Secondary side control power converter
Technical field
The present invention is a kind of power supply changeover device, refers to a kind of secondary side control power converter especially, the direction flyback converter of the switch element open and close action of may command transformer primary side.
Background technology
Exchange type power conversion utensil efficient is higher, the characteristics that volume is little, be widely used on the various electronic installation at present in a large number, be as shown in figure 11 known direction flyback converter circuit framework one, and the main tool input circuit 1 ' of its circuit framework, transformer T1 ', output circuit 2 ', optical coupler 3 ', and this input circuit 1 ' connects input power supply Vin, and main tool on-off action transistor Q1 ', controller 11 ', and this transistor Q1 ' connects the first side winding of transformer T1 ', and controller 11 ' can be done PWM control, and output connection transistor Q1 ', and input FB connects optical coupler 3 ' one end; Output circuit 2 ' connects the secondary side winding of transformer T1 ' again, and its output end voltage Vout optical coupler 3 ' other end in parallel, make optical coupler 3 ' that input circuit 1 ' and output circuit 2 ' are isolated, and output end power Vout feedback to the controller 11 ' of input circuit 1 ', make controller 11 ' can corresponding output with control switch transistor Q1 ' action regulated output voltage.
The output voltage stability of aforementioned circuit must be feedback by optical coupler 3 ' and be controlled, but the characteristic of this optical coupler 3 ' will directly influence the stability of a system and reliability, for example the coupling efficiency of this optical coupler 3 ' will directly influence the accuracy of output end voltage Vout, decide the wild effect that function of current must additionally increase element with the compensation optical coupler if utilize optical coupler 3 ' to make charger (not indicating among the figure) again, to increase circuit cost, and cause the big disappearance of idling consumption than multicomponent.
Figure 12 shows that another known direction flyback converter circuit framework, main tool input circuit 5 ', transformer T2 ', output circuit 6 ', and its input circuit 5 ' connects input power supply Vin, and tool on-off action transistor Q2 ', controller 51 ', and this transistor Q2 ' connects transformer T2 ' the primary side first winding N1 ', the output of controller 51 ' connects transistor Q2 ' again, and the primary side second winding N2 ' of input connection transformer T2 ', and this controller 51 ' is the PWM controller; Output circuit 6 ' connects the secondary side tertiary winding N3 ' of transformer T2 ' again, and tool output end voltage Vout, make controller 51 ' sensing feedback to the change in voltage of the first side winding of transformer T2 ', and the corresponding open and close action of oxide-semiconductor control transistors Q2 ' is with control output end voltage Vout by transformer T2 ' secondary side.
Though the aforementioned circuit element is simplified most, but because of controller 51 ' direct sensing output end voltage not, directly depend on the characteristic sensing control of transformer T2 ', and the voltage of feedbacking is discontinuous, causes poor, the dynamic voltage stabilizing inefficiency disappearance of not good, the unloaded output voltage stability of Circuits System stability, reliability.
Summary of the invention
Purpose of the present invention is providing a kind of control power supply changeover device of secondary side, makes the preferable precision of switch element action tool, the reliability that are positioned at the transformer primary side.
For achieving the above object, the present invention adopts following technical scheme: a kind of secondary side control power converter comprises: an input circuit, tool one switch element at least; One transformer, its first side winding connects aforementioned switches element, and its change in voltage can change switch element open and close state, and the tool secondary side winding; One output circuit, connect the Circuit Fault on Secondary Transformer winding, and tool output, and aforementioned circuit can be passed to output circuit generation output end voltage via transformer with the intake of input circuit, in output circuit controller is set again, but and this controller sensing output voltage, and can influence the transformer first side winding at sensing output voltage variation execution action, but make the first side winding respective action control switch element of transformer do PWM or PFM switch motion with control output voltage, output circuit tool rectifier diode, and in output shunt capacitor ground connection, the controller input of output circuit connects output end power again, this controling appliance first again, these rectifier diode two ends of the second control end cross-over connection, and make first by controller decision, connect resistive load between second control end, short circuit, three kinds of state variation open circuit.
Above-mentioned input circuit, transformer, output circuit are combined as self-excitation direction flyback converter circuit framework.
Identical first winding, second winding of above-mentioned transformer primary side tool polarity, the secondary side tool and the opposite tertiary winding of aforementioned first and second winding polarity again, input circuit tool start-up circuit again, and its input connects first winding, one end of input power supply, start-up circuit input, transformer primary side, this start-up circuit output connects the first transistor B utmost point again, and this first transistor C utmost point connects the aforementioned first winding other end, and this first transistor is described switch element again; Second winding, one end of this transformer primary side connects the resistance and the first transistor B utmost point again, and this second winding other end ground connection; The emitter-base bandgap grading of this first transistor connects grounding through resistance again.
Above-mentioned the first transistor connects current-limiting protection circuit.
Above-mentioned current-limiting protection circuit tool transistor seconds, and the B utmost point of this transistor seconds connection the first transistor emitter-base bandgap grading, and the C utmost point connection the first transistor B utmost point, and its emitter grounding.
Above-mentioned diode is located at output end position.
Above-mentioned diode is located at the earth terminal position.
Controller was controlled first, second control end and is connected resistive load in the time that transformer T energy is transferred to before output time to described the first transistor starts once more fully when above-mentioned output end voltage exceeded setting voltage, and stop the first transistor to excite conducting once more, be off state then, making circuit is stop mode.
First winding, second winding that the transformer first side tool polarity is identical, otherwise secondary side tool and aforementioned first, second winding polarity be the tertiary winding mutually, controller was controlled between first, second control end one blink of short circuit when above-mentioned again output end voltage was not enough, and the capacitor energy that makes output circuit is stored to the tertiary winding and makes controller control first, second control end again opening circuit, and the energy of second winding is restarted described the first transistor conducting.
A kind of secondary side control power converter comprises: a transformer, first winding that primary side tool polarity is identical, second winding, the secondary side tool and the opposite tertiary winding of aforementioned first, second winding polarity again; One input circuit, the tool start-up circuit, and its input connects first winding, one end of input power supply, start-up circuit input, transformer primary side, and this start-up circuit output connects the first transistor B utmost point again, and this first transistor C utmost point connects the aforementioned first winding other end; Second winding, one end of this transformer primary side connects resistance again, and this resistance connection the first transistor B utmost point, and this second winding other end ground connection; The emitter-base bandgap grading of this first transistor connects grounding through resistance again, connects transistor seconds in the first transistor again, and the B utmost point of this transistor seconds connection the first transistor emitter-base bandgap grading, and the C utmost point connection the first transistor B utmost point, and its emitter grounding; One output circuit, the tool rectifier diode, and in output shunt capacitor ground connection, output circuit is provided with controller again, and the controller input connects output end power, first, second control end cross-over connection diode two ends of this controling appliance again; But and this controller sensing output voltage, and can be corresponding the sensing output voltage change and feedback to the transformer first side winding, but make the first side winding respective action control the first transistor of transformer do PWM or PFM switch motion with control output voltage; Between above-mentioned this first, second control end by controller decision connect resistive load, short circuit, three kinds of state variation open circuit.
Above-mentioned diode is located at output end position.
Above-mentioned diode is located at the earth terminal position.
Controller was controlled first, second control end and is connected resistive load in the time that transformer T energy is transferred to before output time to the first transistor starts once more fully when above-mentioned output end voltage exceeded setting voltage, and stop the first transistor to excite conducting once more, be off state then, making circuit is stop mode.
Controller was controlled between first, second control end one blink of short circuit when above-mentioned output end voltage was not enough, and the capacitor energy that makes output circuit is stored to the tertiary winding and makes controller control first, second control end again opening circuit, and the energy of second winding is restarted the first transistor conducting.
Adopt such scheme, the present invention is passed to output circuit with the intake of input circuit via transformer to produce output end voltage, in output circuit controller is set again, but and this controller sensing output voltage, and can carry out at the variation of sensing output voltage action as by the controller decision connect resistive load, short circuit, three kinds of state variation open circuit, influencing the first side winding of transformer, but make the first side winding respective action control switch element of transformer do the switch motion of PWM or PFM with control output voltage; Thus, the present invention is more accurate, reliable by the switch element action of the controller control primary side of secondary side, there is no the light requirement coupling element, can reduce cost and make more stable, the longer service life of circuit, and have the function of synchronous rectification.
Description of drawings
Fig. 1 is a circuit framework schematic diagram of the present invention;
Fig. 2 is the first embodiment of the invention circuit diagram;
Fig. 3 is first embodiment of the invention voltage, current point schematic diagram;
Fig. 4 is the action waveforms schematic diagram of first embodiment of the invention corresponding diagram 3;
Fig. 5 is first embodiment of the invention output end voltage controller stop mode action schematic diagram when excessive;
Controller secondary side start-up mode action schematic diagram when Fig. 6 is first embodiment of the invention output end voltage deficiency;
Controller action schematic diagram when Fig. 7 is first embodiment of the invention output end voltage deficiency;
Fig. 8 is secondary side cycle stop mode and the start-up mode action waveforms schematic diagram of first embodiment of the invention corresponding diagram 5, Fig. 6, Fig. 7;
Fig. 9 makes current-limiting protection effect waveform schematic diagram for the first embodiment of the invention transistor seconds;
Figure 10 is the second embodiment of the invention circuit diagram;
Figure 11 is the direction flyback converter circuit diagram of known tool optical coupling element;
Figure 12 is another known direction flyback converter circuit diagram.
The main element symbol description
Embodiment
Circuit framework tool one input circuit of the present invention, a transformer, an output circuit, and the input of this input circuit connects the input power supply, outlet side connects transformer, and tool one switch element at least; The first side winding of transformer connection aforementioned switches element, and its change in voltage again can change switch element open and close state, and the tool secondary side winding; Output circuit connects the Circuit Fault on Secondary Transformer winding again, and tool output, and aforementioned circuit can be transferred to output circuit generation output end voltage via transformer with the intake of input circuit, in output circuit controller is set again, and but this controller sensing output end voltage changes and feedbacks to the transformer first side winding, but makes the first side winding respective action control switch element of transformer do PWM or the action of PFM mode switch with control output end voltage.
The present invention's circuit more specifically can be self-excitation flyback circuit framework, identical first winding, second winding of the primary side tool polarity of transformer wherein, the secondary side tool and the opposite tertiary winding of aforementioned first and second winding polarity again, the input of input circuit connects first winding, one end of input power supply, start-up circuit input, transformer primary side again, this start-up circuit output connects the first transistor B utmost point of switch element again, and this first transistor C utmost point connects the aforementioned first winding other end; Second winding, one end of this transformer primary side connects the resistance and the first transistor B utmost point again, and this second winding other end ground connection; The emitter-base bandgap grading of this first transistor connects grounding through resistance again; Connect current-limiting protection circuit in the first transistor again, and this current-limiting protection circuit tool transistor seconds, and the B utmost point of this transistor seconds connection the first transistor emitter-base bandgap grading, and the C utmost point connection the first transistor B utmost point, and the emitter grounding of transistor seconds; Output circuit tool rectifier diode again, and its positive pole is connected with the transformer tertiary winding, and this tertiary winding other end ground connection, the negative pole of this diode connects output again, and in the output shunt capacitor, in output circuit controller is set again, and this controller connects output end power, and the input of controller connects the divider resistance contact by the output series connection, and tool error amplifier, reference voltage is with relatively output end voltage variation, this controling appliance first again, the second control end cross-over connection diode, two ends, and this first, connect resistive load by the controller decision between second control end, short circuit, the three kinds of state variation of opening a way, the present invention that makes of mat can control the switch element action of primary side with the preferable precision reliability of tool by the controller of secondary side, and can reduce cost and circuit stability because of no optical coupling element, life-span, and can increase synchronous rectification.
See also Fig. 1, main circuit framework tool one input circuit 1 of the present invention, a transformer T, an output circuit 2, and the input of this input circuit 1 connects input power supply Vin, outlet side connects transformer T, and tool one switch element 11 at least, and this switch element 11 can be the indivedual or composition element of transistor, MOSFET or other on-off action; The first side winding of transformer T connects aforementioned switches element 11 again, and its change in voltage can change switch element 11 open and close states, and the tool secondary side winding; Output circuit 2 connects transformer T secondary side winding again, and tool output, and aforementioned circuit can produce output end voltage Vout by the output that transformer T is transferred to output circuit 2 with the intake of input circuit 1, in output circuit 2 controller 21 is set again, and but this controller 21 sensing output end voltage Vout change and to feedback to the transformer first side winding, but make the first side winding respective action control switch element 11 of transformer T do PWM or PFM switch motion with control output end voltage.
See also Fig. 2, the present invention's first embodiment circuit more specifically is a self-excitation direction flyback converter circuit framework, the first identical winding N1 of the primary side tool polarity of transformer T wherein, the second winding N2, secondary side tool and aforementioned first again, two winding N1, the opposite polarity tertiary winding N3 of N2, the input of input circuit 1 connects input power supply Vin again, start-up circuit 12 inputs, the first winding N1, one end of transformer T primary side, these start-up circuit 12 outputs connect the first transistor Q1B utmost point of switch element again, and this first transistor Q1C utmost point connects the aforementioned first winding N1 other end; The second winding N2, one end of this transformer T primary side connects the current-limiting resistance and the first transistor Q1B utmost point again, and this second winding N2 other end ground connection; The emitter-base bandgap grading of this first transistor Q1 connects resistance R S ground connection again; Connect current-limiting protection circuit in the first transistor Q1 again, and this current-limiting protection circuit tool transistor seconds Q2, and the B utmost point of this transistor seconds Q2 connection the first transistor Q1 emitter-base bandgap grading, and the C utmost point connection the first transistor Q1B utmost point, and its emitter grounding.
Output circuit 2 tool rectifier diode D1 are located at output end position, and its positive pole is connected with transformer T tertiary winding N3, and this tertiary winding N3 other end ground connection, the negative pole of this diode D1 connects output again, and in output shunt capacitor C1 ground connection, output circuit 2 is provided with controller 21 and tool power vd D again, ground connection GND contact, and the VDD contact of this controller 21 connects output end power Vout, and the input FB of controller 21 connects the divider resistance contact by the output series connection, and tool error amplifier, reference voltage (indicating among the figure) is with relatively output end voltage variation, this controller 21 tool power vd D again, ground connection GND contact, and first, the second control end CTL1, CTL2 cross-over connection diode D1 two ends, and this first, the second control end CTL1, connect resistive load by controller 21 decisions between CTL2, short circuit, the three kinds of state variation of opening a way.
See also Fig. 3, Fig. 4, the input input service voltage Vin of input circuit 1 when the present invention moves, and make start-up circuit 12 output pulse wave a make the first transistor Q1 conducting Ton to the first transistor Q1, and collected current Ic arranged, and this moment input current through the first winding N1, the first transistor Q1, the resistance R S ground connection of transformer T, the part electric current is through the second winding N2, the first transistor Q1, the resistance R S ground connection of transformer T again, and this moment the first winding N1, second winding N2 top polarity for just, tertiary winding N3 top polarity is for bearing; The first transistor Q1 ends when the rising of the first transistor Q1 series resistor RS voltage makes transistor seconds Q2 conducting again, and make transformer T primary side energy be transferred to secondary side, and make the tertiary winding N3 polarity inversion of secondary side, and make the electric current diode D1 that can flow through produce output end voltage Vout, and electric current I d arranged, the polarity transition of transformer T when the energy of tertiary winding N3 disengages fully again, and make the transformer T second winding N2 stray inductance storage power can make the first transistor Q1 conducting once more, make automatic soft start of tool of the present invention and ring auto-excitation type framework, and be operated in non-continuous mode, and start-up circuit 12 is not promptly moving and consumed power after starting for the first time, and system stops to surpass behind the Preset Time or the establishment of replacement condition just can be sent starting impulse once again.
But controller 21 sensing output end voltage Vout variation of the present invention is controlled, see also Fig. 3, Fig. 5, Fig. 7 and Fig. 8, controller 21 may command first when the present invention exceeds setting voltage as output end voltage Vout, the second control end CTL1, CTL2 connects resistive load in the time that transformer T energy is transferred to before the output time starts once more to the first transistor Q1 fully, make that this resistive load can consume transformer T leakage inductance institute rudimental energy when Id was zero, its sense of current is as the 5th figure direction of arrow, and stop the first transistor Q1 to excite conducting once more, then reply off state shown in Figure 7, making circuit is stop mode, prevents from that output end voltage Vout from continuing to increase with tool to decide the voltage effect.
See also Fig. 6, Fig. 8, the present invention one blink of short circuit between first, second control end of controller 12 may command CTL1, CTL2 when output end voltage Vout is not enough, and the capacitor C1 store energy that makes output circuit 2 is to tertiary winding N3, and Id can correspondingly descend; Fig. 7 and for example, shown in Figure 8, make controller 21 controls first again, the second control end CTL1, CTL2 opens circuit, this energy will make Vsw voltage reduce, and change and restart the first transistor Q1 conducting by the energy of the second winding N2, circuit enters the self-excitation switching motion once again thus, and make the energy of input circuit 1 can be passed to output circuit 2 rapidly, and promote output end voltage Vout and reach and decide voltage function, thereby the present invention can make the first transistor Q1 of transformer T primary side carry out PWM or PFM action so that output end voltage Vout tool is decided voltage function by the controller 21 of transformer T secondary side, and controller 21 direct sensing output end voltage Vout of the present invention, can have a high effect of precision, and tool synchronous rectification, and can have a preferable reliability, the present invention must optical coupling element again, can have preferable life-span and a reliability.
See also Fig. 3, Fig. 9; the present invention is when if output circuit 2 (as the diode D1) short circuit of transformer T secondary side or overload make the transformer T primary side first winding N1 electric current I c increase rapidly; voltage Vsense on the input circuit 1 resistance R S will make transistor seconds Q2 conducting; and make the first transistor not conducting of Q1 so that Circuits System stops action; and treat to make the Circuits System action by start-up circuit 12 again when situation is got rid of, make transistor seconds Q2 can do the current-limiting protection effect.
Controller 2 also can make first, second control end CTL1, CTL2 stop for a long time during output circuit 2 short circuits again, and etc. start-up circuit 12 do to reset and one remove until short circuit.
In addition, though the present invention's tool start-up circuit 12, the cost of this start-up circuit 12 is low, and consumed power is low, thereby the present invention can be had a low and high efficiency function of cost.
See also Figure 10, the second embodiment of the invention circuit and first embodiment are roughly the same, the rectifier diode D1 that its difference is in output circuit 2 is located at tertiary winding below contact and earth terminal position, and its polar orientation is opposite with first embodiment, and this circuit also can have identical self-excitation translation function with first embodiment, and the control bit of first, second control end CTL1, the CTL2 of controller 21 will definitely cooperate change with the identical controlled function of tool, and this circuit can add synchronous rectification in the controller to raise the efficiency.
Previous embodiment is clear description feature of the present invention, is not that the present invention can change in not exceeding spirit of the present invention and category and revise as the restriction of the present patent application claim.