CN103929086A - Photovoltaic inverter and power-on self-testing method thereof - Google Patents
Photovoltaic inverter and power-on self-testing method thereof Download PDFInfo
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Abstract
The invention discloses a photovoltaic inverter and a power-on self-testing method of the photovoltaic inverter. The power-on self-testing method includes the steps that a direct-current-side on-off control module is added on the direct-current side of the photovoltaic inverter, wherein the direct-current-side on-off control module comprises a soft start on-off element, a soft start resistor, a partial voltage on-off element and a partial voltage resistor, the soft start on-off element and the soft start resistor are connected in series, and the partial voltage on-off element and the partial voltage resistor are connected in series; when the soft start on-off element and the partial voltage on-off element are closed, the soft start resistor is connected with the partial voltage resistor in series, a main on-off element and an alternating-current on-off element of the photovoltaic inverter are controlled to be kept in an off state, the main on-off element is located on the direct-current side of the photovoltaic inverter, and the alternating-current on-off element is located between an inverter bridge of the photovoltaic inverter and a power grid. Through the partial voltage resistor, input voltage is kept in a low-voltage and low-current state, so that due to the low voltage and the low current, even if the inverter bridge has short circuit or other faults, the inverter bridge does not explode with a big sound.
Description
Technical field
The present invention relates to photovoltaic DC-to-AC converter technical field, be specifically related to a kind of photovoltaic DC-to-AC converter and startup self-detection method thereof.
Background technology
Due to reasons such as power generation site environment, power grid environment complicated conditions, photovoltaic DC-to-AC converter bursts in the time of may appearance can starting shooting inversion, and sends very large explosive sound.Generally, as long as the core component inverter bridge of photovoltaic DC-to-AC converter does not go wrong, inverter there will not be the situation of aircraft bombing.So, if can inverter bridge partly not carried out to fault self-checking before start at inverter, can avoid aircraft bombing.Inverter bridge is conventionally by IGBT(Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) module or discrete device build and obtain.IGBT module generally carries CE detection signal, by the quality of this signal judgement IGBT module.But expensive due to IGBT module, has very large restriction for the cost of complete machine, so greatly reduced the price competitiveness of machine on market.Therefore,, for cost consideration, the inverter bridge of a lot of inverters is to be built and obtained by discrete device on the market.Yet, the rare discrete device fault start of inverter bridge that discrete device is built in the market detects, but for the purpose of safety, in order to detect discrete device state, have to build voltage sampling circuit at C, the E two ends of each device, such mode is feasible for two level or the few inverter bridge of discrete device quantity, but when for three level and above or discrete device parallel transistor quantum count are when numerous, to build many voltage sampling circuits undoubtedly, cause cost to rise thereupon.
Summary of the invention
An object of the present invention is, even if make the short circuit of inverter bridge of photovoltaic DC-to-AC converter or have other fault, when start inversion, also bursting of large sound can not occur.
Another object of the present invention is while realizing photovoltaic DC-to-AC converter startup self-detection, can detect inverter bridge and whether have fault, thereby can avoid the aircraft bombing phenomenon of starting shooting.
According to a first aspect of the invention, the invention provides a kind of startup self-detection method of photovoltaic DC-to-AC converter, comprise: in the DC side of photovoltaic DC-to-AC converter, increase DC side break-make control module, described DC side break-make control module comprises soft on-off element of series connection and dividing potential drop on-off element and the divider resistance of soft resistance and series connection; The dividing potential drop on-off element of described series connection and the input capacitance branch circuit parallel connection of divider resistance and photovoltaic DC-to-AC converter, one end of described soft resistance is connected to one end of described divider resistance; Closed described soft on-off element and described dividing potential drop on-off element, described soft resistance is connected with described divider resistance, and, the main on-off element of controlling described photovoltaic DC-to-AC converter with exchange on-off element and remain off-state, wherein said main on-off element is positioned at the DC side of photovoltaic DC-to-AC converter, and described interchange on-off element is between the inverter bridge and electrical network of described photovoltaic DC-to-AC converter.
Further, also comprise: whether the voltage that judges described input capacitance branch road equals the first reference voltage, if be not equal to, determine that the inverter bridge of described photovoltaic DC-to-AC converter exists fault, if equaled, inverter voltage is detected to determine whether inverter bridge exists fault.
Preferably, described inverter voltage is detected to determine whether inverter bridge exists this step of fault to comprise: the control module of described photovoltaic DC-to-AC converter is sent pulse width modulating signal and made described inverter bridge inversion, sampling inverter voltage, and judge whether described inverter voltage equals the second reference voltage, if be not equal to, there is fault in the inverter bridge of determining described photovoltaic DC-to-AC converter, if equaled, the control module of described photovoltaic DC-to-AC converter stops sending pulse width modulating signal, disconnects described soft on-off element and described dividing potential drop on-off element.
Preferably, the inverter bridge of described definite described photovoltaic DC-to-AC converter also comprises after there is this step of fault: disconnect described soft on-off element, finish startup self-detection.
Preferably, described soft on-off element is relay or contactor, and described dividing potential drop on-off element is relay or contactor, and described main on-off element is relay or contactor, and described interchange on-off element is relay or contactor; The inverter bridge that described photovoltaic DC-to-AC converter adopts is IGBT or MOSFET.
According to a second aspect of the invention, the invention provides a kind of photovoltaic DC-to-AC converter inverter bridge fault startup self-detection method, comprise: in the DC side of photovoltaic DC-to-AC converter, increase DC side break-make control module, described DC side break-make control module comprises soft on-off element of series connection and dividing potential drop on-off element and the divider resistance of soft resistance and series connection; The dividing potential drop on-off element of described series connection and the input capacitance branch circuit parallel connection of divider resistance and photovoltaic DC-to-AC converter, one end of described soft resistance is connected to one end of described divider resistance; Closed described soft on-off element and described dividing potential drop on-off element, described soft resistance is connected with described divider resistance, and, the main on-off element of controlling described photovoltaic DC-to-AC converter with exchange on-off element and remain off-state, wherein said main on-off element is positioned at the DC side of photovoltaic DC-to-AC converter, and described interchange on-off element is between the inverter bridge and electrical network of described photovoltaic DC-to-AC converter.
Further, also comprise: whether the voltage that judges described input capacitance branch road equals the first reference voltage, if be not equal to, determine that the inverter bridge of described photovoltaic DC-to-AC converter exists fault, if equaled, inverter voltage is detected to determine whether inverter bridge exists fault.
Preferably, described inverter voltage is detected to determine whether inverter bridge exists this step of fault to comprise: the control module of described photovoltaic DC-to-AC converter is sent pulse width modulating signal and made described inverter bridge inversion, sampling inverter voltage, and judge whether described inverter voltage equals the second reference voltage, if be not equal to, there is fault in the inverter bridge of determining described photovoltaic DC-to-AC converter, if equaled, the control module of described photovoltaic DC-to-AC converter stops sending pulse width modulating signal, disconnects described soft on-off element and described dividing potential drop on-off element.
According to a third aspect of the invention we, the invention provides a kind of photovoltaic DC-to-AC converter, its input is connected with photovoltaic array, output is connected with electrical network, described photovoltaic DC-to-AC converter comprises input capacitance branch road, inverter bridge circuit and the control module connecting successively, also comprises the disconnection module that is controlled by described control module; Described disconnection module comprises and is connected in the DC side break-make control module between described photovoltaic array and described input capacitance branch road and is connected in the interchange break-make module between described inverter bridge circuit and described electrical network; Described DC side break-make control module comprises soft on-off element of the main on-off element that is connected between described photovoltaic array and described input capacitance branch road, series connection and dividing potential drop on-off element and the divider resistance of soft resistance and series connection, the dividing potential drop on-off element of described series connection and divider resistance and described input capacitance branch circuit parallel connection, one end of described soft resistance is connected to one end of described divider resistance, and when described soft on-off element and the equal closure of described dividing potential drop on-off element, described soft resistance is connected with described divider resistance; Described control module remains off-state for control described main on-off element when startup self-detection with the described break-make module that exchanges.
Preferably, described soft on-off element is relay or contactor, described dividing potential drop on-off element is relay or contactor, described main on-off element is relay or contactor, described interchange on-off element is relay or contactor, and the inverter bridge that described photovoltaic DC-to-AC converter adopts is IGBT or MOSFET.
The invention has the beneficial effects as follows: by increasing divider resistance and dividing potential drop on-off element in DC side, make the voltage of input capacitance branch road equal the voltage on divider resistance, the input voltage of inverter bridge remains on low-pressure state during self check thus, and because voltage is low, the energy comparison that input capacitance is deposited is little, realized low current condition, thereby even because low-voltage and low current make short circuit of inverter bridge or other fault also bursting of large sound can not occur.
In a kind of embodiment, by sending pulse width modulating signal, carry out inversion self check, according to the inverter voltage of sampling is judged, and then can judge inverter bridge and whether have fault.
Accompanying drawing explanation
Fig. 1 is the structural representation of the photovoltaic DC-to-AC converter of an embodiment of the present invention;
Fig. 2 is the battery voltage sampling circuit structure chart in an embodiment of the present invention;
Fig. 3 is main on-off element and the control circuit figure thereof in an embodiment of the present invention;
Fig. 4 is interchange on-off element and the control circuit figure thereof in an embodiment of the present invention;
Fig. 5 is the inverter bridge drive circuit figure in an embodiment of the present invention;
Fig. 6 is the circuit diagram of the A phase inversion in an embodiment of the present invention;
Fig. 7 is the schematic flow sheet of startup self-detection method of the photovoltaic DC-to-AC converter of an embodiment of the present invention.
Embodiment
Once start shooting DC voltage up to more than 700 volts based on photovoltaic DC-to-AC converter, high pressure bursts in the time of will inevitably causing starting shooting inversion under the failure conditions such as short circuit of discrete device, and send very large explosive sound, and when bursting, device also there is the danger to personal safety.Design of the present invention is, only in low pressure situation, carries out inversion, guaranteed low-voltage, two almost nil primary conditions of electric current, makes short circuit of discrete device or other faults also bursting of large sound can not occur; Design in addition by sampling inverter voltage and be sent to DSP and reference voltage compares, thereby judging whether inverter bridge discrete device damages.To this, design principle of the present invention is: by controlling the on-off element of DC side, choose suitable resistance, by the positive and negative BUS voltage control before startup self-detection in low pressure low current range; By high resistant, add amplifier mode and realize voltage sample and insulation impedance requirement, and voltage sample is delivered to DSP, by software mode, be correlated with and identify and protection action.
Below by embodiment, by reference to the accompanying drawings the present invention is described in further detail.
Embodiment mono-:
The present embodiment provides a kind of photovoltaic DC-to-AC converter, and its first and second input is connected with negative pole (PV+ in diagram and PV-) with the positive pole that is formed photovoltaic array by linking together of a plurality of photovoltaic cells respectively, and output is connected with electrical network.As shown in Figure 1, this photovoltaic DC-to-AC converter comprises input capacitance branch road, inverter bridge circuit 101, the control module 102 connecting successively and disconnects module.Wherein, input capacitance branch road comprises BUS capacitor C 1 and C2, and it supports for inverter bridge circuit 101 provides energy, is the input voltage of inverter bridge circuit 101 normal work; Inverter bridge circuit 101 is realized direct current is changed into and the alternating current of line voltage with frequency, homophase, and is fed to electrical network to realize parallel network power generation; Control module 102 is general to be adopted by single-chip microcomputer or digital signal processor (DSP) chip as control chip, in order to control the tracking of the maximum power point of photovoltaic array, the power of control inverter grid-connected current and waveform etc., in embodiment, control module 102 is also for controlling the break-make that disconnects module.
Disconnecting module comprises the DC side break-make control module 103 being connected between photovoltaic array and input capacitance branch road and is connected in the interchange break-make module 104 between inverter bridge circuit 101 and electrical network.DC side break-make control module 103 comprises soft on-off element K2 of the main on-off element K1 that is connected between photovoltaic array and input capacitance branch road, series connection and dividing potential drop on-off element K3 and the divider resistance R2 of soft resistance R1 and series connection.Here, the existence of K2 and R1 is for preventing that impulse current from, to guarantee normally operation reliably of Switching Power Supply, can arrange this two elements in general photovoltaic DC-to-AC converter, if do not had, can arranging according to photovoltaic DC-to-AC converter provided by the invention.
In DC side break-make control module 103, K3 and R2 and input capacitance branch circuit parallel connection, one end of R1 is connected to one end being connected with input capacitance branch road of R2, and the other end of R1 is connected with K2, a termination capacitance voltage+BUS of main on-off element K1, another termination photovoltaic electric pressure+PV.K1, K2 and K3 control circuit is separately controlled by control module 102.Control module 102 controls soft on-off element K2 and dividing potential drop on-off element K3 is all closed, makes soft resistance R1 and divider resistance R2 series connection, and obviously, now the voltage at input capacitance branch road two ends equals the voltage at divider resistance R2 two ends.Control module 102 is also for controlling main on-off element K1 when the startup self-detection and exchanging break-make module 104 and remain off-state.
In a kind of realization of embodiment, main on-off element K1 is relay or contactor, and soft on-off element K2 is relay or contactor, and dividing potential drop on-off element K3 is relay or contactor, and exchanging on-off element 104 is relay or contactor.During another is realized, the inverter bridge that the inverter bridge circuit 101 that photovoltaic DC-to-AC converter adopts forms for IGBT module or IGBT discrete device, or be the inverter bridge of MOSFET discrete device formation.
Photovoltaic DC-to-AC converter based on the present embodiment, the present invention also provides a kind of startup self-detection method of photovoltaic DC-to-AC converter, comprise: control soft on-off element K2 and dividing potential drop on-off element K3 closure so that soft resistance R1 connects with divider resistance R2, and, control main on-off element K1 and exchange on-off element K4 and remain off-state.Thereby, by the series connection of soft resistance R1 and divider resistance R2, in input capacitance branch road, positive and negative BUS voltage is taken from divider resistance R2 two ends, thereby realize low pressure request and low current requirement, and owing to being the inversion self check of starting shooting in low-voltage low current situation, avoid inverter bridge inversion in high voltage and high current situation, even also can there is not bursting of large sound while making there are the faults such as short circuit in inverter bridge.Illustrate the process that realizes low pressure and low current below.
Still as shown in Figure 1, at input side, by voltage sampling circuit, can obtain the sampling of battery voltage sampling V0, negative BUS capacitance voltage sampling V01 and positive BUS capacitance voltage sampling V02San road voltage, by voltage sampling circuit, give in real time and uninterruptedly DSP and carry three road voltage sample values.Here take battery voltage sampling 105 as example account for voltage sampling process, the sampling of V01 and V02 is similar.As shown in Figure 2, battery voltage sampling circuit comprises high resistant buffer circuit, difference channel and the sampling unit connecting successively; High resistant buffer circuit for guarantee with carry out to low pressure below effective high-barrier from and the system that effectively guarantees meet the requirement of insulation impedance, it comprise be serially connected in+PV and-the first resistance R 20, the second resistance R 21, the 3rd resistance R 22, R23 and the 4th resistance R 23 between PV, the output of high resistant buffer circuit is connected with two inputs of difference channel respectively; Difference channel comprises amplifier U2; Sampling unit comprises resistance R 26, R27, amplifier U2 and amplifier periphery resistance and capacitor C 22, C23 etc.
For the main on-off element K1 in DC side break-make control module 103, as shown in Figure 3, its control circuit sends high-level control signal by the IO mouth of DSP, make triode Q1 conducting and then make energising in relay K 1 coil have magnetic force and then adhesive K1, for realizing DC B US electric capacity two ends, it is low-pressure state, need to keep main on-off element K1 always in off-state, so the IO mouth of DSP keeps low level state always.
For grid ac voltage is unlikely to by charging to BUS electric capacity as backward diode in the body of IGBT carries out uncontrollable rectification in inverter bridge, in need maintenance interchange on-off element 104, each on-off element is always in off-state, as Fig. 4, on-off element K4 is controlled and the break-make that drives signal 220V by on-off element K5, so the IO mouth of DSP keeps low level control signal, triode Q205 remains open state, so on-off element K5 also remains open state, so also remain open state without driving voltage in on-off element K4 coil.
Adhesive dividing potential drop on-off element K3 and soft on-off element K2, now soft resistance R1 and divider resistance R2 are connected between PV+ and PV-, and now positive and negative BUS electric capacity both end voltage equals the voltage at R2 two ends.Thereby while realizing inverter bridge self check, input voltage remains on low-pressure state; Again due to the metering function of resistance R 1 and R2, thereby realized low current condition.Be appreciated that R2 both end voltage is low, so the energy comparison that electric capacity is deposited is little, can realize low pressure low current.
To sum up, by increasing divider resistance and dividing potential drop on-off element in DC side, make the voltage of input capacitance branch road equal the voltage on divider resistance, the input voltage of inverter bridge remains on low-pressure state during self check thus, and because voltage is low, the energy comparison that input capacitance is deposited is little, has realized low current condition, thereby even because low-voltage and low current make short circuit of inverter bridge or other fault also bursting of large sound can not occur.
Embodiment bis-:
The photovoltaic DC-to-AC converter that the present embodiment provides is with embodiment mono-, but be different from embodiment mono-when startup self-detection, the voltage of the input capacitance branch road also sampling being obtained judges, judge whether it equals the first reference voltage, if be not equal to, there is fault in the inverter bridge of determining photovoltaic DC-to-AC converter, if equaled, finishes startup self-detection.Particularly, by the startup self-detection of embodiment mono-, make now, in low-voltage low current condition, then by control module 102, can to calculate the first reference voltage V
in, its computing formula is
V
in=V
pv×[R
2÷(R
1+R
2)] （1）
Wherein, V
pvfor the real-time magnitude of voltage of solar array voltage input positive and negative terminal.
And can obtain sampled voltage V by voltage sampling circuit
bUS, for
V
BUS=V
+BUS +V
-BUS （2）
Wherein, V
+ BUSfor positive BUS capacitance voltage sampling, V
-BUSfor negative BUS capacitance voltage sampling.
Control module 102 is by adopted voltage V
bUSwith the first reference voltage V
incompare, require:
V
BUS=V
in （3）
Wherein require positive and negative BUS capacitance voltage to be sampled as:
V
+BUS = V
-BUS≠0
（4）
By more than, judge that whether formula (1) to (4) set up simultaneously, if so, continue other known startup self-detection, otherwise control module 102 determines that inverter bridge exists fault.
Exist after fault determining inverter bridge, control module 102 can be controlled and disconnect soft on-off element K2, can also send alarm by display mode and/or voice mode.
To sum up, the relative embodiment mono-of the present embodiment, further provides the detection to inverter bridge fault.
Embodiment tri-:
The present embodiment is from the different of embodiment bis-, at the voltage of judging the input capacitance branch road that sampling obtains, equals after the first reference voltage, is not directly to finish startup self-detection, but inverter voltage is detected to determine whether inverter bridge exists fault.Particularly, control module 102 is sent pulse width modulation (PWM) signal and is made inverter bridge inversion, sampling inverter voltage, and judge whether inverter voltage equals the second reference voltage, if be not equal to, determine that inverter bridge exists fault, if equaled, control module stops sending pwm signal, disconnects soft on-off element K2 and dividing potential drop on-off element K3, finishes startup self-detection.
The present embodiment is sampled as example with three-phase three-wire system line voltage, be BC phase line voltage V1, CA phase line voltage V2, AB phase line voltage V3, it is control module 102 that these samplings form DSP() foundation of judgement, the main differential voltage sample circuit that relies on, this sentences battery voltage sampling circuit for example, similar embodiment one, as shown in Figure 2, delivers to collected AC sine wave voltage waveform the IO mouth of DSP in proportion.Then DSP sends PWM ripple and makes inverter bridge carry out inversion, and the inverter bridge drive circuit 106 of Fig. 1 is as Fig. 5, and optocoupler carries out light isolation and guarantees system safety, and driving voltage consists of the quick closedown that is more conducive to power device IGBT positive voltage and negative voltage.As shown in Figure 1, by discrete device IGBT and diode, jointly form diode neutral point clamp three-phase tri-level I type inverter bridge, this sentences A contrary and becomes example analysis, as shown in Figure 6:
When Q11, the conducting of Q12 switching tube, when Q13, Q14 switching tube turn-off, electric current flows through switching tube Q11, Q12, ignores tube voltage drop, and this phase output terminal voltage U=Udc/2 claims that now the state of A phase is " 1 ".
When Q12, the conducting of Q13 switching tube, when Q11, Q14 switching tube turn-off, sinusoidal wave positive half cycle current flows through clamping diode D11, switching tube Q12, sinusoidal wave negative half-cycle current flows through switching tube Q13, flow through again clamping diode D12, now this phase output terminal voltage U=0, claims that now the state of A phase is " 0 ".
When Q13, the conducting of Q14 switching tube, when Q11, Q12 switching tube turn-off, electric current flows through switching tube Q13, Q14; This phase output terminal voltage U=-Udc/2, claims that now the state of A phase is " 1 ".
When I type three level carry out the positive half cycle PWM Bo Fabo of sine wave, be that Q12 often opens, Q14 is normally closed, and Q11 and Q13 carry out complementary high frequency and open shutoff action, and A phase state constantly switches between " 1 " and " 0 " state.
When I type three level carry out sinusoidal wave negative half period PWM Bo Fabo, be that Q13 often opens, Q11 is normally closed, and Q12 and Q14 carry out complementary high frequency and open shutoff action, and A phase state constantly switches between " 1 " and " 0 " state.
If Q11 short circuit, when the positive half cycle of inversion, Q12 often opens, Q11 and Q13 carry out complementary high frequency and open shutoff action, because Q11 short circuit cannot be turn-offed, and then cause inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q11 open circuit, when the positive half cycle of inversion, Q12 often opens, Q11 and Q13 carry out complementary high frequency and open shutoff action, cannot conducting due to Q11 open circuit, also caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q12 short circuit, when inversion negative half period, Q13 often opens, Q12 and Q14 carry out complementary high frequency and open shutoff action, because Q12 short circuit cannot be turn-offed, and then caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q12 open circuit, when inversion negative half period, Q13 often opens, Q12 and Q14 carry out complementary high frequency and open shutoff action, cannot conducting due to Q12 open circuit, also caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q13 short circuit, when the positive half cycle of inversion, Q12 often opens, Q11 and Q13 carry out complementary high frequency and open shutoff action, because Q13 short circuit cannot be turn-offed, and then caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q13 open circuit, when the positive half cycle of inversion, Q12 often opens, Q11 and Q13 carry out complementary high frequency and open shutoff action, cannot conducting due to Q13 open circuit, also caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q14 short circuit, when inversion negative half period, Q13 often opens, Q12 and Q14 carry out complementary high frequency and open shutoff action, because Q14 short circuit cannot be turn-offed, and then caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If Q14 open circuit, when inversion negative half period, Q13 often opens, Q12 and Q14 carry out complementary high frequency and open shutoff action, because Q14 open circuit cannot conducting, and then caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If D1 short circuit, when Q11 high frequency is opened, or during Q11 short circuit, short circuit between cause+BUS and N,=0, it is box-like 3 not to be inconsistent, and has caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If D11 open circuit, at " 0 " state, when sinusoidal wave positive half cycle current flows through clamping diode D11, switching tube Q12, due to D11 open circuit, cannot electric current be passed through conducting, and then cause inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If D12 short circuit, when Q14 high frequency is opened, or during Q14 short circuit, short circuit between cause-BUS and N, equals 0, is not inconsistent box-like (4), and caused inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
If D12 open circuit, at " 0 " state, when sinusoidal wave negative half-cycle current flows through switching tube Q13, clamping diode D12, due to D12 open circuit, cannot electric current be passed through conducting, and then cause inverter voltage wave distortion, can detect inverter voltage herein different from inversion reference voltage at once;
All inverter voltage wave distortions all need to sample by three-phase three-wire system inverter voltage above, BC phase inverter voltage V11, CA phase inverter voltage V22, AB phase inverter voltage V33San road voltage are sampled and are transported to the IO mouth of DSP, voltage sampling circuit is differential voltage sample circuit, this sentences battery voltage sampling circuit for example, still as Fig. 2.It is in order to compare with inversion reference voltage that DSP is finally delivered in inverter voltage sampling, sets three-phase inversion and with reference to phase voltage be in DSP:
V
A=U
Dref×sin(ωt) （5）
V
B=U
Dref×sin(ωt-120°) （6）
V
C=U
Dref×sin(ωt+120°) （7）
Wherein, U
dreffor the sinusoidal wave peak value that DSP sets, sin (ω t) is the standard sine wave reference value in DSP.
The A of herein still take is example analysis mutually, because DSP is in order to obtain by the inversion of PWM ripple and A phase inversion reference voltage under normal circumstances, mainly by controlling the duty of PWM ripple, recently realizes, therefore DSP need to calculate duty, recently realizes:
D
ref =（U
A×T）÷V
BUS （8）
Wherein, D
reffor mutually given ripple duty ratio of A, the rest may be inferred mutually for B phase and C, and T is switch periods.Because formula (2) and formula (8), obtain DSP and send the duty ratio that PWM ripple need to control and be:
D
ref =（U
Dref×sin(ωt)×T）÷V
BUS （9）
So DSP if according to formula (9) just can determine A mutually the PWM ripple of sending out need to duty ratio, because of inverter voltage that Fig. 1 adopts, be line voltage again, so A phase inversion reference line voltage is:
U
AB=U
A –U
B=V
33 （10）
U
BC=U
B –U
C=V
11 （11）
U
CA=U
C –U
A=V
22 （12）
If voltage V11, V22 that inverter voltage is adopted, V33 meet with above formula (10), formula (11), formula (12), inverter bridge fault-free, can carry out inverter boot action; Otherwise judge that inverter bridge has IGBT or clamp diode to have damage, can not carry out inverter boot action.Send out after ripple stopping PWM, first disconnecting soft on-off element K2, to disconnect minute potential relay be for the tele-release of BUS electric capacity is fallen again, and keeps safety.In addition, disconnected dividing potential drop on-off element K3 also in order to reduce inverter state for preparing open state.After the inversion self check of guaranteeing to start shooting completes, row start again, can reduce the probability that aircraft bombing occurs discrete device IGBT greatly, and the fail safe that has effectively improved equipment is attendant's personal safety now.
To sum up, the photovoltaic DC-to-AC converter inverter bridge fault startup self-detection flow process of a kind of embodiment as shown in Figure 7, comprising:
Step 1: adhesive dividing potential drop relay K 3, first guarantees that positive and negative BUS electric capacity both end voltage equals divider resistance R2 both end voltage;
Step 2: soft relay K 2 of adhesive, makes soft resistance R1 and divider resistance R2 be connected on the positive and negative two ends of solar cell;
Step 3: judge by battery voltage sampling V0 and positive and negative BUS voltage sample V02, V01 whether positive and negative BUS voltage equals reference voltage; Otherwise report inverter bridge fault also disconnects soft relay K 2;
Step 4: make inverter bridge carry out inversion according to a line voltage sampling PWM ripple;
Step 5: judge by positive and negative BUS voltage sample and inverter voltage sampling whether inverter voltage equals reference voltage; Otherwise report inverter bridge fault also stops sending out involving and disconnects soft relay K 2;
Step 6: stop Fa Bo and disconnect soft relay K 2;
Step 7: disconnect dividing potential drop relay K 3;
Step 8: complete inverter bridge startup self-detection.
Known according to the present embodiment, the present embodiment can be realized by mode simple and with low cost the startup self-detection of inverter inverter bridge fault, mainly by the inverter bridge inversion that detects inverter bridge DC capacitor voltage and built by discrete device inverter voltage out, delivering to DSP calculates and checks the two voltage, and then whether the discrete device of judgement composition inverter bridge has damage, if find that DC capacitor voltage and inverter voltage and calculated value are not inconsistent, stop boot action, quote inverter bridge fault, prompting maintenance personnel overhaul replacing, avoid the dangerous situations such as aircraft bombing to occur, greatly guaranteed equipment and Field Force's personal safety.That is to say, the key point of the present embodiment is: first, utilize DC partial voltage relay and divider resistance to realize inversion and send out low-voltage before ripple self check and the state of low current, being unlikely to is that impaired discrete power device large sound occurs bursts, and has guaranteed safety; Secondly, directly, under low pressure low current condition, utilize software to carry out PWM Bo Fabo and carry out inversion self check, utilize the sampling of software combined-voltage to analyze the quality of judgement discrete power device.
In various embodiments of the present invention, all voltage sampling circuits are realized from adding difference channel sampling by high-barrier, soft relay of direct current and dividing potential drop control relay circuit send low and high level control triode by DSP and realize, DSP sends out PWM ripple according to sampling from line voltage, and inverter system just must have line voltage sampling originally.Utilize the more prerequisite configurations of inverter self minimum system, by increasing simply the mode of a relay and a resistance, adopt the mode of electric resistance partial pressure and current limliting to realize to start shooting in low-voltage low current situation inversion self check, thereby avoid inverter bridge inversion in high voltage and high current situation, can effectively avoid the situation that start aircraft bombing occurs to occur, greatly guarantee equipment and Field Force's personal safety.It will be appreciated by those skilled in the art that, in above-mentioned execution mode, all or part of step of the whole bag of tricks can come instruction related hardware to complete by program, this program can be stored in a computer-readable recording medium, and storage medium can comprise: read-only memory, random asccess memory, disk or CD etc.
Above content is in conjunction with concrete execution mode further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace.
Claims (10)
1. a startup self-detection method for photovoltaic DC-to-AC converter, is characterized in that, comprising:
In the DC side of photovoltaic DC-to-AC converter, increase DC side break-make control module, described DC side break-make control module comprises soft on-off element of series connection and dividing potential drop on-off element and the divider resistance of soft resistance and series connection; The dividing potential drop on-off element of described series connection and the input capacitance branch circuit parallel connection of divider resistance and photovoltaic DC-to-AC converter, one end of described soft resistance is connected to one end of described divider resistance;
Closed described soft on-off element and described dividing potential drop on-off element, described soft resistance is connected with described divider resistance, and, the main on-off element of controlling described photovoltaic DC-to-AC converter with exchange on-off element and remain off-state, wherein said main on-off element is positioned at the DC side of photovoltaic DC-to-AC converter, and described interchange on-off element is between the inverter bridge and electrical network of described photovoltaic DC-to-AC converter.
2. the method for claim 1, is characterized in that, also comprises:
Whether the voltage that judges described input capacitance branch road equals the first reference voltage,
If be not equal to, determine that the inverter bridge of described photovoltaic DC-to-AC converter exists fault,
If equaled, inverter voltage is detected to determine whether inverter bridge exists fault.
3. method as claimed in claim 2, is characterized in that, described inverter voltage is detected to determine whether inverter bridge exists this step of fault to comprise:
The control module of described photovoltaic DC-to-AC converter is sent pulse width modulating signal and is made described inverter bridge inversion,
Sampling inverter voltage, and judge whether described inverter voltage equals the second reference voltage,
If be not equal to, determine that the inverter bridge of described photovoltaic DC-to-AC converter exists fault,
If equaled, the control module of described photovoltaic DC-to-AC converter stops sending pulse width modulating signal, disconnects described soft on-off element and described dividing potential drop on-off element.
4. method as claimed in claim 2 or claim 3, is characterized in that, the described inverter bridge of determining described photovoltaic DC-to-AC converter also comprises after there is this step of fault: disconnect described soft on-off element, finish startup self-detection.
5. the method for claim 1, it is characterized in that, described soft on-off element is relay or contactor, and described dividing potential drop on-off element is relay or contactor, described main on-off element is relay or contactor, and described interchange on-off element is relay or contactor; The inverter bridge that described photovoltaic DC-to-AC converter adopts is IGBT or MOSFET.
6. a photovoltaic DC-to-AC converter inverter bridge fault startup self-detection method, is characterized in that, comprising:
In the DC side of photovoltaic DC-to-AC converter, increase DC side break-make control module, described DC side break-make control module comprises soft on-off element of series connection and dividing potential drop on-off element and the divider resistance of soft resistance and series connection; The dividing potential drop on-off element of described series connection and the input capacitance branch circuit parallel connection of divider resistance and photovoltaic DC-to-AC converter, one end of described soft resistance is connected to one end of described divider resistance;
Closed described soft on-off element and described dividing potential drop on-off element, described soft resistance is connected with described divider resistance, and, the main on-off element of controlling described photovoltaic DC-to-AC converter with exchange on-off element and remain off-state, wherein said main on-off element is positioned at the DC side of photovoltaic DC-to-AC converter, and described interchange on-off element is between the inverter bridge and electrical network of described photovoltaic DC-to-AC converter.
7. method as claimed in claim 6, is characterized in that, also comprises:
Whether the voltage that judges described input capacitance branch road equals the first reference voltage,
If be not equal to, determine that the inverter bridge of described photovoltaic DC-to-AC converter exists fault,
If equaled, inverter voltage is detected to determine whether inverter bridge exists fault.
8. method as claimed in claim 7, is characterized in that, described inverter voltage is detected to determine whether inverter bridge exists this step of fault to comprise:
The control module of described photovoltaic DC-to-AC converter is sent pulse width modulating signal and is made described inverter bridge inversion,
Sampling inverter voltage, and judge whether described inverter voltage equals the second reference voltage,
If be not equal to, determine that the inverter bridge of described photovoltaic DC-to-AC converter exists fault,
If equaled, the control module of described photovoltaic DC-to-AC converter stops sending pulse width modulating signal, disconnects described soft on-off element and described dividing potential drop on-off element.
9. a photovoltaic DC-to-AC converter, its input is connected with photovoltaic array, and output is connected with electrical network, and described photovoltaic DC-to-AC converter comprises input capacitance branch road, inverter bridge circuit and the control module connecting successively, it is characterized in that, also comprise the disconnection module that is controlled by described control module;
Described disconnection module comprises and is connected in the DC side break-make control module between described photovoltaic array and described input capacitance branch road and is connected in the interchange break-make module between described inverter bridge circuit and described electrical network;
Described DC side break-make control module comprises soft on-off element of the main on-off element that is connected between described photovoltaic array and described input capacitance branch road, series connection and dividing potential drop on-off element and the divider resistance of soft resistance and series connection, the dividing potential drop on-off element of described series connection and divider resistance and described input capacitance branch circuit parallel connection, one end of described soft resistance is connected to one end of described divider resistance, and when described soft on-off element and the equal closure of described dividing potential drop on-off element, described soft resistance is connected with described divider resistance;
Described control module remains off-state for control described main on-off element when startup self-detection with the described break-make module that exchanges.
10. photovoltaic DC-to-AC converter as claimed in claim 9, it is characterized in that, described soft on-off element is relay or contactor, and described dividing potential drop on-off element is relay or contactor, described main on-off element is relay or contactor, and described interchange on-off element is relay or contactor; The inverter bridge that described photovoltaic DC-to-AC converter adopts is IGBT or MOSFET.
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