate is controlled to open the output winding switch, and the second output winding is in a disabled state, and the output voltage is controlled by the first output winding and the input winding; when the output voltage is detected When the control means detects that the supply and output voltage signal is in a high voltage state, controlling the gate end to turn on the output winding switch, and the second output winding is in a state of uniform energy, and the first output winding and the second output winding are The electrical series state, according to which the output voltage is controlled by the first output winding, the second output winding and the input winding connected in series. The power supply circuit of claim 1, further comprising: a power input switch connected in series with the input winding; and an auxiliary circuit comprising an auxiliary winding for generating an auxiliary voltage; a switch control circuit, wherein an operating voltage is provided by the auxiliary voltage, and a pulse output is generated to control whether the power input switch is turned on or off; when the second output winding is in the disabled state, the auxiliary voltage is received by the auxiliary winding Controlled by the first output winding; when the second output winding is in the enabled state, the auxiliary voltage is controlled by the auxiliary winding and the first output winding and the second output winding connected in series. The power supply circuit of claim 1 or 2, wherein: the first output switch, the first output capacitor and the first output winding are connected in series with each other; the second output winding Connecting a first end of the second output switch to the winding point, the final winding point of the second output winding is connected to the starting point of the first output winding and the first end of the first output switch, the second output switch The second end is connected to the first end of the second output capacitor; the second end of the second output capacitor is connected in series with the first end of the first output capacitor; and the second output winding is in the disabled state The first output switch is turned on, and the second output switch is turned off by the output winding switch; when the second output winding is in the enabled state, the second output switch is turned on, and the first output switch is turned off. The power supply circuit of claim 1 or 2, wherein: the first output switch, the first output capacitor and the first output winding are connected in series with each other; the second output switch One end of the first output winding is connected to the first end of the first output switch, and the second end of the second output switch is connected to a final winding point of the second output winding, the second output winding a first end of the second output capacitor is connected to the second output capacitor, and the second end of the second output capacitor is connected in series with the first end of the first output capacitor; When the second output winding is in the disabled state, the first output switch is turned on, and the second output switch is turned off by the output winding switch; when the second output winding is in the enabled state, the second output switch is turned on The first output switch is turned off. The power supply circuit of claim 1 or 2, wherein: the second output switch, the second output capacitor and the second output winding are connected in series with each other; the first output switch The second end is connected to the final winding point of the second output winding and the first end of the second output switch, the first end of the first output switch is connected to the starting point of the first output winding, and the final winding of the first output winding a second end of the second output capacitor is connected to the first end of the first output capacitor in series with the series connection; when the second output winding is in the disabled state The first output switch and the second output switch are turned on; when the second output winding is in the enabled state, the second output switch is turned off, and the first output switch is turned on. The power supply circuit of claim 1 or 2, wherein: the first output switch, the first output capacitor and the first output winding are connected in series with each other; the end of the second output winding Connecting a second end of the second output switch to the winding point, the winding point of the second output winding is connected to the final winding point of the first output winding and the second end of the first output switch, the second output switch One end is connected to the second end of the second output capacitor; the first end of the second output capacitor is connected in series with the second end of the first output capacitor; the second output winding is in the disabled state The first output switch is turned on, and the second output switch is turned off by the output winding switch; When the second output winding is in the enabled state, the second output switch is turned on, and the first output switch is turned off. An exchange power supply circuit includes: an input line including an input winding, wherein the input winding is for receiving an input voltage; and a first output line including a first output winding and a first output switch And a first output switch, the first output switch is electrically coupled to the first output winding; a second output line includes a second output winding, a second output switch, and a a second output capacitor, the second output switch and the second output capacitor are electrically coupled to the second output winding; the first output winding is electrically coupled in parallel with the second output winding, and the first output capacitor is coupled An output voltage is sent to both ends; an output winding switch has a gate and is electrically coupled between the first output capacitor and the second output capacitor; an output voltage detection means, and the first The output capacitors are connected in parallel to detect a supply voltage signal and control the gate; when the output voltage detection means detects that the supply voltage signal is a low voltage state, the gate is controlled to make the output winding Off, the output voltage is controlled by the first output winding and the input winding; when the output voltage detection means detects that the supply and output voltage signal is a high voltage state, controlling the gate to make the output winding The switch is turned on, and the output voltage is controlled by the second output winding and the input winding. The power supply circuit of claim 13, further comprising: a power input switch connected in series with the input winding; An auxiliary circuit includes an auxiliary winding for generating an auxiliary voltage; a switching control circuit whose operating voltage is supplied by the auxiliary voltage, and generates a pulse output to control whether the power input switch is turned on or off; when the output voltage is When the detecting means detects that the power supply voltage signal is the low voltage state, the auxiliary voltage is controlled by the auxiliary winding and the first output winding; when the output voltage detecting means detects the power supply voltage signal as the In the high voltage state, the auxiliary voltage is controlled by the auxiliary winding and the second output winding. The power supply circuit of claim 7 or 8, wherein: the first output switch, the first output capacitor and the first output winding are connected in series in an end-to-end manner; the second output switch, the second output switch The second output capacitor is connected in series with the second output winding; the final winding point of the first output winding, the final winding point of the second output winding, the second end of the first output capacitor, and the first a second end of the output capacitor is connected to the negative end of the output voltage; one end of the output winding switch is connected to the first end of the first output capacitor and the positive end of the output voltage, and the other end of the output winding switch is connected to the The first end of the second output capacitor. The power supply circuit of claim 7 or 8, wherein: the first output switch, the first output capacitor and the first output winding are connected in series in an end-to-end manner; the second output switch, the second output switch The second output capacitor is connected in series with the second output winding; the starting point of the first output winding, the starting point of the second output winding, the first end of the first output capacitor, and the first a first end of the output capacitor is commonly connected to a positive end of the output voltage; one end of the output winding switch is connected to the second end of the first output capacitor and the output voltage At the negative end, the other end of the output winding switch is connected to the second end of the second output capacitor. The power supply circuit of claim 7 or 8, wherein the number of turns of the first output winding is Nsec1, the number of turns of the second output winding is Nsec2, and Nsec2>Nsec1. The power supply circuit of claim 1, 2, 7, or 8, wherein the output voltage detecting means determines that the power supply voltage signal is the high voltage state or the low voltage state according to a threshold voltage; The high voltage state is when the voltage signal is higher than the threshold voltage, and the low voltage state is when the power supply voltage signal is lower than the threshold voltage, wherein the threshold voltage is not a fixed value, and can be set by the output voltage detection means.