CN108254675A - Pfc circuit failure detector, method and convertible frequency air-conditioner - Google Patents

Abstract

The present invention provides a PFC circuit fault detection device, a method, and an inverter air conditioner; wherein, the PFC circuit fault detection device includes: a circuit signal detection unit, which is used to sample the signal output by the detection circuit and obtain multiple physical quantities of the PFC circuit; And a fault state judging unit, which is used to judge the fault state of the PFC circuit according to the PFC circuit fault judgment rule; wherein, the plurality of physical quantities include: DC bus voltage U _dc , input AC voltage peak value U _acpeak , PFC unit branch current I And the total current I _total of the PFC circuit. The PFC circuit fault detection device and method and the frequency conversion air conditioner provided by the present invention realize the detection and processing of the fault state of two parallel PFC circuits and ensure the reliable operation of the air conditioner.

Description

PFC circuit fault detection device, method and inverter air conditioner

technical field

The invention relates to the technical field of air conditioners, in particular to a PFC circuit fault detection device and method and an inverter air conditioner.

Background technique

In today's situation of vigorously advocating energy saving, the replacement of fixed-frequency air conditioners by inverter air conditioners has become the development trend of the air-conditioning industry at present and in the future.

The interleaved parallel PFC circuit used in the existing inverter air conditioner, if the components (such as inductors, diodes, and switch tubes) in the PFC circuit are damaged during use, the entire PFC circuit will be in an abnormal state and cannot work normally. , affecting the normal use of the air conditioner.

For the existing interleaved parallel PFC circuit, it is usually artificially detected during specific maintenance, which consumes manpower and high cost, and cannot detect faults in a timely, effective, simple and convenient manner, nor can it deal with faults in a timely and effective manner after a fault occurs , and cause the PFC to work abnormally, no effective solution has been proposed yet.

Contents of the invention

In view of this, the present invention aims to provide a PFC circuit fault detection device and method and an inverter air conditioner to detect and process the fault state of two parallel PFC circuits and ensure that the air conditioner is in a reliable operating state.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A PFC circuit fault detection device, including: a circuit signal detection unit, used to sample the signal output by the detection circuit, and obtain multiple physical quantities of the PFC circuit; and a fault state judgment unit, used to judge the PFC according to the PFC circuit fault judgment rule Circuit fault state; wherein, the multiple physical quantities include: DC bus voltage U _dc , input AC voltage peak value U _acpeak , PFC unit branch current I and PFC circuit total current _Itotal .

Further, it is determined whether the PFC circuit has a boosting effect by the DC bus voltage U _dc and the input AC voltage peak U _acpeak of the PFC circuit; the PFC unit branch current I of the PFC circuit, the PFC circuit total The current I _total determines the relationship between the parallel branch current and the total current; thereby determining the fault state of the PFC circuit.

Further, the PFC circuit includes a PFC unit branch A and a PFC unit branch B, and the PFC unit branch current I is the PFC unit branch A current I _A and/or the PFC unit branch B current I _B .

Further, the PFC circuit fault determination rule is as follows: if U _dc <(U _acpeak +ΔU _{PFC fault determination voltage value} ) is detected within a predetermined period of time, it is determined that both the PFC unit branch A and the PFC unit branch B are both Fault; if it is detected that I _total >(2*I+ΔI _{PFC fault judgment current value} ) within a predetermined time, it is judged to be a PFC unit branch A fault; if it is detected within a predetermined time that I _total <(2* I-ΔI _{PFC fault judgment current value} ), it is judged that the PFC unit branch B is faulty; if none of the above is satisfied, it is judged that both the PFC unit branch A and the PFC unit branch B are normal; among them, ΔU _{PFC fault judgment voltage The value} represents the judgment threshold of PFC circuit boost abnormality; ΔI _{PFC fault judgment current value} represents the judgment threshold of PFC circuit branch current abnormality.

Further, the PFC circuit fault detection device further includes: a fault processing unit, configured to perform fault processing according to a preset processing method according to the fault state of the PFC circuit.

Further, the preset processing method is specifically as follows: if it is determined that the two PFC unit branches PFC unit branch A and PFC unit branch B are normal, then the maximum power allowed to operate is P _max =P _rated ; If at least one of the branch circuits of the PFC unit is faulty, then the maximum power P _max allowed to operate is <P _rated .

A PFC circuit fault detection method, comprising: sampling a signal output by a detection circuit to obtain multiple physical quantities of the PFC circuit; and judging the PFC circuit fault state according to the PFC circuit fault determination rule; wherein the multiple physical quantities include: direct current Bus voltage U _dc , input AC voltage peak value U _acpeak , PFC unit branch current I and PFC circuit total current Itotal _.

Further, it is determined whether the PFC circuit has a boosting effect by the DC bus voltage U _dc and the input AC voltage peak U _acpeak of the PFC circuit; the PFC unit branch current I of the PFC circuit, the PFC circuit total The current I _total determines the relationship between the parallel branch current and the total current; thereby determining the fault state of the PFC circuit.

Further, the PFC circuit includes a PFC unit branch A and a PFC unit branch B, and the PFC unit branch current I is the PFC unit branch A current I _A and/or the PFC unit branch B current I _B .

Further, the PFC circuit fault determination rule is as follows: if U _dc <(U _acpeak +ΔU _{PFC fault determination voltage value} ) is detected within a predetermined period of time, it is determined that both the PFC unit branch A and the PFC unit branch B are both Fault; if it is detected that I _total >(2*I+ΔI _{PFC fault judgment current value} ) within a predetermined time, it is judged to be a PFC unit branch A fault; if it is detected within a predetermined time that I _total <(2* I-ΔI _{PFC fault judgment current value} ), it is judged that the PFC unit branch B is faulty; if none of the above is satisfied, it is judged that both the PFC unit branch A and the PFC unit branch B are normal; among them, ΔU _{PFC fault judgment voltage The value} represents the judgment threshold of PFC circuit boost abnormality; ΔI _{PFC fault judgment current value} represents the judgment threshold of PFC circuit branch current abnormality.

Further, the PFC circuit fault detection method further includes: performing fault processing according to a preset processing method according to the fault state of the PFC circuit.

Further, the preset processing method is specifically as follows: if it is determined that the two PFC unit branches PFC unit branch A and PFC unit branch B are normal, then the maximum power allowed to operate is P _max =P _rated ; If at least one of the branch circuits of the PFC unit is faulty, then the maximum power P _max allowed to operate is <P _rated .

An inverter air conditioner, which includes the PFC circuit fault detection device.

An inverter air conditioner, which uses the PFC circuit fault detection method to perform PFC circuit fault detection.

Compared with the prior art, the PFC circuit fault detection device, method and frequency conversion air conditioner of the present invention have the following advantages:

(1) The detection device and method of the present invention are simple, and the fault _can be accurately judged by the DC bus voltage U _dc , the peak value of the input AC voltage U _acpeak , the PFC unit branch current I and the total current I of the PFC circuit. The circuit to be sampled The physical quantity is small, easy to obtain, and no additional detection circuit needs to be added.

(2) The detection device and method of the present invention are effective, and can effectively determine the fault state of each unit branch of the PFC through the boosting effect of the PFC circuit and the current relationship of the parallel branch.

(3) According to the failure state of the PFC circuit, the present invention executes corresponding failure treatment, and derates the air conditioner when the PFC circuit fails, thereby ensuring the reliable operation of the air conditioner.

Description of drawings

The drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

FIG. 1 is a topological diagram of an interleaved parallel PFC circuit adopted by an inverter air conditioner according to an embodiment of the present invention.

FIG. 2 is a block diagram of a PFC circuit fault detection device according to an embodiment of the present invention.

FIG. 3 is a flow chart of a PFC circuit fault detection method according to an embodiment of the present invention.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

In order to realize the detection and processing of the fault state of the interleaved parallel PFC circuit and ensure the reliable operation state of the inverter air conditioner, the present invention proposes a fault detection device and method for the interleaved parallel PFC circuit. As shown in FIG. 1 , the interleaved parallel PFC (Power Factor Correction, power factor correction) circuit adopted by the inverter air conditioner is composed of two basic Boost PFC units, and each PFC unit switch operates in an interleaved parallel state. The two basic Boost PFC units are respectively denoted as PFC unit branch A and PFC unit branch B.

In a specific embodiment, as shown in FIG. 2 , the PFC circuit fault detection device includes: a circuit signal detection unit, a fault state determination unit, and a fault processing unit.

Further, please refer to the accompanying drawings 1-2, the circuit signal detection unit is used to detect the following four physical quantities by sampling the signal output by the detection circuit, the DC bus voltage U _dc , the peak value of the input AC voltage U _acpeak , PFC unit branch A current I _A (and/or PFC unit branch B current I _B ), PFC circuit total current _Itotal . Wherein, the two PFC unit branches only need to sample the current of any one of the branches, and the sampling current I _A is taken as an example for illustration.

The fault state judging unit is used to determine the fault state of the PFC circuit based on the above physical quantity judgment according to the fault judgment rule of the PFC circuit.

Specifically, the determination starts 10s after the PFC is turned on, and the PFC circuit failure determination rules are as follows:

If it is detected that U _dc <(U _acpeak +ΔU _{PFC failure judgment voltage value} ) for 5 seconds, it is determined that the PFC circuit has no boosting effect (boosting abnormality), and it is judged that both PFC unit branches are faulty;

If _Itotal >(2*I _A +ΔI _{PFC fault judgment current value} ) is detected continuously for 5s, it is determined that the parallel branch current is abnormal, and it is judged that the PFC unit branch A is faulty;

If it is detected that I _total <(2*I _A -ΔI _{PFC fault judgment current value} ) for 5 seconds, it is determined that the parallel branch current is abnormal, and it is judged that the PFC unit branch B is faulty;

If none of the above is satisfied, it is determined that the branches of the two PFC units are normal.

The invention effectively judges the fault state of each unit branch of the PFC through the boosting effect of the PFC circuit and the current relationship of the parallel branch circuit.

In the above judgment rules, the ΔU _{PFC fault judgment voltage value} indicates the judgment threshold of whether the PFC circuit has a boost function. According to the minimum boost voltage of the PFC circuit, it is usually set above 20V, and the ΔU _{PFC fault judgment voltage value} is usually 10V. The ΔI _{PFC fault judgment current value} represents the judgment threshold for the abnormal current of the PFC circuit branch. According to the PFC branch current, the current sharing error is usually designed to be within 0.5A, and the ΔI _{PFC fault judgment current value} is usually 2A.

Thus, the present invention can _accurately determine faults from the DC bus voltage U _dc , the peak value of the input AC voltage U _acpeak , the branch current I of the PFC unit and the total current I of the PFC circuit. No need to add additional detection circuit.

The fault processing unit is configured to perform corresponding fault processing according to a preset processing method according to the fault state of the PFC circuit, so as to ensure reliable operation of the air conditioner.

The preset processing methods are as follows:

If it is determined that both PFC unit branches are normal, then the maximum power allowed to operate P _max =P _rated ;

If it is determined that at least one of the two PFC unit branches is faulty, then the maximum power P _max allowed to operate <P _rated . Specifically, if it is determined that both PFC unit branches are faulty, then the maximum power P _max that is allowed to operate = 1/4*P _rated ; if it is determined that the PFC unit branch A is faulty and the PFC unit branch B is normal, then the operation is allowed If it is determined that the PFC unit branch B is faulty and the PFC unit branch A is normal, then the maximum power allowed to operate is P _max =1/2*P _rated .

The PFC circuit fault detection device proposed by the invention has a simple structure, is convenient for fault detection, and is beneficial to the normal operation of the air conditioner.

In another specific embodiment, as shown in Figure 3, the PFC circuit fault detection method includes the following steps:

Step 1: Turn on PFC and start detection.

Step 2: The real-time signal samples the following four physical quantities, DC bus voltage U _dc , input AC voltage peak value U _acpeak , PFC unit branch A current I _A , and PFC circuit total current _Itotal . Wherein, the two PFC unit branches only need to sample the current of any one of the branches, and the sampling current I _A is taken as an example for illustration.

Step 3: After waiting for 10 seconds for the PFC to be turned on, start to judge according to the PFC fault judgment rules.

Step 4: Determine whether the PFC circuit has a boosting effect. If U _dc <(U _acpeak +ΔU _{PFC failure judgment voltage value} ) is detected for 5 seconds, it is considered that the PFC circuit has no boosting effect, that is, it is judged as two PFC unit branches Both fail.

Step 5: Determine whether the current of branch A of the PFC unit is normal. If I _total > (2*I _A + ΔI _{PFC fault judgment current value} ) is detected for 5 seconds, it is considered that the current of branch A of the PFC unit is abnormal, that is, it is judged as PFC Unit branch A is faulty.

Step 6: Determine whether the current of PFC unit branch B is normal. If it is detected that I _total <(2*I _A -ΔI _{PFC fault judgment current value} ) for 5 seconds, it is considered that the current of PFC unit branch B is abnormal, that is, it is judged as PFC Unit branch B is faulty.

Step 7: If none of the above three judging conditions are satisfied, it is judged that the branches of the two PFC units are normal.

In the above judgment rules, the ΔU _{PFc fault judgment voltage value} indicates the judgment threshold of whether the PFC circuit has a boost function. According to the minimum boost voltage of the PFC circuit, it is usually set above 20V, and the ΔU _{PFC fault judgment voltage value} is usually 10V. The ΔI _{PFC fault judgment current value} represents the judgment threshold for the abnormal current of the PFC circuit branch. According to the PFC branch current, the current sharing error is usually designed to be within 0.5A, and the ΔI _{PFC fault judgment current value} is usually 2A.

Step 8: According to the fault state of the PFC circuit, perform corresponding fault processing according to a preset processing method to ensure reliable operation of the air conditioner.

The preset processing methods are as follows:

If it is determined that both PFC unit branches are normal, then the maximum power allowed to operate P _max =P _rated ;

If it is determined that at least one of the two PFC unit branches is faulty, then the maximum power P _max allowed to operate <P _rated . Specifically, if it is determined that both PFC unit branches are faulty, then the maximum power P _max that is allowed to operate = 1/4*P _rated ; if it is determined that the PFC unit branch A is faulty and the PFC unit branch B is normal, then the operation is allowed The maximum power P _max =1/2*P _rating ; if it is determined that the PFC unit branch B is faulty and the PFC unit branch A is normal, then the maximum power P _max that is allowed to operate =1/2*P _rating .

It should be noted that when it is determined that both PFC unit branches are faulty, the maximum power allowed to operate may not be limited to P _max = 1/4*P _rated ; when it is determined that one of the PFC unit branch circuits is faulty, the allowable operating power The maximum power may not be limited to P _max =1/2*P _rated , and it only needs to satisfy P _max <P _rated .

Thus, the present invention can _accurately determine faults from the DC bus voltage U _dc , the peak value of the input AC voltage U _acpeak , the branch current I of the PFC unit and the total current I of the PFC circuit. There is no need to add an additional detection circuit, and the detection method is simple.

In addition, the present invention also provides an inverter air conditioner, which includes the above PFC circuit fault detection device.

The present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor, and the processor implements the PFC when executing the computer program Circuit fault detection method.

The present invention also provides a computer-readable storage medium, on which a computer program is stored, and the computer program implements the PFC circuit fault detection method when executed by a processor.

In the above embodiments, those skilled in the art can make appropriate adjustments to the determination start time, the detection duration during the determination process, etc., without affecting the implementation of the present invention.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (14)

1. a kind of pfc circuit failure detector, which is characterized in that including：

Circuit signal detection unit for the signal of sample detecting circuit output, obtains multiple physical quantitys of pfc circuit；And

Malfunction identifying unit, for judging the pfc circuit malfunction according to pfc circuit fault verification rule；

Wherein, the multiple physical quantity includes：DC bus-bar voltage U_dc, input ac voltage peak value U_acpeak, PFC unit branches Electric current I and pfc circuit total current I_Always。

2. pfc circuit failure detector according to claim 1, which is characterized in that by the direct current of the pfc circuit Busbar voltage U_dcWith input ac voltage peak value U_acpeakDetermine whether pfc circuit has boosting；By the institute of the pfc circuit State PFC unit branch currents I, pfc circuit total current I_AlwaysDetermine the relationship of parallel branch electric current and total current；It is described so as to judge Pfc circuit malfunction.

3. pfc circuit failure detector according to claim 2, which is characterized in that the pfc circuit includes PFC units Branch A and PFC unit branch B, the PFC units branch current I are PFC unit branch A electric currents I_AAnd/or PFC unit branches B Electric current I_B。

4. pfc circuit failure detector according to claim 3, which is characterized in that the pfc circuit fault verification rule It is as follows：

If continue to detect U in a predetermined time_dc＜ (U_acpeak+ΔU_{PFC fault verification voltage values}), then be determined as PFC unit branch A and The equal failures of PFC unit branch B；

If continue to detect I in a predetermined time_Always＞ (2*I+ Δs I_{PFC fault verification current values}), then it is determined as PFC unit branch A failures；

If continue to detect I in a predetermined time_Always＜ (2*I- Δs I_{PFC fault verification current values}), then it is determined as PFC unit branch B failures；

If being unsatisfactory for above, it is determined as that PFC unit branch A and PFC unit branches B is normal；

Wherein, Δ U_{PFC fault verification voltage values}Represent the abnormal decision threshold of pfc circuit boosting；ΔI_{PFC fault verification current values}Represent pfc circuit branch The decision threshold of road current anomaly.

5. pfc circuit failure detector according to claim 1, which is characterized in that further include：Fault processing unit is used According to the pfc circuit malfunction, troubleshooting is performed according to a default processing mode.

6. pfc circuit failure detector according to claim 5, which is characterized in that the default processing mode is specifically such as Under：

If it is determined that two PFC unit branch PFC unit branch A and PFC unit branches B are normal, then allow the maximum work of operation Rate P_max=P_{It is specified}；

If it is determined that at least one failure of two PFC unit branches, then allow the maximum power P run_max＜ P_{It is specified}。

7. a kind of pfc circuit fault detection method, which is characterized in that including：

The signal of sample detecting circuit output obtains multiple physical quantitys of pfc circuit；And

Judge the pfc circuit malfunction according to pfc circuit fault verification rule；

Wherein, the multiple physical quantity includes：DC bus-bar voltage U_dc, input ac voltage peak value U_acpeak, PFC unit branches Electric current I and pfc circuit total current I_Always。

8. pfc circuit fault detection method according to claim 7, which is characterized in that by the direct current of the pfc circuit Busbar voltage U_dcWith input ac voltage peak value U_acpeakDetermine whether pfc circuit has boosting；By the institute of the pfc circuit State PFC unit branch currents I, pfc circuit total current I_AlwaysDetermine the relationship of parallel branch electric current and total current；It is described so as to judge Pfc circuit malfunction.

9. pfc circuit fault detection method according to claim 8, which is characterized in that the pfc circuit includes PFC units Branch A and PFC unit branch B, the PFC units branch current I are PFC unit branch A electric currents I_AAnd/or PFC unit branches B Electric current I_B。

10. pfc circuit fault detection method according to claim 9, which is characterized in that the pfc circuit fault verification rule It is then as follows：

If continue to detect U in a predetermined time_dc＜ (U_acpeak+ΔU_{PFC fault verification voltage values}), then be determined as PFC unit branch A and The equal failures of PFC unit branch B；

If continue to detect I in a predetermined time_Always＞ (2*I+ Δs I_{PFC fault verification current values}), then it is determined as PFC unit branch A failures；

If continue to detect I in a predetermined time_Always＜ (2*I- Δs I_{PFC fault verification current values}), then it is determined as PFC unit branch B failures；

If being unsatisfactory for above, it is determined as that PFC unit branch A and PFC unit branches B is normal；

Wherein, Δ U_{PFC fault verification voltage values}Represent the abnormal decision threshold of pfc circuit boosting；ΔI_{PFC fault verification current values}Represent pfc circuit branch The decision threshold of road current anomaly.

11. pfc circuit fault detection method according to claim 7, which is characterized in that further include：According to the pfc circuit Malfunction performs troubleshooting according to a default processing mode.

12. the pfc circuit fault detection method according to claim 11, which is characterized in that the default processing mode is specific It is as follows：

If it is determined that two PFC unit branch PFC unit branch A and PFC unit branches B are normal, then allow the maximum work of operation Rate P_max=P_{It is specified}；

If it is determined that at least one failure of two PFC unit branches, then allow the maximum power P run_max＜ P_{It is specified}。

13. a kind of convertible frequency air-conditioner, which is characterized in that including pfc circuit failure inspection such as according to any one of claims 1 to 6 Survey device.

14. a kind of convertible frequency air-conditioner, which is characterized in that using the pfc circuit failure inspection as described in any one of claim 7 to 12 Survey method performs pfc circuit fault detect.