CN111900866A - Control circuit and control method of switching circuit and switching circuit - Google Patents
Control circuit and control method of switching circuit and switching circuit Download PDFInfo
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- CN111900866A CN111900866A CN202010897466.1A CN202010897466A CN111900866A CN 111900866 A CN111900866 A CN 111900866A CN 202010897466 A CN202010897466 A CN 202010897466A CN 111900866 A CN111900866 A CN 111900866A
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
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Abstract
The invention discloses a control circuit and a control method of a switch circuit and the switch circuit, wherein a reference voltage outputs a compensation voltage through feedback compensation; obtaining the representation voltage of the inductive current of the switch circuit, carrying out proportional adjustment on the representation voltage according to an adjustment parameter, and outputting an adjustment voltage; and acquiring the compensation voltage and the adjustment voltage, and outputting a correction compensation voltage after the compensation voltage and the adjustment voltage are subjected to difference, wherein the correction compensation voltage is used for controlling the conduction time of the main power tube of the switching circuit. According to the invention, the waveform of the input current can be improved, so that THD is effectively reduced.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a control circuit and a control method of a switch circuit and the switch circuit.
Background
The switch conversion circuit has wide application in the technical field of power electronics. In order to prevent the input current of the converter from polluting the power grid, it is generally required that the THD (total harmonic distortion) generated by the converter should be as low as possible and meet certain national or industry standards. Constant On Time (COT) control is a common mode for controlling a switching circuit, is particularly suitable for application occasions of High Power Factor (HPF) and adjacent continuous inductive voltage (BCM), is simple to control, does not need to sample input voltage, has better efficiency and EMI effect, and is widely applied. Constant on-time control block diagram As shown in FIG. 1, reference voltage Vref and feedback voltage VFBAfter difference is made, the error signal e passes through a compensator to obtain a compensation voltage Vc, and after the compensation voltage Vc is compared with the sawtooth wave, the conduction time T of the MOS is obtainedONFor high PF application, the system bandwidth is low, and the Vc voltage in the power frequency period is basically unchangedBy TONThe time is also unchanged in the power frequency period.
In the Boost circuit, theoretically, the input current and the input voltage have a proportional relationship, and the THD of the input current may be small. However, in practical application, due to the influence of MOS drive delay, zero-crossing detection delay and the like, the actual inductive current IinWhen the switch is operated in an intermittent state, the inductor, various parasitic capacitors, the capacitor of the RC buffer circuit and the like can resonate, and the peak current of the inductor in the switching period is no longer in proportion to the input voltage, as shown in fig. 2 (a); in addition, at the network voltage VinNear the zero crossing, the presence of a negative current causes an inductor current IinThe average value will be earlier to 0, i.e. a "dead zone" phenomenon occurs, as shown in fig. 2 (b). Therefore, the distortion of the current waveform generated in the practical application of the Boost circuit, especially the severe "dead zone" phenomenon, can cause the input current to generate a large THD.
Disclosure of Invention
In view of the above, the present invention provides a control method and a control circuit for a switching circuit, which effectively reduce the THD of the input current of the switching circuit.
In view of the above object, the present invention provides a control circuit for a switching circuit, the control circuit comprising:
a compensation voltage generating circuit for outputting a compensation voltage from the reference voltage by feedback compensation;
the characterization voltage adjusting circuit is used for acquiring the characterization voltage of the inductive current of the switching circuit, carrying out proportional adjustment on the characterization voltage according to an adjustment parameter and outputting an adjustment voltage;
and the correction circuit is used for obtaining the compensation voltage and the adjustment voltage, and outputting the correction compensation voltage after the difference is made between the compensation voltage and the adjustment voltage, and the correction compensation voltage is used for controlling the conduction time of the main power tube of the switching circuit.
Optionally, the adjustment parameter is positively correlated with the compensation voltage.
Optionally, the control circuit further includes:
the conduction time operation circuit compares the correction compensation voltage with a sawtooth wave signal to obtain a first conduction control signal, and when the sawtooth wave signal does not reach the correction compensation voltage, the first control signal controls the main power tube to be normally conducted;
the time delay logic circuit controls the conduction time of the main power tube to be prolonged if the representation voltage is smaller than the threshold voltage when the sawtooth wave signal reaches the correction compensation voltage, and controls the main power tube to be switched off when the prolonged conduction time of the main power tube reaches the threshold voltage; or when the characterization voltage is greater than or equal to the threshold voltage, the delay logic circuit controls the main power tube to be turned off, and the prolonged conduction time of the main power tube is less than or equal to the threshold time.
The invention also provides a control method for the switching circuit, which comprises the following steps:
outputting a compensation voltage through feedback compensation by a reference voltage;
obtaining the representation voltage of the inductive current of the switch circuit, carrying out proportional adjustment on the representation voltage according to an adjustment parameter, and outputting an adjustment voltage;
and acquiring the compensation voltage and the adjustment voltage, and outputting a correction compensation voltage after the compensation voltage and the adjustment voltage are subjected to difference, wherein the correction compensation voltage is used for controlling the conduction time of the main power tube of the switching circuit.
Optionally, when the sawtooth wave signal reaches a correction compensation voltage, and when the sawtooth wave signal reaches the correction compensation voltage, if the characterization voltage is less than a threshold voltage, the conduction time of the main power tube is prolonged, and when the prolonged conduction time of the main power tube reaches the threshold time, the delay logic circuit controls the main power tube to be turned off; or when the characterization voltage is greater than or equal to the threshold voltage, the main power tube is turned off, and the prolonged conduction time of the main power tube is less than or equal to the threshold time.
The invention also provides a switch circuit comprising any one of the control circuits.
Compared with the prior art, the invention has the following advantages: the invention considers the adverse effect of the inductive current on the waveform of the input circuit in the practical application of the switch circuit, corrects the compensation voltage by utilizing the adjustment voltage representing the inductive current, and further adjusts the on-off time of the switch circuit, thereby optimizing the waveform of the input circuit and reducing the THD. In some specific technical schemes, the switching-on and switching-off time of the switch circuit can be further adjusted by prolonging the switching-on time or comparing conditions, so that the THD is further reduced.
Drawings
Fig. 1 schematically shows a block diagram of a constant control circuit based on the prior art.
Fig. 2 schematically shows the voltage and current variation curves in the switching circuit based on the prior art, wherein fig. 2(a) is a graph comparing the variation of the input current Iin with time with a standard sine curve, and fig. 2(b) is a graph comparing the variation of the input voltage Vin and the input current Iin with time.
Fig. 3 schematically shows a schematic diagram of a modified compensation voltage generation circuit according to the present invention.
Fig. 4 schematically shows a control circuit schematic of the switching circuit of the invention.
Fig. 5 schematically shows the voltage and current variation curves in the switching circuit of the present invention, wherein fig. 5(a) is a graph of the variation of the input current Iin with time according to the present invention compared with a standard sinusoidal curve and the prior art, and fig. 5(b) is a graph of the variation of the input voltage Vin and the input current Iin with time according to the present invention compared with the prior art.
Detailed Description
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 only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.
The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale, which is only used for convenience and clarity to assist in describing the embodiments of the present invention.
FIG. 3 showsA block diagram of a control circuit according to an embodiment of the present invention is schematically shown. The control circuit includes: a compensation voltage generating circuit 110 for outputting a compensation voltage Vc from the reference voltage Vref by feedback compensation; the characterization voltage adjusting circuit 120 is used for obtaining a characterization voltage Vcs of the inductive current of the switching circuit, carrying out proportional adjustment on the characterization voltage Vcs according to an adjustment parameter k, and outputting an adjustment voltage k × Vcs; and the correction circuit 130 acquires the compensation voltage Vc and the adjustment voltage k × Vcs, performs a difference between the compensation voltage Vc and the adjustment voltage k × Vcs, and outputs a correction compensation voltage Vc1 for controlling the on-time Ton of the switching circuit. The compensation voltage generation circuit 110 is a common part in constant control circuits, i.e. by means of a reference voltage Vref and a feedback voltage VFBAfter the difference is made, the error signal is compensated by the compensator to obtain the compensation voltage Vc. In the prior art, the compensation voltage Vc is used to control the on-time Ton of the MOS. According to the present invention, the compensation voltage Vc is not directly used to control the on/off of the MOS, but is subjected to some modification. The characterization voltage adjustment circuit 120 first obtains a voltage Vcs that can characterize the inductor current in the switching circuit, but Vcs cannot be directly used to correct the compensation voltage Vc. According to the invention, an adjusting parameter k is set, and the representation voltage Vcs can be used for correcting the compensation voltage Vc through the adjustment of the adjusting parameter k. The correction circuit obtains the compensation voltage Vc and the adjustment voltage k Vcs, and outputs the correction compensation voltage Vc1 after the difference processing is carried out on the compensation voltage Vc and the adjustment voltage k Vcs, the relationship between the compensation voltage Vc1 and the adjustment voltage k Vcs is Vc-k Vcs, and the correction compensation voltage Vc1 can be used for controlling the on-off of the switch circuit. The adjustment parameter k is a constant, the k value determines the compensation degree of the Vcs voltage, when the k value is too small, the compensation effect cannot be achieved, when the k value is too large, the THD becomes poor, and the value taking needs to consider input and output voltage, main inductance, parasitic capacitance of MOS and diode and the like. In a control loop, inductance current negative feedback is introduced, and Vc1 is Vc-kVcs, so that the MOS conduction time near the valley of the power grid is longer, the MOS conduction time near the peak is short, and the influence of the inductance negative current on the input current THD is compensated.
FIG. 4 schematically shows a control circuit schematic diagram according to the present invention, which includes a first comparator U01, a second comparator U03, a delay logic U04, a first flip-flop U02, a second flip-flop U05 and a zero-crossing comparator (ZCD) U06, where the zero-crossing comparator U06 controls the switch circuit main power transistor to conduct when the inductor current crosses zero, the first comparator U01 compares the corrected compensation voltage Vc1 with the ramp signal, when the ramp signal does not reach the corrected compensation voltage Vc1, the first comparator U01 outputs a low level signal, the flip-flop U02 outputs a low level signal, and the main power transistor is normally conducted; when the ramp signal reaches the correction compensation voltage Vc1, the output signal of the first comparator U01 is inverted from low level to high level, and the output signal of the first trigger U02 is inverted from low level to high level; and judging whether the representation voltage VCS of the inductive current reaches the threshold voltage VREF1 through a second comparator U03, if the representation voltage VCS does not reach the threshold voltage VREF1, outputting a low-level signal by the delay logic control circuit, and prolonging the conduction time of the main power tube after the main power tube is normally conducted until the representation voltage VCS reaches the threshold voltage VREF1, wherein the prolonged conduction time is less than or equal to the threshold time. In addition, the delay logic circuit sets a threshold time, and when the representation voltage VCS does not reach the threshold voltage VREF1 yet, but the prolonged on-time reaches the threshold time, the delay logic circuit outputs a high level, and the main power tube is turned off.
Fig. 5 shows schematically the voltage and current curves in a switching circuit according to the invention, where fig. 5(a) shows a graph of the input current Iin as a function of time in comparison with a standard sinusoidal curve and the prior art, and fig. 5(b) shows the input voltage V according to the solution of the inventioninAnd an input current IinThe time-dependent curve is compared with the prior art. As shown in fig. 5(a), according to the technical solution of the present invention, since the Vcs signal substantially follows the input voltage, the Vc1 signal is higher when the input voltage is low and lower when the input voltage is high, that is, the TON time of the MOS is smaller near the peak of the input voltage and larger near the valley, compared with the conventional solution, the peak of the inductor current of the improved solution is smaller at the peak of the input voltage and larger at the valley; the improvement compensates for input current distortion due to inductive negative current, thereby improving THD. As shown in FIG. 5(b), wherein VinIs the input voltage variation curve, Iin-1Is an input current curve according to the prior art, IinIs in accordance with the present inventionAccording to the input current change curve of the technical scheme, because the inductive current near the bottom of the power grid voltage valley is larger, more energy can be transferred in each switching period, the voltage of the capacitor of the filter is lower, the dead time of the input current is shorter, and the influence of the capacitor of the filter on the THD of the input current is compensated.
According to an embodiment, the present invention further provides a switching circuit control method, including the steps of: outputting a compensation voltage through feedback compensation by a reference voltage; obtaining the representation voltage of the inductive current of the switch circuit, carrying out proportional adjustment on the representation voltage according to an adjustment parameter, and outputting an adjustment voltage; and acquiring the compensation voltage and the adjustment voltage, and outputting a correction compensation voltage after the compensation voltage and the adjustment voltage are subjected to difference, wherein the correction compensation voltage is used for controlling the conduction time of the switch circuit.
Compared with the prior art, the invention has the following advantages: the invention considers the adverse effect of the inductive current on the waveform of the input circuit in the practical application of the switch circuit, corrects the compensation voltage by utilizing the adjustment voltage representing the inductive current, and further adjusts the on-off time of the switch circuit, thereby optimizing the waveform of the input current and reducing the THD. In some specific technical schemes, the switching-on and switching-off time of the switch circuit can be further adjusted by adding a delay condition or a comparison condition, so that the THD is further reduced.
The use of "a" or "an" in this specification and claims should be understood to mean "at least one" unless explicitly stated otherwise or to exclude such interpretation based on context. In any method comprising more than one step and acts, as claimed in the present specification and claims, the individual steps or acts of a method are not limited to the order in which the steps or acts of the method are recited, unless expressly stated to the contrary.
The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.
Claims (6)
1. A control circuit for a switching circuit, the control circuit comprising:
a compensation voltage generating circuit for outputting a compensation voltage from the reference voltage by feedback compensation;
the characterization voltage adjusting circuit is used for acquiring the characterization voltage of the inductive current of the switching circuit, carrying out proportional adjustment on the characterization voltage according to an adjustment parameter and outputting an adjustment voltage;
and the correction circuit is used for obtaining the compensation voltage and the adjustment voltage, and outputting the correction compensation voltage after the difference is made between the compensation voltage and the adjustment voltage, and the correction compensation voltage is used for controlling the conduction time of the main power tube of the switching circuit.
2. The control circuit of claim 1, wherein the adjustment parameter is positively correlated with a compensation voltage.
3. The control circuit of claim 1, further comprising:
the conduction time operation circuit compares the correction compensation voltage with a sawtooth wave signal to obtain a first conduction control signal, and when the sawtooth wave signal does not reach the correction compensation voltage, the first control signal controls the main power tube to be normally conducted;
the time delay logic circuit controls the conduction time of the main power tube to be prolonged if the representation voltage is smaller than the threshold voltage when the sawtooth wave signal reaches the correction compensation voltage, and controls the main power tube to be switched off when the prolonged conduction time of the main power tube reaches the threshold voltage; or when the characterization voltage is greater than or equal to the threshold voltage, the delay logic circuit controls the main power tube to be turned off, and the prolonged conduction time of the main power tube is less than or equal to the threshold time.
4. A control method for a switching circuit, comprising the steps of:
outputting a compensation voltage through feedback compensation by a reference voltage;
obtaining the representation voltage of the inductive current of the switch circuit, carrying out proportional adjustment on the representation voltage according to an adjustment parameter, and outputting an adjustment voltage;
and acquiring the compensation voltage and the adjustment voltage, and outputting a correction compensation voltage after the compensation voltage and the adjustment voltage are subjected to difference, wherein the correction compensation voltage is used for controlling the conduction time of the main power tube of the switching circuit.
5. The control method of the switch circuit according to claim 4, wherein when the sawtooth wave signal reaches the correction compensation voltage, if the characterization voltage is smaller than the threshold voltage, the on-time of the main power transistor is extended, and when the extended on-time of the main power transistor reaches the threshold time, the delay logic circuit controls the main power transistor to be turned off; or when the characterization voltage is greater than or equal to the threshold voltage, the main power tube is turned off, and the prolonged conduction time of the main power tube is less than or equal to the threshold time.
6. A switching circuit comprising a control circuit according to any one of claims 1 to 3.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010897466.1A CN111900866A (en) | 2020-08-31 | 2020-08-31 | Control circuit and control method of switching circuit and switching circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010897466.1A CN111900866A (en) | 2020-08-31 | 2020-08-31 | Control circuit and control method of switching circuit and switching circuit |
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| CN111900866A true CN111900866A (en) | 2020-11-06 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113141111A (en) * | 2021-04-22 | 2021-07-20 | 杰华特微电子股份有限公司 | Control method and control circuit of booster circuit |
-
2020
- 2020-08-31 CN CN202010897466.1A patent/CN111900866A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113141111A (en) * | 2021-04-22 | 2021-07-20 | 杰华特微电子股份有限公司 | Control method and control circuit of booster circuit |
| CN113141111B (en) * | 2021-04-22 | 2022-04-15 | 杰华特微电子股份有限公司 | Control method and control circuit of booster circuit |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Applicant before: JOULWATT TECHNOLOGY Inc.,Ltd. |