Switch power supply circuit

Technical Field

The present invention relates to electronic Technical Field, especially relates to a switching power supply circuit.

Background Art

The switch tube switch power supply is connected with the direct control of the inductive component (inductance or transformer), through the inductive element process of the energy storage and release, realize the voltage or current transformation a power supply, which can be widely used in industrial control, communication office, household consumption and the like in various electronic devices. The switch tube in the switching power supply can be a three electrode tube, field-effect transistors, insulated gate bipolar transistor (Insulated   Gate   Transistor   Bipolar, abbreviated as IGBT), thyristors and other three end control device or its derivative device. The switch tube only work in the low power consumption state is turned on or off, the switch power supply than that of the traditional linear power supply has a high conversion efficiency.

In the use of a transformer as an energy transmission element in the switching power supply circuit, with the output port of the switching tube is connected with the primary coil of the transformer, when the switch is turned on to the end of the tube, due to the presence of leakage inductance of the transformer, in a very short period of time, the output end of the switch tube will show relatively oberland reverse electromotive force peak, the electromotive force spikes caused by the leakage inductance, cannot generally be transmitted to the transformer secondary, if there is no protection circuit, the electromotive force spike will exceed the maximum withstanding value the switch tube, lead to the breakdown of the switch tube.

As shown in Figure 1, is the existing a switch of a switching power supply of the anti-breakdown protection circuit schematic, wherein, +VI, -VI to the input end of a power supply, the power supply output terminal +VO; switch tube Q1 through the output end of the transformer T1 +VI end of the primary coil is connected with the, switch Q1 CONTROL access to the control end of the rectangular-wave signal, in order to control the switching transistor Q1 is turned on or off state of the work; diode D1 and the capacitor C1 constitute a peak energy collecting circuit, resistor R1 form a peak energy release circuit. When the switch Q1 is turned on to stop when the, switch Q1 reverse electromotive force present at the output of the peak, the diode D1 is turned on, and to a capacitor C1 charging. Because the capacitor voltage can not be mutation, electromotive force peak is suppressed, the protection of the switching transistor Q1. After capacitor C1 of the collected peak energy through the resistance R1 release, such repeated every cycle.

In the existing a switch of a switching power supply in anti-breakdown protection circuit, the output end of the switch tube peak energy is eventually release circuit is consumed in order to heat form, low conversion efficiency of the switching power supply. And, caused by leakage inductance of transformer the duration of the electromotive force spikes are short, but the current value is very large, is often of several tens times the normal turn on current, the switch it is difficult to raise the efficiency of the power supply.

Content of the invention

The invention aims to solve the technical problem, to provide a switching power supply circuit, to prevent pipe is a switch of a switching power supply breakdown, and to improve the conversion efficiency of the switching power supply.

In order to solve the above technical problem, the invention provides a switching power supply circuit, including:

A conversion module, control the switch tube connected with the inductive elements of the process of the energy storage and release, to the power input for converting input electric energy, and the output from the power source converting the electric energy;

Peak energy collection module, in the switch tube is from on to off, the inductive element is caused by the leakage inductance will cause switch tube breakdown peak energy;

The secondary conversion module, states the peak energy collection module to the peak energy collected by the conversion, the converted energy back to the power supply input terminal.

The power input end of the and-VI +VI end to end, into a direct current voltage ; +VO end to the power source output end;

The primary conversion module comprises a switch tube Q1, transformer T1 and a rectifying and smoothing circuit; switch Q1 via the output end of the transformer T1 is connected to the primary coil of the end +VI, switch Q1 is connected to the common end of the end-VI; switch tube Q1 CONTROL access to the control end of the control signal, the control signal is a periodic rectangular wave signal; diode D2, capacitor C2, the load resistance R2; a rectifying and smoothing circuit, transformer T1 the voltage of the secondary coil through the diode D2, capacitor C2, the load resistance R2 rectifying and smoothing the output voltage, the output voltage from +VO ends of the output;

The states the peak energy collection module is composed of a diode D3, capacitor C3 of the series circuit, diode D3 and switch tube the anode of Q1 is connected to the output end of the, diode D3 and the cathode of the capacitor C3 is connected to one terminal of the, capacitor C3 and the other terminal of the switch transistor Q1 is connected to the common end of the;

The secondary conversion module is arranged in the voltage conversion circuit, is used for the capacitor C3 exceeds the voltage of both ends of the voltage threshold V_X time, to the capacitor C3 the stored peak energy for conversion, in order to control the capacitor C3 in the voltage of both ends of the voltage threshold V_X, and the converted energy back to the power supply input terminal;

The stabilized voltage conversion circuit includes a pulse width modulation control unit U1, the pulse width modulation control unit U1 is internally provided with a voltage comparator, the voltage comparator to the positive input terminal of the "COMP_IN+", the negative input end "COMP_IN-" the; voltage-stabilizing element Z1 of the comparator the voltage of reference voltage, and pulse width modulation control unit U1 "COMP_IN-" of the end is connected with the; capacitor C3 through the voltage of both ends of the resistor R4, resistor R5, and, access pulse width modulation control unit U1 "COMP_IN+" end of the; pulse width modulation control unit U1 "PWM_OUT" end of the PNP-type transistor Q2 is connected with the base of the, control triode Q2 work in the on or off state; a transistor Q2 the emitter of the diode D3 is connected with a cathode of, transistor Q2 via the collector electrode of the inductor L1 and capacitor C4 is connected with the, capacitor C4 are respectively connected with the two terminals of the power supply input terminal +VI, -VI is connected with the; fly-wheel diode D4 of the end is connected with the anode and the-VI, cathode and the transistor Q2 is connected with the collector electrode of the; when the capacitor C3 to the voltage of both ends of the V_X time, negative "PWM_OUT" end of the pulse output, a transistor Q2 is turned on, the output pulse current, the current stored energy in inductance L1 in; when the capacitor C3 is lower than the voltage of both ends of the V_X time, transistor Q2 to cut-off, the inductor L1 through the electric energy stored in the fly-wheel diode D4 is transferred to the capacitor C4 on;

In order to solve the above technical problem, the present invention also provides another kind of switch power supply circuit, including:

A conversion module, control the switch tube connected with the inductive elements of the process of the energy storage and release, to the power input for converting input electric energy, and the output from the power source converting the electric energy;

Peak energy collection module, in the switch tube is from on to off, the inductive element is caused by the leakage inductance will cause switch tube breakdown peak energy;

The secondary conversion module, states the peak energy collection module to the peak energy collected by the conversion, the converted energy back to the power supply output terminal;

The power input end of the and-VI +VI end to end, into a direct current voltage ; +VO end to the power source output end;

The primary conversion module comprises a switch tube Q1, transformer T1 and a rectifying and smoothing circuit; switch Q1 via the output end of the transformer T1 is connected to the primary coil of the end +VI, switch Q1 is connected to the common end of the end-VI; switch tube Q1 CONTROL access to the control end of the control signal, the control signal is a periodic rectangular wave signal; diode D2, capacitor C2, the load resistance R2; a rectifying and smoothing circuit, transformer T1 the voltage of the secondary coil through the diode D2, capacitor C2, the load resistance R2 rectifying and smoothing the output voltage, the output voltage from +VO ends of the output;

The states the peak energy collection module is composed of a diode D3, capacitor C3 of the series circuit, diode D3 and switch tube the anode of Q1 is connected to the output end of the, diode D3 and the cathode of the capacitor C3 is connected to one terminal of the, capacitor C3 and the other terminal of the switch transistor Q1 is connected to the common end of the;

In the secondary conversion module is provided with a voltage stabilization converting circuit; said voltage conversion circuit includes a pulse width modulation control unit U1, the pulse width modulation control unit U1 is internally provided with a voltage comparator, the voltage comparator to the positive input terminal of the "COMP_IN+", the negative input end "COMP_IN-" the; voltage-stabilizing element Z1 forming the reference voltage of the access pulse width modulation control unit U1 "COMP_IN+" end of the, capacitor C3 through the voltage of both ends of the resistor R4, resistor R5 access after partial pressure pulse width modulation control unit U1 "COMP_IN-" end of the; pulse width modulation control unit U1 "PWM_OUT" end of the NPN-type transistor Q2 is connected with the base of the, control transistor Q2 is turned on or off state of the work; when the capacitor C3 to the voltage of both ends of the V_X time, "PWM_OUT" end of the pulse output of a positive level, transistor Q2 is turned on, energy through the transformer T2 of the primary coil, secondary coil and the diode D5 +VO transmitted to the power output end.

The implementation of the invention, has the following beneficial effects:

The embodiment of the invention to provide a switch power supply circuit, the switch tube control connected with the inductive elements of the process of the energy storage and release, implementing the energy conversion; the switch tube is from on to off, collect the leakage inductance of the inductive element is caused by the switch tube to breakdown the peak energy, the peak energy collected by the conversion, and the converted energy back to the power input or power output end. The pipe is a switch of a switching power supply breakdown, the switch tube protection, and to improve the conversion efficiency of the switching power supply.

Description of drawings

Figure 1 is the existing a switch of a switching power supply of the anti-breakdown protection circuit schematic diagram;

Figure 2 is the invention provides a block diagram of the circuit of the switch power supply circuit;

Figure 3 is the present invention is to provide a switch power supply circuit of the schematic circuit of the 1st embodiment;

Figure 4 is the present invention is to provide a switch of the power circuit of the embodiment of the 2nd circuit schematic diagram;

Figure 5 is the present invention provides the 3rd of the switch power supply circuit is circuit schematic diagram of the embodiment of.

Mode of execution

Will be combined with the embodiment of the invention the Figure, in this embodiment of the invention a clear the technical scheme, complete described, obviously, the embodiment described is only a portion of the embodiment of this invention, , but not all, of the embodiment. Based on the embodiment of the invention, one of ordinary skill in the art in the absence of make creative work is obtained on the premise that all of the other embodiments, all belong to the scope of protection of this invention.

See Figure 2, is the present invention is to provide a switch power supply circuit block diagram.

The switching power supply circuit comprises: a conversion module 201, peak energy collection module 202 and secondary conversion module 203, wherein:

A conversion module 201, control the switch tube connected with the inductive elements of the process of the energy storage and release, to the power input for converting input electric energy, and the output from the power source converting the electric energy;

Peak energy collection module 202, in the switch tube is from on to off, the inductive element is caused by the leakage inductance will cause switch tube breakdown peak energy;

The secondary conversion module 203, the states the peak energy collection module 202 the collected peak energy conversion, the converted energy back to the power input or power output end.

Specific, one-time conversion module 201 to complete the major energy conversion, the switch tube, a transformer and a rectifying and smoothing circuit; the output end of the switch tube via the primary winding of the transformer is connected to the power input end, the input end of the power supply into a direct current voltage; the control end of the switch tube access rectangular wave signal, is composed of a rectangular wave signal to control the switch tubes work in the conducting state or a stop state; a rectifying and smoothing circuit is connected to a secondary coil of the transformer, the voltage of the secondary coil of the transformer to produce a rectifying and smoothing the output voltage, and from the power supply output. Wherein, when the switch is turned on to the end of the tube, due to the presence of leakage inductance of the transformer, the output end of the switch tube will be the higher reverse electromotive force peak, a switch tube bear the greatest peak energy, the protected object.

Peak energy collection module 202 is used to collect the output end of the switch pipe peak energy, composed of a diode and a series circuit of the capacitor; the is connected with the series circuit of the output end of the switch tube and a common terminal, the switch tube is from on to off, the output end of the switch tube in the peak energy, stored in the capacitor through the diode.

In the present invention in another embodiment, the peak energy collection module 202 can also be composed of synchronous rectifier and capacitor of the series circuit, the series circuit is connected with the output end of the switch tube and a common terminal, when the switch tube is from on to off, peak energy stored in the capacitor through the synchronous rectifier.

The secondary conversion module 203 is responsible for the peak energy collection module 202 the collected peak energy conversion, its inside is provided with a voltage stabilization converting circuit, used for the peak energy collection module 202 the two ends of the capacitor exceeds the voltage threshold of the voltage of the, storage capacitor to the peak energy for conversion, in order to control the voltage of both ends of the capacitor, the voltage threshold value, the output end of the tube the switch the voltage between the common end of the will not be too high or too low, to prevent the breakdown of the switch tube, and the conversion of the peak energy back to the power input or power output, improve the conversion efficiency of the switching power supply.

Among the specific implementation, switching power supply circuit can be switch tube of the three-pole tube, field effect transistor, IGBT, thyristor, etc. three end control device or its derivative device. Wherein, the control end of the switch tube, common end and an output end, can be respectively correspondent to the base electrode of the transistor, the emitter, collector, the gate of the field effect transistor, source, drain, the gate of the IGBT, the emitter, collector, single to the gate of the thyristor, the cathode, anode, the grid of the two-way thyristor, port 1, port 2.

For the convenience of description below, only to triode, for example to the technical scheme of the embodiment of the invention described, present invention is to provide a switch in the power supply circuit of the triode switch tube is not limited to.

See Figure 3, is the present invention is to provide a switch power supply circuit of the schematic circuit of the 1st embodiment.

In this embodiment, the switch in the power supply circuit of the secondary conversion module peak energy back to the input end of the power supply. Wherein, end +VI, -VI end to the input end of a power supply, a direct-current voltage; power output +VO end of the; power supply input end of the input electric energy after conversion, from the power supply output.

Specific, as shown in Figure 3, a conversion module comprises a switch tube Q1, transformer T1 and a rectifying and smoothing circuit; switch Q1 via the output end of the transformer T1 is connected to the primary coil of the end +VI, switch Q1 is connected to the common end of the end-VI; switch tube Q1 CONTROL access to the control end of the control signal, the control signal is a rectangular wave signal periodically, in order to control the switch tube Q1 work in the on or off state, turning on and off and the time ratio. Diode D2, capacitor C2, the load resistance R2; a rectifying and smoothing circuit, transformer T1 the voltage of the secondary coil through the diode D2, capacitor C2, the load resistance R2 rectifying and smoothing the output voltage, the output voltage from +VO ends of the output.

Peak energy collection module is composed of a diode D3, capacitor C3 of the series circuit, diode D3 and switch tube the anode of Q1 is connected to the output end of the, diode D3 and the cathode of the capacitor C3 is connected to one terminal of the, capacitor C3 and the other terminal of the switch transistor Q1 is connected to the common end. When the switch Q1 is from on to off, the transformer T1 presence of leakage inductance, switch Q1 will be the output of a larger reverse electromotive force peak, at this moment, the diode D3 is turned on, and to a capacitor C3 charging, peak energy storage in the capacitor C3 in.

In the secondary conversion module is provided with a voltage stabilization converting circuit, the capacitor C3 exceeds the magnitude of voltage of the voltage threshold V_X time, to the capacitor C3 the stored peak energy for conversion, in order to control the capacitor C3 to keep the voltage value of the voltage threshold V_X the upper, and the converted energy back to the power supply input terminal.

Specific, the stabilized voltage conversion circuit includes a pulse width modulation (Pulse   Modulation   Width, abbreviated as PWM) control unit U1, the internal is provided with a voltage comparator, the voltage comparator to the positive input terminal of the "COMP_IN+", to the negative input end "COMP_IN-". Pulse width modulation control unit U1 is the working principle of the: end "PWM_OUT" is controlled by the output of the "COMP_IN+" end and "COMP_IN-" end of the voltage the result of the comparison, if the "COMP_IN+" terminal voltage is higher than the terminal voltage of the "COMP_IN-", then the output "PWM_OUT" negative level end of the pulse width of the wide, on the other hand the more narrow. Among the specific implementation, the pulse width modulation control unit U1 can be a integrated circuit chip, or a collection of a plurality of elements of the functional module.

Stabilizing elements Z1 of the comparator the voltage of reference voltage, and pulse width modulation control unit U1 "COMP_IN-" of the end is connected with the; capacitor C3 through the voltage of both ends of the resistor R4, resistor R5, and, access pulse width modulation control unit U1 "COMP_IN+" end of the. The specific implementation, may be by calculation or experiment the threshold value of voltage of an appropriate V_X, and choose the appropriate component parameter value, make V_X through a resistor R4, resistor R5 is equal to the partial pressure of stabilizing elements Z1 voltage.

Furthermore, the pulse width modulation control unit U1 "PWM_OUT" end of the PNP-type transistor Q2 is connected with the base of the, control transistor Q2 is turned on or off state of the work. Transistor Q2 the emitter of the diode D3 is connected with a cathode of, transistor Q2 via the collector electrode of the inductor L1 and capacitor C4 is connected with the, capacitor C4 are respectively connected with the two terminals of the power supply input terminal +VI, -VI is connected with the; fly-wheel diode D4 of the end is connected with the anode and the-VI, cathode and the transistor Q2 is connected with the collector electrode of the.

Specific, in a conversion module to begin working at the beginning, capacitor C3 has not reached the voltage of both ends of the voltage threshold V_X, pulse width modulation control unit U1 of the voltage is lower than "COMP_IN+" "COMP_IN-" voltage, "PWM_OUT" no negative level of the end of the pulse output, a transistor Q2 is on the cut-off state; the conversion module to continue to work at a time, switching transistor Q1 continuously periodically switching between the conduction and cut-off, capacitor C3 collect more peak energy, the voltage between two ends of the same gradually rises. When the capacitor C3 to the voltage of both ends of the V_X time, negative "PWM_OUT" end of the pulse output, a transistor Q2 is turned on, the output pulse current, the current stored energy in inductance L1 in. The triode Q2 to turned off, the inductor L1 through the electric energy stored in the fly-wheel diode D4 is transferred to the capacitor C4 is, since the capacitor C4 is in fact the two ends of the power supply input terminal +VI, -VI, therefore, peak energy after conversion is sent back to the input end of the power supply, thereby improving the conversion efficiency of the switch power supply circuit.

In the embodiment of the invention, because the role of the deep negative feedback, each when the capacitor C3 is higher than the voltage of both ends of the V_X time, the secondary conversion module to be sustained after conversion back to the power supply input terminal of the peak energy, until the capacitor C3 is lower than the voltage of both ends of the V_X so far; when the capacitor C3 is lower than the voltage of both ends of the V_X time, the secondary conversion module sustained low power or zero power to the power supply input terminal back to the energy, until the capacitor C3 is higher than the voltage of both ends of the date Vx; therefore, capacitor C3 the voltage of both ends of the right and left is kept in the Vx value always , because the diode D3 role of the clamping, switch Q1 is the output end of the clamp in the capacitor C3 on the voltage Vx (in the ignore diode D3 of the case of the on-state voltage), prevent the switch tube Q1 is breakdown. And, a pulse width modulation control unit U1, resistor R4, resistor R5 and the like belong to the low-power-consumption component, the current is very small, the capacitor C3 the majority of the discharge current through the transistor Q2, that is to say the majority of the energy is recovered, not only can protect the switching transistor Q1, but also improve the conversion efficiency of the switching power supply.

See Figure 4, is the present invention provides the 2nd of the switch power supply circuit is circuit schematic diagram of the embodiment of.

This embodiment is to provide a switch power supply circuit, and compared with the 1st embodiment, the difference lies in the secondary conversion module will be converted back to the peak energy output of the power supply.

As shown in Figure 4, the embodiment of the switching power supply circuit is also the difference, in the secondary conversion module, voltage-stabilizing element Z1 forming the reference voltage of the access pulse width modulation control unit U1 "COMP_IN+" end of the, capacitor C3 through the voltage of both ends of the resistor R4, resistor R5 access after partial pressure pulse width modulation control unit U1 "COMP_IN-" end of the. The pulse width modulation control unit U1 "PWM_OUT" end of the NPN-type transistor Q2 is connected with the base of the, control transistor Q2 is turned on or off state of the work. When the capacitor C3 to the voltage of both ends of the V_X time, "PWM_OUT" end of the pulse output of a positive level, transistor Q2 is turned on, energy through the transformer T2 of the primary coil, secondary coil and the diode D5 +VO transmitted to the power output end.

Furthermore, because the secondary conversion module adopting the transformer T2 as an energy transmission element, transformer T2 presence of leakage inductance, in order to prevent the transistor Q2 is breakdown, this embodiment also designed the transistor Q2 anti-breakdown protection circuit. As shown in Figure 4, diode D4 and capacitor C4 form a peak energy collecting circuit, resistor R7 form a peak energy release circuit. When the transistor Q2 is from on to off, transistor Q2 in the collector electrode of the reverse electromotive force peak, diode D4 is turned on, and to a capacitor C4 charging, the spike voltage is suppressed, preventing the transistor Q2 is breakdown, after capacitor C4 of the collected peak energy is resistance R7 release. It should be explained that, because the power supply input end of the input electric energy by the one-time conversion module and the secondary conversion module converts the, most of the energy is transmitted to the output of the power supply, capacitor C4 has the plurality of the rest of the energy, therefore, this embodiment through a resistor R7 in a heat release of capacitor C4 energy. However, in fact, the capacitor C4 can also be the energy of the again to adopting the method of the invention, in its same rights of the present invention, range of requirements.

This embodiment with above-mentioned 1st embodiment is the same as the peak energy conversion principle, every when the capacitor C3 is higher than the voltage of both ends of the V_X time, the secondary conversion module to be sustained after conversion back to the power supply output terminal of the peak energy, until the capacitor C3 is lower than the voltage of both ends of the V_X so far; when the capacitor C3 is lower than the voltage of both ends of the V_X time, the secondary conversion module sustained low power or zero power to the power supply output end back to the energy, until the capacitor C3 is higher than the voltage of both ends of the date Vx; therefore, capacitor C3 the voltage of both ends of the right and left is kept in the Vx value always , switch Q1 is the output end of the clamp in the capacitor C3 on the voltage Vx, prevent the switching transistor Q1 breakdown, the protection of the switching transistor Q1. And, capacitor C3 the majority of the discharge current through the transistor Q2, the most of the energy is recovered, increasing the conversion efficiency of the switching power supply.

It should be explained that, the above-mentioned embodiment in the power supply switch circuit, a switch tube Q1, Q2 to triode only as an example for description, also can be replaced for the field-effect transistor, IGBT, thyristor, etc. three end control device or its derivative device; peak energy collection module in the diode D3, also can be replaced for the other-controlled one-way conductive element (for example, synchronous rectification module or circuit) in order to reduce the conduction voltage drop; and, in the peak energy collection module is used for storing the peak energy of the capacitor C3, it has not and the diode D3 is connected with a terminal of the other, in addition to the can be connected to switch pipe Q1 outside the common end of the, can also be connected to other of the AC electric potential with the common end of the same local, such as end +VI, specific see Figure 5, its operating principle is the same as the 1st example, in the do not repeat.

The embodiment of the invention to provide a switch power supply circuit, the switch tube control connected with the inductive elements of the process of the energy storage and release, implementing the energy conversion; the switch tube is from on to off, collect the leakage inductance of the inductive element is caused by the switch tube to breakdown the peak energy, the peak energy collected by the conversion, and the converted energy back to the power input or power output end. The pipe is a switch of a switching power supply breakdown, the switch tube protection, and to improve the conversion efficiency of the switching power supply.

The above is the preferred embodiment of the invention, it should be noted that, for the ordinary Technical Field technical personnel, without breaking away from the premise of the principle of the present invention, can also make a number of improved and deformation, these improved and deformation is also regarded as the scope of protection of this invention.