CN116632768A - Primary side current detection circuit and method for resonance topology-variable overcurrent protection - Google Patents
Primary side current detection circuit and method for resonance topology-variable overcurrent protection Download PDFInfo
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- CN116632768A CN116632768A CN202310051851.8A CN202310051851A CN116632768A CN 116632768 A CN116632768 A CN 116632768A CN 202310051851 A CN202310051851 A CN 202310051851A CN 116632768 A CN116632768 A CN 116632768A
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- 238000001514 detection method Methods 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title abstract description 7
- 230000000737 periodic effect Effects 0.000 claims abstract description 11
- 238000005259 measurement Methods 0.000 claims description 3
- 238000005070 sampling Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 7
- 239000003990 capacitor Substances 0.000 description 6
- 230000007547 defect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC 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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The application relates to a primary side current detection circuit for resonance variable topology overcurrent protection, which comprises an average current detection circuit, a peak current detection circuit and a current threshold judgment circuit, wherein the average current detection circuit is used for integrating and amplifying an input Vcs to obtain a direct current voltage without ripple, and the direct current voltage is in direct proportion to an input current and is output to the threshold judgment circuit; the peak current detection circuit is used for detecting a Vcs real-time signal at an input end, amplifying the Vcs voltage in real time, maintaining the periodic peak voltage and outputting the periodic peak voltage to the threshold value judgment circuit; and a threshold value judging circuit for setting a reference threshold value, receiving the DC voltage of the average current detecting circuit and the peak voltage detecting signal of the peak current detecting circuit, comparing with the set reference threshold value, and if the set value exceeds the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive. Compared with the prior art, the method and the device can simultaneously ensure real-time performance.
Description
Technical Field
The application relates to the technical field of power electronics, in particular to a primary side current detection circuit and a primary side current detection method for overcurrent protection of a variable topology LLC resonant converter.
Background
The overcurrent protection needs to sample the primary side or secondary side current of the switching power supply. The principle of sampling the secondary side current is simple and accurate, and is irrelevant to the adopted topology. However, the main control chip is generally on the primary side, and if the current is sampled on the secondary side, an additional isolation circuit and a power supply circuit are needed, so that the overall control is more complex.
It is common in the industry to place over-current protected current sampling circuits on the primary side. The current sampling circuit is placed on the primary side, so that different sampling modes are needed for different topologies. For example, the LLC topology can be divided into a resonant current and an exciting current, wherein the resonant current is transmitted to the output terminal, and the exciting current is not transmitted to the output terminal. In general LLC topology, the voltage fluctuation amplitude of the primary side resonance capacitor can be sampled to reflect the output load size. For example, the half-bridge LLC, the resonant capacitor is grounded, and the control circuit can sample the voltage across the resonant capacitor in a very small way.
For the full-bridge LLC, the resonant capacitor is not grounded, so an additional circuit is required to process the sampled signals at both ends of the capacitor, for example, patent 202010895001.2 samples the voltages at both ends of the resonant capacitor by means of a voltage division and differential sampling; the current of the resonant inductor is sampled by a transformer as in patent 202111094177.9. The above scheme is possible for LLC topologies without mode switching. The above scheme may have certain disadvantages for LLC with mode switching control, which is a topology change. As in the scheme of patent 201911006674.1, for the purpose of wide gain control, LLC main power is switched by half-bridge and full-bridge, and the control mode is also PWM and PFM control.
In the case of such a variable topology and variable control mode, the current detection method is not applicable. Because of different topological structures and different control modes, the corresponding relation between the primary side current and the load current is different, and the overcurrent protection threshold value is greatly different in the whole wide gain range, so that the requirement of productization cannot be met. The existing current control scheme is characterized by identifying by a voltage feedback signal when short circuit and overcurrent are output, and hysteresis is provided.
Disclosure of Invention
The application aims to solve the technical problem of providing a primary side current detection circuit based on overcurrent protection of a variable topology LLC resonant converter, which has high consistency of overcurrent points, can simultaneously ensure real-time performance and has high short-circuit current detection speed for the variable topology LLC resonant converter with mode switching control in the whole wide gain range.
The application provides a primary side current detection circuit for resonance variable topology overcurrent protection, which comprises an average current detection circuit, a peak current detection circuit and a current threshold judgment circuit, wherein the average current detection circuit is used for integrating and amplifying an input Vcs to obtain a direct current voltage without ripple, and the direct current voltage is in direct proportion to an input current and is output to the threshold judgment circuit; the peak current detection circuit is used for detecting a Vcs real-time signal at an input end, amplifying the Vcs voltage in real time, maintaining the periodic peak voltage and outputting the periodic peak voltage to the threshold value judgment circuit; and a threshold value judging circuit for setting a reference threshold value, receiving the DC voltage of the average current detecting circuit and the peak voltage detecting signal of the peak current detecting circuit, comparing with the set reference threshold value, and if the set value exceeds the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive.
Preferably, the average current detection circuit outputs the output current average signal Vcs (Avg) after the voltage signal of the resistor Rcs is differentially collected by the operational amplifier OP1 and passes through the low-pass filter, and then compares the output current average signal Vcs (Avg) with the set output current limit threshold Vref (Avg), and when the output actual measurement is greater than the set threshold, the comparator CM1 outputs a high level, so that the primary current detection circuit Ctrl outputs a high level, and the control system stops sending out driving.
Preferably, the peak current detection circuit collects the voltage signal of the resistor Rcs cycle by cycle through the operational amplifier OP2, amplifies the voltage signal, and compares the voltage signal with the set peak threshold Vref (pk) to protect the circuit, when the voltage signal collected by the resistor Rcs is greater than the set threshold Vref (pk), the comparator CM2 outputs a high level, at this time, the primary current detection circuit Ctrl terminal becomes a high level, and the control system stops sending out the drive.
The application also provides a primary side current detection method for resonance variable topology overcurrent protection, which is used for collecting the average value of Vcs voltage to obtain ripple-free direct current voltage, wherein the direct current voltage is in direct proportion to input current; and detecting Vcs real-time signals at the input end cycle by cycle to obtain periodic peak voltage, comparing the two detection signals of the direct current voltage and the peak voltage with a set reference threshold value respectively, and if the detection signals exceed the set value of the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive.
The input voltage Vin and the current Vcs are collected to control the PWM generator.
The function of the average current detection circuit is that the input Vcs is integrated and amplified, and the output voltage signal reflects the output average current.
And the function of the peak current detection circuit is to process the Vcs real-time signal at the input end and output real-time peak current.
The current threshold value judging circuit sets a judging threshold value according to Vin voltage and Vcs signals, so that consistency of overcurrent points and instantaneity of short-circuit protection are ensured.
Compared with the prior art, the application has the beneficial effects that,
1. the sampling scheme of the average current output by the average current detection circuit is a low-pass filter formed by an operational amplifier, and the direct-current voltage output by the operational amplifier can represent the output current.
2. The cycle-by-cycle peak current limiting circuit, which is formed by the comparator of the primary current detection circuit, can be used for short-circuit protection.
3. The accurate output current Is and the accurate peak current can be obtained by only collecting the average value of the Vcs voltage, and the method can be used for overcoming the defects of poor accuracy and large tolerance of the existing scheme.
Drawings
FIG. 1 is a topology diagram of an application system of a primary side current detection circuit for resonance topology-variable over-current protection of the present application;
FIG. 2 is a schematic block diagram of a primary current detection circuit according to the present application;
FIG. 3 is a circuit diagram of a primary side current detection circuit according to the present application;
FIG. 4 is a PFM current waveform diagram of the primary side current detection circuit of the resonant variable topology over-current protection of the present application;
fig. 5 is a PWM current waveform diagram of the primary side current detection circuit of the resonant topology overcurrent protection of the present application.
Detailed Description
For a better understanding of the application, reference is made to the detailed description of embodiments of the application, which are to be taken in connection with the accompanying drawings.
Examples
As shown in FIG. 1, the topology diagram of the application system of the primary side current detection circuit for resonance topology-variable overcurrent protection is shown, and the whole control system consists of a CLLC topology, a current control module, a driving control module and a voltage control module.
The application is an innovation aiming at a current control module, as shown in figure 2, and is a schematic block diagram of a primary side current detection circuit of resonance topology-variable overcurrent protection, which comprises an average current detection circuit, a peak current detection circuit and a current threshold judgment circuit,
the average current detection circuit is used for integrating and amplifying the input Vcs to obtain a direct-current voltage without ripple, and the direct-current voltage is directly proportional to the input current and is output to the threshold value judgment circuit;
the peak current detection circuit is used for detecting a Vcs real-time signal at an input end, amplifying the Vcs voltage in real time, maintaining the periodic peak voltage and outputting the periodic peak voltage to the threshold value judgment circuit;
and a threshold value judging circuit for setting a reference threshold value, receiving the DC voltage of the average current detecting circuit and the peak voltage detecting signal of the peak current detecting circuit, comparing with the set reference threshold value, and if the set value exceeds the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive.
The application relates to a primary side current detection method for resonance variable topology overcurrent protection, which is characterized in that an average value of Vcs voltage is collected to obtain direct current voltage without ripple, and the direct current voltage is in direct proportion to input current; and detecting Vcs real-time signals at the input end cycle by cycle to obtain periodic peak voltage, comparing the two detection signals of the direct current voltage and the peak voltage with a set reference threshold value respectively, and if the detection signals exceed the set value of the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive.
The working principle of the current control module is as follows:
1. the output current Is converted to the source side Ip: is=ip Nps
2. Source side resonant inductor current ILr: ilr=ip+ilm
3. The voltage drop Vcs across the sampling resistor Rcs per cycle is: vcs=rcs×ilr
4. The excitation inductance ILm current is characterized by an average value of 0 for one period, and therefore the average value of ILr:
5. the average output current after Rcs sampling is:
6. the peak current is a real-time sampling signal, and the cycle-by-cycle control relation is as follows: is_pk=vcs Nps/Rcs
7. From theoretical analysis, it can be seen that accurate output current Is and accurate peak current can be obtained by only collecting the average value of Vcs voltage. The method can be used for overcoming the defects of poor precision and large tolerance of the existing scheme.
8. The primary side current detection circuit of resonance topology change overcurrent protection is shown in fig. 3, and firstly, the sampling scheme of the average current of detection output is a low-pass filter formed by an operational amplifier, and the direct current voltage output by the operational amplifier represents the output current; and secondly, a cycle-by-cycle peak current limiting circuit formed by a comparator is used for performing a short-circuit protection function.
The circuit principle of output current sampling is as follows:
output current: the operational amplifier OP1 differentially collects voltage signals of the resistor Rcs, outputs an output current average value signal Vcs (Avg) after passing through a low-pass filter, compares the output current average value signal with a set output current limiting threshold Vref (Avg), and outputs a high level by the comparator CM1 when the output actual measurement is larger than the set threshold, so that the primary current detection circuit Ctrl end outputs the high level, and the control system stops sending out driving.
Peak current: the operational amplifier OP2 collects the voltage signal of the resistor Rcs cycle by cycle, amplifies the voltage signal, protects the circuit by comparing the voltage signal with a set peak value threshold Vref (pk), and when the voltage signal collected by the resistor Rcs is larger than the set threshold Vref (pk), the comparator CM2 outputs a high level, at the moment, the primary side current detection circuit Ctrl end becomes a high level, and the control system stops sending out driving.
The above embodiments are only for aiding in understanding the inventive concept and are not intended to limit the application, and any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art without departing from the principles of the present application should be included in the scope of the present application.
Claims (4)
1. A primary side current detection circuit for resonance topology-variable overcurrent protection comprises an average current detection circuit, a peak current detection circuit and a current threshold judgment circuit,
the average current detection circuit is used for integrating and amplifying the input Vcs to obtain a direct-current voltage without ripple, and the direct-current voltage is directly proportional to the input current and is output to the threshold value judgment circuit;
the peak current detection circuit is used for detecting a Vcs real-time signal at an input end, amplifying the Vcs voltage in real time, maintaining the periodic peak voltage and outputting the periodic peak voltage to the threshold value judgment circuit;
and a threshold value judging circuit for setting a reference threshold value, receiving the DC voltage of the average current detecting circuit and the peak voltage detecting signal of the peak current detecting circuit, comparing with the set reference threshold value, and if the set value exceeds the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive.
2. The primary side current detection circuit of the resonant topology-variable overcurrent protection according to claim 1, wherein the average current detection circuit outputs an output current average signal Vcs (Avg) after a voltage signal of a resistor Rcs is differentially collected through an operational amplifier OP1 and passes through a low-pass filter, and then compares the output current average signal Vcs (Avg) with a set output current limit threshold Vref (Avg), and when the output actual measurement is greater than the set threshold, the comparator CM1 outputs a high level, so that a primary side current detection circuit Ctrl end outputs a high level, and the control system stops sending out driving.
3. The primary side current detection circuit for resonant topology-variable over-current protection according to claim 1, wherein the peak current detection circuit collects a voltage signal of the resistor Rcs cycle by cycle through the operational amplifier OP2, amplifies the voltage signal, and protects the circuit by comparing the voltage signal with a set peak threshold value Vref (pk), when the voltage signal collected by the resistor Rcs is greater than the set threshold value Vref (pk), the comparator CM2 outputs a high level, and at this time, the primary side current detection circuit Ctrl terminal becomes a high level, and the control system stops sending out the drive.
4. The primary side current detection method for resonance topology-variable overcurrent protection acquires the average value of Vcs voltage to obtain ripple-free direct current voltage, wherein the direct current voltage is in direct proportion to input current; and detecting Vcs real-time signals at the input end cycle by cycle to obtain periodic peak voltage, comparing the two detection signals of the direct current voltage and the peak voltage with a set reference threshold value respectively, and if the detection signals exceed the set value of the reference threshold value, changing the control signal from low level to high level to trigger the drive control circuit to close the drive.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310001933 | 2023-01-03 | ||
| CN2023100019331 | 2023-01-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116632768A true CN116632768A (en) | 2023-08-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310051851.8A Pending CN116632768A (en) | 2023-01-03 | 2023-02-02 | Primary side current detection circuit and method for resonance topology-variable overcurrent protection |
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| CN (1) | CN116632768A (en) |
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2023
- 2023-02-02 CN CN202310051851.8A patent/CN116632768A/en active Pending
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