CN108462395A - Switching power unit - Google Patents
Switching power unit Download PDFInfo
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- CN108462395A CN108462395A CN201711171500.1A CN201711171500A CN108462395A CN 108462395 A CN108462395 A CN 108462395A CN 201711171500 A CN201711171500 A CN 201711171500A CN 108462395 A CN108462395 A CN 108462395A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The present invention provides a kind of switching power unit, even low input also obtains peak power.The switching power unit has：ON/OFF controls waveshaping circuit (24), output voltage detected by output voltage detection unit (6) and formed and be supplied to switch element (3) for output voltage control to be controlled signal for constant ON/OFF；And correcting current detection signal generation unit (40a), it controls the signal of the conducting start time of the expression switch element in waveshaping circuit in response to ON/OFF, the 1st correction signal with steady state value is formed during duty ratio is less than defined value the conducting start time from switch element, increased 2nd correction signal with time going by is formed from the value of the 1st correction signal during duty ratio is more than defined value, is subtracted the 1st correction signal and the 2nd correction signal successively from current detection signal and is generated correcting current detection signal.
Description
Technical field
The present invention relates to the switching power units such as DC-DC converter.
Background technology
As shown in figure 8, previous switching power unit has switch element 3, output rectifier smoothing circuit 4, output voltage
Detection circuit 6, control unit 7, control power supply rectifier smoothing circuit 8, controlling power circuit 9 and current sense resistor 10.Transformation
Device 2 has primary coil N1, secondary coil N2 and tertiary coil (control power coil) N3.
Export rectifier smoothing circuit 4 have rectifier diode 4a and smoothing capacitor 4b, smoothing capacitor 4b via
Rectifier diode 4a and be connected in parallel with secondary coil N2.Control power supply with rectifier smoothing circuit 8 have rectifier diode 8a and
Smoothing capacity device 8b, via controlling power circuit 9 by DC voltage after switch element 3 proceeds by ON/OFF action
It is supplied to control unit 7.
Controlling power circuit 9 is connect with control power supply rectifier smoothing circuit 8 and control unit 7.Controlling power circuit 9 is three
Secondary coil N3 obtains driving control unit 7 using the voltage of the 1st DC power supply terminal 1a before voltage.In tertiary coil N3
After obtaining voltage, control unit 7 is driven by the voltage of control power supply rectifier smoothing circuit 8.Output voltage detecting circuit 6 is right
Output voltage is detected, and has secondary side section 22 and a side section 23.Secondary side section 22 by light emitting diode 22a and
The series circuit of Zener diode 22b is constituted.Side section 23 is by the phototransistor with light emitting diode 22a optical couplings
23a and capacitor 23b are constituted.
As shown in figure 9, control unit 7 has ON/OFF control waveshaping circuit 24, overcurrent protection circuit 25 and low
Bandpass filter 26.In ON/OFF controls waveshaping circuit 24, one end of resistance 27 is connect with DC power supply terminal 27a,
The other end is connect via the 4th terminal 18 with the collector of phototransistor 23a.Resistance 27 is mutual with phototransistor 23a's
Tie point P1 is connect with the negative input terminal of feedback comparator 28, and low-pass filter 26 is via correcting circuit 42 and compared with feedback
The positive input terminal of device 28 connects.Low-pass filter 26 is connect via the 3rd terminal 17 with one end of current sense resistor 10.Instead
Feedback comparator 28 is compared the voltage V1 of correcting current detection signal and phototransistor 23a and exports expression switch element
The trigger signal of finish time during 3 conducting.
If the amplitude of the correcting current detection signal of the positive input terminal of feedback comparator 28 reaches the electricity of negative input terminal
V1 is pressed, then generates the pulse of high level from the leading-out terminal of feedback comparator 28 or circuit (OR circuits) 29 exports high level
Pulse.Or the leading-out terminal of circuit 29 is connect with the reseting terminal R of rest-set flip-flop 30, or circuit 29 export high level pulse
When, rest-set flip-flop 30 is reset.The setting terminal S of rest-set flip-flop 30 is connect with clock generator 31.If from clock generator 31
Clock signal is generated, then rest-set flip-flop 30 is triggered and becomes SM set mode.The Q of rest-set flip-flop 30-Shown in reversed-phase output
Son is low level in SM set mode.The reverse phase of the input terminal and rest-set flip-flop 30 of one side of NOR circuit (NOR circuit) 32
Leading-out terminal connects, and the input terminal of another party of NOR circuit 32 is connect with clock generator 31.
Current sense resistor 10 is corresponding with current detecting unit, is connected in series with switch element 3, to flowing through switch element 3
Electric current be detected, obtain the current detection signal as the voltage proportional to electric current.Overcurrent protection circuit 25 has
Overcurrent detection comparator 35, overcurrent reference voltage source 36 and correcting current detection signal generation unit 40.Overcurrent detects
The positive input terminal of comparator 35 is connect via correcting circuit 42 with low-pass filter 26, and leading-out terminal AND circuit 29 connects
It connects.If the correcting current detection signal from correcting circuit 42 is more than the overcurrent threshold value as overcurrent reference voltage source 36
Overcurrent reference voltage V r, then from overcurrent detection comparator 35 generate trigger signal, trigger signal via or circuit 29 carried
Supply the reseting terminal R of rest-set flip-flop 30.Rest-set flip-flop 30 resets, and switch element 3 disconnects.Overcurrent reference voltage V r is set
For load 21 be in normal condition when not crosscutting correcting current detect signal, be set in load 21 in short-circuit condition or
Crosscutting correcting current detects signal when person's low impedance state.
Correcting current detection signal generation unit 40 inhibits the maximum output current generated by the variation of input voltage vin
Variation, be made of slope voltage generating circuit 41 and correcting circuit 42.Slope voltage generating circuit 41 and come from clock
Generate to the clock signal synchronization of device 31 the ramp voltage V2 being made of triangle wave voltage.Slope voltage generating circuit 41 in response to
Clock signal and leaned on than the finish time during the maximum conducting of switch element 3 from the conducting start time of switch element 3
The positive slopes voltage Va with positive slope is continuously generated during afterwards, then continuously generates the negative ramp voltage with negative slope
Vb。
Correcting circuit 42, which is formed, to be subtracted with the current detection signal V3 from low-pass filter 26 obtained from correction voltage V2
It is worth comparable correcting current detection signal V4, is sent to feedback comparator 28 and overcurrent detection comparator 35.As shown in Figure 10,
There is correcting circuit 42 voltage conversion resistance Ra, electric current to convert with the control element Q1, Q2 of resistance Rb, the 1st and the 2nd, the 3rd control
The constant-current source circuit 45,46 of the control element Q4, Q5 of element Q3, the 4th and the 5th, the 1st and the 2nd.Voltage conversion with one end of resistance Ra with
Low-pass filter 26 connects, and the other end is connect with the output line 47 of correcting current detection signal V4.If flowing through voltage conversion electricity consumption
The value for hindering the electric current I5 of Ra changes, then voltage conversion is changed with voltage V5 between the two-terminal of resistance Ra.Flow through voltage conversion electricity consumption
The electric current I5 of resistance Ra increases with the process of the turn-on time of switch element 3.Therefore, current detection signal V3 and correcting current
The difference of vibration (that is, voltage V5) of detection signal V4 increases with the process of turn-on time.Current detection signal V3, correcting current
Detect signal V4 has the relationship of V4=V3-V5, therefore voltage conversion resistance Ra with voltage conversion with the voltage V5 of resistance Ra
It is functioned as subtraction operator.Voltage V5 is correction voltage or correction signal.
The source electrode as the 1st main electrode of the 1st and the 2nd control element Q1, Q2 of Figure 10 respectively with DC power supply terminal 43
Connection, the grid as coordination electrode of the 1st and the 2nd control element Q1, Q2 are commonly connected each other and with the 1st control element Q1
Drain electrode as the 2nd main electrode connects.The drain electrode of 1st control element Q1 is connect with the collector of the 3rd control element Q3.3rd control
The emitter of element Q3 processed is connect with resistance Rb with ground terminal 44 via electric current conversion.The base stage of 3rd control element Q3 with
The output line 41a connections of slope voltage generating circuit 41.The drain electrode of 2nd control element Q2 connects with the drain electrode of the 4th control element Q4
It connects.The source electrode of 4th control element Q4 is connect via the 1st constant-current source circuit 45 with ground terminal 44.4th and the 5th control element
The grid of Q4, Q5 are commonly connected each other and are connect with the drain electrode of the 4th control element Q4.The source electrode of 5th control element Q5 is via the 2nd
Constant-current source circuit 46 and connect with ground terminal 44, the other end of the drain electrode of the 5th control element Q5 and voltage conversion resistance Ra
Connection.
It is high that 1st and the 2nd constant-current source circuit 45,46 limits value as defined in correction voltage V5 ratios.That is, the 1st and the 2nd constant-current source is electric
The limitation of road 45,46 is bigger than defined current value I3, I4 with the comparable correcting current I5 of leakage current of the 5th control element Q5.1st is permanent
The defined current value I3 of current source circuit 45 is set to identical as the defined current value I4 of the 2nd constant-current source circuit 46.
According to the switching power unit, if generating the clock signal for making switch element 3 be connected, synchronous real estate
Raw ramp voltage V2.Ramp voltage V2 is applied to the base stage of the 3rd control element Q3.Ramp voltage V2 is converted into the 3rd control as a result,
The impedance of the impedance of element Q3, the 3rd control element Q3 inversely proportionally changes relative to ramp voltage V2.As a result, with oblique
The 1st proportional slope voltage V2 electric current I1 flows through electric current conversion resistance Rb.
The 2nd electric current I2 equal with the 1st electric current I1 flows through the drain electrode of the 2nd control element Q2.If with ramp voltage V2 at than
2nd electric current I2 of example flows through the drain electrode of the 2nd control element Q2, then is also flowed through in the drain electrode of the 5th control element Q5 and the 2nd electric current
The corresponding electric current I5 of I2.The electric current I5 and ramp voltage V2 of 5th control element Q5 is proportionally flowed until the 2nd constant-current source circuit
Until 46 defined current value I4=I3, but it is limited in defined current value I4=I3.Correcting current I5 is according to the 1st direct current
Source terminal 1a, primary coil N1, switch element 3, low-pass filter 26, voltage conversion resistance Ra, the 5th control element Q5, the 2nd
It flows in the path of constant-current source circuit 46 and ground terminal 44.Therefore, voltage is converted with the voltage between terminals V5 of resistance Ra into I5
×Ra.The correcting current detection signal V4 exported from correcting circuit 42 is from the current detection signal V3 from low-pass filter 26
Subtract value obtained from correction voltage V5 (V3-V5).Correction voltage V5 during the conducting of switch element 3 Ton with the time
By and increase.
In this way in the input correction voltage characteristic of previous overcurrent protection circuit 25, conducting dutycycle is smaller, then school
The value of positive voltage V5 is smaller, and conducting dutycycle is bigger, then the value of correction voltage V5 is bigger.
Patent document 1：No. 5169135 bulletins of Japanese Patent Publication No.
However, in the case of obtain peak power or making switch when increasing conducting dutycycle in low input
Frequency and in the case of obtaining peak power, generate subharmonic (sub-harmonic) phenomenon, peak work can not be obtained
Rate.1 pair of subharmonic phenomenon illustrates referring to Fig.1.If being connected by clock enabling signal switch element 3 in moment t0, leak electricity
It is linearly increasing to flow Id.If being applied to the base stage of the 3rd control element Q3, correcting current from zero linear increased ramp voltage V2
Signal V4 is detected also from zero linear increase.
If in moment t1, switch element 3 disconnects, then leakage current Id becomes zero, but electric current flows through secondary coil N2.Secondary line
Loop current is linearly reduced, but t2 at the time of before electric current is zero, and switch element 3 is connected, therefore secondary coil N2 will not be answered
Position.Therefore, leakage current Id is applied DC component and linearly increasing.The current detection signal V3 proportional to leakage current Id also by
Be superimposed DC component and it is linearly increasing.Ramp voltage V2 is from zero linear increase.Since voltage V4 is V3-V5, voltage V4
It is applied DC component and linearly increasing.
Then, if in moment t3, switch element 3 disconnects, then leakage current Id is zero, but secondary coil electric current is linearly reduced.
If t4 at the time of electric current is before zero, switch element 3 is connected, then enters overcurrent protection action, therefore leakage current Id is narrow
Pulse.In addition, secondary coil electric current gradually decreases, become zero in moment t5, transformer 2 is reset.Due to being returned in moment t6
To the state of moment t0, therefore cycle T 1 is repeated until moment t0 to moment t6.Leakage current Id in period t3~t6 not
Flowing, therefore peak power can not be obtained.
Invention content
Problem of the present invention is that providing following switching power unit：Even if in low input and making switching frequency
Also peak power can be obtained in the case of high frequency.
The switching power unit of the present invention is characterized in that having：Transformer, with primary coil and secondary line
Circle；Switch element connect with DC power supply via the primary coil of the transformer and carries out ON/OFF；It is defeated
Go out voltage detection unit, the output voltage of the secondary coil side of the transformer is detected；ON/OFF controls
Waveshaping circuit is formed according to the output voltage of the output voltage detection unit for by the output voltage
Control is that constant ON/OFF controls signal, and ON/OFF control signal is supplied to the switch element；Electricity
Detection unit is flowed, the electric current to flowing through the switch element is detected and output electric current measure signal；Correcting current detects
Signal generation unit controls the conducting of the expression switch element in waveshaping circuit in response to the ON/OFF
The signal of start time forms tool during duty ratio is less than defined value the conducting start time from the switch element
The 1st correction signal for having steady state value is formed during the duty ratio is defined value or more from the 1st correction signal
It has been worth with time going by and increased 2nd correction signal, the 1st correction letter is subtracted successively from the current detection signal
Number and the 2nd correction signal and generate correcting current detection signal；And comparing unit, the correcting current is detected and is believed
Number and indicate that the overcurrent threshold value of over-current level for flowing through the electric current of the switch element is compared, in the correcting current
The signal for making the switch element disconnect is output to the ON/OFF when detection signal reaches the overcurrent threshold value
Control waveshaping circuit.
The switching power unit of the present invention is characterized in that having：Transformer, with primary coil and secondary line
Circle；Switch element connect with DC power supply via the primary coil of the transformer and carries out ON/OFF；It is defeated
Go out voltage detection unit, the output voltage of the secondary coil side of the transformer is detected；ON/OFF controls
Waveshaping circuit is formed according to the output voltage of the output voltage detection unit for by the output voltage
Control is that constant ON/OFF controls signal, and ON/OFF control signal is supplied to the switch element；Electricity
Detection unit is flowed, the electric current to flowing through the switch element is detected and output electric current measure signal；Correcting current detects
Signal generation unit controls the conducting of the expression switch element in waveshaping circuit in response to the ON/OFF
The signal of start time, and in the case where input voltage is less than defined voltage, since the conducting of the switch element
Duty ratio forms the 1st correction signal with steady state value during being less than defined value from moment, is described in the duty ratio
During more than defined value formed from the value of the 1st correction signal with time going by and it is increased 2nd correction letter
Number, the 1st correction signal and the 2nd correction signal are subtracted successively from the current detection signal and generate correcting current inspection
Signal is surveyed, is formed in the case where the input voltage is more than the defined voltage and is increased with time going by from zero
The 3rd big correction signal subtracts the 3rd correction signal from the current detection signal and generates correcting current and detect signal；
And comparing unit, the over-current level of the electric current of the switch element is flowed through to correcting current detection signal and expression
Overcurrent threshold value be compared, will be used to make described open when correcting current detection signal reaches the overcurrent threshold value
It closes the signal that element disconnects and is output to the ON/OFF control waveshaping circuit.
Invention effect
According to the present invention, correcting current detects signal generation unit duty ratio the conducting start time from switch element
The 1st correction signal with steady state value is formed during less than defined value, subtract the 1st correction signal from current detection signal and
It generates correcting current and detects signal.That is, subtracting constant correcting value during duty ratio is less than defined value, therefore correct electricity
Stream detection signal becomes smaller.
Therefore, even if DC component is superimposed, overcurrent protection action will not be entered in the conducting of switch element, therefore
Subharmonic phenomenon is not will produce.Therefore, it is possible to provide following switching power unit：Even if in low input and making switch frequency
Also peak power can be obtained in the case of rate high frequency.
Description of the drawings
Fig. 1 is the circuit diagram for the switching power unit for showing the embodiment of the present invention 1.
Fig. 2 is the detailed circuit diagram of control unit shown in FIG. 1.
Fig. 3 is the detailed circuit diagram of adder calculator and correcting circuit shown in Fig. 2.
Fig. 4 is the figure of the waveform amplification of each section for the switching power unit for showing embodiment 1.
Fig. 5 is disposed on the detailed circuit diagram of the control unit in the switching power unit of the embodiment of the present invention 2.
Fig. 6 is the detailed circuit diagram of adder calculator shown in fig. 5, switch and correcting circuit.
Fig. 7 is disposed on the detailed circuit diagram of the control unit in the switching power unit of the embodiment of the present invention 3.
Fig. 8 is the circuit diagram for showing previous switching power unit.
Fig. 9 is the detailed circuit diagram of control unit shown in Fig. 8.
Figure 10 is the detailed circuit diagram of correcting circuit shown in Fig. 9.
Figure 11 is the figure for showing the waveform amplification of each section of subharmonic phenomenon in previous switching power unit.
Label declaration
1a、1b：1st and the 2nd DC power supply terminal；2：Transformer；3：Switch element；4：Export rectifier smoothing circuit；6：
Output voltage detecting circuit；7：Control unit；10：Current sense resistor；14：Integrated circuit；24：ON/OFF controls signal shape
At circuit；25：Overcurrent protection circuit；35：Overcurrent detection comparator；36：Overcurrent reference voltage source；40、40a、40b、
40c：Correcting current detects signal generation unit；41：Slope voltage generating circuit；42、42a、42b、42c：Correcting circuit；51、
51a、51b：Adder calculator；52：Duty detection circuit；53：Input voltage monitoring circuit；SW：Switch；Ra：Voltage is converted
Use resistance；V3：Current detection signal；V4：Correcting current detects signal；V5：Correction voltage；I5：Correcting current；Vr1：Benchmark electricity
Potential source；D1、D2：Diode.
Specific implementation mode
Then, on one side with reference to attached drawing, several embodiments of the switching power unit of the present invention are illustrated on one side.
【Embodiment 1】
The switching power unit of embodiment 1 shown in FIG. 1 is characterized in that being provided with control unit 7a, and replaces shown in Fig. 8
Previous switching power unit control unit 7.In Fig. 1, a pair part identical with Fig. 8 assigns identical reference numeral, saves
Slightly its explanation.
As shown in Fig. 2, control unit 7a shown in FIG. 1 is electric in correction relative to the structure of previous control unit 7 shown in Fig. 8
It is different in the structure of stream detection signal generation unit 40a.Correcting current detection signal generation unit 40a has ramp voltage
Circuit 41, reference voltage source Vr1, adder calculator 51 and correcting circuit 42a.
Correcting current detects signal generation unit 40a in response to the expression in ON/OFF control waveshaping circuit 24
The signal of the conducting start time of switch element 3, duty ratio is less than defined value the conducting start time from switch element 3
During formed with steady state value the 1st correction signal, duty ratio be defined value more than during formed from the 1st correction letter
Number value start with time going by and increased 2nd correction signal, subtract the 1st correction signal successively from current detection signal
With the 2nd correction signal and generate correcting current detect signal.
Slope voltage generating circuit 41 is identical as structure shown in Fig. 9, therefore the description thereof will be omitted.Reference voltage source Vr1 productions
Raw reference voltage, is supplied to adder calculator 51.
Adder calculator 51 will come from reference voltage source during conducting dutycycle is less than defined value (such as 10%)
The reference voltage of Vr1 is output to correcting circuit 42a.Adder calculator 51 conducting dutycycle be defined value (such as 10%) with
It will be superimposed on reference voltage during upper obtained from the ramp voltage V2 from slope voltage generating circuit 41 and be superimposed electricity
Pressure is output to correcting circuit 42a.
Correcting circuit 42a creates the 1st correction signal according to the reference voltage from adder calculator 51, according to from adding
The superimposed voltage of method arithmetic unit 51 and create and be superimposed DC component and 2nd correction signal proportional to ramp voltage, from electricity
The current detection signal of stream detection unit 10 subtracts the 1st correction signal and the 2nd correction signal and generates correcting current detection successively
Signal.That is, correcting circuit 42a subtracts the voltage V2a from adder calculator 51 from the voltage V3 from low-pass filter 26, make
It is exported for correction voltage V4a.
Fig. 3 is the detailed circuit diagram of adder calculator 51 and correcting circuit 42a shown in Fig. 2.As shown in figure 3, addition
Arithmetic unit 51 is made of diode D1 and diode D2, wherein the output of the anode of diode D1 and slope voltage generating circuit 41
Line 41a connections, cathode are connect with the base stage of the 3rd control element Q3, and the anode of diode D2 connects with the anode of reference voltage source Vr1
It connects, cathode is connect with the base stage of the 3rd control element Q3.
Then, the dynamic of the switching power unit of the embodiment 1 constituted in this way is directed at while with reference to sequence diagram shown in Fig. 4
It illustrates.
First, in moment t0, switch element 3 is made to be connected.In adder calculator 51, slope voltage generating circuit will be come from
41 ramp voltage V2 is applied to diode D1, and the reference voltage from reference voltage source Vr1 is applied to diode D2.When
T0~t01 (during conducting dutycycle is less than defined value) is carved, reference voltage V r1 is higher than ramp voltage V2, therefore diode
D2 is connected, diode D1 cut-offs.
Therefore, reference voltage V r1 is applied to the base stage of the 3rd control element Q3.It is created in correcting circuit 42a as a result,
1st correction signal proportional to reference voltage V r1.Therefore, the correcting current exported from correcting circuit 42a detects signal V4
It subtracts from the current detection signal V3 from low-pass filter 26 and is worth obtained from the 1st correction signal.
Then, moment t01~t11 (during conducting dutycycle is defined value or more), ramp voltage V2 compares benchmark
Voltage Vr1 high, therefore diode D1 conductings, diode D2 cut-offs.Therefore, on reference voltage V r1 be superimposed ramp voltage V2 and
Obtained superimposed voltage is applied to the base stage of the 3rd control element Q3.
2nd correction signal proportional to superimposed voltage is created in correcting circuit 42a as a result,.Therefore, from correcting circuit
The correcting current detection signal V4 of 42a outputs is to subtract the 2nd correction letter from the current detection signal V3 from low-pass filter 26
It is worth obtained from number.
Then, if making switch element 3 disconnect in moment t11~t12, secondary coil electric current is flowed through.After moment t12
Processing is identical as the processing of moment t0~t12.
In this way, according to the switching power unit of embodiment 1, correcting current detects signal generation unit 40a first from switch
Duty ratio forms the 1st correction signal with steady state value during being less than defined value from the conducting start time of part 3, from electric current
Detection signal subtracts the 1st correction signal and generates correcting current detection signal.That is, subtracting during duty ratio is less than defined value
Constant correcting value is removed, therefore correcting current detection signal becomes smaller.
Therefore, even if DC component is superimposed, overcurrent protection action will not be entered in the conducting of switch element 3, because
This not will produce subharmonic phenomenon.Therefore, it is possible to provide following switching power unit：Even low input can also obtain
To peak power.That is, input voltage range can be expanded.
【Embodiment 2】
Fig. 5 is disposed on the detailed circuit diagram of the control unit 7b in the switching power unit of embodiment 2.Fig. 6 is Fig. 5 institutes
The detailed circuit diagram of the adder calculator 51a, switch SW and the correcting circuit 42b that show.Correcting current possessed by control unit 7b
Detecting signal generation unit 40b has slope voltage generating circuit 41, reference voltage source Vr1, adder calculator 51a and benchmark
The switch SW and correcting circuit 42b that voltage source Vr1 is connected with adder calculator 51a.
In addition, there is control unit 7b duty detection circuit 52, the duty detection circuit 52 to be detected to duty ratio,
It is connected switch SW during duty ratio is less than defined value, makes switch SW disconnected during duty ratio is defined value or more
It opens.
Specifically, the leading-out terminal connection of 52 andorinverter 32 of duty detection circuit, input is for keeping switch first
Part 3 conducting disconnect grid signal (gate signal) and grid signal is integrated, grid signal will be integrated and
Obtained integrated value is compared with the threshold value corresponding to the defined value (duty ratio is such as 10%).
Duty detection circuit 52 is set as duty ratio less than during defined value in the case where integrated value is less than threshold value
And switch SW is made to be connected.Therefore, reference voltage V r1 is applied to the base stage of the 3rd control element Q3.As a result, in correcting circuit 42b
It is middle to create 1st correction signal proportional to reference voltage V r1.Therefore, the correcting current exported from correcting circuit 42b detects letter
Number V4 is to subtract to be worth obtained from the 1st correction signal from the current detection signal V3 from low-pass filter 26.
Then, duty detection circuit 52 is set as in duty ratio being defined in the case where integrated value is threshold value or more
Disconnect switch SW during value is above.That is, will switch SW disconnect when, ramp voltage V2 is identical as reference voltage V r1
Voltage.Therefore, it has been superimposed superimposed voltage obtained from ramp voltage V2 on reference voltage V r1 and has been applied to the 3rd control member
The base stage of part Q3.
2nd correction signal proportional to superimposed voltage is created in correcting circuit 42b as a result,.Therefore, from correcting circuit
The correcting current detection signal V4 of 42b outputs is to subtract the 2nd correction letter from the current detection signal V3 from low-pass filter 26
It is worth obtained from number.Therefore, in the switching power unit of embodiment 2, the switching power unit with embodiment 1 can also be obtained
The identical effect of effect.
Also, in the switching power unit of embodiment 1, determine to lead according to the reference voltage value of reference voltage source Vr1
The defined value of logical duty ratio, but in the switching power unit of embodiment 2, conducting can be determined by duty detection circuit 52
The defined value of duty ratio.
【Embodiment 3】
Fig. 7 is disposed on the detailed circuit diagram of the control unit 7c in the switching power unit of the embodiment of the present invention 3.Control
Correcting current detection signal generation unit 40c possessed by portion 7c processed has slope voltage generating circuit 41, reference voltage source
Vr1, adder calculator 51b, with reference voltage source Vr1 and adder calculator 51b the switch SW connecting and correcting circuit 42c.
Correcting current detects signal generation unit 40c in response to the expression in ON/OFF control waveshaping circuit 24
The signal of the conducting start time of switch element 3, and in the case where input voltage is less than defined voltage, from switch element
Duty ratio forms the 1st correction signal with steady state value during being less than defined value from 3 conducting start time, in duty ratio
To form from the value of the 1st correction signal increased 2nd correction signal with time going by during more than defined value,
It subtracts the 1st correction signal and the 2nd correction signal successively from current detection signal and generates correcting current detection signal.
Also, correcting current detects signal generation unit 40c shapes in the case where input voltage is defined voltage or more
At increased 3rd correction signal with time going by from zero, subtracts the 3rd correction signal from current detection signal and generate
Correcting current detects signal.
Adder calculator 51b is less than defined value in the case where input voltage is less than defined voltage value in duty ratio
Period exports the reference voltage from reference voltage source Vr1, and output is in benchmark electricity during duty ratio is defined value or more
It has been superimposed superimposed voltage obtained from the ramp voltage of slope voltage generating circuit 41 in pressure, has been defined voltage in input voltage
Ramp voltage is exported in the case that value is above.Switch SW is connect with reference voltage source Vr1 and adder calculator 51b.
Correcting circuit 42c creates the 1st correction signal according to the reference voltage from adder calculator 51b, according to superposition
Voltage and create the 2nd correction signal, subtract the 1st correction signal and the 2nd correction signal successively from current detection signal and generate school
Positive current detects signal.Correcting circuit 42c is created according to the ramp voltage V2 from slope voltage generating circuit 41 and slope
The 3rd proportional correction signal of voltage subtracts the 3rd correction signal from current detection signal and generates correcting current and detect signal.
There is control unit 7c input voltage monitoring circuit 53, the input voltage monitoring circuit 53 to be supervised to input voltage
Depending on being connected switch SW in the case where input voltage vin is less than defined voltage value, being defined electricity in input voltage vin
Disconnect switch SW in the case of more than pressure value.
According to the switching power unit of the embodiment 3 constituted in this way, input voltage monitoring circuit 53 carries out input voltage
Monitoring is connected switch SW in the case where input voltage vin is less than defined voltage value.Then, adder calculator 51b is being accounted for
Sky is than being defined value or more in duty ratio less than the reference voltage from reference voltage source Vr1 is exported during defined value
During output superimposed voltage obtained from the ramp voltage of slope voltage generating circuit 41 has been superimposed on reference voltage.
Correcting circuit 42c creates the 1st correction signal according to the reference voltage from adder calculator 51b, according to superposition
Voltage and create the 2nd correction signal, subtract the 1st correction signal and the 2nd correction signal successively from current detection signal and generate school
Positive current detects signal.
Therefore, it is possible to obtain effect identical with the effect of the switching power unit of embodiment 1.
Then, input voltage monitoring circuit 53 monitors input voltage, is defined voltage value in input voltage vin
Disconnect switch SW in the case of above.Then, adder calculator 51b is in the situation that input voltage is defined voltage value or more
Lower output increased ramp voltage at any time from zero.
Correcting circuit 42c creates 3rd correction signal proportional to ramp voltage according to ramp voltage, from current detecting
Signal subtracts the 3rd correction signal and generates correcting current detection signal.
That is, higher in input voltage, duty is narrow, not will produce subharmonic phenomenon, therefore need not be from
Correcting current detection signal subtracts the 1st correction signal.
Claims (5)
1. a kind of switching power unit, which is characterized in that the switching power unit has：
Transformer, with primary coil and secondary coil；
Switch element connect with DC power supply via the primary coil of the transformer and carries out ON/OFF；
Output voltage detection unit is detected the output voltage of the secondary coil side of the transformer；
ON/OFF controls waveshaping circuit, is formed according to the output voltage of the output voltage detection unit
For being that constant ON/OFF controls signal, and ON/OFF control signal is provided by the output voltage control
To the switch element；
Current detecting unit, the electric current to flowing through the switch element is detected and output electric current measure signal；
Correcting current detects signal generation unit, and the expression institute in waveshaping circuit is controlled in response to the ON/OFF
The signal of the conducting start time of switch element is stated, duty ratio is less than regulation the conducting start time from the switch element
Value during formed with steady state value the 1st correction signal, the duty ratio be defined value more than during formed from
The value of 1st correction signal plays increased 2nd correction signal with time going by, successively from the current detection signal
It subtracts the 1st correction signal and the 2nd correction signal and generates correcting current detection signal；And
Comparing unit flows through correcting current detection signal and expression the over-current level of the electric current of the switch element
Overcurrent threshold value be compared, will be used to make described open when correcting current detection signal reaches the overcurrent threshold value
It closes the signal that element disconnects and is output to the ON/OFF control waveshaping circuit.
2. switching power unit according to claim 1, which is characterized in that
The correcting current detection signal generation unit has：
Slope voltage generating circuit is generated synchronously with ramp voltage with the conducting start time of the switch element, makes slope
The generation of voltage continueed to after the finish time during the maximum conducting of the switch element；
Reference voltage source generates reference voltage；
Adder calculator exports the base from the reference voltage source during duty ratio is less than defined value
Quasi- voltage exports during the duty ratio is the defined value or more and has been superimposed the slope on the reference voltage
Superimposed voltage obtained from the ramp voltage of voltage generating circuit；And
Correcting circuit, basis create the 1st correction signal from the reference voltage of the adder calculator, according to
The superimposed voltage and create and be superimposed DC component and 2nd correction signal proportional to the ramp voltage, from institute
The current detection signal for stating current detecting unit subtracts the 1st correction signal and the 2nd correction signal and gives birth to successively
Signal is detected at correcting current.
3. switching power unit according to claim 1, which is characterized in that
The correcting current detection signal generation unit has：
Slope voltage generating circuit is generated synchronously with ramp voltage with the conducting start time of the switch element, makes slope
The generation of voltage continueed to after the finish time during the maximum conducting of the switch element；
Reference voltage source generates reference voltage；
Adder calculator exports the base from the reference voltage source during duty ratio is less than defined value
Quasi- voltage exports during the duty ratio is the defined value or more and has been superimposed the slope on the reference voltage
Superimposed voltage obtained from the ramp voltage of voltage generating circuit；
Switch, is connected to the reference voltage source and the adder calculator；And
Correcting circuit, basis create the 1st correction signal from the reference voltage of the adder calculator, according to
The superimposed voltage and create and be superimposed DC component and 2nd correction signal proportional to the ramp voltage, from institute
The current detection signal for stating current detecting unit subtracts the 1st correction signal and the 2nd correction signal and gives birth to successively
Signal is detected at correcting current,
Also there is the switching power unit duty detection circuit, the duty detection circuit to be examined to the duty ratio
Survey, the duty ratio be less than defined value during make the switch conduction, the duty ratio be it is described as defined in value with
Disconnect the switch during upper.
4. a kind of switching power unit, which is characterized in that the switching power unit has：
Transformer, with primary coil and secondary coil；
Switch element connect with DC power supply via the primary coil of the transformer and carries out ON/OFF；
Output voltage detection unit is detected the output voltage of the secondary coil side of the transformer；
ON/OFF controls waveshaping circuit, is formed according to the output voltage of the output voltage detection unit
For being that constant ON/OFF controls signal, and ON/OFF control signal is provided by the output voltage control
To the switch element；
Current detecting unit, the electric current to flowing through the switch element is detected and output electric current measure signal；
Correcting current detects signal generation unit, and the expression institute in waveshaping circuit is controlled in response to the ON/OFF
The signal of the conducting start time of switch element is stated, and in the case where input voltage is less than defined voltage, is opened from described
Duty ratio forms the 1st correction signal with steady state value during being less than defined value from the conducting start time for closing element,
The duty ratio for formed during more than the defined value from the value of the 1st correction signal with time going by and
Increased 2nd correction signal subtracts the 1st correction signal and the 2nd correction signal successively from the current detection signal
And generate correcting current detection signal, the input voltage be it is described as defined in it is more than voltage in the case of formed from zero with
It the process of time and increased 3rd correction signal, subtracts the 3rd correction signal from the current detection signal and generate school
Positive current detects signal；And
Comparing unit flows through correcting current detection signal and expression the over-current level of the electric current of the switch element
Overcurrent threshold value be compared, will be used to make described open when correcting current detection signal reaches the overcurrent threshold value
It closes the signal that element disconnects and is output to the ON/OFF control waveshaping circuit.
5. switching power unit according to claim 4, which is characterized in that
The correcting current detection signal generation unit has：
Slope voltage generating circuit is generated synchronously with ramp voltage with the conducting start time of the switch element, makes slope
The generation of voltage continueed to after the finish time during the maximum conducting of the switch element；
Reference voltage source generates reference voltage；
Adder calculator, in the case where the input voltage is less than defined voltage value in the duty ratio less than defined
The reference voltage from the reference voltage source is exported during value, is the defined value or more in the duty ratio
Period output has been superimposed obtained from the ramp voltage of the slope voltage generating circuit on the reference voltage and has been superimposed
Voltage exports the ramp voltage in the case where the input voltage is defined voltage value or more；
Switch, is connected to the reference voltage source and the adder calculator；And
Correcting circuit, basis create the 1st correction signal from the reference voltage of the adder calculator, according to
The superimposed voltage and create the 2nd correction signal, created proportional to the ramp voltage according to the ramp voltage
The 3rd correction signal,
The switching power unit also has voltage monitoring circuit, and the voltage monitoring circuit is to being input to the switching power unit
Input voltage is monitored, makes the switch conduction in the case where the input voltage is less than defined voltage value, described
Input voltage is to make switch disconnection in the case of defined voltage value or more.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017027926A JP6436177B2 (en) | 2017-02-17 | 2017-02-17 | Switching power supply |
| JP2017-027926 | 2017-02-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108462395A true CN108462395A (en) | 2018-08-28 |
| CN108462395B CN108462395B (en) | 2020-06-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711171500.1A Active CN108462395B (en) | 2017-02-17 | 2017-11-22 | Switching power supply device |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP6436177B2 (en) |
| CN (1) | CN108462395B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114285251A (en) * | 2021-12-24 | 2022-04-05 | 西安理工大学 | Circuit for improving carrying capacity of switching power supply |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1369953A (en) * | 2001-01-31 | 2002-09-18 | 松下电器产业株式会社 | Switching mains |
| US20090103335A1 (en) * | 2007-10-22 | 2009-04-23 | Sanken Electric Co., Ltd. | Overcurrent-protected switching-mode power supply |
| CN101557166A (en) * | 2008-04-11 | 2009-10-14 | 株式会社瑞萨科技 | Power supply apparatus and semiconductor integrated circuit device |
| JP2016158398A (en) * | 2015-02-25 | 2016-09-01 | ミツミ電機株式会社 | Semiconductor device for power supply control |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004040856A (en) * | 2002-06-28 | 2004-02-05 | Fuji Electric Holdings Co Ltd | Switching power supply |
-
2017
- 2017-02-17 JP JP2017027926A patent/JP6436177B2/en active Active
- 2017-11-22 CN CN201711171500.1A patent/CN108462395B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1369953A (en) * | 2001-01-31 | 2002-09-18 | 松下电器产业株式会社 | Switching mains |
| US20090103335A1 (en) * | 2007-10-22 | 2009-04-23 | Sanken Electric Co., Ltd. | Overcurrent-protected switching-mode power supply |
| CN101557166A (en) * | 2008-04-11 | 2009-10-14 | 株式会社瑞萨科技 | Power supply apparatus and semiconductor integrated circuit device |
| JP2016158398A (en) * | 2015-02-25 | 2016-09-01 | ミツミ電機株式会社 | Semiconductor device for power supply control |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114285251A (en) * | 2021-12-24 | 2022-04-05 | 西安理工大学 | Circuit for improving carrying capacity of switching power supply |
| CN114285251B (en) * | 2021-12-24 | 2024-05-17 | 西安理工大学 | Circuit for improving load capacity of switching power supply |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108462395B (en) | 2020-06-09 |
| JP6436177B2 (en) | 2018-12-12 |
| JP2018133957A (en) | 2018-08-23 |
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