Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of being suitable for according to the gas concentration of gas discharge outlet to control the control gear of titanium rotation speed of fan
In order to solve the problems of the technologies described above, the invention provides a kind of control gear being suitable for controlling titanium rotation speed of fan, comprise: the gas concentration sensor being located at gas discharge outlet, this gas concentration sensor is connected with MCU module, and this MCU module is suitable for the motor speed controlling described titanium blower fan.
Further, in order to the wattless power produced machine operation compensates, improve the load capacity of electrical network, connect at the three-phase power input end of described motor the chain type SVG device that is suitable for correcting power factor.
Described chain type SVG device comprises:
The multi-electrical level inverter of H electrical bridge multi-type, it is made up of the three-phase H bridge power model being connected to described three phase mains, wherein, sets up at least one H electrical bridge element circuit for subsequent use in every phase H bridge power model; The H-bridge unit circuit that this multi-electrical level inverter energy auto by pass breaks down, to ensure that H electrical bridge multi-type multi-electrical level inverter normally works, makes described chain type SVG device continue to reach the object of correcting power factor,
Auto by pass circuit, is located at the output terminal of each H electrical bridge element circuit, and when a H electrical bridge element circuit is damaged, by this H electrical bridge element circuit bypass;
Sample circuit, is suitable for the momentary value of the voltage and current gathering described three phase mains;
Divide phase current independent controling circuit, what it was connected with described sample circuit is suitable for the modulation ratio M and the phase angle that calculate the sinusoidal modulation wave needed for described pulse-width modulation circuit according to the momentary value of the voltage and current of described three phase mains
;
Pulse-width modulation circuit, is connected with described point of phase current independent controling circuit, for according to the modulation ratio M of described sinusoidal modulation wave and phase angle
the carrier triangular wave phase shift SPWM adopted between each H electrical bridge element circuit is controlled; Namely, when after the H electrical bridge element circuit bypass damaged, this pulse-width modulation circuit is suitable on the basis keeping the sampling period of described sample circuit constant, change the carrier frequency of the described carrier triangular wave phase shift SPWM of a phase H bridge power model at the H electrical bridge element circuit place of this damage, to obtain the Sampling waveform of the carrier triangular wave phase shift SPWM corresponding with H electrical bridge element circuit quantity remaining in this phase H bridge power model.
Further, described point of phase current independent controling circuit, comprising:
Phaselocked loop, according to the momentary value of the voltage of described three phase mains to follow the tracks of the voltage-phase of described three phase mains;
The given module of wattless current, the voltage-phase being suitable for drawing according to described phaselocked loop calculates the cosine amount of this voltage-phase and is multiplied with a wattless current reference value, exports to obtain actual wattless current;
The given module of active current, the voltage-phase being suitable for drawing according to described phaselocked loop calculates the sinusoidal quantity of this voltage-phase, to subtract each other with the voltage reference value of a DC bus capacitor according to the average voltage of the DC bus capacitor of described each phase H bridge power model simultaneously and be multiplied with described sinusoidal quantity again after PI controls, to obtain the active current output of reality;
Transient current tracing module, for first the electric current that given for described wattless current module and the given module of active current export being superposed, then the transient current in described three phase mains is deducted, and by controller to calculate modulation ratio M and the phase angle of the sinusoidal modulation wave needed for described pulse-width modulation circuit
.
Compared with prior art, the control gear tool being suitable for controlling titanium rotation speed of fan of the present invention has the following advantages: (1) utilizes described chain type SVG device, corrects the problem because machine operation causes the power factor of electrical network to decline, improves the utilization ratio of transformer; (2) in described chain type SVG device, H-bridge unit circuit for subsequent use is provided with, can again a H-bridge unit circuit malfunctions time, the H-bridge unit circuit auto by pass of this fault, and ensure that H electrical bridge multi-type multi-electrical level inverter normally works, that is, grid power factor is corrected; (3) and when this H bridge power model is damaged, without the need to maintenance down, ensure that the stable of electrical network; (4) pulse-width modulation circuit regulates the modulated wave of the phase H bridge power model be damaged, and effectively avoids harmonic wave and produces; (5) by dividing the phase current independence control realization three phase mains compensation problem that imbalance exports; (6) can detect gas purging concentration in time by gas concentration sensor, to control titanium rotation speed of fan, when gas is dense, rotating speed is fast, otherwise then rotating speed is slow; Power consumption can be effectively reduced.
The technical problem that the present invention also will solve is to provide a kind of method of work being suitable for the control gear of the titanium rotation speed of fan correcting grid power factor.
In order to solve the problem, the method for work of the control gear of control titanium rotation speed of fan of the present invention, comprising:
Be suitable for a method of work for chain type SVG device, comprise:
A: when a H electrical bridge element circuit damages, this H electrical bridge element circuit of corresponding auto by pass circuits bypass;
B: described pulse-width modulation circuit is on the basis keeping the sampling period of described sample circuit constant, change the carrier frequency of the described carrier triangular wave phase shift SPWM of a phase H bridge power model at the H electrical bridge element circuit place of described damage, to obtain the Sampling waveform of the carrier triangular wave phase shift SPWM corresponding with H electrical bridge element circuit quantity remaining in this phase H bridge power model;
The method of work of described point of phase current independent controling circuit comprises the steps:
(1) by phaselocked loop according to the momentary value of voltage of the described three phase mains of input to follow the tracks of the voltage-phase of described three phase mains;
(2) voltage-phase drawn according to described phaselocked loop calculates the cosine amount of this voltage-phase and is multiplied with a wattless current reference value, exports to obtain actual wattless current;
(3) voltage-phase drawn according to described phaselocked loop calculates the sinusoidal quantity of this voltage-phase, to subtract each other with the voltage reference value of a DC bus capacitor according to the average voltage of the DC bus capacitor of described each phase H bridge power model simultaneously and be multiplied with described sinusoidal quantity again after PI controls, to obtain the active current output of reality;
(4) for first the electric current that given for described wattless current module and the given module of active current export being superposed, then the transient current in described three phase mains is deducted, and by controller to calculate modulation ratio M and the phase angle of the sinusoidal modulation wave needed for described pulse-width modulation circuit
.
Compared with prior art, the method of work tool of the control gear of control titanium rotation speed of fan of the present invention has the following advantages: (1) is by setting up at least one H electrical bridge element circuit for subsequent use in every phase H bridge power model, when H bridge power model is damaged, auto by pass malfunctioning module, without the need to maintenance down; (2) pulse-width modulation circuit regulates the modulated wave of the phase H bridge power model be damaged, and effectively avoids harmonic wave and produces; (3) by dividing the phase current independence control realization three phase mains compensation problem that imbalance exports.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in detail:
Embodiment 1
As shown in Figure 1, a kind of control gear being suitable for control titanium rotation speed of fan, comprising: the gas concentration sensor being located at gas discharge outlet, this gas concentration sensor is connected with MCU module, and this MCU module is suitable for the motor speed controlling described titanium blower fan.
The chain type SVG device that one is suitable for correcting power factor is connected at the three-phase power input end of described motor.
As Figure 2-3, described chain type SVG device comprises:
The multi-electrical level inverter of H electrical bridge multi-type, it is made up of the three-phase H bridge power model being connected to described three phase mains, wherein, sets up at least one H electrical bridge element circuit for subsequent use in every phase H bridge power model;
Auto by pass circuit, is located at the output terminal of each H electrical bridge element circuit, and when a H electrical bridge element circuit is damaged, by this H electrical bridge element circuit bypass;
Sample circuit, is suitable for the momentary value of the voltage and current gathering described three phase mains, and this momentary value comprises amplitude, the cycle of voltage and current;
Divide phase current independent controling circuit, what it was connected with described sample circuit is suitable for the modulation ratio M and the phase angle that calculate the sinusoidal modulation wave needed for described pulse-width modulation circuit according to the momentary value of the voltage and current of described three phase mains
;
Pulse-width modulation circuit, is connected with described point of phase current independent controling circuit, for according to the modulation ratio M of described sinusoidal modulation wave and phase angle
the carrier triangular wave phase shift SPWM adopted between each H electrical bridge element circuit is controlled; Namely, when after the H electrical bridge element circuit bypass damaged, this pulse-width modulation circuit is suitable on the basis keeping the sampling period of described sample circuit constant, change the carrier frequency of the described carrier triangular wave phase shift SPWM of a phase H bridge power model at the H electrical bridge element circuit place of this damage, to obtain the Sampling waveform of the carrier triangular wave phase shift SPWM corresponding with H electrical bridge element circuit quantity remaining in this phase H bridge power model.
See Fig. 4, described point of phase current independent controling circuit, comprising:
Phaselocked loop, according to the momentary value of the voltage of described three phase mains to follow the tracks of the voltage-phase of described three phase mains;
The given module of wattless current, the voltage-phase being suitable for drawing according to described phaselocked loop calculates the cosine amount of this voltage-phase and is multiplied with a wattless current reference value, exports to obtain actual wattless current;
The given module of active current, the voltage-phase being suitable for drawing according to described phaselocked loop calculates the sinusoidal quantity of this voltage-phase, to subtract each other with the voltage reference value of a DC bus capacitor according to the average voltage of the DC bus capacitor of described each phase H bridge power model simultaneously and be multiplied with described sinusoidal quantity again after PI controls, to obtain the active current output of reality;
Transient current tracing module, for first the electric current that given for described wattless current module and the given module of active current export being superposed, then the transient current in described three phase mains is deducted, and by controller to calculate modulation ratio M and the phase angle of the sinusoidal modulation wave needed for described pulse-width modulation circuit
.
Wherein reference current is the offset current expected, direct voltage reference value is the offset voltage expected.
Described pulse-width modulation circuit relates to SPWM pulse width modulation method, this SPWM pulse width modulation method does modulated wave with a sine wave, doubly do that carrier wave carries out waveform comparison and one group of amplitude producing is equal to the pyramidal wave of sinusoidal modulation wave frequency with F, the rectangular pulse train that width is proportional to sinusoidal modulation wave carrys out equivalent sine wave, thus the break-make of control switch device (switching device namely in multi-electrical level inverter).
The hybrid algo-rithm that the present invention adopts carrier triangular wave phase shift SPWM to control and the stacked SPWM of carrier triangular wave controls: as a whole, carrier triangular wave phase shift SPWM is adopted to control between each H electrical bridge element circuit, and the method that single H electrical bridge element circuit adopts stacked SPWM to control, this modulator approach, output harmonic wave content is little, switching frequency is low, and can solve the low problem of inversion efficiency well.
Carrier triangular wave phase shift SPWM control methods, refer to for N number of H electrical bridge element circuit, adopt N number of phase place different, but the carrier triangular wave that frequency is identical with amplitude and same sinusoidal modulation wave compare, produce N group SPWM control impuls waveform to go respectively to control N number of H bridge, make each H electrical bridge element circuit all export the identical SPWM voltage waveform of fundamental voltage, and then the SPWM voltage waveform that this N number of H electrical bridge element circuit exports is carried out superposing and synthesizes SPWM voltage with multiple levels waveform.
The Initial phase of N number of carrier triangular wave should remove an angle successively, and according to bipolarity carrier triangular wave, this angle is
; If unipolarity carrier triangular wave, angle is
.
Carrier triangular wave stacked SPWM control methods is the SPWM modulation method of Application comparison a kind of multi-electrical level inverter early.The stacked SPWM modulation method of carrier triangular wave can be divided into two kinds, i.e. the stacked SPWM modulation method of individual layer and multilayer layer stacked SPWM modulation method, and these two kinds of methods can reach the technique effect of this patent.
Carrier triangular wave individual layer stacked SPWM modulation method can be divided into again the anti-phase individual layer of carrier triangular wave stacked SPWM modulation method (phase place of two carrier triangular wave is contrary) and carrier triangular wave homophase individual layer stacked SPWM modulation method (phase place of two carrier triangular wave is identical) according to the phase relationship of two triangular carriers.The anti-phase individual layer of carrier triangular wave stacked SPWM modulation method and the stacked SPWM modulation method of carrier triangular wave homophase individual layer this in two modulator approach do not have what quality point, the present invention adopts the stacked SPWM modulation method of carrier triangular wave homophase individual layer.
In the stacked SPWM modulation method of carrier triangular wave homophase individual layer, two carrier triangular wave
with
phase place identical, its work wave is as shown in Figure 5.Wherein
with
for the carrier triangular wave of the upper and lower layer of transverse axis,
for sinusoidal modulation wave.Compare, at sine wave with pyramidal wave with sinusoidal wave
the part being greater than pyramidal wave can produce and export SPWM pulse, at sine wave
the part being less than pyramidal wave can produce the zero pulse of output voltage.Due to
with
homophase, that is
with
be asymmetric with abscissa line, so by sinusoidal wave comparing with pyramidal wave, the positive half cycle of the output voltage SPWM waveform of generation is not identical with negative semiaxis.
Appoint and get a H electrical bridge element circuit and study, from power perspective analysis.If
for the output voltage of H electrical bridge element circuit,
for phase current,
for the angle of output voltage and phase current, then the active power that H electrical bridge element circuit absorbs is:
, visible, the active power of H bridge absorption just can be changed by changing H electrical bridge element circuit output voltage size, phase current size and the angle between them.Because phase current
size and Orientation fix, so the size and Orientation of H electrical bridge element circuit output voltage can only be changed, namely correspond to pulse-width modulation circuit export modulation ratio M and phase shifting angle
.
The control strategy of chain type SVG adopts the control structure of layering: top level control mainly determines total meritorious and wattless power, and lower floor controls mainly to regulate the reasonable distribution of gaining merit between this mutually each H bridge, ensures DC capacitor voltage balance.The method of top level control of the present invention adopts a point phase current independently to control, calculate modulation ratio and the phase angle of the modulated wave of expectation, be that sine function is superimposed upon on the modulated wave of this H electrical bridge element circuit by the error quantization of each bridge DC side voltage, the modulated wave phase place of each H electrical bridge element circuit is finely tuned, regulates the distribution of gaining merit between each H electrical bridge element circuit.
There is not coupled relation in the three-phase dc side of chain type SVG, thus can realize individual-phase control, compensate respectively three-phase system, all can have reasonable compensation effect to balance sysmte and unbalanced system.The control strategy proposed in leading portion, its top level control adopts the full decoupled control of current status, and transient response is fast, and good stability, but situation when only considered three-phase equilibrium during Controller gain variations, do not consider the unbalanced problem of three-phase system.Show power grid quality investigation, more or less there is the asymmetric of phase place or amplitude in line voltage, that is in a practical situation, three-phase system is unbalanced mostly.
Auto by pass circuit, adopt auto by pass technology, auto by pass technology is exactly direct by the bypass of fault power module AC, thus realizes being separated of malfunctioning module and device.Auto by pass is realized by arranging a bypass mechanism at the outlet side of each power unit module.
Can adopt and be provided with a relay at the output terminal of each H electrical bridge element circuit, utilize and control often to open to be separated with this phase H bridge power model to realize fault H electrical bridge element circuit with normally off; Also can adopt rectifier bridge and thyristor, the output terminal of each H electrical bridge element circuit is connected to the rectifier bridge of two pairs of diodes compositions, so under thyristor is in forward voltage drop all the time.When supervisory system detects power model internal fault, block IGBT pulse immediately, and trigger turn on thyristors, realize bypass and be separated; Or employing bidirectional thyristor.
After having fault H electrical bridge element circuit to be bypassed in a certain phase H bridge power model, if the pulse of the sinusoidal modulation signal that pulse-width modulation circuit exports sends or send according to during normal operation, and the output of this chain type SVG control system only has N number of H electrical bridge element circuit output voltage to superpose, harmonic content will increase.Therefore, for remaining N number of non-faulting H electrical bridge element circuit, modulation strategy need do corresponding adjustment.
Because the stacked SPWM of carrier triangular wave just works in single H electrical bridge element circuit inside, therefore malfunctioning module is separated the stacked SPWM modulation of carrier triangular wave not impact, only impacts carrier triangular wave phase shift SPWM.So, conveniently analyze, only carrier triangular wave phase shift SPWM is analyzed.If during N+1 H electrical bridge element circuit series connection, the carrier frequency of this chain type SVG control system is 1/T
c, the sampling period is T
s, when carrier wave is unipolarity, sampling period T
s=T
c/ [2 (N+1)].The conventional adjusting method of latter two is separated below to the H electrical bridge element circuit that is out of order.
First method: T
cconstant, T
schange
For simplifying the analysis, before selecting fault, if described multi-electrical level inverter number is n+1=6, then the sampling period T of each phase H bridge power model
s=T
c/ 12, at 0/6T
s, T
s/ 7T
s, 2T
s/ 8T
s, 3T
s/ 9T
s, 4T
s/ 10T
s, 5T
s/ 11T
smoment sample modulation ripple, and compare the corresponding trigger impulse of generation, as shown in Figure 6.
If a certain H electrical bridge element circuit is because of break down separated rear (supposing that first H electrical bridge element circuit is separated), if not being adjusted accordingly modulation strategy, then remain the pulse generate sequential of N number of non-faulting H electrical bridge element circuit as shown in Fig. 7 (a).As can be seen from the figure the sampling interval between H electrical bridge element circuit 0 and H electrical bridge element circuit 2 is 2T
sbut the sampling interval between other power H electrical bridge element circuits is T
s, this does not obviously meet the basic principle of phase-shifted SPWM modulation.The harmonic content of the output voltage of SVG device must increase.
If carrier cycle is constant, be still T
cbut, by the sampling period at T
cinside readjust.As shown in Fig. 7 (b), after fault, the quantity of described multi-electrical level inverter becomes 5, thus the sampling period after modulation is T
s'=T
c/ 10.So the complete phase-shifting carrier wave producing N=5 is exported pulse.
The method adjusts the switch modulation strategy of this phase phase-shifted SPWM by the sampling period changing fault phase (a phase H bridge power model at the H electrical bridge element circuit place of breaking down).Concerning this phase, good regulating action can be played.
Second method: T
cchange, T
sconstant
When first H electrical bridge element circuit breaks down separated, keep sampling period T
sconstant, adjust the carrier triangular period of wave of this phase.As shown in Figure 8.
After adjustment, the carrier cycle of fault phase is Tc ', keeps the carrier cycle Tc of other healthy phases constant.Pulse sequence after adjustment is as shown in Fig. 8 (b): in 0/5Ts, Ts/6Ts, 2Ts/7Ts, 3Ts/8Ts, 4Ts/9Ts moment, and a sample modulation ripple generates the trigger impulse of H bridge power model.Like this, the phase-shifted SPWM Sampling waveform of complete N=5 is obtained.Because the sampling period of fault phase does not change before and after malfunctioning module is separated, after fault reconstruction, the synchronism that three phase circuit is sampled still can be ensured.
The method of work of described point of phase current independent controling circuit.See Fig. 4, in figure
,
,
, collect three-phase voltage momentary value for Acquisition Circuit;
,
,
for the voltage-phase of the three phase mains that PLL traces into;
,
,
, be each phase wattless current reference value;
,
,
for the average voltage of the DC bus capacitor of each phase H bridge power model;
the voltage reference value of DC bus capacitor;
,
,
for Acquisition Circuit collects three phase circuit momentary value; The reference signal of SVG output voltage can be calculated by corresponding PI controller, then calculate the voltage reference value of corresponding each phase wattless current reference value and DC bus capacitor according to Instantaneous Power Theory further.The concrete grammar of the voltage reference value of above-mentioned acquisition each phase wattless current reference value and DC bus capacitor refers to document: Yang Jun, Wang Zhaoan, Qiu Guanyuan. a kind of detecting method [J] of Harmonic in Single-phase Circuit and wattless current, electrotechnics journal, 1996 (3), 11 (3): 42-46; Jiang Bin, Yan Gangfeng, Zhao Guangzhou. single-phase circuit Instantaneous Harmonic and real time sampling idle new method [J]. power system automation, 2000 (11): 36-39.
Embodiment 2
See Fig. 2-4, on the basis of embodiment 1, the method for work of the control gear of described titanium rotation speed of fan, comprising:
The method of work of described chain type SVG device comprises the steps:
A: when a H electrical bridge element circuit damages, this H electrical bridge element circuit of corresponding auto by pass circuits bypass;
B: described pulse-width modulation circuit is on the basis keeping the sampling period of described sample circuit constant, change the carrier frequency of the described carrier triangular wave phase shift SPWM of a phase H bridge power model at the H electrical bridge element circuit place of described damage, to obtain the Sampling waveform of the carrier triangular wave phase shift SPWM corresponding with H electrical bridge element circuit quantity remaining in this phase H bridge power model;
The method of work of described point of phase current independent controling circuit comprises the steps:
(1) by phaselocked loop according to the momentary value of voltage of the described three phase mains of input to follow the tracks of the voltage-phase of described three phase mains;
(2) voltage-phase drawn according to described phaselocked loop calculates the cosine amount of this voltage-phase and is multiplied with a wattless current reference value, exports to obtain actual wattless current;
(3) voltage-phase drawn according to described phaselocked loop calculates the sinusoidal quantity of this voltage-phase, to subtract each other with the voltage reference value of a DC bus capacitor according to the average voltage of the DC bus capacitor of described each phase H bridge power model simultaneously and be multiplied with described sinusoidal quantity again after PI controls, to obtain the active current output of reality;
(4) for first the electric current that given for described wattless current module and the given module of active current export being superposed, then the transient current in described three phase mains is deducted, and by controller to calculate modulation ratio M and the phase angle of the sinusoidal modulation wave needed for described pulse-width modulation circuit
.
Obviously, above-described embodiment is only for example of the present invention is clearly described, and is not the restriction to embodiments of the present invention.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without the need to also giving all mode of executions.And these belong to spirit institute's apparent change of extending out of the present invention or change and are still among protection scope of the present invention.