CN111324160B - Power supply and compensation method thereof - Google Patents
Power supply and compensation method thereof Download PDFInfo
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- CN111324160B CN111324160B CN201811531537.5A CN201811531537A CN111324160B CN 111324160 B CN111324160 B CN 111324160B CN 201811531537 A CN201811531537 A CN 201811531537A CN 111324160 B CN111324160 B CN 111324160B
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- adjustment ratio
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/561—Voltage to current converters
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Abstract
A power supply and a compensation method thereof. The compensation method of the power supply comprises the following steps: setting a design point resistance value of the compensator; detecting output voltage and output current output by a power converter of a power supply; calculating a load resistance value according to the output voltage and the output current; calculating an adjustment ratio according to the load resistance value and the compensator design point resistance value; and compensating the power supply according to the adjustment ratio so as to stabilize the output current of the power supply.
Description
Technical Field
The present disclosure relates to a power supply, and more particularly, to a power supply and a compensation method thereof.
Background
A Switching Power Supply (SPS) is a device capable of converting input Power according to a Power type required by a load. Usually, the switching power supply is designed with at least one set of Constant-parameter compensators to achieve the required stability and transient response, however, when the switching power supply operates in Constant Current mode (CC) and the load becomes very small, the cross-over frequency (cross frequency) becomes large, and the corresponding phase margin (phase margin) and gain margin (gain margin) also decrease, in which case, once the phase and/or gain is insufficient, the output Current of the switching power supply is unstable.
In addition, in a conventional switching power supply with a large load range, two sets of controllers are usually designed, and a user needs to switch to an appropriate controller at an initial stage according to actual usage conditions (e.g., according to the load range). Therefore, the user needs to manually switch the controller before using the controller, and the design will reduce the convenience of use when the user cannot predict the load range in advance.
Disclosure of Invention
The present disclosure provides a power supply and a compensation method thereof, which can increase the load range of the switching power supply for stable operation, and keep the bandwidth of the switching power supply consistent when the load varies, without requiring a switching controller.
According to the above object of the present disclosure, a compensation method for a power supply is provided, which includes: setting a design point resistance value of the compensator; detecting output voltage and output current output by a power converter of a power supply; calculating a load resistance value according to the output voltage and the output current; calculating an adjustment ratio according to the load resistance value and the compensator design point resistance value; and compensating the power supply according to the adjustment ratio so as to stabilize the output current of the power supply.
In some embodiments, the power Converter is a Buck Converter (Buck Converter), and the power supply operates in a constant current mode.
In some embodiments, the compensation method of the power supply further comprises: before detecting the output voltage and the output current, the upper and lower limits of the adjustment ratio are set, and pole/zero (pole/zero) configuration is performed.
In some embodiments, the compensation method of the power supply further comprises: after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to a phase margin (phase margin) so that the power supply has a sufficient phase margin.
In some embodiments, the compensation method of the power supply further comprises: after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to a gain margin (gain margin) so that the power supply has a sufficient gain margin.
According to the above object of the present disclosure, a power supply is provided, comprising: a power converter and a Microcontroller (MCU). The microcontroller is electrically connected with the power converter and is used for executing the following steps: setting a design point resistance value of the compensator; detecting output voltage and output current output by the power converter; calculating a load resistance value according to the output voltage and the output current; calculating an adjustment ratio according to the load resistance value and the compensator design point resistance value; and compensating the power supply according to the adjustment ratio so as to stabilize the output current of the power supply.
In some embodiments, the power converter is a buck converter, and the power supply operates in a constant current mode.
In some embodiments, the microcontroller is further configured to perform the following steps: before detecting the output voltage and the output current, setting the upper and lower limit ranges of the adjustment ratio, and carrying out pole zero point configuration.
In some embodiments, the microcontroller is further configured to perform the following steps: after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to the phase margin, so that the power supply has enough phase margin.
In some embodiments, the microcontroller is further configured to perform the following steps: after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to the gain margin, so that the power supply has a sufficient gain margin.
In order to make the aforementioned and other features and advantages of the disclosure more comprehensible, embodiments accompanied with figures are described in detail below.
Drawings
Aspects of the present disclosure may be better understood from the following detailed description when considered in conjunction with the accompanying drawings. It is noted that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
Fig. 1 is a schematic diagram of an architecture of a power supply according to an embodiment of the present disclosure;
FIG. 2 is a flowchart of a compensation method of a power supply according to an embodiment of the present disclosure;
fig. 3 is a flowchart of a compensation method of a power supply according to an embodiment of the disclosure.
Detailed Description
Embodiments of the present disclosure are discussed in detail below. It should be appreciated, however, that the embodiments provide many applicable concepts that can be embodied in a wide variety of specific contexts. The discussed and disclosed embodiments are merely illustrative and are not intended to limit the scope of the present disclosure.
The adjustment of the output voltage of the switching power supply means that the output voltage can still be maintained within the error range of the set value even when the load or the input voltage varies. Since the switching power supply belongs to a nonlinear circuit, it is usually analyzed by using a small signal disturbance model, so as to design a useful compensator according to its transient response characteristic. For example, when a conventional power supply including a Buck Converter (Buck Converter) operates in a Constant Current mode (CC), the closed loop gain can be expressed as follows:
G＝Gio×Gid×Gca (1)
wherein, with G caThe Transfer Function (G) of the compensator is shown as GioShowing the multiplying power of the feedback circuit by GidThe current transfer function of the buck converter under the condition that the load is pure resistance is expressed, and the transfer function of the buck converter can be expressed as a relation of output disturbance and Duty Cycle (Duty Cycle) through a small signal disturbance model as follows:
wherein iOFor output current, d is duty cycle, VinFor input voltage, RLIs a load resistance, ZCIs the capacitive impedance of the secondary side, ZLIs the inductive impedance of the secondary side. According to formula (1), GidThe corresponding direct current Gain (DC Gain) of the open loop is Vin/RLThat is, the open-loop dc gain is affected by the load resistor, which may cause the phase and/or gain to be insufficient when the load resistor is very small, thereby causing the output current of the power supply to be unstable.
The present disclosure provides a power supply and a compensation method thereof, which actively adjust the compensation of the power supply according to a load resistance, wherein the adjustment is performed through an adjustment ratio. The details of the present disclosure will be described below.
Fig. 1 is a schematic diagram of an architecture of a power supply 100 according to an embodiment of the disclosure. The power supply 100 includes a microcontroller 120 and a power converter 140, wherein the microcontroller 120 is electrically connected to the power converter 140. In the embodiment of the present disclosure, the power converter 140 is a buck converter. In the embodiment of the present disclosure, the power supply 100 is operated in a constant current mode. Fig. 2 is a flowchart of a compensation method 1000 of a power supply according to an embodiment of the disclosure. The microcontroller 120 of the power supply 100 is used to perform the compensation method 1000.
Referring to fig. 1 and 2, in step 1100, a design point resistance R of the compensator of the power supply 100 is setcompensatorWherein the compensator has a design point resistance RcompensatorCorresponding to a design point (design point) of a compensator (not shown) of the power supply 100. Specifically, since the design point of the compensator of the power supply 100 is derived through some design rules, the resistance value R when the resistance value of the load of the power supply 100 falls at the compensator design pointcompensatorIn this case, the power supply 100 can have sufficient phase margin and gain margin.
In step 1200, the output voltage V output by the power converter 140 of the power supply 100 is detectedOAnd an output current IOThe microcontroller 120 includes an Analog-to-digital converter (ADC) module 122 for converting the detected output voltage VOAnd an output current IOThe analog signal is converted into a Digital signal to facilitate subsequent calculation processing by a Digital Signal Processor (DSP) of the microcontroller 120.
In step 1300, the digital signal processor of the microcontroller 120 outputs the voltage V according to the output voltageOAnd an output current IOTo calculate the load resistance value R L. In the embodiment of the present disclosure, the load resistance RLThe formula of (c) is as follows:
RL＝VO/IO (3)
in step 1400, the digital signal processor of the microcontroller 120 determines the load resistance value RLAnd the designed point resistance R of the compensatorcompensatorTo calculate the adjustment ratio K. In the embodiment of the present disclosure, the dc gain of the open loop corresponding to the power supply 100 connected to different loads is adjusted back to the dc gain of the open loop corresponding to the design point (design point) of the compensator of the power supply 100, and the power supplyThe supply 100 is connected to a load resistance RLThe closed loop gain at load of (a) may be expressed as follows:
G＝Gio×Gid×Gca×K (4)
the formula (1), (2), (3) and (4) can be used to derive the adjustment ratio K as follows:
in other words, in step 1400, the load resistance value R is determinedLAnd the designed point resistance R of the compensatorcompensatorThe formula for calculating the adjustment ratio K is K ═ RL/Rcompensator。
In step 1500, the digital signal processor of the microcontroller 120 compensates the power supply 100 according to the adjustment ratio K, so as to stabilize the output current of the power supply 100. Specifically, the digital signal processor of the microcontroller 120 multiplies the adjustment ratio K calculated in step 1400 by the compensation loop of the power supply 100 during the constant current operation, so that the dc gain of the open loop corresponding to the load of the power supply 100 connected to the load with the load resistance RL is adjusted back to the dc gain of the open loop corresponding to the design point (design point) of the compensator of the power supply 100, thereby ensuring that the power supply 100 has sufficient phase margin and gain margin, so that when the load resistance of the power supply 100 is extremely small, the situation of insufficient phase and/or gain will not occur, and the output current of the power supply 100 is stable.
Besides, the power supply 100 is connected to the load resistance RLThe dc gain of the open loop corresponding to the load is adjusted back to the dc gain of the open loop corresponding to the design point (design point) of the compensator of the power supply 100, so that the power supply 100 can keep the bandwidth of the power supply 100 consistent when the load varies. Furthermore, since the compensation of the power supply 100 is actively adjusted according to the load resistance in the present disclosure, the power supply 100 only needs to design one set of controllers, so that the user does not need to design the controllerThe controller is switched to a proper controller in the initial stage according to the actual use condition, thereby improving the convenience in use. In addition, since the compensation method of the present disclosure is implemented by the microcontroller 120 of the power supply 100, the present disclosure does not need to add additional hardware circuits, and can increase the stable operation range of the power supply 100 without increasing hardware cost.
Fig. 3 is a flowchart of a compensation method 2000 of a power supply according to an embodiment of the disclosure. Fig. 3 is similar to fig. 2, with one difference that in step 2100, in addition to setting the compensator design point resistance of the power supply 100 as described in step 1100, the upper and lower limits of the adjustment ratio K of the power supply 100 are set, and pole/zero (pole/zero) configuration is performed. Specifically, since the power supply 100 has its own hardware limitation, some design rules are needed to set the upper and lower limits of the adjustment ratio K of the power supply 100, and when the adjustment ratio K calculated in step 1400 exceeds the upper and lower limits of the adjustment ratio K, corresponding corrections are made to enable the power supply 100 to operate normally. In addition, the pole (pole) and the zero (zero) of the compensator of the power supply 100 are designed, that is, configured with pole-zero, in a manner known to those skilled in the art and will not be further described herein.
It should be noted that, after the hardware circuit is determined, when the design point of the compensator is set in step 1100 or step 2100, the load value in the boundary mode (boundary mode) can be estimated according to the actual hardware circuit, and the load value is used as the design point of the compensator. The boundary Mode is the load at the lightest load in the Continuous Current Conduction Mode (CCM), and is usually the worst case (worst case) when the CCM is just deviated from, so the load value at this time can be taken as the design point of the compensator. It should be noted that the selection of the design point is merely exemplary and not limited thereto.
Another difference between fig. 3 and fig. 2 is that, between step 1400 and step 1500, step 2200 is further performed, in which the dsp of the microcontroller 120 selectively adjusts the upper and lower limits of the adjustment ratio K according to the phase limit and/or the gain limit: when the adjustment ratio K is in the upper and lower limit ranges, the adjustment ratio K is not adjusted; on the contrary, when the adjustment ratio K exceeds the upper and lower limits, the adjustment ratio K is adjusted so that the power supply 100 has sufficient phase margin and/or gain margin. Specifically, the dc gain of the closed loop Bode Plot (Bode Plot) of an ideal power supply falls at a slope of 20dB per 10 octaves. However, in the actual closed loop bode diagram, due to the structure of the circuit itself and the requirement of the lc filter, especially at the multiple poles (complex poles), the dc gain will be raised, which may result in insufficient gain margin, and in addition, at the multiple poles, the phase will be abruptly lowered, which may result in insufficient phase margin. Therefore, the adjustment ratio K needs to be correspondingly modified for the above situation so that the power supply 100 has a sufficient phase margin and/or gain margin. For example, the adjustment ratio K is modified to shift the dc gain of the closed loop bode diagram of the power supply 100 downward, so that the power supply 100 has a sufficient gain margin.
In summary, the present disclosure provides a power supply and a compensation method thereof, which can make the output current of the power supply 100 still stable when the load resistance of the power supply is very small. The power supply and the compensation method thereof can increase the load range of the stable operation of the switching power supply, and keep the bandwidth of the switching power supply consistent when the load changes.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. It should also be understood by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
Claims (10)
1. A compensation method for a power supply, comprising:
setting a design point resistance value of a compensator;
detecting an output voltage and an output current output by a power converter of the power supply;
Calculating a load resistance value according to the output voltage and the output current;
calculating an adjustment ratio according to the load resistance value and the compensator design point resistance value; and
compensating the power supply according to the adjustment ratio so as to stabilize the output current of the power supply.
2. The compensation method of claim 1, wherein the power Converter is a Buck Converter (Buck Converter), and wherein the power supply is operated in a Constant Current (CC) mode.
3. The compensation method of claim 1, further comprising:
before detecting the output voltage and the output current, an upper and lower limit range of the adjustment ratio is set, and a pole/zero (pole/zero) configuration is performed.
4. The compensation method of claim 1, further comprising:
after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to a phase margin (phase margin) so that the power supply has a sufficient phase margin.
5. The compensation method of claim 1, further comprising:
after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to a gain margin (gain margin) so that the power supply has a sufficient gain margin.
6. A power supply, comprising:
a power converter; and
a Microcontroller Unit (MCU) electrically connected to the power converter, the Microcontroller being configured to perform the following steps:
setting a design point resistance value of a compensator;
detecting an output voltage and an output current output by the power converter;
calculating a load resistance value according to the output voltage and the output current;
calculating an adjustment ratio according to the load resistance value and the compensator design point resistance value; and
compensating the power supply according to the adjustment ratio so as to stabilize the output current of the power supply.
7. The power supply of claim 6, wherein the power converter is a buck converter, and wherein the power supply is operated in a constant current mode.
8. The power supply of claim 6, wherein the microcontroller is further configured to perform the steps of:
before detecting the output voltage and the output current, setting an upper limit range and a lower limit range of the adjustment ratio, and carrying out pole zero point configuration.
9. The power supply of claim 6, wherein the microcontroller is further configured to perform the steps of:
After the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to the phase margin, so that the power supply has a sufficient phase margin.
10. The power supply of claim 6, wherein the microcontroller is further configured to perform the steps of:
after the adjustment ratio is calculated, the adjustment ratio is selectively adjusted according to the gain margin, so that the power supply has a sufficient gain margin.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103762849A (en) * | 2013-01-08 | 2014-04-30 | 崇贸科技股份有限公司 | Control circuit of adjustable power supply |
| CN105471261A (en) * | 2014-09-09 | 2016-04-06 | 龙芯中科技术有限公司 | Buck single-phase voltage feedback transformation circuit compensation balance method and device |
| JP2017091316A (en) * | 2015-11-12 | 2017-05-25 | 新日本無線株式会社 | Stabilized power supply circuit |
| CN107171559A (en) * | 2017-06-13 | 2017-09-15 | 厦门理工学院 | A kind of phase compensating method of Width funtion power supply |
| CN108536206A (en) * | 2018-03-22 | 2018-09-14 | 广州慧智微电子有限公司 | A kind of voltage regulator and voltage adjusting method |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103762849A (en) * | 2013-01-08 | 2014-04-30 | 崇贸科技股份有限公司 | Control circuit of adjustable power supply |
| CN105471261A (en) * | 2014-09-09 | 2016-04-06 | 龙芯中科技术有限公司 | Buck single-phase voltage feedback transformation circuit compensation balance method and device |
| JP2017091316A (en) * | 2015-11-12 | 2017-05-25 | 新日本無線株式会社 | Stabilized power supply circuit |
| CN107171559A (en) * | 2017-06-13 | 2017-09-15 | 厦门理工学院 | A kind of phase compensating method of Width funtion power supply |
| CN108536206A (en) * | 2018-03-22 | 2018-09-14 | 广州慧智微电子有限公司 | A kind of voltage regulator and voltage adjusting method |
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