CN106787730B - Control method and control circuit of switching circuit and switching circuit - Google Patents
Control method and control circuit of switching circuit and switching circuit Download PDFInfo
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- CN106787730B CN106787730B CN201710079791.5A CN201710079791A CN106787730B CN 106787730 B CN106787730 B CN 106787730B CN 201710079791 A CN201710079791 A CN 201710079791A CN 106787730 B CN106787730 B CN 106787730B
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Classifications
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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
- H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
- H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
- H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Power Engineering (AREA)
- Inverter Devices (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a control method of a switching circuit, a control circuit and the switching circuit, wherein when a switching period starts, a first switching tube and a third switching tube are conducted, a second switching tube and a fourth switching tube are turned off, and the magnitudes of an inductance current and an instruction current are compared through a first conduction time; when the inductance current is smaller than the instruction current, the first switching tube and the fourth switching tube are conducted, the second switching tube and the third switching tube are turned off until the inductance current is larger than or equal to the instruction current, and the switching period is ended; when the inductance current is greater than or equal to the instruction current, the first switching tube and the fourth switching tube are turned off, and the second switching tube and the third switching tube are turned on until the inductance current is less than or equal to the instruction current, and the switching period is ended.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a control method and a control circuit of a switching circuit and the switching circuit.
Background
The topology structure of the four-switch-tube Buck-Boost voltage-boosting circuit is shown in figure 1. The circuit comprises four power switching tubes Q1, Q2, Q3 and Q4, an energy storage inductor L and an input end capacitor Cin and an output end capacitor Co. The switching tube Q1 is connected with the switching tube Q2 in series, the common end of the switching tube Q1 and the switching tube Q2 is a first node SW1, the switching tube Q1 is connected to the input end, the switching tube Q2 is connected to the ground, the input end is connected to the ground through a capacitor Cin, the switching tube Q3 is connected with the switching tube Q4 in series, the common end of the switching tube Q3 and the switching tube Q4 is a second node SW2, the switching tube Q3 is connected to the output end, the switching tube Q4 is connected to the ground, the output end is connected to the ground through a capacitor Co, and an inductor L is connected between the first node SW1 and the second node SW 2.
When the input voltage V IN Specific output voltage V O When a certain value is large, the circuit works in a Buck Buck mode, the switching tubes Q1 and Q2 work in a high-frequency switching state, the switching tube Q3 is always on, and the switching tube Q4 is always off; when the input voltage V IN Specific output voltage V O When the value is smaller than a certain value, the circuit works in Boost mode and is openedThe switching tube Q3, the switching tube Q4 works in the high-frequency switch state, the switching tube Q1 is always on, and the switching tube Q2 is always off; when V is IN And V is equal to O When the circuit is close, the circuit works in a Buck-Boost Buck mode, and the switching tubes Q1, Q2, Q3 and Q4 are all in a high-frequency switching state.
Different control strategies are different in switching conditions and control methods of three working modes (Buck, boost, buck-Boost), and different in working conditions of the Buck-Boost Buck mode. Since the efficiency of the Buck and Boost modes is high, the narrower the operating interval of the Buck-Boost Buck mode is, the better the operating interval is.
An existing control method is to sample the input voltage V for a control circuit IN And output voltage V O According to V IN And V O Three modes of operation:
V O ≤V IN -Vth1, the circuit is operating in Buck mode;
V O ≥V IN when +Vt2, the circuit works in Boost mode;
V IN -Vth1<V O <V IN +Vt2, the circuit works in Buck-Boost Buck mode;
wherein Vth1 and Vth2 are voltage thresholds.
The control method distinguishes three working modes according to the magnitude relation of input and output voltages. In order to stabilize the output voltage, a wider operation interval of a Buck-Boost Buck mode is generally required to be set, so that the average efficiency of the system is reduced.
Another conventional control method is shown in fig. 2 (a), in which the control circuit samples the output voltage V through sampling resistors R01, R02 O The obtained sampling voltage FB is compared with the internal reference signal Vref by the operational amplifier U00, a compensation signal Vc is output, the compensation signal Vc and two carrier signals generated by the clock circuit U01 are input to the input terminal of the comparison circuit U02, and the comparison circuit U02 generates the driving signals PWM of 4 pipes. As shown in fig. 2 b, the two carrier signals generated by the clock circuit U01 are saw-tooth signals, and when the compensation signal Vc falls in the region 1 (gray part), the switching transistors Q1, Q4 are turned onThe method comprises the steps of carrying out a first treatment on the surface of the When the compensation signal Vc falls in the area 2 (white part), the switching tubes Q1 and Q3 are conducted; when the compensation signal Vc falls in the region 3 (diagonal line portion), the switching transistors Q2, Q3 are turned on. I.e.
When Vc is more than or equal to Vc1, the circuit works in Boost mode;
when Vc is less than or equal to Vc2, the circuit works in a Buck Buck mode;
when Vc2 is less than Vc1, the circuit works in a Buck-Boost Buck mode.
The control method needs to adopt voltage mode control, and the dynamic response of the system is poor. The reason is that the voltage signal changes with a certain hysteresis relative to the current signal, and the control loop is designed to enable the system to work stably by reducing the bandwidth of the system, which is a cost of reducing the dynamic performance of the system.
Disclosure of Invention
Therefore, the invention aims to provide a control method, a control circuit and a switching circuit of a four-switch tube circuit, which are used for solving the problems of low average efficiency and poor dynamic response of a system in the prior art.
The technical solution of the present invention is to provide a control method of a switching circuit, comprising: the control method comprises the steps of connecting a first switching tube, a second switching tube, a third switching tube, a fourth switching tube and an inductor in series, wherein the common end of the first switching tube and the second switching tube is a first node, the first switching tube is connected to an input end, the second switching tube is connected to the ground, the common end of the third switching tube and the fourth switching tube is a second node, the third switching tube is connected to an output end, the fourth switching tube is connected to the ground, and the inductor is connected between the first node and the second node, and the control method comprises the following steps:
when a switching period starts, the first switching tube and the third switching tube are conducted, the second switching tube and the fourth switching tube are turned off, and the magnitude of the inductance current and the magnitude of the instruction current are compared through a first conduction time;
when the inductance current is smaller than the instruction current, the first switching tube and the fourth switching tube are conducted, the second switching tube and the third switching tube are turned off until the inductance current is larger than or equal to the instruction current, the switching period is ended, and the next switching period is entered;
when the inductance current is greater than or equal to the instruction current, the first switching tube and the fourth switching tube are turned off, the second switching tube and the third switching tube are turned on until the inductance current is less than or equal to the instruction current, the switching period is ended, and the next switching period is entered.
Alternatively, the command current is obtained by amplifying an output feedback signal and a reference signal by an error.
Optionally, the output feedback signal includes: an output voltage feedback signal, an output current feedback signal, and an output power feedback signal.
Alternatively, the first on-time is proportional to the smaller of the first ratio and the second ratio; the first ratio is the ratio of the output voltage to the input voltage, and the second ratio is the ratio of the input voltage to the output voltage.
According to another technical scheme, the control circuit of the switching circuit comprises a first switching tube, a second switching tube, a third switching tube, a fourth switching tube and an inductor, wherein the first switching tube and the second switching tube are connected in series, a common end of the first switching tube and the second switching tube is a first node, the first switching tube is connected to an input end, the second switching tube is connected to the ground, the third switching tube and the fourth switching tube are connected in series, a common end of the third switching tube and the fourth switching tube is a second node, the third switching tube is connected to an output end, the fourth switching tube is connected to the ground, and the inductor is connected between the first node and the second node, and the control circuit is characterized by comprising:
a first comparison circuit and a logic circuit;
the inductor current signal and the command current signal are connected to the input end of the first comparison circuit; the output signal of the first comparison circuit is connected to the input end of the logic circuit;
when a switching period starts, the logic circuit controls the first switching tube and the third switching tube to be conducted, the second switching tube and the fourth switching tube are turned off, and the first comparison circuit compares the magnitude of the inductance current with the magnitude of the instruction current after a first conduction time;
when the inductance current is smaller than the instruction current, the logic circuit controls the first switching tube and the fourth switching tube to be conducted, the second switching tube and the third switching tube are turned off until the first comparison circuit detects that the inductance current is larger than or equal to the instruction current, the switching period is ended, and the next switching period is entered;
when the inductance current is larger than or equal to the instruction current, the logic circuit controls the first switching tube and the fourth switching tube to be turned off, the second switching tube and the third switching tube are turned on until the first comparison circuit detects that the inductance current is smaller than or equal to the instruction current, the switching period is ended, and the next switching period is started.
Optionally, the control circuit further includes: and the first operational amplifier outputs a feedback signal and a reference signal through error amplification, and the instruction current is obtained.
Optionally, the control circuit further includes: a first on-time generating circuit that generates a first on-time proportional to a small value of the first ratio and the second ratio; the first ratio is the ratio of the output voltage to the input voltage, and the second ratio is the ratio of the input voltage to the output voltage.
Optionally, the first on-time generating circuit includes: the second comparison circuit compares the input voltage with the output voltage and outputs a first comparison voltage and a second comparison voltage, wherein the higher voltage is the first comparison voltage, and the lower voltage is the second comparison voltage; and the first division proportion circuit divides the second comparison voltage by the first comparison voltage, and the first conduction time is obtained after proportion adjustment.
Optionally, the first on-time generating circuit includes: the second division proportion circuit divides the input voltage by the output voltage, obtains the first time after proportion adjustment, divides the output voltage by the input voltage, and obtains the second time after proportion adjustment; and a third comparison circuit that compares the first time and the second time and outputs a shorter one of the first time and the second time as the first on time.
A further technical solution of the present invention is to provide a switching circuit.
Compared with the prior art, the circuit structure and the method have the following advantages: the buck-boost mode has a narrow working range, and the system has high conversion efficiency in a wider input-output voltage range. The invention adopts current mode control, and has better dynamic performance than voltage mode control, including input voltage step response and output load step response. The invention adopts cycle-by-cycle current control, can limit the current of each switching cycle, prevent the damage caused by overlarge current, thus having higher reliability. When the input voltage V IN And output voltage V o When the size relation is different, the circuit can be naturally switched to different working modes, so that the normal working of the circuit is ensured, and the system requirement is met.
Drawings
FIG. 1 is a prior art four-switch-tube Buck-Boost voltage step-down circuit;
FIG. 2 (a) is a control circuit block diagram of a four-switch-tube Buck-Boost Buck circuit in the prior art;
FIG. 2 (b) is a compensation signal and a carrier signal in a control circuit of a four-switch-tube Buck-Boost circuit in the prior art;
FIG. 3 is a flow chart of a four-switch tube control method of the present invention;
FIG. 4 is a steady state waveform in Buck Buck mode of the present invention;
FIG. 5 is a steady state waveform of the present invention in Boost mode;
FIG. 6 is a steady-state waveform in Buck-Boost Buck mode of the present invention;
FIG. 7 is a circuit block diagram of the present invention;
FIG. 8 is a circuit diagram of a first on-time generating circuit;
FIG. 9 is another circuit configuration diagram of the first on-time generating circuit;
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments only. The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention.
In the following description of preferred embodiments of the invention, specific details are set forth in order to provide a thorough understanding of the invention, and the invention will be fully understood to those skilled in the art without such details.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. It should be noted that the drawings are in a simplified form and are not to scale precisely, but rather are merely intended to facilitate and clearly illustrate the embodiments of the present invention.
Referring to fig. 3, a flow chart of a four-switch tube control method of the present invention is illustrated. The control method is based on the four-switch topology of fig. 1. In fig. 1, a switching tube Q1 is a first switching tube, a switching tube Q2 is a second switching tube, a switching tube Q3 is a third switching tube, and a switching tube Q4 is a fourth switching tube. The switching tube Q1 is connected with the switching tube Q2 in series, the common end of the switching tube Q1 and the switching tube Q2 is a first node SW1, the switching tube Q1 is connected to the input end, the switching tube Q2 is connected to the ground, the input end is connected to the ground through a capacitor Cin, the switching tube Q3 is connected with the switching tube Q4 in series, the common end of the switching tube Q3 and the switching tube Q4 is a second node SW2, the switching tube Q3 is connected to the output end, the switching tube Q4 is connected to the ground, the output end is connected to the ground through a capacitor Co, and an inductor L is connected between the first node SW1 and the second node SW 2. The technical solution of the invention is to provide a control method of the following steps:
step S001: at the beginning of the switching cycle, the first switching tube and the third switching tube are turned on, and the second switching tube and the fourth switching tube are turned off.
Step S002: judging whether the first on time is reached, if the first on time is not reached, continuing to keep the first switching tube and the third switching tube on, and turning off the second switching tube and the fourth switching tube.
Step S003: when the first conduction time is reached, the magnitude of the inductor current and the command current are compared.
Step S004: after step S003, if the inductor current is smaller than the command current, the first switching tube and the fourth switching tube are turned on, and the second switching tube and the third switching tube are turned off.
Step S005: judging the magnitude of the inductance current and the command current, and when the inductance current is larger than or equal to the command current, ending the switching period, entering the next switching period, namely returning to the step S001, wherein the first switching tube and the third switching tube are conducted, and the second switching tube and the fourth switching tube are turned off.
Step S006: after step S003, if the inductor current is equal to or greater than the command current, the first switching tube and the fourth switching tube are turned off, and the second switching tube and the third switching tube are turned on.
Step S007: judging the magnitude of the inductance current and the command current, and when the inductance current is smaller than the command current, ending the switching cycle, entering the next switching cycle, namely returning to the step S001, wherein the first switching tube and the third switching tube are conducted, and the second switching tube and the fourth switching tube are turned off.
The command current is obtained by amplifying the output feedback signal and the reference signal through errors. The feedback signal includes: an output voltage feedback signal, an output current feedback signal, and an output power feedback signal. When the feedback signal is an output voltage feedback signal, the constant voltage control is output; when the feedback signal is an output current feedback signal, the output constant current control is performed; and when the feedback signal is an output power feedback signal, the constant power control is output.
Taking output constant voltage control as an example, the operation of the control method under various input/output voltage conditions will be described.
For convenience of description, defining UU state as the first and third switching tubes are turned on, and the second and fourth switching tubes are turned off; the DU state is that the second and third switching tubes are turned on, and the first and fourth switching tubes are turned off; the UD state is that the second switching tube and the third switching tube are turned off, and the first switching tube and the fourth switching tube are turned on.
Referring to FIG. 4, when the input voltage V IN Greater than the output voltage V O And when the Buck maximum duty cycle limit is not exceeded, the circuit operates in the Buck step-down mode. In Buck mode, the level of the first node SW1 is switched high and the level of the second node SW2 is always high. The first switching tube Q1 and the second switching tube Q2 are complementarily switched, the third switching tube Q3 is normally on, and the fourth switching tube Q4 is normally off. In Buck mode, the two states of UU and DU are switched back and forth. As shown in fig. 4, at time t=0, the first node SW1 is at a high level, the SW2 is at a high level, the first switching tube Q1 is turned on, the second switching tube Q2 is turned off, the third switching tube Q3 is turned on, and the fourth switching tube Q4 is turned off. The inductor current iL rises linearly. When the first on-time is reached, the inductor current iL is greater than the command current ic. Thus, the DU state is entered. At this time, the level of the first node SW1 is low, the level of the second node SW2 is high, the first switching tube Q1 is turned off, the second switching tube Q2 is turned on, the third switching tube Q3 is turned on, and the fourth switching tube Q4 is turned off. On the other hand, the command current ic remains relatively stable due to the constant voltage control. The inductor current iL drops linearly and enters a next cycle, i.e. enters the UU state again, when the inductor current iL is equal to the command current ic.
Referring to FIG. 5, when the input voltage V IN Less than the output voltage V O And the Boost minimum duty cycle limit is not exceeded, the circuit operates in Boost mode. In Boost mode, the level of the first node SW1 is always high and the level of the second node SW2 is switched. Correspondingly, the first switching tube Q1 is normally on, the second switching tube Q2 is normally off, and the third switching tube Q3 and the fourth switching tube Q4 are complementarily switched. In Boost mode, the two states of UU and UD are switched back and forth. As shown in fig. 5, at time t=0, the state machine is in UU state, at this time, the level of the first node SW1 is high, the level of the second node SW2 is high, the first switching tube Q1 is turned on, the second switching tube Q2 is turned off, the third switching tube Q3 is turned on, and the fourth switching tube Q4 is turned off. The inductor current iL drops linearly. When the first on-time is reached, the inductor current iL is smaller than the command current ic. Thus, the state machine enters the UD state. At this time, the level of the first node SW1 is high, the second nodeThe level of the point SW2 is low, the first switching tube Q1 is turned on, the second switching tube Q2 is turned off, the third switching tube Q3 is turned off, and the fourth switching tube Q4 is turned on. On the other hand, the command current ic remains relatively stable due to the constant voltage control. The inductor current iL rises linearly and enters a next cycle, i.e. enters the UU state again, when the inductor current iL is equal to the command current ic.
Referring to FIG. 6, when the input voltage V IN And output voltage V O When close enough, the circuit cannot operate alone in Buck or Boost mode, where the circuit operates in Buck-Boost mode. In the Buck-Boost mode, the level of the first node SW1 is switched, and the level of the second node SW2 is switched. Correspondingly, the first switching tube Q1 and the second switching tube Q2 are complementarily switched, and the third switching tube Q3 and the fourth switching tube Q4 are complementarily switched. In the Buck-Boost mode, the state machine switches back and forth among DD, UD and UU states. At time t=0, the first node SW1 is in a UU state, the second node SW2 is in a high level, the first switching tube Q1 is turned on, the second switching tube Q2 is turned off, the third switching tube Q3 is turned on, and the fourth switching tube Q4 is turned off. When the first on time is reached, the inductance current iL is smaller than the instruction current ic, the state machine enters the UD state, at this time, the level of the first node SW1 is high, the level of the second node SW2 is low, the first switching tube Q1 is turned on, the second switching tube Q2 is turned off, the third switching tube Q3 is turned off, and the fourth switching tube Q4 is turned on. When the inductor current iL is equal to the command current ic, the UU state is entered again. Note that at this time the magnitude relationship of iL to ic changes. When the first conduction time arrives, the UU state ends. When the UU state ends, the inductor current iL is greater than the command current ic. Thus, the state machine enters the DU state. At this time, the level of the first node SW1 is low, the level of the second node SW2 is high, the first switching tube Q1 is turned off, the second switching tube Q2 is turned on, the third switching tube Q3 is turned on, and the fourth switching tube Q4 is turned off. When the inductance current iL is equal to the command current ic, the UU state is entered again, and a next cycle is entered.
The control method of the invention is suitable for the input voltage V IN And output voltage V O Various cases of different sizes. When the input voltage V IN And output ofVoltage V O When the size relation is different, the circuit can be naturally switched to different working modes, so that the normal working of the circuit is ensured, and the system requirement is met.
First on time T in step S002 UU Proportional to the smaller of the first ratio and the second ratio; wherein the first ratio is the output voltage V O And input voltage V IN The second ratio is the input voltage V IN And output voltage V O Ratio of (T) UU ∝min(V O /V IN ,V IN /V O ). In Buck step-down mode, V O <V IN T is then UU ∝V O /V IN . Due to the duty cycle d=t UU /TS＝V O /V IN Wherein TS is a switching period, so that the switching period can be kept constant, and the system frequency fixing can be realized. In Boost mode, V IN <V O T is then UU ∝V IN /V O The same principle can keep the switching period constant, namely, the system frequency fixing can be realized. First on time T UU The calculation method of (c) is not limited to the above method, and other methods are also possible.
Referring to fig. 7, a four-switch-tube control circuit according to a first embodiment of the present invention is illustrated. The control circuit comprises a first comparison circuit U10 and a logic circuit U11; the inductor current signal iL and the command current signal ic are connected to the input terminal of the first comparison circuit U10; the output signal OFF of the first comparison circuit U10 is connected to the input end of the logic circuit U11; when the switching period starts, the logic circuit U11 controls the first switching tube Q1 and the third switching tube Q3 to be turned on, and the second switching tube Q2 and the fourth switching tube Q4 to be turned off for a first on time T UU The first comparison circuit U10 compares the magnitudes of the inductive current iL and the command current ic; when the inductance current iL is smaller than the instruction current ic, the logic circuit U11 controls the first switching tube Q1 and the fourth switching tube Q4 to be turned on, and the second switching tube Q2 and the third switching tube Q3 to be turned off until the first comparison circuit U10 detects that the inductance current iL is greater than or equal to the instruction current ic, the switching period is ended, and the next switching period is entered; when the inductor isThe logic circuit U11 controls the first switching tube Q1 and the fourth switching tube Q4 to be turned off when the current iL is greater than or equal to the command current ic, and the second switching tube Q2 and the third switching tube Q3 are turned on until the first comparison circuit U10 detects that the inductance current iL is less than or equal to the command current ic, and the switching cycle is ended and the next switching cycle is entered.
In the first embodiment, the first comparing circuit may employ a comparator, and the inductor current signal iL is connected to an inverting input terminal of the comparator; the compensation signal ic is connected to the non-inverting input of the comparator.
In the first embodiment, the first operational amplifier U12 is further included, and the error amplification output feedback signal and the reference signal obtain the command current ic. The feedback signals can be a voltage feedback signal, a current feedback signal and a power feedback signal, and the three feedback signals respectively correspond to constant voltage control, constant current control and constant power control. Taking constant voltage control as an example, i.e. the feedback signal is a voltage feedback signal, the voltage V is output O The divided voltage V is obtained through the voltage dividing resistors R10 and R11 FB Is input to the inverting input terminal of the first operational amplifier U12, and is used for outputting a reference voltage signal V REF Is input to the non-inverting input of the first op-amp U12.
In the first embodiment, the first on-time T generated by the first on-time generating circuit U13 UU Proportional to the smaller of the first ratio and the second ratio; wherein the first ratio is the output voltage V O And input voltage V IN The second ratio is the input voltage V IN And output voltage V O Ratio of (T) UU ∝min(V O /V IN ,V IN /V O )。
The first on-time generation circuit U13 may employ a circuit as shown in fig. 8, which includes a comparison circuit U130 and a division ratio circuit U131. Input voltage V IN And output voltage V O Is connected to two input ends of the comparison circuit U130, the comparison circuit U130 compares two voltages and outputs a first comparison voltage and a second comparison voltage, and is connected to the input end of the division ratio circuit U131, the first comparison voltage is the higher voltage value of the two input voltages, and the second comparison voltage isThe comparison voltage is a lower voltage value of the two voltages inputted. The division ratio circuit divides the second comparison voltage by the first comparison voltage and obtains a first on time through a certain ratio, and the first on time is used as the output of the division ratio circuit U131, namely the output of the first on time generating circuit U13.
The first on-time generation circuit U13 may also employ a circuit as shown in fig. 9, which includes a division ratio circuit U132 and a comparison circuit U133. Input voltage V IN And output voltage V O Connected to two input terminals of the dividing and scaling circuit U132, the dividing and scaling circuit U132 outputs an input voltage V IN Divided by output voltage V O And a certain proportion is passed to obtain a first time; will output voltage V O Divided by input voltage V IN And a certain proportion of the second time is obtained. The first time and the second time are connected to the input terminal of the comparison circuit U133, and the comparison circuit U133 compares the first time and the second time, and takes the shorter time of the first time and the second time as the output of the comparison circuit U133, that is, the output of the first on-time generating circuit U13.
The implementation of the first on-time generating circuit U13 is not limited to the above-described one, but other ways are possible.
In addition, although the embodiments are described and illustrated separately above, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and that reference may be made to another embodiment without explicitly recited in one of the embodiments.
The above-described embodiments do not limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the above embodiments should be included in the scope of the present invention.
Claims (8)
1. The control method of the switching circuit comprises a first switching tube, a second switching tube, a third switching tube, a fourth switching tube and an inductor, wherein the first switching tube and the second switching tube are connected in series, the common end of the first switching tube and the second switching tube is a first node, the first switching tube is connected to an input end, the second switching tube is connected to the ground, the third switching tube and the fourth switching tube are connected in series, the common end of the third switching tube and the fourth switching tube is a second node, the third switching tube is connected to an output end, the fourth switching tube is connected to the ground, and the inductor is connected between the first node and the second node, and the control method is characterized by comprising the following steps:
when a switching period starts, the first switching tube and the third switching tube are conducted, the second switching tube and the fourth switching tube are turned off, and the magnitude of the inductance current and the magnitude of the instruction current are compared through a first conduction time;
when the inductance current is smaller than the instruction current, the first switching tube and the fourth switching tube are conducted, the second switching tube and the third switching tube are turned off until the inductance current is larger than or equal to the instruction current, the switching period is ended, and the next switching period is entered;
when the inductance current is greater than or equal to the instruction current, the first switching tube and the fourth switching tube are turned off, the second switching tube and the third switching tube are turned on until the inductance current is less than or equal to the instruction current, the switching period is ended, and the next switching period is entered;
the first on-time is proportional to the smaller of the first ratio and the second ratio; the first ratio is the ratio of the output voltage to the input voltage, and the second ratio is the ratio of the input voltage to the output voltage.
2. The control method of a switching circuit according to claim 1, wherein: the instruction current is obtained by amplifying an output feedback signal and a reference signal through errors.
3. The control method of a switching circuit according to claim 2, wherein the output feedback signal includes:
an output voltage feedback signal, an output current feedback signal, and an output power feedback signal.
4. The utility model provides a control circuit of switch circuit, switch circuit includes first switch tube, second switch tube, third switch tube, fourth switch tube and inductance, first switch tube and second switch tube establish ties, the public end of first switch tube and second switch tube is first node, first switch tube is connected to the input, the second switch tube is connected to ground, third switch tube and fourth switch tube establish ties, the public end of third switch tube and fourth switch tube is the second node, the third switch tube is connected to the output, the fourth switch tube is connected to ground, the inductance is connected between first node and second node, its characterized in that:
a first comparison circuit and a logic circuit;
the inductor current signal and the command current signal are connected to the input end of the first comparison circuit; the output signal of the first comparison circuit is connected to the input end of the logic circuit;
when a switching period starts, the logic circuit controls the first switching tube and the third switching tube to be conducted, the second switching tube and the fourth switching tube are turned off, and the first comparison circuit compares the magnitude of the inductance current with the magnitude of the instruction current after a first conduction time;
when the inductance current is smaller than the instruction current, the logic circuit controls the first switching tube and the fourth switching tube to be conducted, the second switching tube and the third switching tube are turned off until the first comparison circuit detects that the inductance current is larger than or equal to the instruction current, the switching period is ended, and the next switching period is entered;
when the inductance current is larger than or equal to the instruction current, the logic circuit controls the first switching tube and the fourth switching tube to be turned off, the second switching tube and the third switching tube are turned on until the first comparison circuit detects that the inductance current is smaller than or equal to the instruction current, the switching period is ended, and the next switching period is started;
the circuit also comprises a first conduction time generation circuit for generating a first conduction time, wherein the first conduction time is in direct proportion to the smaller value of the first ratio and the second ratio; the first ratio is the ratio of the output voltage to the input voltage, and the second ratio is the ratio of the input voltage to the output voltage.
5. The control circuit of the switching circuit according to claim 4, wherein the control circuit further comprises:
and the first operational amplifier outputs a feedback signal and a reference signal through error amplification, and the instruction current is obtained.
6. The control circuit of the switching circuit according to claim 5, wherein the first on-time generating circuit includes:
the second comparison circuit compares the input voltage with the output voltage and outputs a first comparison voltage and a second comparison voltage, wherein the higher voltage is the first comparison voltage, and the lower voltage is the second comparison voltage;
and the first division proportion circuit divides the second comparison voltage by the first comparison voltage, and the first conduction time is obtained after proportion adjustment.
7. The control circuit of the switching circuit according to claim 5, wherein the first on-time generating circuit includes:
the second division proportion circuit divides the input voltage by the output voltage, obtains the first time after proportion adjustment, divides the output voltage by the input voltage, and obtains the second time after proportion adjustment;
and a third comparison circuit that compares the first time and the second time and outputs a shorter one of the first time and the second time as the first on time.
8. A switching circuit, characterized in that: comprising a control circuit according to any of claims 4-7.
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| CN201710079791.5A CN106787730B (en) | 2017-02-15 | 2017-02-15 | Control method and control circuit of switching circuit and switching circuit |
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| CN107290581B (en) * | 2017-06-30 | 2023-07-25 | 杰华特微电子（张家港）有限公司 | Current detection circuit of switch circuit and switch circuit |
| CN107276412B (en) * | 2017-07-14 | 2023-10-27 | 杰华特微电子股份有限公司 | Control method and control circuit of switching circuit and switching circuit |
| CN107561343B (en) * | 2017-09-30 | 2023-07-18 | 杰华特微电子股份有限公司 | Current detection circuit and current detection method of switching circuit and switching circuit |
| CN112769182A (en) * | 2020-12-31 | 2021-05-07 | 湖北工业大学 | Efficient and rapid active equalization circuit for echelon battery |
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| CN203504788U (en) * | 2013-09-18 | 2014-03-26 | 美的集团股份有限公司 | Buck-boost circuit for electromagnetic heating apparatus |
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