CN215268053U - Novel power electronic low-loss damping resonant filter - Google Patents
Novel power electronic low-loss damping resonant filter Download PDFInfo
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Abstract
The utility model discloses a can wide application in power electronic equipment inverter circuit's low-loss damping resonance filter structure. The utility model discloses contained the inductance L1 of being connected with the contravariant unit, the L2 of being connected with the electric wire netting, resonant frequency is the resonance branch road of switching frequency integral multiple (L3C1 branch road and L4C2 branch road), R1C3 damping branch road to and the combination relation and each device parametric design between each branch road. The utility model discloses a wave filter structure mainly utilizes resonance absorption switching frequency's electric current ripple, and the filter effect is very ideal, and the damping link loss is little, and the transient state impulse voltage tolerance of abominable electric wire netting is strong.
Description
Technical Field
The utility model relates to a wave filter, in particular to novel power electronics low-loss damping resonance filter.
Background
With the development of new energy, high-power inverters such as photovoltaic inverters, energy storage converters, and active power filters are beginning to be widely applied to power systems. The inverter generally outputs modulated pulse voltage in a PWM manner, and high-frequency ripples are filtered by an output filter to realize continuous current output.
The current inverter equipment generally adopts a simple LCL filter structure, and the LCL filter belongs to a third-order filter, has stronger harmonic attenuation capability in a high-frequency band, and has the problem of easy resonance. In factory power grid environments such as a large-power intermediate frequency furnace and direct current speed regulation, peak voltage pulses with amplitude values of more than 200V and pulse widths of only about 200us exist, and due to the fact that pulse response convergence is slow and oscillation amplitude values are high, an LCL filter often causes the inverter to be incapable of working normally, and even filter capacitors are damaged.
Therefore, it is necessary to design a filter with good stability, fast pulse response convergence, and good switching frequency ripple filtering effect.
SUMMERY OF THE UTILITY MODEL
In order to overcome the not enough of background art, the utility model provides a high novel power electronics low-loss damping resonance filter of stability under abominable electric wire netting environment.
The utility model adopts the technical proposal that: novel power electronic low-loss damping resonance filter, including main return circuit contravariant side inductance L1, the electric wire netting side inductance L2 of being connected with the electric wire netting, resonance branch road and R1C3 damping branch road that is connected with the contravariant unit, resonance branch road including L3C1 branch road and L4C2 branch road, resonance branch road is in the parallelly connected coupling between main return circuit contravariant side inductance L1 and electric wire netting side inductance L2 with R1C3 damping branch road.
The utility model discloses further set up to: the resonant frequency of the resonant branch circuit is integral multiple of the switching frequency Fk of the inversion unit, the resonant frequency of the L3C1 branch circuit is 1 time of the switching frequency, and the resonant frequency of the L4C2 branch circuit is 2 times of the switching frequency.
The utility model discloses further set up to: the resonance frequency of the resonance branch is 1 time and 2 times of the switching frequency Fk of the inversion unit.
The utility model discloses further set up to: the inductance of the L3C1 branch and the inductance of the L4C2 branch are 1/4 × L2 to 1 × L2.
The utility model discloses further set up to: the damping branch of the R1C3 and the grid side inductor L2 form a resonant ring.
The utility model discloses further set up to: the resonance frequency Fr of the damping branch of the R1C3 and the grid-side inductor L2 is less than the switching frequency Fk of the 1/2 inverter unit.
The utility model discloses further set up to: the resonance frequency Fr of the damping branch of the R1C3 and the grid-side inductor L2 is 1/2Fk to 1/4Fk of the switching frequency of the inverter unit.
The utility model has the advantages that: the utility model discloses a wave filter structure mainly utilizes resonance absorption switching frequency's electric current ripple, and the filter effect is very ideal, and the damping link loss is little, and the transient state impulse voltage tolerance of abominable electric wire netting is strong, and stability is high.
The embodiments of the present invention will be further explained with reference to the drawings.
Drawings
Fig. 1 is a circuit diagram of the present invention;
fig. 2 is a current waveform diagram obtained by setting 750V for the medium three-level dc bus voltage and 220V for the single-phase ac voltage effective value according to the present invention;
FIG. 3 is a waveform diagram of the output current of the inverter circuit of the present invention;
FIG. 4 is a waveform of the present invention after being filtered by a filter;
fig. 5 is a diagram of the impulse voltage impulse state of the middle filter of the present invention;
FIG. 6 is a circuit diagram of the LCL of comparative example 1;
7-8 are graphs of amplitude-frequency characteristics for the LCL structure of comparative example 1 with C designed to be 15 uF;
FIG. 9 is a waveform diagram of the grid-connected current obtained by analyzing the LCL structure spectrum in comparison 1;
FIG. 10 is a circuit diagram of the damped LCL of comparative example 2;
FIG. 11 is a current waveform of the damping LCL in comparative example 2;
FIG. 12 is a grid-tied current waveform for the damped LCL of comparative example 2;
fig. 13 is a diagram of the voltage surge condition of the damped LCL pulses in comparative example 2.
Detailed Description
The utility model adopts the technical proposal that: novel power electronic low-loss damping resonance filter, including main return circuit contravariant side inductance L1, the electric wire netting side inductance L2 of being connected with the electric wire netting, resonance branch road and R1C3 damping branch road that is connected with the contravariant unit, resonance branch road including L3C1 branch road and L4C2 branch road, resonance branch road is in the parallelly connected coupling between main return circuit contravariant side inductance L1 and electric wire netting side inductance L2 with R1C3 damping branch road.
The resonant frequency of the resonant branch circuit is integral multiple of the switching frequency Fk of the inversion unit, the resonant frequency of the L3C1 branch circuit is 1 time of the switching frequency, and the resonant frequency of the L4C2 branch circuit is 2 times of the switching frequency.
The resonance frequency of the resonance branch is 1 time and 2 times of the switching frequency Fk of the inversion unit.
The inductance of the L3C1 branch and the inductance of the L4C2 branch are 1/4 × L2 to 1 × L2. The resonant branch absorbs most of the ripple current. The damping branch circuit is mainly used for inhibiting the resonance branch circuit from diverging and ensuring the stability of the resonance branch circuit, so that the current flowing through the damping branch circuit is not large and the loss of the damping branch circuit is small.
The damping branch of the R1C3 and the grid side inductor L2 form a resonant ring. To suppress this loop resonance, the value of R1 should be close to the inductive reactance of C3 at this resonance frequency.
In order to ensure the stability of the resonant branch, the resonant frequency Fr of the damping branch and L2 needs to be less than the switching frequency Fk of 1/2, and if Fr is too small, the loss of R1 will be increased, so the value of Fr needs to be about 1/2Fk to 1/4Fk with reference to the standard specification of C3.
The specific embodiment is as follows:
take 30 kvar's static var generator as an example, design the utility model discloses the wave filter parameter.
As is known, L1 equals 360uH, L2 equals 100uH, and the inverter circuit switching frequency Fk is 20 kHz.
The L3C1 branch circuit has a resonance frequency of 20kHz, a reference capacitor current specification selects a 1uF capacitance of C1, and a calculation formula is obtained according to LC resonance frequency
The L3 sensitivity was calculated and the whole was taken to be 64 uH.
L3 ═ 64uH, C1 ═ 1uF, and the actual resonant frequency was 19.894 kHz.
The L4C2 branch circuit takes the resonant frequency as 2Fk which is 40kHz, the reference capacitance specification selects 0.47uF capacitance as C2, and the L4 inductance is solved according to the LC resonant frequency calculation formula, and the whole is 33 uH.
L4-33 uH, C1-0.47 uF, with an actual resonance frequency of 40.4 kHz.
The R1C3 damping branch mainly considers that the resonant frequency formed by L2 and C3 is lower than the switching frequency, the resonant frequency Fr is 1/2Fk which is 10kHz, C3 capacity is calculated by referring to L2 according to a resonant frequency calculation formula, the specification of a reference capacitor is rounded to 3uF, and in order to ensure stable resonance convergence of the damping branch, the optimal value range of R1 is the harmonic frequency
After the parameters are determined, filter model linear analysis is carried out by means of an MATLAB/Simulink tool, inverter control loop voltage is used as input, grid-connected current is used as output, an amplitude-frequency response curve of the design parameter analysis filter is substituted, and whether the design meets the expectation or not is verified. As can be seen from the amplitude response curves in fig. 1 and fig. 2, the filter can greatly filter the ripples of 20kHz and 40kHz, and the full frequency band remains stable in convergence, which is the most ideal filtering requirement of the inverter.
And a three-level inverter circuit, a filter and a power grid are used for complete modeling, the output current ripple and the grid-connected current ripple of the inverter are subjected to spectrum analysis, and the filtering effect of the filter is verified. Setting 750V of three-level direct current bus voltage, and setting 220V of effective value of single-phase alternating current voltage to obtain current waveform;
the waveform of the output current of the inverter circuit is shown in fig. 3, wherein the total harmonic content is 9.73%, the 20kHz harmonic content is about 6%, and the 40kHz harmonic content is about 1%.
As shown in fig. 4, after being filtered by the filter, the total harmonic distortion rate of the output current is only 0.29%, the 20kHz harmonic content rate is only 0.06%, and the 40kHz harmonic content rate is only 0.01%, so that the filtering effect is significant and is close to an ideal state.
As shown in fig. 5, the filter impulse response can converge quickly within 300us without fear of grid transient surge voltages.
Most of ripple current of the inverter circuit is absorbed by the resonant circuit in a lossless manner, and the current of the damping branch circuit is very small in a steady state, so that the power consumption of the damping resistor R1 is very small. The power consumption of the resistor R1 in the simulink model is calculated, the power consumption of the resistor R1 is only 1W, and the heating problem of the resistor R1 does not need to be considered when the resistor R is applied to an actual product.
So far the utility model discloses a wave filter design flow has been accomplished, verifies through the model machine, has gained the effect unanimous with theoretical model.
The following article will adopt equal L1, L2 sensing quantity, equal other external parameters, equal PID current control loop parameter, analyze with two comparison files the utility model discloses contrast the superiority of LCL wave filter and other wave filter structures.
Comparing one:
as shown in fig. 6, firstly, an LCL undamped structure is adopted for simulation, and as the resonant frequency point of the LCL filter is closer to the PID current loop control frequency, the oscillation is more likely to be out of control, so C in the LCL structure is designed to be 15uF, and if the capacitance value is too small, the oscillation is more likely to be caused.
The amplitude-frequency characteristic of the structure under the parameter is analyzed as shown in FIG. 7:
it can be seen that the gain at frequencies between 4-5 kHz is positive, with the risk of resonance divergence. The control current is reflected in the current control, and when the control target is stepped, the control current generates a section of continuous oscillation and converges under the action of a control loop, as shown in fig. 8;
as shown in fig. 9, when the grid-connected current is subjected to spectrum analysis, the total harmonic distortion rate of the output current is 0.58%, and the 20kHz harmonic content is about 0.27%.
And (4) comparing:
a damping resistor is connected in series on the capacitance branch to solve the stability of the LCL filter, and in order to minimize loss and ensure stability, the damping R takes 1 omega, and modeling and simulation are carried out, as shown in FIG. 10;
as can be seen from fig. 11, the resonance peak is significantly suppressed after increasing the damping R, but the attenuation of the high frequency band is reduced.
As can be seen from fig. 12, the total harmonic content of the grid-connected current of the LCL damping filter is 0.98%, the 20khz harmonic content is 0.58%, and the loss of the damping R reaches 11W.
As shown in fig. 13, the pulse response convergence of the LCL damping filter is inferior to the present invention.
Summarized, as in Table 1
From the aforesaid, the cost, the loss, the filter effect, adaptability is no matter from which aspect is relatively, the utility model discloses all far superior to traditional wave filter to possess very strong feasibility, can be applied to all kinds of high-power electronic equipment's wave filter design.
The skilled person should understand that: although the present invention has been described in accordance with the above embodiments, the inventive concept is not limited thereto, and any modification of the inventive concept will be included in the scope of the patent claims.
Claims (7)
1. Novel power electronics low-loss damping resonator filter, its characterized in that: the damping device comprises a main loop inversion side inductor L1 connected with an inversion unit, a grid side inductor L2 connected with a grid, a resonance branch and an R1C3 damping branch, wherein the resonance branch comprises an L3C1 branch and an L4C2 branch, and the resonance branch is connected between a main loop inversion side inductor L1 and a grid side inductor L2 in parallel by an R1C3 damping branch.
2. The novel power electronic low-loss damping resonator filter according to claim 1, characterized in that: the resonance frequency of the resonance branch circuit is integral multiple of the switching frequency Fk of the inversion unit, and the resonance frequency of the resonance branch circuit is 1 time and 2 times of the switching frequency Fk of the inversion unit.
3. The novel power electronic low-loss damped resonator filter of claim 2, characterized in that: the resonant frequency of the L3C1 branch is 1 time of the switching frequency, and the resonant frequency of the L4C2 branch is 2 times of the switching frequency.
4. A novel power electronic low loss damped resonator filter according to claim 1 or 2 or 3, characterized in that: the inductance of the L3C1 branch and the inductance of the L4C2 branch are 1/4 × L2 to 1 × L2.
5. A novel power electronic low loss damped resonator filter according to claim 1 or 2 or 3, characterized in that: the damping branch of the R1C3 and the grid side inductor L2 form a resonant ring.
6. The novel power electronic low-loss damped resonator filter of claim 5, characterized in that: the resonance frequency Fr of the damping branch of the R1C3 and the grid-side inductor L2 is less than the switching frequency Fk of the 1/2 inverter unit.
7. The novel power electronic low-loss damped resonator filter of claim 6, characterized in that: the resonance frequency Fr of the damping branch of the R1C3 and the grid-side inductor L2 is 1/2Fk to 1/4Fk of the switching frequency of the inverter unit.
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| CN113394958A (en) * | 2021-06-03 | 2021-09-14 | 浙江亿德科技有限公司 | Novel power electronic low-loss damping resonant filter |
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Denomination of utility model: A new low loss damping resonant filter for power electronics Effective date of registration: 20221102 Granted publication date: 20211221 Pledgee: Wenzhou Financing Guarantee Co.,Ltd. Pledgor: ZHEJIANG YIDEK TECHNOLOGY CO.,LTD. Registration number: Y2022110000291 |
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