CN104993470A - Control mode for active filter in DC link - Google Patents
Control mode for active filter in DC link Download PDFInfo
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- CN104993470A CN104993470A CN201510364986.5A CN201510364986A CN104993470A CN 104993470 A CN104993470 A CN 104993470A CN 201510364986 A CN201510364986 A CN 201510364986A CN 104993470 A CN104993470 A CN 104993470A
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- active filter
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Abstract
The invention discloses a control mode for an active filter in a DC link, and the mode achieves the purposes of improving the efficiency of a main converter under a light-load condition and improving the dynamic performance of the main converter through controlling the minimum value or maximum value of an output voltage of the active filter. The mode comprises the steps: enabling an output value of a peak detection circuit to be compared with the minimum value or maximum value of the output voltage of the active filter, and then generating an error signal transmitted to a voltage regulator; detecting a low-frequency AC current in the DC link of the active filter, adding the low-frequency AC current to an output signal of the voltage regulator, and generating a current reference signal; detecting the input current of the active filter, comparing the input current with the current reference signal, generating an error signal, transmitting the error signal to a current regulator, and obtaining a modulation signal; transmitting the modulation signal into a PWM modulation circuit, and obtaining a drive signal of a switching tube.
Description
Technical field
The present invention relates to a kind of control mode of active filter of DC link, belong to the category of power electronic converter.
Background technology
In power electronic converter field, all need in a lot of occasion to suppress the mains ripple in DC link and current pulsation.Such as, the power supply of Power Solid-state Radar Transmitter needs the pulsating current providing low frequency, its input power requires to be flat form as far as possible, and export as low frequency pulsating power, if require that this pulsating power is all born by output storage capacitor, enough little in order to ensure the pulsation of output voltage, need jumbo output storage capacitor, the volume and weight of power supply can be increased so significantly.And for example, in the LED drive power of single stage type PWM rectifier and Alternating Current Power Supply, input power contains the flutter component of larger twice incoming frequency, and instantaneous output approximately constant, in order to mate Instantaneous input power and power output, need the storage capacitor that use capacity is larger, this electric capacity generally selects electrochemical capacitor.And electrochemical capacitor life is lower, do not mate with the entire system life-span.According to above analysis, in DC link for bearing the big capacity electrolyte capacitor of low frequency pulsating power, need to adopt certain method to reduce its capacitance, even remove electrochemical capacitor.
By at DC link parallel active filter, utilize active filter to absorb the pulsating power of low frequency, significantly can reduce capacitor's capacity required on DC bus.Here DC port is seen as the input port of active filter, its general principle is from converter, detect the low-frequency harmonics electric current needing filtering, then the input current controlling active filter is equal with it, thus make it provide the power of the low frequency pulsating in system, play the object reducing dc-link capacitance.
For the active filter adopting Buck/Boost reversible transducer, when the Instantaneous input power of main converter is higher than power output, active filter works in Boost pattern, by unnecessary energy storage in its output capacitance; When Instantaneous input power is lower than power output, active filter works in Buck pattern, and output capacitor releases energy.This active filter adopts double-closed-loop control, and current inner loop controls its input current and follows the tracks of the low frequency pulsating electric current needing filtering or needs to provide; In order to ensure the normal work of source filter, needing to ensure its output voltage all the time higher than the voltage of input, therefore needing to add an outer voltage and it is controlled.Existing scheme is control the mean value of output voltage, i.e. sampling and outputting voltage, compares with mean value benchmark, on the low frequency pulsating current signal that the voltage error obtained is sampled obtain through being added to after voltage regulator, and given as current inner loop.When converter load reduction, because the mean value of active filter output voltage is still higher compared with input voltage, make active filter there is larger switching loss, affect efficiency during converter underloading.In addition, because outer voltage bandwidth is lower, make the dynamic response of converter comparatively slow, be the application scenario of low frequency pulsating form in load, still there is certain falling and overshoot in output voltage, is therefore necessary the control mode improving active filter.
Summary of the invention
The object of the invention is the active filter being used for alternative larger capacity electrochemical capacitor for being connected in parallel in DC link, propose to adopt the method controlling active filter output voltage minimum and peak, improve the efficiency in converter underloading situation and reduce converter dynamically the falling of output voltage when shock load.
The present invention is for solving the problems of the technologies described above by the following technical solutions:
A control mode for the active filter of DC link,
Active filter adopts double-closed-loop control, and current inner loop follows the tracks of the low frequency pulsating electric current of required filtering, and outer voltage controls minimum or the peak of active filter output voltage, and concrete control mode is:
Utilize voltage sampling circuit to detect the output voltage of active filter, subtract each other with the output voltage obtained of sampling, by its result feeding peak detection circuit by a fixing value; Or the output voltage directly obtained sampling sends into peak detection circuit; The former is for controlling the control mode of active filter output voltage minimum, and the latter is the control mode controlling active filter output voltage peak;
After the output valve of peak detection circuit and active filter output voltage minimum or peak benchmark are compared, produce error signal and send into voltage regulator;
Utilize the electric current in current sampling circuit detection active filter DC link, after its DC component of filtering, be added through add circuit with the output signal of voltage regulator, the reference signal of generation current inner ring;
Detect the input current of active filter, compare with current reference signal, produce error signal and send into current regulator, thus obtain modulation signal; Modulation signal is sent into PWM circuit, and obtain the drive singal of switching tube by drive circuit.
The method provides a kind of active filter, and described active filter is Buck/Boost reversible transducer.
Described Buck/Boost two-way changing implement body comprises inductance, two switching tubes, storage capacitors, concrete, and one end of inductance is an input of reversible transducer, and the other end of inductance connects one end of two switching tubes respectively; Wherein the other end of the first switching tube connects another input of reversible transducer and one end of storage capacitor, and the other end of described second switch pipe connects the other end of storage capacitor.
This active filter is connected in parallel on the main converter DC link of conventional electron circuit, is used for reducing the capacitance of filter capacitor needed for DC link.
When the Instantaneous input power of described main converter is higher than fluctuating output power, active filter works in Boost pattern; When the Instantaneous input power of described main converter is lower than power output, active filter works in Buck pattern.
When adopting the method controlling active filter output voltage minimum, utilizing voltage sampling circuit to detect the output voltage of active filter, subtracting each other with the output voltage obtained of sampling, by its result feeding peak detection circuit by a fixing value;
After the output valve of peak detection circuit and active filter output voltage minimum benchmark are compared, produce error signal and send into voltage regulator;
Utilize the electric current in current sampling circuit detection active filter DC link, after its DC component of filtering, be added through add circuit with the output signal of voltage regulator, the reference signal of generation current inner ring;
Detect the input current of active filter, compare with current reference signal, produce error signal and send into current regulator, thus obtain modulation signal; Modulation signal is sent into PWM circuit, and obtain the drive singal of switching tube by drive circuit.
When adopting the method controlling active filter output voltage peak, utilize voltage sampling circuit to detect the output voltage of active filter, the output voltage obtained sampling sends into peak detection circuit;
After the output valve of peak detection circuit and active filter output voltage peak benchmark are compared, produce error signal and send into voltage regulator;
Utilize the electric current in current sampling circuit detection active filter DC link, after its DC component of filtering, be added through add circuit with the output signal of voltage regulator, the reference signal of generation current inner ring;
Detect the input current of active filter, compare with current reference signal, produce error signal and send into current regulator, thus obtain modulation signal; Modulation signal is sent into PWM circuit, and obtain the drive singal of switching tube by drive circuit.
The present invention adopts above technical scheme compared with prior art, has following technique effect:
When converter load lightens, active filter output voltage reduces adaptively along with lightening of load, and if adopt the method for traditional control output voltage average value, active filter output voltage still keeps higher value when underloading.Therefore when the method for control active filter output voltage minimum that the present invention proposes can effectively reduce underloading, the switching loss of active filter switching tube, improves the light-load efficiency of converter.
When adopting the method controlling active filter output voltage peak, compared with the method for traditional control output voltage average value, after converter start during shock load, because outer voltage voltage reference value is higher, make the output of Voltage loop relatively higher, thus obtain higher electric current loop benchmark, make active filter can provide more instantaneous pulsating power, the falling of main converter output voltage when therefore can effectively reduce shock load, improves the dynamic response performance of converter.
Accompanying drawing explanation
The structural representation of changer system when accompanying drawing 1 is using active filter in pulse load situation;
Accompanying drawing 2 is circuit theory diagrams of active filter;
Accompanying drawing 3 is key operation waveforms of active filter;
Accompanying drawing 4 is the control block diagrams controlling active filter output voltage minimum method in the present invention;
Accompanying drawing 5 is the control block diagrams controlling active filter output voltage peak method in the present invention;
Accompanying drawing 6 is the circuit theory diagrams of the peak detection circuit adopted in the present invention;
Wherein,
v in for whole converter DC input voitage,
c o for output filter capacitor,
i o for pulse load electric current,
i o for its mean value,
v o for output voltage;
v o for active filter approximate input voltage,
l a with
c a be respectively the input inductance of active filter and storage capacitor,
q 1with
q 2for two switching tubes of active filter;
i a with
v a be respectively input current and output voltage, the Δ of active filter
v a ,
v a_min ,
v a_max with
v a be respectively the pulsating quantity of output voltage, minimum, peak and mean value,
q 1_
dr with
q 2_
dr be respectively switching tube
q 1with
q 2drive singal,
r 1with
r 2for active filter output voltage sampling resistor;
g v (
s) and
g c (
s) be respectively voltage regulator and current regulator,
v a_ min_
ref with
v a_ max_
ref be respectively active filter output voltage minimum benchmark and peak benchmark under two schemes,
i a_ref for obtain after pulse load electric current filtering DC component current reference,
d 1,
d 2for form peak detection circuit diode,
r p ,
r f for peak detection circuit resistance,
c p for the electric capacity of peak detection circuit.
Embodiment
The invention provides a kind of control mode of active filter of DC link, for making object of the present invention, clearly, clearly, and the present invention is described in more detail with reference to accompanying drawing examples for technical scheme and effect.Should be appreciated that concrete enforcement described herein is only in order to explain the present invention, is not intended to limit the present invention.
Be described in detail below in conjunction with the technical scheme of accompanying drawing to invention:
Fig. 1 illustrates and adopt active filter to reduce an embody rule occasion of DC link electric capacity, its load current is low-frequency pulse form, enough little in order to ensure the pulsation of output voltage, an energy-storage units is needed to provide pulsating power needed for load, and in order to the size of the storage capacitor that reduces output, the mode at an output active filter in parallel can be adopted, utilize this active filter to provide pulsating power.It is pointed out that occasion that the present invention is suitable for is not limited to the situation of pulse load, every DC link parallel active filter at converter is used for reducing the occasion of filter capacitor, all can adopt the control method in the present invention.
Figure 2 shows the circuit theory diagrams of the active filter that the present invention adopts, its topology is a Buck/Boost reversible transducer, above-mentioned Buck/Boost two-way changing implement body comprises inductance, two switching tubes, storage capacitors, concrete, one end of inductance is an input of reversible transducer, and the other end of inductance connects one end of two switching tubes respectively; Wherein the other end of the first switching tube connects another input of reversible transducer and one end of storage capacitor, and the other end of described second switch pipe connects the other end of storage capacitor.
When the input power of main converter is higher than instantaneous fluctuating output power, active filter works in Boost pattern, by unnecessary stored energy to storage capacitor
c a in, when input power is lower than instantaneous output, active filter works in Buck pattern,
c a release energy, insufficient section power is provided, thus adopt the pulsating power in active mode process load.Working waveform figure in respective figure 3 can be found out, active filter provides load pulse electric current
i o in alternating current component
i a , when
i a during > 0,
c a release energy, voltage reduces; When
i a during < 0,
c a absorb energy, voltage rise.
Fig. 4 shows the control block diagram of control active filter output voltage minimum method proposed by the invention.It is made up of subtraction circuit, peak detection circuit, voltage regulator, PWM device and drive circuit.Active filter output voltage is through resistor voltage divider network
r 1,
r 2after obtain voltage sampling signal
v a_f , then use a fixing value
v set deduct
v a_f , the value obtained obtains the value of feedback of output voltage minimum through peak detection circuit
v a_min
_ f , by itself and voltage minimum benchmark
v a_min
_ ref produce error signal after relatively making difference, then pass through voltage regulator
g v (
s) produce output signal
v o_Gv , the pulse load electric current of converter
i o obtain after filtering DC component
i a_ref ,
i a_ref with
v o_Gv be added, as the benchmark of current inner loop, with the active filter input current obtained of sampling
i a_f compare, its error signal
i e again through current regulator
g c (
s) obtain modulation signal
v o_Gc , finally will
v o_Gc switching tube is obtained by PWM circuit
q 1control signal
q 1
_ dr , switching tube
q 2 with
q 1complementary conducting.
Figure 5 provides the control block diagram of control active filter output voltage peak method proposed by the invention.It is made up of peak detection circuit, voltage regulator, PWM device and drive circuit.Active filter output voltage is through resistor voltage divider network
r 1,
r 2after obtain voltage sampling signal
v a_f , then the value of feedback of output voltage peak is obtained through peak detection circuit
v a_max
_ f , by itself and voltage peak benchmark
v a_max
_ ref produce error signal after relatively making difference, then pass through voltage regulator
g v (
s) produce output signal
v o_Gv , the pulse load electric current of converter
i o obtain after filtering DC component
i a_ref ,
i a_ref with
v o_Gv be added, as the benchmark of current inner loop, with the active filter input current obtained of sampling
i a_f compare, its error signal
i e again through current regulator
g c (
s) obtain modulation signal
v o_Gc , finally will
v o_Gc switching tube is obtained by PWM circuit
q 1control signal
q 1
_ dr , switching tube
q 2 with
q 1complementary conducting.
In accompanying drawing 4 and accompanying drawing 5, the design of voltage regulator should make the bandwidth of outer voltage enough low, the low frequency component contained in avoiding voltage regulator to export brings impact to current reference, and therefore the design of voltage regulator should make the cut-off frequency of outer voltage much smaller than the frequency for required filtering electric current.The design of current regulator should make electric current loop have enough large loop gain in low-frequency range, and to improve the follow-up control of electric current, consider the ripple that the switching frequency of suppression system is secondary in addition, the cut-off frequency of electric current loop should be less than the switching frequency of 1/5.
Accompanying drawing 6 gives the connected mode of peak detection circuit, amplifier
a 1in-phase input end and amplifier
a 2output be respectively input and the output of peak detection circuit, diode
d 1anode be connected amplifier respectively with negative electrode
a 1inverting input and output, diode
d 2anode be connected amplifier respectively with negative electrode
a 1output and amplifier
a 2in-phase input end,
r p with
c p and be connected in
a 2in-phase input end,
r f be connected across
a 1inverting input and
a 2output.When adopting the control method of the control active filter output voltage minimum provided in accompanying drawing 4, when converter load lightens, active filter output voltage reduces adaptively along with lightening of load, if and adopt the method for traditional control output voltage average value, active filter output voltage still keeps higher value when underloading.Therefore when the method for control output voltage minimum that the present invention proposes can effectively reduce underloading, the switching loss of active filter switching tube, improves the light-load efficiency of converter.
Adopt the control method of the control active filter output voltage peak provided in accompanying drawing 5, compared with the method for traditional control output voltage average value, after converter start during shock load, because outer voltage voltage reference value is higher, make the output of Voltage loop relatively higher, thus obtain higher electric current loop benchmark, make active filter can provide more instantaneous pulsating power, the falling of main converter output voltage when therefore can effectively reduce shock load, improves the dynamic response performance of converter.
Be understandable that, for those of ordinary skills, can be equal to according to technical scheme of the present invention and inventive concept thereof and replace or change, and all these change or replace the protection range that all should belong to the claim appended by the present invention.
Claims (7)
1. a control mode for the active filter of DC link, is characterized in that:
Active filter adopts double-closed-loop control, and current inner loop follows the tracks of the low frequency pulsating electric current of required filtering, and outer voltage controls minimum or the peak of active filter output voltage, and concrete control mode is:
Utilize voltage sampling circuit to detect the output voltage of active filter, subtract each other with the output voltage obtained of sampling, by its result feeding peak detection circuit by a fixing value; Or the output voltage directly obtained sampling sends into peak detection circuit; The former is for controlling the control mode of active filter output voltage minimum, and the latter is the control mode controlling active filter output voltage peak;
After the output valve of peak detection circuit and active filter output voltage minimum or peak benchmark are compared, produce error signal and send into voltage regulator;
Utilize the electric current in current sampling circuit detection active filter DC link, after its DC component of filtering, be added through add circuit with the output signal of voltage regulator, the reference signal of generation current inner ring;
Detect the input current of active filter, compare with current reference signal, produce error signal and send into current regulator, thus obtain modulation signal; Modulation signal is sent into PWM circuit, and obtain the drive singal of switching tube by drive circuit.
2. the control mode of the active filter of a kind of DC link according to claim 1, is characterized in that:
The method provides a kind of active filter, and described active filter is Buck/Boost reversible transducer.
3. the control mode of the active filter of a kind of DC link according to claim 2, is characterized in that:
Described Buck/Boost two-way changing implement body comprises inductance, two switching tubes, storage capacitors, concrete, and one end of inductance is an input of reversible transducer, and the other end of inductance connects one end of two switching tubes respectively; Wherein the other end of the first switching tube connects another input of reversible transducer and one end of storage capacitor, and the other end of described second switch pipe connects the other end of storage capacitor.
4. the control mode of the active filter of a kind of DC link according to claim 3, is characterized in that: this active filter is connected in parallel on the main converter DC link of conventional electron circuit, is used for reducing the capacitance of filter capacitor needed for DC link.
5. the control mode of the active filter of a kind of DC link according to claim 4, is characterized in that:
When the Instantaneous input power of described main converter is higher than fluctuating output power, active filter works in Boost pattern; When the Instantaneous input power of described main converter is lower than power output, active filter works in Buck pattern.
6. the control mode of the active filter of a kind of DC link according to claim 5, it is characterized in that: when adopting the method controlling active filter output voltage minimum, voltage sampling circuit is utilized to detect the output voltage of active filter, subtract each other by a fixing value and the output voltage obtained of sampling, its result is sent into peak detection circuit;
After the output valve of peak detection circuit and active filter output voltage minimum benchmark are compared, produce error signal and send into voltage regulator;
Utilize the electric current in current sampling circuit detection active filter DC link, after its DC component of filtering, be added through add circuit with the output signal of voltage regulator, the reference signal of generation current inner ring;
Detect the input current of active filter, compare with current reference signal, produce error signal and send into current regulator, thus obtain modulation signal; Modulation signal is sent into PWM circuit, and obtain the drive singal of switching tube by drive circuit.
7. the control mode of the active filter of a kind of DC link according to claim 5, it is characterized in that: when adopting the method controlling active filter output voltage peak, utilize voltage sampling circuit to detect the output voltage of active filter, the output voltage obtained sampling sends into peak detection circuit;
After the output valve of peak detection circuit and active filter output voltage peak benchmark are compared, produce error signal and send into voltage regulator;
Utilize the electric current in current sampling circuit detection active filter DC link, after its DC component of filtering, be added through add circuit with the output signal of voltage regulator, the reference signal of generation current inner ring;
Detect the input current of active filter, compare with current reference signal, produce error signal and send into current regulator, thus obtain modulation signal; Modulation signal is sent into PWM circuit, and obtain the drive singal of switching tube by drive circuit.
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| CN201510364986.5A CN104993470B (en) | 2015-06-29 | 2015-06-29 | A kind of control mode of the active filter of DC link |
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|---|---|---|---|
| CN201510364986.5A CN104993470B (en) | 2015-06-29 | 2015-06-29 | A kind of control mode of the active filter of DC link |
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| CN104993470A true CN104993470A (en) | 2015-10-21 |
| CN104993470B CN104993470B (en) | 2017-09-19 |
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Cited By (5)
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| CN108322024A (en) * | 2017-01-18 | 2018-07-24 | 冯阳 | DC side active compensator |
| CN110504621A (en) * | 2018-05-20 | 2019-11-26 | 同祥科技(北京)股份有限公司 | A kind of ion generating unit of wisdom air cleaning system |
| CN110854938A (en) * | 2019-11-19 | 2020-02-28 | 深圳航天科技创新研究院 | Control device and system for reducing power pulse type load input current pulsation |
| CN112993966A (en) * | 2021-04-02 | 2021-06-18 | 上海交通大学 | Active filtering method applied to direct current system |
| US11606849B2 (en) * | 2019-06-28 | 2023-03-14 | Texas Instruments Incorporated | Active shunt filtering |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108322024A (en) * | 2017-01-18 | 2018-07-24 | 冯阳 | DC side active compensator |
| CN110504621A (en) * | 2018-05-20 | 2019-11-26 | 同祥科技(北京)股份有限公司 | A kind of ion generating unit of wisdom air cleaning system |
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| CN110854938A (en) * | 2019-11-19 | 2020-02-28 | 深圳航天科技创新研究院 | Control device and system for reducing power pulse type load input current pulsation |
| CN112993966A (en) * | 2021-04-02 | 2021-06-18 | 上海交通大学 | Active filtering method applied to direct current system |
| CN112993966B (en) * | 2021-04-02 | 2023-03-24 | 上海交通大学 | Active filtering method applied to direct current system |
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