CN110764410A - Method for accelerating transient response of negative feedback control system - Google Patents
Method for accelerating transient response of negative feedback control system Download PDFInfo
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- CN110764410A CN110764410A CN201911025665.7A CN201911025665A CN110764410A CN 110764410 A CN110764410 A CN 110764410A CN 201911025665 A CN201911025665 A CN 201911025665A CN 110764410 A CN110764410 A CN 110764410A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
- G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
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Abstract
The invention relates to a method for accelerating transient response of negative feedback control system, comprising ⑴ sending VFB to transconductance amplifier U1To the transconductance amplifier U, and the inverting input terminal of the second transistor for sending VREF to the transconductance amplifier U1⑵ transconductance amplifier U1Flows through a resistor R and generates a voltage drop VR across the resistor R, which is a transconductance amplifier U1Proportional amplification of the voltage difference between the two inputs ⑶ voltage comparator U2Detecting the voltage drop VR at the two ends of the resistor R, comparing the voltage drop VR at the two ends of the resistor R with a set threshold value, and when the voltage drop VR exceeds the set threshold value voltage, comparing the voltage with a voltage comparator U2Output signal Y of1Flipping, thereby activating the auxiliary circuit to accelerate the transient response of the system.
Description
Technical Field
The invention relates to the field of electronics, in particular to a method for accelerating transient response of a negative feedback control system.
Background
The negative feedback control system is widely applied to various electronic devices, for example, the common PWM operating mode and the peak current mode DC-DC are both negative feedback control systems. For a negative feedback control system, the bandwidth of the system may limit the speed of the control loop's response to the output target transients. For example, when the output target amount deviates from the reference value by more than a certain margin, it may not be acceptable in practical use.
The most straightforward way to improve the dynamic response of the system is to increase the system bandwidth, which is limited by factors such as the allowable operating frequency of the system, the loop stability tradeoff, etc. Additional ancillary circuitry may be required to speed up the response of the system under output transient conditions.
Referring to fig. 1, fig. 1 is a circuit diagram illustrating an accelerated transient response of a conventional negative feedback control system. The sampled feedback signal VFB, which is output in a steady state, is stabilized at the level of the reference signal VREF. When the output is transient, the output sampled feedback signal VFB deviates from the reference signal VREF, and when the deviation value of the output sampled feedback signal VFB exceeds a set amplitude, for example, the deviation value exceeds VREF1Then the comparator U2Output voltage Y of1Turnover, Y1The signal is used to activate a circuit that accelerates the transient response of the system.
The above structure has a drawback in integrated circuits: because of the transconductance amplifier U1And a comparator U2All have input offsets and therefore VREF1The difference from VREF must be higher than the offset voltage for the system to operate stably. E.g. U1Input offset of VOS1,U2Input offset of VOS2The following conditions are satisfied:
|VREF1-VREF|>|VOS1|+|VOS2|
this can cause the acceleration circuit to act too late, thereby affecting the effect of the transient response.
Disclosure of Invention
The invention aims to provide a method for accelerating the transient response of a negative feedback control system, which can remarkably improve the transient response characteristic of the system.
The invention relates to a method for accelerating the transient response of a negative feedback control system, which is characterized by comprising the following steps:
⑴ provides the output or sampled feedback signal VFB to the transconductance amplifier U1The inverting input terminal of the second stage, the reference signal VREF is sent to the transconductance amplifier U1The positive input end of the comparator is used for comparison;
⑵ transconductance amplifier U1Flows through a resistor R and generates a voltage drop VR across the resistor R, saidVoltage drop VR is transconductance amplifier U1Amplifying the proportion of the pressure difference between the two input ends;
⑶ Voltage comparator U2Voltage drop VR across detection resistor R, voltage comparator U2Comparing the voltage drop VR of two ends of the resistor R with a set threshold value, and when the voltage drop VR exceeds the set threshold voltage, a voltage comparator U2Output signal Y of1Flipping, thereby activating the auxiliary circuit to accelerate the transient response of the system.
Preferably, the method comprises the following steps: the implementation method of the auxiliary circuit further comprises the following steps:
⑴ the frequency compensation unit U is changed by changing the resistance value of the frequency compensation3The zero point position of the frequency compensation unit U3The system consists of a network consisting of a resistor and a capacitor element and is used for setting the positions of a zero point and a pole to realize the frequency compensation of the system;
⑵ pairs frequency compensation unit U3The compensation capacitor is charged in an accelerated manner, and the charging current of the compensation capacitor is a transconductance amplifier U1The proportion of the output current is amplified;
⑶ skipping transconductance amplifier U1The output error control signal increases or decreases the output energy of the system.
Preferably, the proportional amplification of the output current in step ⑵ is selected from a transconductance amplifier U1And mirror image amplification of the output current, or sending the voltage drop VR between two ends of the resistor R to another transconductance amplifier to generate the output current for charging the compensation capacitor.
Preferably, the method comprises the following steps:
the output current IO of the transconductance amplifier is the product of the differential voltage of the input end of the operational amplifier (VREF-VFB) and the transconductance Gm of the operational amplifier, wherein IO is (VREF-VFB) × Gm
The voltage difference between two ends of the resistor R is VR, VR is IO R, (VREF-VFB) Gm R
From the above formula, VR is the proportional amplification of the transconductance amplifier input voltage difference VREF-VFB when Gm × R >1 is satisfied.
Compared with the prior art, the invention has the beneficial effects that:
⑴ the present invention accelerates the speed of the transient response of the system and reduces the magnitude of the deviation of the output from the reference.
⑵ the present invention reduces the sensitivity of the circuit to input offset voltages of operational amplifiers or comparators.
⑶ the invention can realize higher sensitivity and reduce the sensitivity to input offset of the operational amplifier and the comparator by comparing whether the voltage drop VR across the resistor exceeds the set threshold voltage2Output signal Y of1Flipping, thereby activating the auxiliary circuit to accelerate the transient response of the system.
Drawings
FIG. 1 is a circuit schematic of a conventional negative feedback control system accelerating transient response;
FIG. 2 is a circuit of the present invention for accelerating dynamic response; where VFB is the sampled feedback signal of the output, VREF is the reference signal, U1Is a transconductance amplifier, U2Is a voltage comparator, U3Is a frequency compensation unit;
FIG. 3 is a diagram illustrating the effect of the dynamic response of the acceleration system of the present invention.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings:
referring to fig. 2, the method for accelerating the transient response of the negative feedback control system includes the following steps:
⑴ provides the output or sampled feedback signal VFB to the transconductance amplifier U1The inverting input terminal of the second stage, the reference signal VREF is sent to the transconductance amplifier U1The positive input end of the comparator is used for comparison;
⑵ transconductance amplifier U1Flows through a resistor R and generates a voltage drop VR across the resistor R, which is a transconductance amplifier U1Amplifying the proportion of the pressure difference between the two input ends;
⑶ Voltage comparator U2Voltage drop VR across detection resistor R, voltage comparator U2Comparing the voltage drop VR of two ends of the resistor R with a set threshold value, and when the voltage drop VR exceeds the set threshold valueAfter the threshold voltage, the voltage comparator U2Output signal Y of1Flipping, thereby activating the auxiliary circuit to accelerate the transient response of the system.
In this embodiment, the implementation method of the auxiliary circuit further includes:
⑴ the frequency compensation unit U is changed by changing the resistance value of the frequency compensation3The zero point position of the frequency compensation unit U3The system consists of a network consisting of a resistor and a capacitor element and is used for setting the positions of a zero point and a pole to realize the frequency compensation of the system;
⑵ pairs frequency compensation unit U3The compensation capacitor is charged in an accelerated manner, and the charging current of the compensation capacitor is a transconductance amplifier U1The proportion of the output current is amplified;
⑶ skipping transconductance amplifier U1The output error control signal increases or decreases the output energy of the system.
The proportional amplification of the output current in step ⑵ may optionally be a transconductance amplifier U1And mirror image amplification of the output current, or sending the voltage drop VR between two ends of the resistor R to another transconductance amplifier to generate the output current for charging the compensation capacitor.
The output current IO of the transconductance amplifier is the product of the differential voltage of the input end of the operational amplifier (VREF-VFB) and the transconductance Gm of the operational amplifier, wherein IO is (VREF-VFB) × Gm
The voltage difference between two ends of the resistor R is VR, VR is IO R, (VREF-VFB) Gm R
From the above formula, VR is the proportional amplification of the transconductance amplifier input voltage difference VREF-VFB when Gm × R >1 is satisfied.
Referring to fig. 3, fig. 3 is a schematic diagram illustrating the effect of the dynamic response of the acceleration system according to the present invention; where the solid line is the VFB transient response waveform using the proposed technique of the present invention and the dashed line is the VFB transient response waveform of the conventional control system.
The above-mentioned embodiments are only preferred embodiments of the present invention, and all equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.
Claims (4)
1. A method for accelerating the transient response of a negative feedback control system, comprising the steps of:
⑴ provides the output or sampled feedback signal VFB to the transconductance amplifier U1The inverting input terminal of the second stage, the reference signal VREF is sent to the transconductance amplifier U1The positive input end of the comparator is used for comparison;
⑵ transconductance amplifier U1Flows through a resistor R and generates a voltage drop VR across the resistor R, which is a transconductance amplifier U1Amplifying the proportion of the pressure difference between the two input ends;
⑶ Voltage comparator U2Voltage drop VR across detection resistor R, voltage comparator U2Comparing the voltage drop VR of two ends of the resistor R with a set threshold value, and when the voltage drop VR exceeds the set threshold voltage, a voltage comparator U2Output signal Y of1Flipping, thereby activating the auxiliary circuit to accelerate the transient response of the system.
2. The method of claim 1, wherein the method of implementing the auxiliary circuit further comprises:
⑴ the frequency compensation unit U is changed by changing the resistance value of the frequency compensation3The zero point position of the frequency compensation unit U3The system consists of a network consisting of a resistor and a capacitor element and is used for setting the positions of a zero point and a pole to realize the frequency compensation of the system;
⑵ pairs frequency compensation unit U3-3The compensation capacitor is charged in an accelerated manner, and the charging current of the compensation capacitor is a transconductance amplifier U1The proportion of the output current is amplified;
⑶ skipping transconductance amplifier U1The output error control signal increases or decreases the output energy of the system.
3. The method of claim 2 wherein the step ⑵ of scaling the output current is selected from the group consisting of transconductance amplificationDevice U1And mirror image amplification of the output current, or sending the voltage drop VR between two ends of the resistor R to another transconductance amplifier to generate the output current for charging the compensation capacitor.
4. The method of accelerating the transient response of a negative feedback control system according to claim 1,
the output current IO of the transconductance amplifier is the product of the operational amplifier input terminal voltage difference (VREF-VFB) and the operational amplifier transconductance Gm:
IO＝(VREF-VFB)*Gm
the voltage difference between two ends of the resistor R is VR, VR is IO R, (VREF-VFB) Gm R
From the above formula, VR is the proportional amplification of the transconductance amplifier input voltage difference VREF-VFB when Gm × R >1 is satisfied.
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| CN108241396A (en) * | 2016-12-23 | 2018-07-03 | 北京同方微电子有限公司 | A kind of low pressure difference linear voltage regulator for improving transient response speed |
| CN108874008A (en) * | 2018-06-22 | 2018-11-23 | 佛山科学技术学院 | A kind of LDO circuit with double feedbacks |
| CN110048592A (en) * | 2019-04-28 | 2019-07-23 | 西安拓尔微电子有限责任公司 | A kind of fast transient response circuit applied to DC-DC power source managing chip |
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2019
- 2019-10-25 CN CN201911025665.7A patent/CN110764410B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1949121A (en) * | 2006-10-25 | 2007-04-18 | 华中科技大学 | Double ring low differential voltage linear voltage stabilizer circuit |
| CN201229514Y (en) * | 2008-07-11 | 2009-04-29 | 贵州航天林泉电机有限公司 | Low loss series voltage stabilizing and over-current protection circuit |
| CN101957628A (en) * | 2009-07-17 | 2011-01-26 | 上海沙丘微电子有限公司 | Self-adaption zero-frequency compensation circuit in low-voltage difference linear voltage regulator |
| CN101782787A (en) * | 2010-02-02 | 2010-07-21 | 中国人民解放军国防科学技术大学 | Current control type low-pressure drop voltage-stabilizing circuit |
| CN103427636A (en) * | 2013-08-27 | 2013-12-04 | 电子科技大学 | Transient response enhancement control circuit used for switch power source |
| CN104460802A (en) * | 2014-11-27 | 2015-03-25 | 电子科技大学 | Self-adapting current multiplication circuit and low-dropout-voltage linear voltage regulator integrating same |
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| CN108874008A (en) * | 2018-06-22 | 2018-11-23 | 佛山科学技术学院 | A kind of LDO circuit with double feedbacks |
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