CN203608104U

CN203608104U - Dual-closed loop control-type single-phase inverter

Info

Publication number: CN203608104U
Application number: CN201320768405.0U
Authority: CN
Inventors: 李海军; 尚桦; 赵克明; 罗凯
Original assignee: China Three Gorges University CTGU
Current assignee: China Three Gorges University CTGU
Priority date: 2013-11-29
Filing date: 2013-11-29
Publication date: 2014-05-21
Anticipated expiration: 2023-11-29

Abstract

A dual-closed loop control-type single-phase inverter comprises an AC input terminal, which is connected to a first rectification filter circuit connected to a bridge inverter circuit connected to a voltage current dual-closed loop circuit, which is connected to a single-chip microcomputer module via an A/D converter. The single-chip microcomputer is connected to an LCD module and a keyboard module separately. The single-chip microcomputer transmits a 50Hz SPWM wave and a 30KHz square wave simultaneously. The voltage comparator is connected to an IR2110 driver module, which is connected to the bridge inverter circuit. The inverter employs a dual-closed loop control method, which has high stable state precision, a high-quality output waveform and good dynamic performance, compared to a common digital closed loop.

Description

A kind of two closed-loop control formula Single-Phase Inverter Source

Technical field

The utility model relates to a kind of Single-Phase Inverter Source, particularly a kind of two closed-loop control formula Single-Phase Inverter Source.

Background technology

In daily life, people inevitably will carry some power-supply devices and conduct a field operation.Be single phase alternating current power supply but most of equipment uses, and energy storage device mostly is DC power supply, therefore the design of single-phase inverter is necessary.And the quality of inverter depends on the quality of output waveform, and the output waveform of high-quality has the requirement of two aspects: stable state accuracy is high and dynamic response is fast.The stability boundaris of traditional acquisition system that is difficult to take voltage control theory as basic control mode, so be difficult to obtain desirable dynamic response in the time of external disturbance.

Summary of the invention

For solving the problems of the technologies described above, the utility model provides a kind of two closed-loop control formula Single-Phase Inverter Source, has adopted the control mode of two closed loops, and it is high that more general digital closed loop has stable state accuracy, there is the output waveform of high-quality, good, the adaptable feature of dynamic property.

The technical scheme that the utility model is taked is: a kind of two closed-loop control formula Single-Phase Inverter Sources, comprise ac input end, ac input end connects the first current rectifying and wave filtering circuit, the first current rectifying and wave filtering circuit connects bridge inverter main circuit, bridge inverter main circuit connects voltage and current double closed-loop circuit, voltage and current double closed-loop circuit connects one-chip computer module by A/D converter, and one-chip computer module connects respectively LCD MODULE, Keysheet module.Described one-chip computer module sends the SPWM ripple of 50Hz, the square wave of 30KHz simultaneously, one road SPWM ripple connects voltage and current double closed-loop circuit by the first low pass filter, voltage and current double closed-loop circuit connects voltage comparator, the square wave of another road 30KHz connects voltage comparator by integrator, voltage comparator connects IR2110 driver module, and described IR2110 driver module connects described bridge inverter main circuit.

Described voltage and current double closed-loop circuit comprises: the second low pass filter, voltage feedback circuit, current feedback circuit, the second low pass filter connects bridge inverter main circuit, and second current rectifying and wave filtering circuit of leading up to of the second low pass filter connects A/D converter, another road connection voltage feedback circuit and current feedback circuit.

Described one-chip computer module is: MSP430F2618 single-chip microcomputer, described LCD MODULE is: FYD12864 liquid crystal display, described Keysheet module is: 8279 keyboards.

A kind of two closed-loop control formula Single-Phase Inverter Sources of the utility model, have introduced respectively voltage, stream feedback.Voltage Feedback is output voltage feedback, i.e. voltage in load, is also the voltage at filter capacitor two ends.For the input variable of Voltage Feedback.Current feedback is that filter capacitor electric current is the input variable of current feedback.Capacitance current is the differential of output voltage, so ring has the dynamic compensation ability to disturbance in capacitor current feedback, comprises the sudden change of reference input and load.As long as the corresponding speed of capacitive current inner ring is enough fast, disturbance just can obtain better must the inhibition by interior ring to the impact of output voltage.A kind of two closed-loop control formula Single-Phase Inverter Sources of the utility model, have the output waveform of high-quality; Adopted the control mode of two closed loops, more general digital closed loop has that stable state accuracy is high, dynamic property good, adaptable feature.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the utility model is described in further detail:

Fig. 1 is that a kind of two closed-loop control formula Single-Phase Inverter Sources of the utility model connect block diagram.

Fig. 2 is the utility model dicyclo control structure figure.

Fig. 3 is the utility model AC power current rectifying and wave filtering circuit figure.

Fig. 4 is the utility model voltage, current feedback circuit figure.

Fig. 5 is that the utility model SPWM produces circuit diagram.

Fig. 6 is triangular wave figure.

Fig. 7 is single-phase voltage SPWM inverter main circuit topology.

Fig. 8 is LC filter circuit figure.

Fig. 9 is inverter output voltage spectrogram.

Embodiment

As shown in Figure 1, a kind of two closed-loop control formula Single-Phase Inverter Source, comprise ac input end, ac input end connects the first current rectifying and wave filtering circuit, the first current rectifying and wave filtering circuit connects bridge inverter main circuit, bridge inverter main circuit connects voltage and current double closed-loop circuit, and voltage and current double closed-loop circuit connects one-chip computer module by A/D converter, and one-chip computer module connects respectively LCD MODULE, Keysheet module.Described one-chip computer module sends the SPWM ripple of 50Hz, the square wave of 30KHz simultaneously, one road SPWM ripple connects voltage and current double closed-loop circuit by the first low pass filter, voltage and current double closed-loop circuit connects voltage comparator, the square wave of another road 30KHz connects voltage comparator by integrator, voltage comparator connects IR2110 driver module, and described IR2110 driver module connects described bridge inverter main circuit.Described voltage and current double closed-loop circuit comprises: the second low pass filter, voltage feedback circuit, current feedback circuit, the second low pass filter connects bridge inverter main circuit, and second current rectifying and wave filtering circuit of leading up to of the second low pass filter connects A/D converter, another road connection voltage feedback circuit and current feedback circuit.

Described one-chip computer module is: MSP430F2618 single-chip microcomputer.Described LCD MODULE is: FYD12864 liquid crystal display.Described Keysheet module is: 8279 keyboards.

Single-phase Sinusoidal Inverter composition: Single-Phase Inverter Source system block diagram as shown in Figure 1.Control core adopts MSP430F2618 High Performance SCM.Form man-machine interface by FYD12864 liquid crystal display, 8279 keyboards.Single-chip microcomputer sends the SPWM ripple of 50Hz and the square wave of 30KHz simultaneously.

Dicyclo control structure: as shown in Figure 2, Voltage loop is as contrary feedback Instantaneous Control outer shroud, and electric current loop is as encircling in contrary feedback Instantaneous Control.Inverter output voltage is through proportional component and reference voltage comparison, error through PI regulate after as a part of benchmark encircling in Current Control, this benchmark with from the capacitance current of proportional component relatively after, then regulate and amplifying element has just obtained the output voltage of inverter switching device pipe through ratio.

AC power current rectifying and wave filtering circuit design: the civil power of 220V/50Hzd, through a voltage regulator, must step direct current through rectification.Obtain a direct current through a large electric capacity 10000uF/100V capacitor filtering, its circuit diagram as shown in Figure 3.In circuit diagram, F1 is 5A fuse.And series current Hall U1 in main circuit.Bus current is monitored in real time.In the time that its peak value reaches 4A, protect, produce guard signal by protective circuit, block and drive signal, reach the object to four switching tube protections.

Selecting of feedback element: here feedback element all use be Hall element, Hall element is the voltage of application Hall effect closed loop principle, current sensor can be measured the electric current of direct current, interchange, pulse and various irregular waveforms under electrically isolated condition.Be equivalent to the method with resistance sampling, have the following advantages with Hall element: outstanding precision, the good linearity, printed board is installed, and antijamming capability is strong, and current overload ability is strong.

Feedback circuit: as shown in Figure 4, the specified rate of the reponse system of electric current and voltage is all the in-phase end output from amplifier, and feedback quantity is all to input from inverting input.If given sine is

Figure 2013207684050100002DEST_PATH_IMAGE001

, Voltage Feedback is , the voltage of TL082 the first pin is , in-phase end (voltages of 3 pin) is

, end of oppisite phase (voltages of 2 pin) is

.

Solution:

Current segment is similar with it.

SPWM produces circuit: concrete grammar, take a sine wave as reference wave, is called modulating wave.Be called carrier wave with the triangular wave of a row constant amplitude, crossing with baseline sinusoidal wave, determined the switching mode of inverter by their intersection point.The feature of the output voltage waveforms that inverter obtains is: within the scope of half period, always middle pulse is wide.The pulse on both sides is narrow, and the area under each pulse area and this interval sine wave is proportional.With this ripple control switch pipe, make output voltage pulse duration become sinusoidal variations.Here, we have used voltage comparator: LM311, there is 80ns its typical response time.Meet the carrier wave demand of 30KHz.Fig. 5 is its SPWM generation circuit.

Reference sine wave

obtain to such an extent that pulse removes to control each device for power switching with triangle wave.Because on off state is discontinuous, when analysis, we adopt State-space Averaging Principle.State-space Averaging Principle opportunity, in a switch periods, replaces its instantaneous value with the mean value of variable, thereby obtains the averaging model of continuous state space based on output frequency in the situation of switching frequency.As shown in Figure 6, within a triangular wave cycle, the amplitude of first-harmonic is approximately sinusoidal wave instantaneous value.If D is duty ratio.By two similar obtaining of triangular form.

In formula,

for with reference to sinusoidal signal ripple. for the amplitude of triangular carrier.

Output to switching tube input from comparator, due to the variation except waveforms amplitude, there is no other variation, intermediateness can be regarded proportional component as.In the time that bipolar SPWM is modulated, the input of single-phase bridge type inverter can be expressed as

In formula, S is switch function,

for DC bus-bar voltage.

In the time of Q1 and Q4 conducting, S=1; In the time of Q2 and Q3 conducting, S=0.

For easy analysis, we are we can obtain S=D substitution above formula here:

Continue handle

substitution can obtain:

The transfer function that is input to inverter output from modulator is:

Inverter output filter:

Because this inverter adopts Pulse Width Modulation mode, because determining the output voltage of switching device, the characteristic of SPWM ripple itself contains more harmonic component.At this, filter adopts typical LC filter.The output LC filter of inverter is mainly used to leach near the harmonic wave of the frequency band of switching frequency.Therefore, the quality of LC design of filter directly has influence on the quality of output waveform.

At single-phase voltage SPWM inverter main circuit topology, as shown in Figure 7.For simplifying the analysis, take following mode to simplify circuit: 1, direct voltage

for ideal voltage source; 2, the switch of inverter is perfect switch; 3, ignore the parasitic parameter of inductance and electric capacity; 4, load is linear load.

Because inverter is worked in high-frequency PWM mode, the effect of output filter is to filter higher harmonic components, output voltage is approached sinusoidal wave, therefore the while also wants the factors such as the power density of taking into account inverter system, and design of filter target comprises: 1, the harmonic content of output voltage is little; 2, filtering parameter and volume are little; 3, characteristic is good frequently in the resistance of filter; 4, the power that filtering system consumes is little.According to above principle, can analyze the characteristic of filter.

LC filter transfer function is:

In formula,

for undamped nature hunting angle frequency,

,

;

for damping ratio, s is Laplacian.

Filter is determined by frequency:

For Single-phase PWM Inverter output voltage spectrum analysis, each harmonic forms with n=jk (j=1,2,3) the humorous wavestrip of upper and lower side frequency that centered by, amplitude is successively decreased, wherein k is the modulation ratio ratio of fundamental frequency (carrier frequency with), and in band, each harmonic can be expressed as n=jk ± b, wherein j+b ≠ even number, inverter output voltage spectrogram, as shown in Figure 9.

Can be found out by Fig. 9 inverter output voltage frequency spectrum, the minimum harmonic group of SPWM inverter output voltage is: n=k ± b, because sideband harmonic amplitude is decayed, the b value that is enough to exert an influence can be very not high, therefore k value is depended in the position of low harmonic group, be that k value is higher, a minimum lower sideband from first-harmonic just more away from.In order to make filter output voltage approach sinusoidal wave resonance problems, the cut-off frequency of LC filter of can not causing again simultaneously

must be much smaller than contained minimum subfrequency in SPWM voltage, simultaneously again much larger than fundamental frequency.LC cut-off frequency fL elects as:

10

<?

?<

for fundamental frequency; for minimum subfrequency.

Select the noninductive electric capacity of 10uF, the nanocrystalline inductance of 5mH here.Can be calculated it

for 712.12Hz, =4472.1rad/s.

Claims

1. a two closed-loop control formula Single-Phase Inverter Source, comprise ac input end, it is characterized in that, ac input end connects the first current rectifying and wave filtering circuit, the first current rectifying and wave filtering circuit connects bridge inverter main circuit, bridge inverter main circuit connects voltage and current double closed-loop circuit, and voltage and current double closed-loop circuit connects one-chip computer module by A/D converter, and one-chip computer module connects respectively LCD MODULE, Keysheet module;

Described one-chip computer module sends the SPWM ripple of 50Hz, the square wave of 30KHz simultaneously, one road SPWM ripple connects voltage and current double closed-loop circuit by the first low pass filter, voltage and current double closed-loop circuit connects voltage comparator, the square wave of another road 30KHz connects voltage comparator by integrator, voltage comparator connects IR2110 driver module, and described IR2110 driver module connects described bridge inverter main circuit.

2. a kind of two closed-loop control formula Single-Phase Inverter Sources according to claim 1, it is characterized in that, described voltage and current double closed-loop circuit comprises: the second low pass filter, voltage feedback circuit, current feedback circuit, the second low pass filter connects bridge inverter main circuit, and second current rectifying and wave filtering circuit of leading up to of the second low pass filter connects A/D converter, another road connection voltage feedback circuit and current feedback circuit.

3. a kind of two closed-loop control formula Single-Phase Inverter Sources according to claim 1, is characterized in that, described one-chip computer module is: MSP430F2618 single-chip microcomputer.

4. a kind of two closed-loop control formula Single-Phase Inverter Sources according to claim 1, is characterized in that, described LCD MODULE is: FYD12864 liquid crystal display.

5. a kind of two closed-loop control formula Single-Phase Inverter Sources according to claim 1, is characterized in that, described Keysheet module is: 8279 keyboards.