CN113572353A - Bidirectional Boost converter, control system and control method - Google Patents
Bidirectional Boost converter, control system and control method Download PDFInfo
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- CN113572353A CN113572353A CN202110808551.0A CN202110808551A CN113572353A CN 113572353 A CN113572353 A CN 113572353A CN 202110808551 A CN202110808551 A CN 202110808551A CN 113572353 A CN113572353 A CN 113572353A
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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
- H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider
- H02M3/07—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider using capacitors charged and discharged alternately by semiconductor devices with control electrode, e.g. charge pumps
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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
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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
- H02M1/14—Arrangements for reducing ripples from dc input or output
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Abstract
The invention discloses a bidirectional Boost converter, a control system and a control method, wherein the bidirectional Boost converter comprises an inductor, a first ripple transfer circuit and a second ripple transfer circuit; the redundant energy input by the direct current bus flows into the first ripple transfer circuit and the second ripple transfer circuit through the inductor; controlling the first energy storage unit to store redundant energy or release the stored energy through a first switch unit of the first ripple transfer circuit; and controlling the second energy storage unit to store the redundant energy or release the stored energy through a second switching unit of the second ripple transfer circuit. The invention adopts an active network topology structure to isolate the energy storage capacitor from the direct current bus, and realizes the non-electrolytic capacitor by transferring the position of the energy storage capacitor to increase the voltage pulsation of the energy storage capacitor.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a bidirectional Boost converter with double power frequency ripple transfer, a control system and a control method.
Background
The electric automobile can be used as a mobile distributed energy storage power supply, and is connected to a power Grid to supply power to the power Grid when necessary, namely, a technology (V2G) for interaction between the electric automobile and the power Grid, and the load leveling and the power Grid efficiency of the power Grid can be improved to a certain extent through the technology. To realize the V2G technology, an interconnection channel between the power grid and the electric vehicle, such as an electric vehicle-mounted charging and discharging machine, must be constructed, and to realize the conversion of electric energy, the power electronic conversion device is an indispensable key technical device, such as an inverter, a rectifier, and the like. However, the dc side of the single-phase rectifier contains a ripple of twice the fundamental frequency in addition to the dc fundamental wave.
In order to reduce the power frequency ripple twice of the direct current bus voltage, due to factors such as cost, the traditional solution method is to adopt a passive filtering technology, and add a large-capacity electrolytic capacitor on the direct current side to filter out low-frequency harmonic current, but the electrolytic capacitor has two main disadvantages, namely, the service life is short, and the electrolytic capacitor is also an element with a high failure rate and is not suitable for places with severe working environments. The service life of the electrolytic capacitor mainly depends on the internal temperature, and the voltage, ripple current, device switching frequency, installation form, heat dissipation mode and the like in practical application all influence the service life of the electrolytic capacitor.
The electrolytic capacitor has the functions of balancing instantaneous power and inhibiting voltage ripples, and due to the defects of the electrolytic capacitor, the non-electrolytic capacitor can be adopted to replace the functions of the electrolytic capacitor. However, the capacitance of the non-electrolytic capacitor is generally relatively small, and in practical application, it is not feasible to directly connect a plurality of non-electrolytic capacitors in parallel to replace the electrolytic capacitor on the dc bus.
Therefore, how to design a Boost converter capable of replacing an electrolytic capacitor to realize ripple transfer remains a technical problem to be solved.
Disclosure of Invention
In view of the above, the invention provides a bidirectional Boost converter with double power frequency ripple transfer, a control system and a control method, an active network topology is constructed through a power electronic switching device so as to isolate an energy storage capacitor from a direct current bus, and a non-electrolytic capacitor is realized in a manner of increasing voltage pulsation of the energy storage capacitor by transferring the position of the energy storage capacitor, so that a thin film capacitor and a ceramic capacitor with long service life can be used for replacing an electrolytic capacitor in conventional equipment.
The invention provides a bidirectional Boost converter in a first aspect, which comprises an inductor, a first ripple transfer circuit and a second ripple transfer circuit; one end of the inductor is connected with a direct current bus, the other end of the inductor is respectively connected with the first ripple transfer circuit and the second ripple transfer circuit, and redundant energy input by the direct current bus flows into the first ripple transfer circuit and the second ripple transfer circuit through the inductor; the first ripple transfer circuit comprises a first switch unit and a first energy storage unit, one end of the first switch unit is connected with the inductor, the other end of the first switch unit is connected with one end of the first energy storage unit, the other end of the first energy storage unit is connected with the direct current bus, and the first switch unit is used for controlling the first energy storage unit to store redundant energy or release stored energy; the second ripple transfer circuit comprises a second switch unit and a second energy storage unit, one end of the second switch unit is connected with the inductor, the other end of the second switch unit is connected with one end of the second energy storage unit, and the other end of the second energy storage unit is connected with the direct current bus; the second switch unit is used for controlling the second energy storage unit to store redundant energy or release stored energy.
Furthermore, the first switch unit includes a first power switch tube and a first diode, a collector of the first power switch tube is connected to the inductor, an emitter of the first power switch tube is connected to the first energy storage unit, and the first diode is connected in parallel to two ends of the first power switch tube.
Furthermore, the first energy storage unit comprises a first energy storage capacitor, one end of the first energy storage capacitor is connected with the emitter of the first power switch tube, and the other end of the first energy storage capacitor is connected with the direct current bus;
when the first power switch tube is conducted and the first diode is not conducted, the first energy storage capacitor is controlled to store redundant energy input by the direct current bus; when the first diode is conducted and the first power switch tube is not conducted, the first energy storage capacitor is controlled to release stored energy and the stored energy flows to the direct current bus.
Furthermore, the second switch unit includes a second power switch tube and a second diode, an emitter of the second power switch tube is connected to the inductor, a collector of the second power switch tube is connected to the first energy storage unit, and the first diode is connected in parallel to two ends of the first power switch tube.
Furthermore, the second energy storage unit comprises a second energy storage capacitor, one end of the second energy storage capacitor is connected with the collector of the second power switch tube, and the other end of the second energy storage capacitor is connected with the direct current bus; when the second diode is conducted and the second power switch tube is not conducted, the second energy storage capacitor is controlled to store redundant energy input by the direct current bus; when the second power switch tube is conducted and the second diode is not conducted, the second energy storage capacitor is controlled to release stored energy and the stored energy flows to the direct current bus.
Further, the bidirectional Boost converter includes four operating modes, which are respectively: when the first power switch tube is conducted and the second power switch tube, the first diode and the second diode are not conducted, redundant energy input by the direct current bus flows into the first energy storage capacitor through the inductor, so that the first energy storage capacitor stores the redundant energy; when the second diode is conducted, and the first power switch tube, the second power switch tube and the first diode are not conducted, redundant energy input by the direct current bus flows into the second energy storage capacitor through the inductor, so that the second energy storage capacitor stores the redundant energy; when the second power switch tube is conducted and the first power switch tube, the first diode and the second diode are not conducted, the first energy storage capacitor and the inductor release stored energy and flow into a direct current bus to charge the direct current bus; when the first diode is conducted and the first power switch tube, the second power switch tube and the second diode are not conducted, the first energy storage capacitor and the inductor release stored energy and flow into the direct current bus to charge the direct current bus.
A second aspect of the present invention provides a control system for a bidirectional Boost converter, which is applied to the bidirectional Boost converter described above, and includes: the device comprises a detection module, a voltage regulation module, a reference signal generation module and a control module; the detection module is used for detecting an inductive current signal of the bidirectional Boost converter, voltage signals of the first energy storage unit and the second energy storage unit and a double-frequency current signal of the direct-current bus; the reference voltage signal, the voltage signals of the first energy storage unit and the second energy storage unit are regulated by the voltage regulation module and then output voltage loop control signals; the voltage loop control signal and a frequency doubling current signal of the direct current bus are superposed by the reference signal generating module to generate a reference inductive current signal; and the control module is used for comparing the detected inductive current signal with the reference inductive current signal and outputting a switch control signal of the bidirectional Boost converter according to a comparison result.
Furthermore, the control module comprises a hysteresis comparison module, a logic judgment module and a driving module, and the detected inductive current signal and the reference inductive current signal are compared by the hysteresis comparison module to obtain a comparison result of the inductive current signal and the set upper and lower thresholds of the current hysteresis; and the logic judgment module outputs corresponding control signals according to the comparison result, and the control signals are output to the bidirectional Boost converter through the driving module so as to control the first switch unit and the second switch unit of the bidirectional Boost converter to be switched on or switched off.
A third aspect of the present invention provides a control method for a bidirectional Boost converter, which is applied to the bidirectional Boost converter described above, and includes: acquiring an inductive current signal of a bidirectional Boost converter, voltage signals of a first energy storage unit and a second energy storage unit and a double-frequency current signal of a direct-current bus; the reference voltage signal, the voltage signals of the first energy storage unit and the second energy storage unit output voltage loop control signals after voltage regulation; the voltage loop control signal and a double-frequency current signal of the direct current bus are superposed to generate a reference inductive current signal; and comparing the inductive current signal with the reference inductive current signal, and outputting a switch control signal of the bidirectional Boost converter according to the comparison result.
Further, the step of comparing the inductor current signal with the reference inductor current signal and outputting a switching control signal of the bidirectional Boost converter according to a comparison result includes: setting a loop width, and setting an upper limit threshold and a lower limit threshold of a current hysteresis according to a reference inductive current signal and the loop width; comparing the inductive current signal with an upper limit threshold and a lower limit threshold of a current hysteresis loop respectively; when the reference inductor current signal is smaller than or equal to the lower limit threshold value of the current hysteresis loop, outputting a control signal to enable a switching unit of the bidirectional Boost converter to be conducted, and charging an inductor and an energy storage unit; when the reference inductive current signal is in the upper limit threshold value and the lower limit threshold value interval of the current hysteresis loop, the state of a switch unit of the bidirectional Boost converter is kept unchanged; when the reference inductor current signal is larger than or equal to the upper limit threshold value of the current hysteresis loop, a control signal is output to turn off a switch unit of the bidirectional Boost converter, so that the inductor and the energy storage unit are discharged.
According to the invention, the energy storage capacitor is isolated from the direct current bus through an active network topological structure in the bidirectional Boost converter, and the voltage of the energy storage capacitor is controlled to pulsate as much as possible, namely, the voltage ripple peak value is increased, and the energy storage capacitance value is further reduced, so that a non-electrolytic capacitor can be adopted.
Drawings
For purposes of illustration and not limitation, the present invention will now be described in accordance with its preferred embodiments, particularly with reference to the accompanying drawings, in which:
fig. 1 is a schematic diagram of a bidirectional Boost converter with twice power frequency ripple transfer according to an embodiment of the present invention.
Fig. 2 is a circuit diagram of a bidirectional Boost converter with twice power frequency ripple transfer according to an embodiment of the present invention.
Fig. 3 is a diagram of four operating states of a bidirectional Boost converter with twice power frequency ripple transfer according to an embodiment of the present invention.
Fig. 4 is a graph of input voltage and bus voltage waveforms without the addition of a bidirectional Boost converter with twice the power frequency ripple transfer.
Fig. 5 is a graph of input voltage and bus voltage waveforms after the addition of a bi-directional Boost converter with twice the power frequency ripple transfer.
Fig. 6 is a block diagram of a control system applied to a bidirectional Boost converter according to a second embodiment of the present invention.
Fig. 7 is a waveform diagram of an inductor current and a PWM applied to a control system of a bidirectional Boost converter according to a second embodiment of the present invention.
Fig. 8 is a flowchart of a control method applied to a bidirectional Boost converter according to a third embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a detailed description of the present invention will be given below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.
In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention, and the described embodiments are merely a subset of the embodiments of the present invention, rather than a complete embodiment. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Example one
Fig. 1 is a schematic diagram of a bidirectional Boost converter with twice power frequency ripple transfer according to an embodiment of the present invention. The bidirectional Boost converter with twice power frequency ripple transfer is connected in parallel at two ends of a direct current bus and is used for replacing an electrolytic capacitor connected in parallel on the direct current bus originally and absorbing and releasing corresponding energy.
Fig. 2 is a circuit diagram of a bidirectional Boost converter with twice power frequency ripple transfer according to an embodiment of the present invention. Referring to fig. 2, the bidirectional Boost converter 100 includes an inductor L, a first ripple transfer circuit 101, and a second ripple transfer circuit 102, where one end of the inductor L is connected to the dc bus, and the other end of the inductor L is respectively connected to the first ripple transfer circuit 101 and the second ripple transfer circuit 102, and is configured to receive excess energy input by the dc bus and transmit the excess energy to the first ripple transfer circuit 101 and the second ripple transfer circuit 102; one end of the first ripple transfer circuit 101 and one end of the second ripple transfer circuit 102 are respectively connected to the inductor L, and the other end of the first ripple transfer circuit 101 and the other end of the second ripple transfer circuit 102 are respectively connected to the dc bus, and are configured to receive excess energy transmitted by the inductor and store the excess energy, or release the stored energy and flow the stored energy to the dc bus, so as to make up for energy loss on the dc bus, thereby implementing bidirectional energy flow and suppressing voltage ripple of the dc bus.
The bidirectional Boost converter 100 is connected in parallel at two ends of the dc bus, and excess energy of the dc bus flows to the first ripple transfer circuit 101 and the second ripple transfer circuit 102 through the inductor L, and is stored in the first ripple transfer circuit 101 and the second ripple transfer circuit 102; or the stored energy is released by the first ripple transfer circuit 101 and the second ripple transfer circuit 102, so that the stored energy flows to the dc bus to compensate for different energies on the dc bus, thereby realizing bidirectional flow of current and energy and reducing voltage ripple of the dc bus.
The first ripple transfer circuit 101 includes a first switch unit 111 and a first energy storage unit 112, wherein one end of the first switch unit 111 is connected to the inductor L, and the other end is connected to the first energy storage unit 112; one end of the first energy storage unit 112 is connected to the first switch unit 111, and the other end is connected to the dc bus, so that the excess energy input through the inductor L is stored in the first energy storage unit 112 through the first switch unit 111. The first switch unit 111 further enables the first energy storage unit 112 to release the stored energy, so that the stored energy flows to the direct current bus to make up for the energy shortage on the direct current bus.
The second ripple transfer circuit 102 includes a second switch unit 121 and a second energy storage unit 122, one end of the second switch unit 121 is connected to the inductor L, the other end of the second switch unit is connected to the second energy storage unit 122, one end of the second energy storage unit 122 is connected to the second switch unit 121, the other end of the second energy storage unit 122 is connected to the negative terminal of the dc bus, and the second switch unit 121 stores the excess energy input through the inductor L into the second energy storage unit 122. The second switch unit 121 further enables the second energy storage unit 122 to release the stored energy, so that the stored energy flows to the dc bus, and the energy shortage on the dc bus is compensated.
In this embodiment, the first switch unit 111 includes a first power switch Q1And a first diode D1First power switch tube Q1The collector of the power converter is connected with an inductor L and a first power switch tube Q1Is connected to the first energy storage unit 112, the first diode D1Connected in parallel to the first power switch tube Q1Across the collector and emitter.
The first energy storage unit 112 includes a first energy storage capacitor C1A first energy storage capacitor C1One end of the first power switch tube Q is connected with1The other end of the emitter is connected with a direct current bus.
When the first power switch tube Q1Conducting the first diode D1When not conducting, the first energy storage capacitor C is used1Absorbing redundant energy input by the direct current bus; when the first diode D1Conducting, first power switch tube Q1When not conducting, the first energy storage capacitor C is used1And releasing the stored energy, enabling the stored energy to flow to the direct current bus, and making up for the insufficient energy on the direct current bus to reduce the size of the voltage pulsation peak value on the direct current bus.
In this embodiment, the second switch unit 121 includes a second power switch Q2And a second diode D2Second power switchTube Q2The emitting electrode of the first power switch tube is connected with an inductor L and a second power switch tube Q2Is connected to the second energy storing unit 122, the second diode D2Connected in parallel to the second power switch tube Q2Across the emitter and collector.
The second energy storage unit 122 comprises a second energy storage capacitor C2A second diode D2One end of the first power switch tube Q is connected with the second power switch tube Q2The other end of the collector is connected with a direct current bus.
When the second diode D2Conducting, second power switch tube Q2When not conducting, the second energy storage capacitor C is passed2Absorbing redundant energy input by the direct current bus; when the second power switch tube Q2On, the second diode D2When not conducting, the second energy storage capacitor C is passed2And releasing the stored energy, enabling the stored energy to flow to the direct current bus, and making up for the insufficient energy on the direct current bus to reduce the size of the voltage pulsation peak value on the direct current bus.
In this embodiment, the first energy storage capacitor C1And a second energy storage capacitor C2Long-life thin film capacitors and ceramic capacitors can be used instead of electrolytic capacitors in conventional device applications. First power switch tube Q1And a second power switch tube Q2The voltage resistance of the circuit is low, the switching loss is reduced, the loss of the whole circuit is further reduced, energy conservation and emission reduction are realized, and the energy utilization rate is improved.
The bidirectional Boost converter with twice power frequency ripple transfer is directly connected in parallel to a direct current bus, and an active network topology is constructed through a power switch tube and a diode, so that an energy storage capacitor is isolated from the direct current bus.
The bidirectional Boost converter provided by the embodiment is formed by improving a basic unidirectional Boost conversion circuit, and the original second power switching tube Q of the unidirectional Boost conversion circuit2Upper anti-parallel connection of a second diode D2While also in the original first diode D1Upper anti-parallel connection of a first power switch tube Q1A first energy storage capacitor C is added below1Thereby ensuring the currentAnd energy can flow in two directions, so that the direct current bus voltage ripple is reduced.
As shown in fig. 3, in the present embodiment, the bidirectional Boost converter includes 4 different operating states in a normal switching cycle: the first power switch tube Q is arranged at the positive half cycle in one cycle1And a second diode D2The first ripple transfer circuit and the second ripple transfer circuit are in a Boost working state; at the negative half cycle, the second power switch tube Q2And a first diode D1The first ripple transfer circuit and the second ripple transfer circuit work successively, the first ripple transfer circuit and the second ripple transfer circuit are in a Buck working state, and the positive half cycle and the negative half cycle can be divided into a front working state and a rear working state which are respectively a working state when the power switch tube is conducted and a follow current state when the diode is conducted.
In the embodiment, when the bidirectional Boost converter works in the Boost state, the input instantaneous power PinSpecific output instantaneous power PoTherefore, the excessive input energy flows to the first ripple transfer circuit or the second ripple transfer circuit from the direct current bus, and then the first power switch tube Q is controlled1Or a second power switch tube Q2Make the redundant energy temporarily stored in the first energy storage capacitor C1Or a second energy storage capacitor C2The above step (1); according to the dual relation, when the first ripple transfer circuit or the second first ripple transfer circuit works in the Buck state, the input instantaneous power PinInstantaneous power P of specific outputoAnd the energy in the working state flows from the first ripple transfer circuit or the second ripple transfer circuit to the direct current bus, so that the bidirectional flow of the energy is realized, and the voltage ripple of the direct current bus is restrained.
In this embodiment, the specific process of the 4 operating states of the bidirectional Boost converter is as follows:
(1) boost mode 1:
as shown in Boost mode 1 in fig. 3, the first power switch Q is now turned on1Conducting, second power switch tube Q2A first diode D1And a second diode D2And is not conductive. Inductor current iLThe direct current bus is a positive direction and is increased from zero to a positive direction maximum value, and the direct current bus is opposite to the inductor L and the first energy storage capacitor C1Charging, the voltage at two ends of the inductor L is positive, and the value of the voltage is the DC bus voltage and the first energy storage capacitor C1The difference in voltage of (c).
(2) Boost mode 2:
as shown in Boost mode 2 in fig. 3, the second diode D is now connected to the first diode D2Conducting, first power switch tube Q1A second power switch tube Q2And a first diode D1And is not conductive. Inductor current iLThe positive direction is reduced from the maximum value to zero, and the direct current bus and the inductor L are coupled with the second energy storage capacitor C2Charging, the voltage at two ends of the inductor is in negative direction, and the value of the voltage is the second energy storage capacitor C2And the difference between the dc bus voltage and the voltage of (d).
(3) Buck mode 1:
as shown in Buck mode 1 in fig. 3, the second power switch Q is now turned on2Conducting, first power switch tube Q1A first diode D1And a second diode D2And is not conductive. Inductor current iLIs negative and increases from zero to a negative maximum value, and a second energy storage capacitor C2Discharging, charging the direct current bus and the inductor L, wherein the voltage at two ends of the inductor is in a negative direction, and the value of the voltage is the second energy storage capacitor C2And the difference between the dc bus voltage and the voltage of (d).
(4) Buck mode 2:
as shown in Buck mode 2 of fig. 3, the first diode D is now connected1Conducting, first power switch tube Q1A second power switch tube Q2And a second diode D2And is not conductive. Inductor current iLIs negative and is reduced to zero from the negative maximum value, and a first energy storage capacitor C1Discharging with the inductor L, charging with the DC bus, wherein the voltage at two ends of the inductor is positive, and the value of the voltage is the DC bus voltage and the first energy storage capacitor C1The difference in voltage of (c).
Fig. 4 is a graph of input voltage and bus voltage waveforms without the addition of a bidirectional Boost converter with twice the power frequency ripple transfer.
Fig. 5 is a graph of input voltage and bus voltage waveforms after the addition of a bidirectional Boost converter with twice the power frequency ripple transfer.
By the bidirectional Boost converter, the purpose that in an active direct current filter, a thin film capacitor and a ceramic capacitor with long service life are used for replacing an electrolytic capacitor in equipment application, and voltage ripples with double frequency on a direct current bus are effectively suppressed is achieved. Meanwhile, the bidirectional Boost converter has the advantages that the withstand voltage of the switching tube is low, the switching loss is reduced, the loss of the whole circuit is further reduced, the energy conservation and emission reduction are realized, and the energy utilization rate is improved.
Example two
Fig. 6 is a block diagram of a control system applied to the bidirectional Boost converter in the second embodiment. The control system controls the bidirectional Boost converter to reduce voltage ripples on a direct current bus, so that the voltage is close to constant direct current voltage.
Referring to fig. 6, a control system 200 applied to the bidirectional Boost converter includes a detection module 201, a voltage regulation module 202, a reference signal generation module 203 and a control module 204, where the detection module 201 is configured to detect voltage signals of a first energy storage unit and a second energy storage unit of a first energy storage capacitor of the bidirectional Boost converter, a double-frequency current signal of a dc bus, and a current signal i of an inductor LL(ii) a The input reference voltage signal and the voltage signals of the first energy storage unit and the second energy storage unit are regulated by the voltage regulation module 202, a voltage loop control signal is output, and the voltage loop control signal and a double-frequency current signal of the direct current bus are superposed by the reference signal generation module 203 to generate a reference inductance current signal; a control module 204 for detecting the current signal i of the inductor LLAnd comparing the current signal with a reference inductive current signal, outputting a corresponding control signal to a first switch unit and a second switch unit of the bidirectional Boost converter according to a comparison result, and controlling the power switch tubes in the first switch unit and the second switch unit of the bidirectional Boost converter to be switched on or switched off.
In the present embodiment, the detection moduleThe voltage detection module 211 is configured to detect voltage signals of a first energy storage capacitor C1 in the first energy storage unit and a second energy storage capacitor C2 in the second energy storage unit; the dc bus current detection module 212 is configured to detect a double frequency current signal of the dc bus; the inductor current detecting module 213 is used for detecting the current signal i of the inductor LL。
In this embodiment, the voltage adjusting module 202 uses a voltage regulator to generate the voltage loop control signal, and the voltage reference signal and the detected voltage signals of the first energy storage unit and the second energy storage unit are simultaneously input into the voltage regulator.
When the difference value between the reference voltage signal and the reference current signal of the control system is very small, compensation improvement and proper adjustment are carried out through the voltage regulator, so that the problem of current dead zone at the zero crossing point is solved.
In the present embodiment, the control module 204 includes a hysteresis comparing module 241, a logic determining module 242 and a driving module 243, and detects the current signal i of the inductor LLAnd a reference inductor current signal ILThe current signal i of the inductor L is obtained through comparison by a hysteresis comparison module 241LAnd a logic judgment module 242 outputs corresponding control signals according to the comparison result of the upper and lower thresholds of the set current hysteresis loop, and the control signals are output to the first switch unit and the second switch unit of the bidirectional Boost converter through a driving module 243 to control the conduction or the disconnection of corresponding power switch tubes in the first switch unit and the second switch unit of the bidirectional Boost converter. When i is shown in FIG. 7L≤ILWhen the voltage is higher than the first voltage, the control signal enables the first power switch tube or the second diode to be conducted, the inductor L is charged, and the inductor current is gradually increased; when I isL-h<iL<ILThe power switch tube is kept in the state during + h when iL≥ILWhen + h, the control signal turns off the first power switch tube or the second diode, at the moment, the inductor L starts to discharge, and the inductor current is gradually reduced; when the inductive current is reduced to the minimum value of the lower limit, the control signal enables the workThe rate switch tube is turned on again, and the inductor is charged again, thereby continuously cycling.
Wherein, the hysteresis comparison module 241 sets the loop width to be 2h, and the upper and lower thresholds of the current hysteresis are I respectivelyL+ h and ILH, detecting the current signal i of the inductor LLAnd comparing the current hysteresis with upper and lower threshold values of the current hysteresis to determine the turn-off and turn-on of the switching tube.
The loop width is selected, 10% to 20% of the current value of the inductor L is used as the maximum current ripple, and the appropriate loop width is selected according to the maximum current ripple.
The driving module 243 includes an amplifier, and the control signal is amplified by the amplifier and then output to the first switch unit and the second switch unit of the bidirectional Boost converter, so as to control the corresponding power switch tubes in the first switch unit and the second switch unit of the bidirectional Boost converter to be turned on or turned off.
The operating frequency of the control system applied to the bidirectional Boost converter is a frequency which changes along with time, and the frequency also has a change range, wherein the minimum value of the frequency is obtained when the hysteresis current crosses zero, and the maximum value of the frequency is obtained at the peak value of the hysteresis current.
The voltage of an energy storage capacitor in the bidirectional Boost converter is pulsed as much as possible through the control system, namely, the voltage ripple peak-to-peak value is increased, and then the energy storage capacitance value is reduced, so that a non-electrolytic capacitor can be adopted.
The control system controls the bidirectional Boost converter to work so as to control the capacitor to absorb and release corresponding energy, thereby achieving the purpose of reducing the size of a voltage pulsation peak value on the direct current bus, inhibiting voltage ripples with double frequency on the direct current bus and enabling the voltage on the bus to be close to constant direct current voltage.
EXAMPLE III
Fig. 8 is a flow chart of a control method provided for application to the bidirectional Boost converter described above.
Referring to fig. 8, the control method applied to the bidirectional Boost converter includes the following steps:
s301, collectingInductor current signal i to Boost converterLThe voltage signals of the first energy storage unit and the second energy storage unit, and the double-frequency current signal of the direct current bus.
Specifically, the control system is used for collecting an inductor L current signal i in the bidirectional Boost converterLA first energy storage capacitor C in the first energy storage unit1And a second energy storage capacitor C in the second energy storage unit2And a frequency-doubled current signal of the dc bus.
S302, outputting a voltage loop control signal after voltage regulation of the reference voltage signal and the voltage signals of the first energy storage unit and the second energy storage unit.
And S303, superposing the voltage loop control signal and a double-frequency current signal of the direct current bus to generate a reference inductive current signal.
S304, converting the inductive current signal iLAnd comparing the current signal with a reference inductive current signal, and outputting a switch control signal of the bidirectional Boost converter according to a comparison result.
Specifically, the specific implementation method of step 304 is:
(1) setting the loop width to be 2h according to a reference inductive current signal ILThe upper and lower thresholds of the current hysteresis are respectively IL+ h and IL-h。
(2) The inductor current signal iLComparing with upper and lower threshold values of current hysteresis;
(3) when i isL≤ILWhen the voltage is lower than the preset voltage, outputting a control signal to enable a first power switching tube or a second diode of the bidirectional Boost converter to be conducted, charging an inductor L, and increasing the inductor current gradually; when I isL-h<iL<ILThe power switch tube of the bidirectional Boost converter is kept in the state in the + h process, when iL≥ILWhen the voltage is + h, the control signal turns off a first power switch tube or a second diode of the bidirectional Boost converter, at the moment, the inductor L starts to discharge, and the inductor current is gradually reduced; when the current of the inductor is reduced to the minimum value of the lower limit, the control signal enables the power switch tube to be conducted again, and the inductor is charged again, so that the process is continuously circulated.
The voltage of an energy storage capacitor in the bidirectional Boost converter is pulsed as much as possible by a control method, namely, the peak-to-peak value of voltage ripple is increased, and the energy storage capacitance value is further reduced, so that a non-electrolytic capacitor can be adopted.
The work of the bidirectional Boost converter is controlled by the control method, the capacitor is controlled to absorb and release corresponding energy, and therefore the purpose of reducing the size of a voltage pulsation peak value on the direct current bus is achieved, voltage ripples with double frequency on the direct current bus are restrained, and the voltage on the bus is close to constant direct current voltage.
The above-described embodiments should not be construed as limiting the scope of the invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions can occur, depending on design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A bidirectional Boost converter is characterized by comprising an inductor, a first ripple transfer circuit and a second ripple transfer circuit;
one end of the inductor is connected with a direct current bus, the other end of the inductor is respectively connected with the first ripple transfer circuit and the second ripple transfer circuit, and redundant energy input by the direct current bus flows into the first ripple transfer circuit and the second ripple transfer circuit through the inductor;
the first ripple transfer circuit comprises a first switch unit and a first energy storage unit, one end of the first switch unit is connected with the inductor, the other end of the first switch unit is connected with one end of the first energy storage unit, the other end of the first energy storage unit is connected with the direct current bus, and the first switch unit is used for controlling the first energy storage unit to store redundant energy or release stored energy;
the second ripple transfer circuit comprises a second switch unit and a second energy storage unit, one end of the second switch unit is connected with the inductor, the other end of the second switch unit is connected with one end of the second energy storage unit, and the other end of the second energy storage unit is connected with the direct current bus; the second switch unit is used for controlling the second energy storage unit to store redundant energy or release stored energy.
2. The bidirectional Boost converter according to claim 1, wherein the first switching unit comprises a first power switching tube and a first diode, a collector of the first power switching tube is connected to the inductor, an emitter of the first power switching tube is connected to the first energy storage unit, and the first diode is connected in parallel to two ends of the first power switching tube.
3. The bidirectional Boost converter according to claim 2, wherein the first energy storage unit comprises a first energy storage capacitor, one end of the first energy storage capacitor is connected with an emitter of the first power switch tube, and the other end of the first energy storage capacitor is connected with the direct current bus;
when the first power switch tube is conducted and the first diode is not conducted, the first energy storage capacitor is controlled to store redundant energy input by the direct current bus; when the first diode is conducted and the first power switch tube is not conducted, the first energy storage capacitor is controlled to release stored energy and the stored energy flows to the direct current bus.
4. The bidirectional Boost converter according to claim 3, wherein the second switching unit comprises a second power switch tube and a second diode, an emitter of the second power switch tube is connected to the inductor, a collector of the second power switch tube is connected to the first energy storage unit, and the first diode is connected in parallel to two ends of the first power switch tube.
5. The bidirectional Boost converter according to claim 4, wherein the second energy storage unit comprises a second energy storage capacitor, one end of the second energy storage capacitor is connected with a collector of the second power switch tube, and the other end of the second energy storage capacitor is connected with the direct current bus;
when the second diode is conducted and the second power switch tube is not conducted, the second energy storage capacitor is controlled to store redundant energy input by the direct current bus; when the second power switch tube is conducted and the second diode is not conducted, the second energy storage capacitor is controlled to release stored energy and the stored energy flows to the direct current bus.
6. A bidirectional Boost converter as claimed in claim 5, characterized in that said bidirectional Boost converter comprises four operating modes, respectively:
when the first power switch tube is conducted and the second power switch tube, the first diode and the second diode are not conducted, redundant energy input by the direct current bus flows into the first energy storage capacitor through the inductor, so that the first energy storage capacitor stores the redundant energy;
when the second diode is conducted, and the first power switch tube, the second power switch tube and the first diode are not conducted, redundant energy input by the direct current bus flows into the second energy storage capacitor through the inductor, so that the second energy storage capacitor stores the redundant energy;
when the second power switch tube is conducted and the first power switch tube, the first diode and the second diode are not conducted, the first energy storage capacitor and the inductor release stored energy and flow into a direct current bus to charge the direct current bus;
when the first diode is conducted and the first power switch tube, the second power switch tube and the second diode are not conducted, the first energy storage capacitor and the inductor release stored energy and flow into the direct current bus to charge the direct current bus.
7. A control system of a bidirectional Boost converter, applied to the bidirectional Boost converter according to any one of claims 1 to 6, the control system comprising: the device comprises a detection module, a voltage regulation module, a reference signal generation module and a control module;
the detection module is used for detecting an inductive current signal of the bidirectional Boost converter, voltage signals of the first energy storage unit and the second energy storage unit and a double-frequency current signal of the direct-current bus; the reference voltage signal, the voltage signals of the first energy storage unit and the second energy storage unit are regulated by the voltage regulation module and then output voltage loop control signals; the voltage loop control signal and a frequency doubling current signal of the direct current bus are superposed by the reference signal generating module to generate a reference inductive current signal; and the control module is used for comparing the detected inductive current signal with the reference inductive current signal and outputting a switch control signal of the bidirectional Boost converter according to a comparison result.
8. The control system of the bidirectional Boost converter according to claim 7, wherein the control module comprises a hysteresis comparison module, a logic judgment module and a driving module, and the detected inductive current signal and the reference inductive current signal are compared by the hysteresis comparison module to obtain a comparison result of the inductive current signal and the set upper and lower thresholds of the current hysteresis; and the logic judgment module outputs corresponding control signals according to the comparison result, and the control signals are output to the bidirectional Boost converter through the driving module so as to control the first switch unit and the second switch unit of the bidirectional Boost converter to be switched on or switched off.
9. A control method of a bidirectional Boost converter, applied to the bidirectional Boost converter according to any one of claims 1 to 6, the control method comprising:
acquiring an inductive current signal of a bidirectional Boost converter, voltage signals of a first energy storage unit and a second energy storage unit and a double-frequency current signal of a direct-current bus;
the reference voltage signal, the voltage signals of the first energy storage unit and the second energy storage unit output voltage loop control signals after voltage regulation;
the voltage loop control signal and a double-frequency current signal of the direct current bus are superposed to generate a reference inductive current signal;
and comparing the inductive current signal with the reference inductive current signal, and outputting a switch control signal of the bidirectional Boost converter according to the comparison result.
10. The method of claim 9, wherein the step of comparing the inductor current signal with the reference inductor current signal and outputting a switching control signal of the bidirectional Boost converter according to a magnitude of a comparison result comprises:
setting a loop width, and setting an upper limit threshold and a lower limit threshold of a current hysteresis according to a reference inductive current signal and the loop width;
comparing the inductive current signal with an upper limit threshold and a lower limit threshold of a current hysteresis loop respectively;
when the reference inductor current signal is smaller than or equal to the lower limit threshold value of the current hysteresis loop, outputting a control signal to enable a switching unit of the bidirectional Boost converter to be conducted, and charging an inductor and an energy storage unit;
when the reference inductive current signal is in the upper limit threshold value and the lower limit threshold value interval of the current hysteresis loop, the state of a switch unit of the bidirectional Boost converter is kept unchanged;
when the reference inductor current signal is larger than or equal to the upper limit threshold value of the current hysteresis loop, a control signal is output to turn off a switch unit of the bidirectional Boost converter, so that the inductor and the energy storage unit are discharged.
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| CN202110808551.0A CN113572353A (en) | 2021-07-16 | 2021-07-16 | Bidirectional Boost converter, control system and control method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114285282A (en) * | 2022-02-28 | 2022-04-05 | 深圳原能电器有限公司 | Converter with wide voltage input and control method |
| WO2023179066A1 (en) * | 2022-03-21 | 2023-09-28 | 无锡雷利电子控制技术有限公司 | Circuit protection method based on direct-current bus capacitor, and control system for in-vehicle controller |
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2021
- 2021-07-16 CN CN202110808551.0A patent/CN113572353A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114285282A (en) * | 2022-02-28 | 2022-04-05 | 深圳原能电器有限公司 | Converter with wide voltage input and control method |
| WO2023179066A1 (en) * | 2022-03-21 | 2023-09-28 | 无锡雷利电子控制技术有限公司 | Circuit protection method based on direct-current bus capacitor, and control system for in-vehicle controller |
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