The quasi-resonance testing circuit and the quasi-resonance control circuit of inverter
Technical field
The present invention relates to quasi-resonance and detect and the control technology field, specifically, the present invention relates to a kind of quasi-resonance testing circuit and quasi-resonance control circuit of inverter.
Background technology
In the existing inverter field, the quasi-resonance technology is the widely used method raising the efficiency, improve reliability and reduce cost.It makes the main switch of inverter open-minded at the trough of both end voltage, thereby has reduced the energy loss of main switch.By main switch being opened and the control of turn-off time, can realize the quasi-resonant switching function, thereby reduce energy loss effectively, raise the efficiency.In addition, softer switch can improve the EMI characteristic of power supply, allows the designer to reduce the number that uses filter, thereby reduces cost.
Prior art utilizes testing circuit to come effectively first minimum value or the valley of the main switch drain-source voltage of " sensing " inverter usually, and only at this moment starts the ON time of main switch.Because parasitic capacitance is charged to minimum voltage, the current spike of conducting will minimize, and this situation often is called as valley switch (Valley Switching).Under certain conditions, designer even may obtain quasi-resonant switching (ZVS) does not promptly have drain-source voltage when main switch is activated.In this case, owing to parasitic capacitance is not recharged, so the current spike of conducting can not occur.
Fig. 1 is the change curve schematic diagram of a main switch drain-source voltage under two different input voltage vin 1 and Vin2 of the prior art.As shown in the figure, suppose input voltage vin 1>Vin2, input voltage vin 1 time, the first trough voltage Vds_v1 of the drain-source voltage Vds of curve 101 representatives is higher than quasi-resonance threshold voltage VQR, so quasi-resonance is not worked, drain-source voltage Vds continues to keep the concussion waveform; Input voltage vin 2 times, the first trough (not shown) of the drain-source voltage Vds of curve 102 representatives is lower than quasi-resonance threshold voltage VQR, and then quasi-resonance control circuit produces the main switch drive signal, and quasi-resonance is started working.Along with main switch is open-minded, drain-source voltage Vds is along with time t drops to zero.
Fig. 2 is the schematic diagram that concerns of trough voltage Vds_v, a quasi-resonance threshold voltage VQR of the prior art and input voltage vin.Trough voltage Vds_v increases along with the increase of input voltage vin, and quasi-resonance threshold voltage VQR is a steady state value.As shown in the figure, the crosspoint of two lines provides the scope of quasi-resonance work: the left side of vertical line in the drawings, and trough voltage Vds_v is lower than the crosspoint, quasi-resonance work; The right of vertical line in the drawings, trough voltage Vds_v is higher than the crosspoint, and quasi-resonance is not worked.
Fig. 3 is the rough schematic of a quasi-resonance control circuit of the prior art.As shown in the figure, quasi-resonance control circuit 300 can comprise:
Quasi-resonance testing circuit 302, the one end is couple to the source terminal of the main switch Qfb of inverter, the other end is couple to a common ground end GND with the drain electrode end of main switch Qfb, is used for according to the source-drain voltage Vds unlatching of main switch Qfb or the quasi-resonance function of not opening main switch Qfb;
Main switch control circuit 301 is connected across between the gate terminal of quasi-resonance testing circuit 302 and main switch Qfb, is used for opening or turn-offing according to the output signal control main switch Qfb of quasi-resonance testing circuit 302;
Wherein, quasi-resonance testing circuit 302 can comprise:
Bleeder circuit 303, one end are couple to the source terminal of the main switch Qfb of inverter, and the other end is couple to a common ground end GND with the drain electrode end of main switch Qfb, are used for the source-drain voltage Vds of main switch Qfb is exported in proportion;
Voltage-selected switch pipe Q, its source terminal sees through one the 3rd resistance R 3 and is couple to a high voltage end Vcc, drain electrode end is couple to the other end of bleeder circuit 303, gate terminal couples mutually with the voltage output end of bleeder circuit 303, and the size that is used for the output voltage (being the grid voltage Vg of voltage-selected switch pipe Q) according to bleeder circuit 303 is selected to open or turn-off it.
Wherein, bleeder circuit 303 can comprise:
The first divider resistance R1, the one end is couple to the source terminal of main switch Qfb;
The second divider resistance R2, the one end couples mutually with the other end of the first divider resistance R1, and the other end is couple to common ground end GND with the drain electrode end of main switch Qfb.The common joint of the first divider resistance R1 and the second divider resistance R2 is couple to the gate terminal of voltage-selected switch pipe Q, be used for source-drain voltage Vds in proportion (R2/ (R1+R2)) output to the gate terminal of voltage-selected switch pipe Q, as its grid voltage Vg.
In addition, can also one voltage-stabiliser tube D be arranged coupled in parallel, be used for stablizing the output voltage V g of bleeder circuit 303 at the two ends of the second divider resistance R2.
Continue with reference to quasi-resonance control circuit figure shown in Figure 3, when grid voltage Vg surpassed the cut-in voltage Vth of voltage-selected switch pipe Q, Q was open-minded for the voltage-selected switch pipe, and quasi-resonance control circuit 300 offers main switch control circuit 301 low-voltages; When grid voltage Vg was lower than the cut-in voltage Vth of voltage-selected switch pipe Q, voltage-selected switch pipe Q turn-offed, and quasi-resonance control circuit 300 offers main switch control circuit 301 high voltages.
Can see Vg/R2=Vds/ (R1+R2) thus, Vds=Vg (R1+R2)/R2 then is so cause that the quasi-resonance threshold voltage that main switch Qfb starts is VQR=Vth (R1+R2)/R2.That is to say that when first minimum value of main switch Qfb drain-source voltage Vds or valley (trough voltage) Vds_v dropped to quasi-resonance threshold voltage VQR, main switch Qfb started.When first minimum value of switching tube Qfb drain-source voltage Vds or valley Vds_v were higher than quasi-resonance threshold voltage VQR, main switch Qfb just can not start, and just can't realize quasi-resonance work yet.
In order to realize the quasi-resonant switching of main switch Qfb, need to use as far as possible little quasi-resonance threshold voltage VQR, but guarantee that again quasi-resonance threshold voltage VQR is higher than first minimum value or the valley Vds_v of drain-source voltage Vds.And first minimum value of drain-source voltage Vds or valley Vds_v are relevant with input voltage vin, and when input voltage vin was high more, trough voltage Vds_v was also high more, and this can bring corresponding problem to application.For example, when input voltage vin=50V, trough voltage Vds_v=10V, and at input voltage vin=40V, trough voltage Vds_v=1V.In order to reach the best effects that quasi-resonance is opened, quasi-resonance threshold voltage VQR=2V just can realize that the quasi-resonance of input voltage vin=40V is open-minded.But, because the trough voltage Vds_v=10V of quasi-resonance threshold voltage VQR=2V during, just can't realize quasi-resonance during so input voltage vin=50V less than input voltage vin=50V.
This shows that a problem of existing quasi-resonant switching technology is being limited in scope of input voltage.For the inverter that big input voltage range is arranged, for example solar photovoltaic inverter can't be implemented in the quasi-resonant switching in the whole operating voltage range.Usually input voltage is high more, and the trough of voltage is high more.For realizing quasi-resonance, use the quasi-resonance testing circuit to detect the drain-source voltage of main switch usually, and realize when drain-source voltage drops to the value (being VQR) of setting, opening main switch.If trough voltage is lower than this value when improving the value of this setting and guaranteeing high input voltage, then when low input, main switch is also opened in this set point, and can not open in the lower value that they originally can reach again, cause the more energy loss, reduced operating efficiency.
Summary of the invention
Technical problem to be solved by this invention provides a kind of quasi-resonance testing circuit and quasi-resonance control circuit of inverter, make main switch being suitable for the quasi-resonance function in the input voltage range completely, reduce energy loss effectively, increase work efficiency and reduce cost.
For solving the problems of the technologies described above, the invention provides a kind of quasi-resonance testing circuit of inverter, comprising:
Bleeder circuit, the one end is couple to the source terminal of the main switch of described inverter, the other end is couple to a common ground end with the drain electrode end of described main switch, is used for according to the input voltage of described inverter the source-drain voltage of described main switch being exported in proportion;
The first voltage-selected switch pipe, its source terminal sees through one the 3rd resistance and is couple to a high voltage end, drain electrode end is couple to the other end of described bleeder circuit, gate terminal couples mutually with the voltage output end of described bleeder circuit, is used for selecting to open or turn-off it according to the size of the output voltage of described bleeder circuit.
Alternatively, described bleeder circuit comprises:
First partial pressure unit, the one end is couple to the source terminal of described main switch;
Second partial pressure unit, the one end couples mutually with the other end of described first partial pressure unit, and the other end is couple to described common ground end with the drain electrode end of described main switch;
Wherein, the resistance of at least one is to change according to the size of described input voltage in described first partial pressure unit and second partial pressure unit, its common joint is couple to the gate terminal of the described first voltage-selected switch pipe, is used for according to described input voltage the source-drain voltage of described main switch being outputed in proportion the gate terminal of the described first voltage-selected switch pipe.
Alternatively, described second partial pressure unit comprises:
The second voltage-selected switch pipe, its source terminal couples mutually with described first partial pressure unit, and drain electrode end is couple to described common ground end with the drain electrode end of described main switch;
The 4th resistance, the one termination is received the input voltage of described inverter;
The 5th resistance, the one end couples mutually with the other end of described the 4th resistance, and the other end is couple to the drain electrode end of the described second voltage-selected switch pipe;
Wherein, the common joint of described the 4th resistance and the 5th resistance is couple to the gate terminal of the described second voltage-selected switch pipe, is used for described input voltage is outputed in proportion the gate terminal of the described second voltage-selected switch pipe.
Alternatively, described quasi-resonance testing circuit also comprises:
Voltage-stabiliser tube, it is connected across between the other end of common joint in the middle of described first partial pressure unit and second partial pressure unit and described second partial pressure unit, is used to stablize the output voltage of described bleeder circuit.
Alternatively, the described first voltage-selected switch pipe or the second voltage-selected switch pipe are nmos fet.
Correspondingly, the present invention also provides a kind of quasi-resonance control circuit of inverter, comprising:
The quasi-resonance testing circuit, the one end is couple to the source terminal of the main switch of described inverter, the other end is couple to a common ground end with the drain electrode end of described main switch, is used for detecting the quasi-resonance function that whether should open described main switch according to the input voltage of described inverter;
The main switch control circuit is connected across between the gate terminal of described quasi-resonance testing circuit and described main switch, is used for controlling described main switch according to the output signal of described quasi-resonance testing circuit and opens or turn-off;
Wherein, described quasi-resonance testing circuit comprises:
Bleeder circuit, the one end is couple to the source terminal of the main switch of described inverter, the other end is couple to a common ground end with the drain electrode end of described main switch, is used for according to the input voltage of described inverter the source-drain voltage of described main switch being exported in proportion;
The first voltage-selected switch pipe, its source terminal sees through one the 3rd resistance and is couple to a high voltage end, drain electrode end is couple to the other end of described bleeder circuit, gate terminal couples mutually with the voltage output end of described bleeder circuit, is used for selecting to open or turn-off it according to the size of the output voltage of described bleeder circuit.
Alternatively, described bleeder circuit comprises:
First partial pressure unit, the one end is couple to the source terminal of described main switch;
Second partial pressure unit, the one end couples mutually with the other end of described first partial pressure unit, and the other end is couple to described common ground end with the drain electrode end of described main switch;
Wherein, the resistance of at least one is to change according to the size of described input voltage in described first partial pressure unit and second partial pressure unit, its common joint is couple to the gate terminal of the described first voltage-selected switch pipe, is used for according to described input voltage the source-drain voltage of described main switch being outputed in proportion the gate terminal of the described first voltage-selected switch pipe.
Alternatively, described second partial pressure unit comprises:
The second voltage-selected switch pipe, its source terminal couples mutually with described first partial pressure unit, and drain electrode end is couple to described common ground end with the drain electrode end of described main switch;
The 4th resistance, the one termination is received the input voltage of described inverter;
The 5th resistance, the one end couples mutually with the other end of described the 4th resistance, and the other end is couple to the drain electrode end of the described second voltage-selected switch pipe;
Wherein, the common joint of described the 4th resistance and the 5th resistance is couple to the gate terminal of the described second voltage-selected switch pipe, is used for described input voltage is outputed in proportion the gate terminal of the described second voltage-selected switch pipe.
Alternatively, described quasi-resonance testing circuit also comprises:
Voltage-stabiliser tube, it is connected across between the other end of common joint in the middle of described first partial pressure unit and second partial pressure unit and described second partial pressure unit, is used to stablize the output voltage of described bleeder circuit.
Alternatively, the described first voltage-selected switch pipe or the second voltage-selected switch pipe are nmos fet.
Compared with prior art, the present invention has the following advantages:
The present invention is transformable with the element resistance of bleeder circuit instead, can control by input voltage, make main switch automatically to regulate the quasi-resonance threshold voltage according to input voltage, thereby main switch can both be suitable for the quasi-resonance function in input voltage range completely, reduces energy loss effectively, increases work efficiency.
Description of drawings
The above and other features of the present invention, character and advantage will become more obvious by the description below in conjunction with drawings and Examples, wherein:
Fig. 1 is the change curve schematic diagram of a main switch drain-source voltage under two different input voltages of the prior art;
Fig. 2 is the schematic diagram that concerns of a trough voltage of the prior art, quasi-resonance threshold voltage and input voltage;
Fig. 3 is the rough schematic of a quasi-resonance control circuit of the prior art;
Fig. 4 is the schematic diagram of quasi-resonance control circuit of the inverter of one embodiment of the invention;
Fig. 5 is that the quasi-resonance cut-in voltage of main switch of inverter of one embodiment of the invention is with the change curve schematic diagram of input voltage.
Embodiment
The invention will be further described below in conjunction with specific embodiments and the drawings, but should not limit protection scope of the present invention with this.
Fig. 4 is the schematic diagram of quasi-resonance control circuit of the inverter of one embodiment of the invention.As shown in the figure, this quasi-resonance control circuit 400 can comprise:
Quasi-resonance testing circuit 402, the one end is couple to the source terminal of the main switch Qfb of inverter, the other end is couple to a common ground end GND with the drain electrode end of main switch Qfb, is used for detecting the quasi-resonance function that whether should open main switch Qfb according to the input voltage vin of inverter;
Main switch control circuit 401 is connected across between the gate terminal of quasi-resonance testing circuit 402 and main switch Qfb, is used for opening or turn-offing according to the output signal control main switch Qfb of quasi-resonance testing circuit 402;
Wherein, quasi-resonance testing circuit 402 can comprise:
Bleeder circuit 403, the one end is couple to the source terminal of the main switch Qfb of inverter, the other end is couple to common ground end GND with the drain electrode end of main switch Qfb, is used for exporting in proportion according to the input voltage vin of the inverter source-drain voltage Vds with main switch Qfb;
The first voltage-selected switch pipe Q, for example can be nmos fet, its source terminal sees through one the 3rd resistance R 3 and is couple to a high voltage end Vcc, drain electrode end is couple to the other end of bleeder circuit 403, gate terminal couples mutually with the voltage output end of bleeder circuit 403, and the size that is used for the output voltage (i.e. the grid voltage Vg of the first voltage-selected switch pipe Q) according to bleeder circuit is selected to open or turn-off it.
In the present embodiment, bleeder circuit 403 can comprise:
First partial pressure unit 404, the one end is couple to the source terminal of main switch Qfb;
Second partial pressure unit 405, the one end couples mutually with the other end of first partial pressure unit 404, and the other end is couple to common ground end GND with the drain electrode end of main switch Qfb;
Wherein, the resistance of at least one is to change according to the size of input voltage vin in first partial pressure unit 404 and second partial pressure unit 405, its common joint is couple to the gate terminal of the first voltage-selected switch pipe Q, is used for according to input voltage vin the source-drain voltage Vds of main switch Qfb being outputed in proportion the gate terminal of the first voltage-selected switch pipe Q.
In the present embodiment, first partial pressure unit 404 can comprise for first resistance R, 1, the second partial pressure unit 405:
The second voltage-selected switch pipe Q2 for example can be nmos fet, and its source terminal couples mutually with first resistance R 1, and drain electrode end is couple to common ground end GND with the drain electrode end of main switch Qfb;
The 4th resistance R 4, the one termination is received the input voltage vin of inverter;
The 5th resistance R 5, the one end couples mutually with the other end of the 4th resistance R 4, and the other end is couple to the drain electrode end of the second voltage-selected switch pipe Q2;
Wherein, the common joint of the 4th resistance R 4 and the 5th resistance R 5 is couple to the gate terminal of the second voltage-selected switch pipe Q2, be used for input voltage vin is outputed in proportion the gate terminal of the second voltage-selected switch pipe Q2, as the grid voltage Vg2 of the second voltage-selected switch pipe Q2.
In the present embodiment, quasi-resonance testing circuit 403 can also comprise:
Voltage-stabiliser tube D, it is connected across between the other end of the common joint in the middle of first partial pressure unit 404 and second partial pressure unit 405 and second partial pressure unit 405, promptly be connected across between the source terminal and drain electrode end of the second voltage-selected switch pipe Q2, be used for stablizing the output voltage of bleeder circuit 403.
In the present embodiment, the above-mentioned first voltage-selected switch pipe Q or the second voltage-selected switch pipe Q2 are except can being the MOSFET, can also be other voltage control variable resistor such as JFET, or Current Control variable resistor, as triode BJT, reach other and have the element of similar characteristics, this can do to change arbitrarily in scope well known to those skilled in the art.
In the present invention, the drain-source resistance Rq2 of the second voltage-selected switch pipe Q2 is by grid voltage Vg2 and cut-in voltage Vth2 decision, its scope can be when the second voltage-selected switch pipe Q2 opens 1 ohm of hundreds of when turn-offing kilohm.
In the present invention, can have: Rq2~A/ (Vg2-Vth2-B*Vds2), wherein A, B are the characterisitic parameters of the second voltage-selected switch pipe Q2, Vds2 is the source-drain voltage of the second voltage-selected switch pipe Q2.
In addition, Vg2=Vin*R5/ (R4+R5), then VQR=Vth* (R1+Rq2)/Rq2.
This shows,, can realize first minimum value or the valley Vds_v of a little higher than all the time main switch Qfb of VQR drain-source voltage Vds, guarantee the operate as normal of quasi-resonance and the best effects that quasi-resonance is opened by selecting the value of suitable R 4, R5, Vth2.
Fig. 5 is that the quasi-resonance cut-in voltage of main switch of inverter of one embodiment of the invention is with the change curve schematic diagram of input voltage.As shown in the figure, be 40V when following in input voltage vin, the second voltage-selected switch pipe Q2 turn-offs, and quasi-resonance cut-in voltage VQR remains 2V.After this, quasi-resonance cut-in voltage VQR is linear increase with the increase of input voltage vin, and VQR is 14V when input voltage vin is 50V.Can see that quasi-resonance cut-in voltage VQR is designed in the scope of whole input voltage vin than trough voltage Vds_v height, but low as far as possible, to obtain the best effects of quasi-resonance.
The present invention is transformable with the element resistance of bleeder circuit instead, can control by input voltage, make main switch automatically to regulate the quasi-resonance threshold voltage according to input voltage, thereby main switch can both be suitable for the quasi-resonance function in input voltage range completely, reduces energy loss effectively, increases work efficiency.
Though the present invention with preferred embodiment openly as above; but it is not to be used for limiting the present invention; any those skilled in the art without departing from the spirit and scope of the present invention; can make possible change and modification, so protection scope of the present invention should be as the criterion with the scope that claim of the present invention was defined.