Three-phase rectifying circuit and intelligent equipment

Abstract

The invention discloses a three-phase rectification circuit and intelligent equipment. The three-phase rectification circuit comprises a three-phase power supply, a load and a rectification unit located between the three-phase power supply and the load, the detection protection unit is connected with the three-phase power supply and the load respectively, and the detection protection unit is used for detecting whether the three-phase rectification circuit breaks down or not and generating a fault signal when the fault occurs; and the execution unit is respectively connected with the rectification unit, the detection protection unit and the load, and the execution unit is used for receiving the fault signal so as to discharge excess energy of a bus capacitor in the load. According to the three-phase rectification circuit, the execution unit receives the fault signal sent by the detection protection unit, the rectification unit is controlled to be disconnected, excess energy of a bus capacitor in the load is discharged, the safety of the load and the rectification unit is further protected, and the stability and reliability of the three-phase rectification circuit are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power transformation, and in particular to a three-phase rectifier circuit and intelligent equipment. Background Art

[0002] In the traditional variable frequency drive circuit, the rectifier bridge (rectifier unit) is one of the most important power devices. One side of it is directly connected to the main power supply or directly to the power grid, and the other side is connected to the circuit load. That is to say, the rectifier bridge is located between the circuit load and the power supply. Therefore, the rectifier bridge, as an intermediate bridge, is very susceptible to some shocks such as overcurrent and overvoltage, causing damage to the rectifier bridge.

[0003] It is difficult to analyze the specific cause of rectifier bridge damage, because whether the front-end power supply or the back-end load is abnormal, it may directly damage the rectifier bridge. On the other hand, damage to the rectifier bridge caused by unstable power supply is also likely to cause damage to the back-end load, resulting in a series of accidents or equipment losses.

[0004] Therefore, how to provide a three-phase rectifier circuit that can protect the safety of the rectifier unit and the load on the busbar is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present invention provides a three-phase rectifier circuit and an intelligent device, which are used to solve the problem in the prior art that the three-phase rectifier circuit cannot simultaneously protect the rectifier unit and the load on the bus.

[0006] The technical solution of the present invention is a three-phase rectifier circuit, comprising a three-phase power supply, a load and a rectifier unit located therebetween; and further comprising:

[0007] a detection and protection unit, which is connected to the three-phase power supply and the load respectively, and is used to detect whether the three-phase rectifier circuit has a fault and generate a fault signal when a fault occurs;

[0008] An execution unit is connected to the rectifying unit, the detection and protection unit and the load respectively, and is used to receive the fault signal to discharge the excess energy of the bus capacitor in the load.

[0009] Further, the execution unit includes a plurality of first IGBTs, second IGBTs and triodes;

[0010] The rectifier unit comprises a plurality of bridge arms, a midpoint of each bridge arm is connected to a collector of a corresponding first IGBT, and an upper bridge arm of each bridge arm is connected to an emitter of a corresponding first IGBT;

[0011] The base of the transistor is connected to the output end of the detection and protection unit, the collector of the transistor is used to connect to the 15V pin, the base of the transistor is respectively connected to the gates of all the first IGBTs and the gates of the second IGBTs, the emitter of the second IGBT is also respectively connected to the upper bridge arms of all the bridge arms, and the collector of the second IGBT is grounded.

[0012] Furthermore, the three-phase rectifier circuit also includes a cut-off diode, the anode of the cut-off diode is connected to the emitter of the second IGBT, and the anode of the cut-off diode is connected to the first end of the bus capacitor.

[0013] Furthermore, the three-phase rectifier circuit also includes a plurality of amplification sampling units;

[0014] Each phase of the three-phase power supply is respectively connected in series with a sampling resistor, and both ends of each sampling resistor are respectively connected to two input ends of the corresponding amplifying sampling unit.

[0015] Furthermore, each of the amplification sampling units includes a first operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor;

[0016] The first end of the sampling resistor is connected to the first end of the second resistor, and the second end of the sampling resistor is connected to the first end of the third resistor;

[0017] The in-phase end of the first operational amplifier is respectively connected to the first end of the first resistor and the second end of the second resistor, and the second end of the first resistor is used to connect to the VREF pin; the inverting end of the first operational amplifier is respectively connected to the second end of the third resistor and the first end of the fourth resistor, and the second end of the fourth resistor and the output end of the first operational amplifier are both connected to the input end of the detection protection unit.

[0018] Further, the detection protection unit includes a current detection protection unit, and the current detection protection unit includes three first comparators, three second comparators, three first AND gate elements, a second AND gate element, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor;

[0019] The output end of each of the amplifying sampling units and the current sampling end of the main control MCU are respectively connected to the in-phase end of one of the first comparators and the inverting end of the second comparator; the inverting end of each of the first comparators is connected to a first wiring terminal, and the first wiring terminal is also respectively connected to the first end of the fifth resistor and the first end of the sixth resistor; the in-phase end of each of the second comparators is connected to a second wiring terminal, and the second wiring terminal is also respectively connected to the first end of the seventh resistor and the first end of the eighth resistor;

[0020] The output end of each first comparator and the corresponding output end of the second comparator are respectively connected to two input ends of one of the first AND gate elements, the output end of each first AND gate element is connected to the first input end of the second AND gate element, and the output end of the second AND gate element is connected to the input end of the execution unit;

[0021] The second end of the fifth resistor, the second end of the seventh resistor and the second input end of the second AND gate element are all used to connect to the 5V pin; the second end of the sixth resistor and the second end of the eighth resistor are both grounded.

[0022] Further, the detection protection unit includes a voltage detection protection unit, and the voltage detection protection unit includes a third comparator, a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor;

[0023] The in-phase terminal of the third operational amplifier is respectively connected to the first end of the ninth resistor and the first end of the tenth resistor, the inverting terminal of the third operational amplifier is respectively connected to the voltage sampling terminal of the main control MCU, the first end of the eleventh resistor and the first end of the twelfth resistor, and the output terminal of the third operational amplifier is connected to the input terminal of the execution unit;

[0024] The second end of the twelfth resistor is used to connect to the first end of the bus capacitor; the second end of the ninth resistor is used to connect to the 5V pin; the second end of the tenth resistor and the second end of the eleventh resistor are both grounded.

[0025] Furthermore, the three-phase rectifier circuit further includes an overvoltage protection unit, and the overvoltage protection unit includes a plurality of varistors;

[0026] At least one varistor is connected between any two phases of the three-phase power supply.

[0027] Furthermore, the three-phase rectifier circuit further includes a dummy load maintaining unit, and the dummy load maintaining unit includes a plurality of dummy loads;

[0028] At least one dummy load is connected between any two phases of the three-phase power supply.

[0029] The present invention further provides an intelligent device, which includes a frequency converter, and the frequency converter includes the three-phase rectifier circuit described above.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] When a fault occurs in the three-phase rectifier circuit of the present invention, the execution unit receives a fault signal sent by the detection and protection unit, controls the rectifier unit to open the circuit, discharges the excess energy of the bus capacitor in the load, thereby protecting the safety of the load and the rectifier unit and improving the stability and reliability of the three-phase rectifier circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 The module block diagram of the three-phase rectifier circuit proposed by the present invention;

[0035] Figure 2 The circuit diagram of the three-phase rectifier circuit proposed by the present invention.

[0036] Reference numerals:

[0037] 1. Three-phase power supply;

[0038] 2. Load;

[0039] 3. Rectification unit;

[0040] 4. Amplification sampling unit; 41. First amplification sampling unit; 42. Second amplification sampling unit

[0041] Element; 43, the third amplification sampling unit;

[0042] 5. Current detection protection unit;

[0043] 6. Execution unit;

[0044] 7. Voltage detection protection unit;

[0045] 8. Overvoltage protection unit;

[0046] 9. Fake load maintenance unit;

[0047] 10. Main control MCU. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Thus, a feature indicated in this specification will be used to illustrate one of the features of an embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described features. In addition, it should be noted that this specification describes many features. Although certain features can be combined together to illustrate possible system designs, these features can also be used in other combinations that are not explicitly described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0049] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] In the traditional variable frequency drive circuit, the rectifier bridge (rectifier unit) is one of the most important power devices. One side of it is directly connected to the main power supply or directly to the power grid, and the other side is connected to the circuit load. That is to say, the rectifier bridge is located between the circuit load and the power supply. Therefore, the rectifier bridge, as an intermediate bridge, is very susceptible to some shocks such as overcurrent and overvoltage, causing damage to the rectifier bridge.

[0052] It is difficult to analyze the specific cause of rectifier bridge damage, because whether the front-end power supply or the back-end load is abnormal, it may directly damage the rectifier bridge. On the other hand, damage to the rectifier bridge caused by unstable power supply is also likely to cause damage to the back-end load, resulting in a series of accidents or equipment losses.

[0053] Therefore, in order to solve the above problems, refer to the attached Figure 1 The present invention proposes a three-phase rectifier circuit that can protect the safety of the rectifier unit and the load on the bus, including a three-phase power supply 1, a load 2 and a rectifier unit 3 located therebetween; and also includes:

[0054] A detection and protection unit, which is connected to the three-phase power supply 1 and the load 2 respectively, and is used to detect whether a fault occurs in the three-phase rectifier circuit and generate a fault signal when a fault occurs;

[0055] The execution unit 6 is connected to the rectifying unit 3 , the detection and protection unit and the load 2 respectively. The execution unit 6 is used to receive a fault signal to discharge the excess energy of the bus capacitor C1 in the load 2 .

[0056] It should be noted that the fault of the three-phase rectifier circuit proposed in this embodiment includes an overvoltage fault and / or an overcurrent fault, and correspondingly, the fault signal includes an overvoltage signal and / or an overcurrent signal.

[0057] Therefore, when a fault occurs in the three-phase rectifier circuit, that is, an overvoltage fault and / or an overcurrent fault occurs in the three-phase power supply 1 and / or the load 2, the detection and protection unit detects the fault and generates a corresponding overvoltage signal and / or overcurrent signal. After the execution unit 6 receives the corresponding overvoltage signal and / or overcurrent signal, the execution unit 6 will control the rectifier unit 3 to open the circuit and discharge the excess energy of the bus capacitor C1 in the load 2, thereby protecting the safety of the load 2 and the rectifier unit 3 and improving the stability and reliability of the three-phase rectifier circuit; when the excess energy of the bus capacitor C1 is discharged and the current and / or voltage in the three-phase rectifier circuit are normal, the execution unit 6 controls the rectifier unit 3 to reset so that the three-phase rectifier circuit works normally.

[0058] Among them, refer to the attached Figure 2 , the execution unit 6 includes a plurality of first IGBTs, a second IGBTM4 and a transistor M5;

[0059] It should be noted that, in this embodiment, the number of the first IGBTs is preferably three, namely, the first IGBTM1, the first IGBTM2 and the first IGBTM3;

[0060] The rectifier unit 3 includes three bridge arms, which are a first bridge arm formed by a diode D1 and a diode D2 connected in series, a second bridge arm formed by a diode D3 and a diode D4 connected in series, and a third bridge arm formed by a diode D5 and a diode D6 connected in series; and one end of the first bridge arm, the second bridge arm and the third bridge arm are all connected to the first end P of the bus capacitor C1 in the load 2, and the other ends of the first bridge arm, the second bridge arm and the third bridge arm are all connected to the second end N of the bus capacitor C1.

[0061] The midpoint of the first bridge arm is connected to the collector of the first IGBTM1, and the anode of the diode D1 is connected to the emitter of the first IGBTM1; the midpoint of the second bridge arm is connected to the collector of the first IGBTM2, and the anode of the diode D3 is connected to the emitter of the first IGBTM2; the midpoint of the third bridge arm is connected to the collector of the first IGBTM3, and the anode of the diode D5 is connected to the emitter of the first IGBTM3;

[0062] The base of the transistor M5 is connected to the output end of the detection protection unit, the collector of the transistor M5 is used to connect to the 15V pin, the base of the transistor M5 is respectively connected to the gate of the first IGBTM1, the gate of the first IGBTM2, the gate of the first IGBTM3 and the gate of the second IGBTM4, the collector of the second IGBTM4 is grounded, and the emitter of the second IGBTM4 is also respectively connected to the upper bridge arms of all the bridge arms (that is, equivalent to the emitter of the second IGBTM4 being connected to the first end P of the bus capacitor C1).

[0063] It should be noted that, in this embodiment, the collector of the second IGBTM4 is connected to the PE ground; the first IGBTM1, the first IGBTM2 and the first IGBTM3 are all N-type IGBTs, the second IGBTM4 is a P-type IGBT, and the transistor M5 is an N-type transistor.

[0064] Therefore, when the detection protection unit detects that the three-phase rectifier circuit has a fault and generates a corresponding overvoltage signal and / or overcurrent signal, the transistor M5 is disconnected, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also disconnected accordingly, resulting in a circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 is turned on to discharge the excess energy of the bus capacitor C1 into the PE ground, thereby protecting the safety of the load 2 and the rectifier unit 3; when the excess energy of the bus capacitor C1 is completely discharged and the current and / or voltage in the three-phase rectifier circuit is normal, the level output by the second AND gate element G2 is reversed (that is, the second AND gate element G2 outputs a low level), resulting in the transistor M5 being turned on, the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also turned on accordingly, resulting in no circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 is disconnected, so that the three-phase rectifier circuit works normally.

[0065] If the three-phase rectifier circuit does not have an overvoltage fault and / or an overcurrent fault, the transistor M5 is turned on, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also turned on accordingly, resulting in no circuit breakage between the first bridge arm, the second bridge arm and the third bridge arm, the second IGBTM4 is disconnected, and the rectifier unit 3 or the three-phase rectifier circuit operates normally.

[0066] In order to prevent the energy of load 2 or bus capacitor C1 from being reversed, refer to the attached Figure 2 The three-phase rectifier circuit further includes a cut-off diode D7, an anode of the cut-off diode D7 is connected to the emitter of the second IGBTM4, and an anode of the cut-off diode D7 is connected to the first end P of the bus capacitor C1.

[0067] In order to ensure the detection and amplification of the current signal change of the three-phase power supply 1 and suppress the common mode signal, refer to the attached Figure 2The three-phase rectifier circuit also includes a plurality of amplifying sampling units 4; each phase of the three-phase power supply 1 is respectively connected in series with a sampling resistor, and both ends of each sampling resistor are respectively connected to two input ends of the corresponding amplifying sampling unit 4.

[0068] It should be noted that the three-phase power supply 1 includes three phases, namely, L1 phase, L2 phase and L3 phase; therefore, the present embodiment proposes three sampling resistors, namely, sampling resistor RS1, sampling resistor RS2 and sampling resistor RS3; correspondingly, there are also three amplifying sampling units 4, namely, a first amplifying sampling unit 41, a second amplifying sampling unit 42 and a third amplifying sampling unit 43.

[0069] Specifically, the L1 phase is connected in series with the sampling resistor RS1 and then connected to the midpoint of the first bridge arm, and the two ends of the sampling resistor RS1 are respectively connected to the two input ends of the first amplifying sampling unit 41; the L2 phase is connected in series with the sampling resistor RS2 and then connected to the midpoint of the second bridge arm, and the two ends of the sampling resistor RS2 are respectively connected to the two input ends of the second amplifying sampling unit 42; the L3 phase is connected in series with the sampling resistor RS3 and then connected to the midpoint of the third bridge arm, and the two ends of the sampling resistor RS3 are respectively connected to the two input ends of the third amplifying sampling unit 43.

[0070] Specifically, in order to ensure the detection and amplification of the current signal change of the three-phase power supply 1 and suppress the common mode signal, refer to the attached Figure 2 , this embodiment proposes a circuit structure of an amplifying sampling unit 4:

[0071] Among them, the first amplifying sampling unit 41 includes a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; the second amplifying sampling unit 42 includes a first operational amplifier U1', a first resistor R1', a second resistor R2', a third resistor R3' and a fourth resistor R4'; the third amplifying sampling unit 43 includes a first operational amplifier U1", a first resistor R1", a second resistor R2", a third resistor R3" and a fourth resistor R4".

[0072] A first end of the sampling resistor RS1 is connected to a first end of the second resistor R2, and a second end of the sampling resistor RS1 is connected to a first end of the third resistor R3;

[0073] The in-phase end of the first operational amplifier U1 is respectively connected to the first end of the first resistor R1 and the second end of the second resistor R2, and the second end of the first resistor R1 is used to connect to the VREF pin; the inverting end of the first operational amplifier U1 is respectively connected to the second end of the third resistor R3 and the first end of the fourth resistor R4, and the second end of the fourth resistor R4 and the output end of the first operational amplifier U1 are both connected to the first input end of the detection protection unit.

[0074] A first end of the sampling resistor RS2 is connected to a first end of the second resistor R2', and a second end of the sampling resistor RS2 is connected to a first end of the third resistor R3';

[0075] The in-phase end of the first operational amplifier U1' is respectively connected to the first end of the first resistor R1' and the second end of the second resistor R2', and the second end of the first resistor R1' is used to connect to the VREF pin; the inverting end of the first operational amplifier U1' is respectively connected to the second end of the third resistor R3' and the first end of the fourth resistor R4', and the second end of the fourth resistor R4' and the output end of the first operational amplifier U1' are both connected to the second input end of the detection protection unit.

[0076] The first end of the sampling resistor RS3 is connected to the first end of the second resistor R2″, and the second end of the sampling resistor RS3 is connected to the first end of the third resistor R3″;

[0077] The in-phase end of the first operational amplifier U1" is respectively connected to the first end of the first resistor R1" and the second end of the second resistor R2", and the second end of the first resistor R1" is used to connect to the VREF pin; the inverting end of the first operational amplifier U1" is respectively connected to the second end of the third resistor R3" and the first end of the fourth resistor R4", and the second end of the fourth resistor R4" and the output end of the first operational amplifier U1" are both connected to the third input end of the detection protection unit.

[0078] It should be noted that R2=R3=R2′=R3′=R2″=R3″, and R4=R1=R4′=R1′=R4″=R1″.

[0079] The calculation formulas for the sampled output VOUT of the first operational amplifier U1, the first operational amplifier U1' and the first operational amplifier U1" are all:

[0080]

[0081] Wherein, (V+)-(V-) is the voltage difference between the two ends of the corresponding sampling resistor, and VREF is the preset bias voltage.

[0082] Among them, refer to the attached Figure 2 , the detection protection unit includes a current detection protection unit 5, the current detection protection unit 5 includes a first comparator U2, a first comparator U2', a first comparator U2", a second comparator U3, a second comparator U3', a second comparator U3", a first AND gate element G1, a first AND gate element G1', a first AND gate element G1", a second AND gate element G2, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and an eighth resistor R8;

[0083] The output end of the first operational amplifier U1 and the first current sampling end of the main control MCU10 are respectively connected to the in-phase end of the first comparator U2 and the inverting end of the second comparator U3; the output end of the first operational amplifier U1' and the second current sampling end of the main control MCU10 are respectively connected to the in-phase end of the first comparator U2' and the inverting end of the second comparator U3'; the output end of the first operational amplifier U1" and the third current sampling end of the main control MCU10 are respectively connected to the in-phase end of the first comparator U2" and the inverting end of the second comparator U3";

[0084] The inverting end of the first comparator U2, the inverting end of the first comparator U2' and the inverting end of the first comparator U2" are all connected to the first terminal, and the first terminal is respectively connected to the first end of the fifth resistor R5 and the first end of the sixth resistor R6; the non-inverting end of the second comparator U3, the non-inverting end of the second comparator U3' and the non-inverting end of the second comparator U3" are all connected to the second terminal, and the second terminal is respectively connected to the first end of the seventh resistor R7 and the first end of the eighth resistor R8;

[0085] The output end of the first comparator U2 and the output end of the second comparator U3 are respectively connected to the two input ends of the first AND gate element G1; the output end of the first comparator U2' and the output end of the second comparator U3' are respectively connected to the two input ends of the first AND gate element G1'; the output end of the first comparator U2" and the output end of the second comparator U3" are respectively connected to the two input ends of the first AND gate element G1"; the output end of the first AND gate element G1, the output end of the first AND gate element G1' and the output end of the first AND gate element G1" are all connected to the first input end of the second AND gate element G2, and the output end of the second AND gate element G2 is connected to the base of the transistor M5;

[0086] The second end of the fifth resistor R5, the second end of the seventh resistor R7 and the second input end of the second AND gate element G2 are all used to connect to the 5V pin; the second end of the sixth resistor R6 and the second end of the eighth resistor R8 are both grounded.

[0087] It should be noted that the overcurrent fault of the three-phase rectifier circuit includes forward overcurrent and reverse overcurrent. Therefore, the three-phase rectifier circuit includes the following situations:

[0088] 1. When the three-phase rectifier circuit is normal, the voltages at the in-phase terminals of the first comparator U2, the first comparator U2' and the first comparator U2" are all higher than the voltages at the inverting terminals of the first comparator U2, the first comparator U2' and the first comparator U2", resulting in the first comparator U2, the first comparator U2' and the first comparator U2" all outputting a high level; the voltages at the in-phase terminals of the second comparator U3, the second comparator U3' and the second comparator U3" are all higher than the voltages at the inverting terminals of the second comparator U3, the second comparator U3' and the second comparator U3", resulting in The second comparator U3, the second comparator U3' and the second comparator U3" all output a high level to the outside, which causes the corresponding first AND gate element G1, the first AND gate element G1' and the first AND gate element G1" to output a high level accordingly, causing the second AND gate element G2 to output a high level, the transistor M5 to be turned on, the first IGBTM1, the first IGBTM2 and the first IGBTM3 to be turned on accordingly, resulting in no short circuit between the first bridge arm, the second bridge arm and the third bridge arm, the second IGBTM4 to be disconnected, and the rectifier unit 3 or the three-phase rectifier circuit to operate normally.

[0089] 2. When a forward current overcurrent occurs in the three-phase rectifier circuit, the voltage at the in-phase terminal of the first comparator U2 and / or the first comparator U2' and / or the first comparator U2" is higher than the voltage at the inverting terminal of the corresponding first comparator U2 and / or the first comparator U2' and / or the first comparator U2", causing the first comparator U2 and / or the first comparator U2' and / or the first comparator U2" to output a high level externally; the voltage at the inverting terminal of the second comparator U3 and / or the second comparator U3' and / or the second comparator U3" is higher than the voltage at the in-phase terminal of the corresponding second comparator U3 and / or the second comparator U3' and / or the second comparator U3", causing the second comparator U3, the second comparator U3' and the second comparator U3" to output a low level externally; and further causing the corresponding first AND gate element G1 and / or the first AND gate element G1' and / or the first AND gate element G1" to output a low level correspondingly. level, causing the second AND gate element G2 to output a low level, the triode M5 to be disconnected, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 to be disconnected accordingly, resulting in a circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 to be turned on to discharge the excess energy of the bus capacitor C1 to the PE ground, thereby protecting the safety of the load 2 and the rectifier unit 3; and when the excess energy of the bus capacitor C1 is discharged, when the current in the three-phase rectifier circuit drops to within the safety threshold, the level output by the second AND gate element G2 is reversed (that is, the second AND gate element G2 outputs a low level), causing the triode M5 to be turned on, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 to be turned on accordingly, resulting in no circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 to be turned off, so that the three-phase rectifier circuit works normally.

[0090] 3. When reverse current overcurrent occurs in the three-phase rectifier circuit, the voltage at the in-phase terminal of the first comparator U2 and / or the first comparator U2' and / or the first comparator U2" is lower than the voltage at the inverting terminal of the corresponding first comparator U2 and / or the first comparator U2' and / or the first comparator U2", causing the first comparator U2 and / or the first comparator U2' and / or the first comparator U2" to output a low level; the voltage at the inverting terminal of the second comparator U3 and / or the second comparator U3' and / or the second comparator U3" is lower than the voltage at the in-phase terminal of the corresponding second comparator U3 and / or the second comparator U3' and / or the second comparator U3", causing the second comparator U3, the second comparator U3' and the second comparator U3" to output a high level; and then causing the corresponding first AND gate element G1 and / or the first AND gate element G1' and / or the first AND gate element G1" to output a low level. level, causing the second AND gate element G2 to output a low level, the transistor M5 to be disconnected, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 to be disconnected accordingly, resulting in a circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 to be turned on to discharge the excess energy of the bus capacitor C1 to the PE ground, thereby protecting the safety of the load 2 and the rectifier unit 3; and when the excess energy of the bus capacitor C1 is discharged, the current in the three-phase rectifier circuit drops to within the safety threshold, the level output by the second AND gate element G2 is reversed (that is, the second AND gate element G2 outputs a low level), causing the transistor M5 to be turned on, the first IGBTM1, the first IGBTM2 and the first IGBTM3 to be turned on accordingly, resulting in no circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 to be turned off, so that the three-phase rectifier circuit works normally.

[0091] 4. When the forward current overcurrent and reverse current overcurrent occur in the three-phase rectifier circuit, the first comparator U2 and / or the first comparator U2' and / or the first comparator U2" output a low level, and the second comparator U3, the second comparator U3' and the second comparator U3" output a low level, which causes the corresponding first AND gate element G1 and / or the first AND gate element G1' and / or the first AND gate element G1" to output a low level, causing the second AND gate element G2 to output a low level, the transistor M5 is disconnected, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also disconnected accordingly, resulting in the first bridge arm, the second bridge arm and the third bridge arm being disconnected. When a short circuit occurs, the second IGBTM4 is turned on to discharge the excess energy of the bus capacitor C1 into the PE ground, thereby protecting the safety of the load 2 and the rectifier unit 3; and when the excess energy of the bus capacitor C1 is discharged, when the current in the three-phase rectifier circuit drops below the safety threshold, the level output by the second AND gate element G2 is reversed (that is, the second AND gate element G2 outputs a low level), causing the transistor M5 to be turned on, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also turned on accordingly, resulting in no short circuit between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 is disconnected, so that the three-phase rectifier circuit works normally.

[0092] Further, in order to ensure that the three-phase rectifier circuit can continue to perform current sampling when the rectifier unit 3 is disconnected, refer to the attached Figure 2 , the three-phase rectifier circuit further includes a dummy load maintaining unit 9, and the dummy load maintaining unit 9 includes a plurality of dummy loads;

[0093] At least one dummy load is connected between any two phases of the three-phase power supply 1 .

[0094] It should be noted that the dummy load maintaining unit 9 in this embodiment includes three dummy loads, which are respectively a dummy load R_DL1 , a dummy load R_DL2 , and a dummy load R_DL3 .

[0095] Specifically, a dummy load R_DL1 is connected between the L1 phase and the L2 phase, a dummy load R_DL2 is connected between the L1 phase and the L3 phase, and a dummy load R_DL3 is connected between the L2 phase and the L3 phase.

[0096] Among them, refer to the attached Figure 2 , the detection protection unit includes a voltage detection protection unit 7, and the voltage detection protection unit 7 includes a third comparator U4, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a twelfth resistor R12;

[0097] The in-phase terminal of the third operational amplifier U4 is respectively connected to the first end of the ninth resistor R9 and the first end of the tenth resistor R10, the inverting terminal of the third operational amplifier U4 is respectively connected to the voltage sampling terminal of the main control MCU10, the first end of the eleventh resistor R11 and the first end of the twelfth resistor R12, and the output terminal of the third operational amplifier U4 is also connected to the base of the transistor M5;

[0098] The second end of the twelfth resistor R12 is used to connect to the anode of the cut-off diode D7; the second end of the ninth resistor R9 is used to connect to the 5V pin; the second end of the tenth resistor R10 and the second end of the eleventh resistor R11 are both grounded.

[0099] In this way, when the three-phase rectifier circuit operates normally, the voltage at the inverting end of the third comparator U4 is lower than the voltage at the non-inverting end of the third comparator U4, causing the third comparator U4 to output a high level externally, the transistor M5 is turned on, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also turned on accordingly, resulting in no short circuit between the first bridge arm, the second bridge arm and the third bridge arm, the second IGBTM4 is disconnected, and the rectifier unit 3 or the three-phase rectifier circuit operates normally.

[0100] When the three-phase rectifier circuit is over-voltaged, the voltage at the inverting terminal of the third comparator U4 is higher than the voltage at the in-phase terminal of the third comparator U4, causing the third comparator U4 to output a low level, the transistor M5 is disconnected, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also disconnected accordingly, resulting in a circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 is turned on to discharge the excess energy of the bus capacitor C1 into the PE ground, thereby protecting the safety of the load 2 and the rectifier unit 3; and when the excess energy of the bus capacitor C1 is completely discharged, when the voltage of the bus capacitor C1 drops to within the safety threshold, the level of the output of the third comparator U4 is reversed (that is, the third comparator U4 outputs a low level), causing the transistor M5 to be turned on, and the first IGBTM1, the first IGBTM2 and the first IGBTM3 are also turned on accordingly, resulting in no circuit break between the first bridge arm, the second bridge arm and the third bridge arm, and the second IGBTM4 is turned off, so that the three-phase rectifier circuit works normally.

[0101] Among them, refer to the attached Figure 2 , the three-phase rectifier circuit also includes an overvoltage protection unit 8, and the overvoltage protection unit 8 includes a plurality of varistors;

[0102] At least one varistor is connected between any two phases of the three-phase power supply 1 .

[0103] It should be noted that the overvoltage protection unit 8 in this embodiment includes three varistors, which are a varistor Z1 , a varistor Z2 and a varistor Z3 .

[0104] Specifically, a varistor Z1 is connected between the L1 phase and the L2 phase, a varistor Z2 is connected between the L1 phase and the L3 phase, and a varistor Z3 is connected between the L2 phase and the L3 phase.

[0105] In this way, when an overvoltage fault occurs in the three-phase rectifier circuit, all varistors in the overvoltage protection unit 8 can absorb part of the voltage, effectively preventing excessive voltage from damaging other sensitive components in the three-phase rectifier circuit, reducing faults caused by overvoltage in the three-phase rectifier circuit, and improving the stability and reliability of the three-phase rectifier circuit.

[0106] The main control MCU 10 is also connected to a display module (not shown, the same as in the whole text). The main control MCU 10 collects the voltage signal and the current signal in the three-phase rectifier circuit, and calculates the actual current value and voltage value through the internal algorithm module in the main control MCU 10, and then transmits them to the display module to display the actual current value and voltage value in the three-phase rectifier circuit on the display module, so as to facilitate the detection of the situation of the three-phase rectifier circuit.

[0107] Example 2

[0108] Based on the same inventive concept, the present invention further proposes an intelligent device, which includes a frequency converter, and the frequency converter includes the three-phase rectifier circuit described above.

[0109] Therefore, when an overvoltage fault and / or an overcurrent fault occurs in the three-phase rectifier circuit in the inverter, the detection and protection unit detects the fault and generates a corresponding overvoltage signal and / or overcurrent signal. After the execution unit 6 receives the corresponding overvoltage signal and / or overcurrent signal, the execution unit 6 will control the rectifier unit 3 to open the circuit and discharge the excess energy of the bus capacitor C1 in the load 2, thereby protecting the safety of the load 2 and the rectifier unit 3 and improving the stability and reliability of the three-phase rectifier circuit; when the excess energy of the bus capacitor C1 is discharged and the current and / or voltage in the three-phase rectifier circuit are normal, the execution unit 6 will control the rectifier unit 3 to reset so that the three-phase rectifier circuit and the inverter can work normally.

[0110] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are given in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific embodiments, or to perform equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A three-phase rectifier circuit, comprising a three-phase power supply, a load and a rectifier unit located between the three-phase power supply and a load; characterized in that: Also includes: a detection and protection unit, which is connected to the three-phase power supply and the load respectively, and is used to detect whether the three-phase rectifier circuit has a fault and generate a fault signal when a fault occurs; An execution unit is connected to the rectifying unit, the detection and protection unit and the load respectively, and is used to receive the fault signal to discharge the excess energy of the bus capacitor in the load.

2. The three-phase rectifier circuit according to claim 1, characterized in that: The execution unit includes a plurality of first IGBTs, second IGBTs and triodes; The rectifier unit comprises a plurality of bridge arms, a midpoint of each bridge arm is connected to a collector of a corresponding first IGBT, and an upper bridge arm of each bridge arm is connected to an emitter of a corresponding first IGBT; The base of the transistor is connected to the output end of the detection and protection unit, the collector of the transistor is used to connect to the 15V pin, the base of the transistor is respectively connected to the gates of all the first IGBTs and the gates of the second IGBTs, the emitter of the second IGBT is also respectively connected to the upper bridge arms of all the bridge arms, and the collector of the second IGBT is grounded.

3. The three-phase rectifier circuit according to claim 2, characterized in that: The three-phase rectifier circuit further includes a cut-off diode, an anode of which is connected to the emitter of the second IGBT, and an anode of which is connected to the first end of the bus capacitor.

4. The three-phase rectifier circuit according to claim 1, characterized in that: The three-phase rectifier circuit also includes a plurality of amplification sampling units; Each phase of the three-phase power supply is respectively connected in series with a sampling resistor, and both ends of each sampling resistor are respectively connected to two input ends of the corresponding amplifying sampling unit.

5. The three-phase rectifier circuit according to claim 4, characterized in that: Each of the amplification sampling units includes a first operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; The first end of the sampling resistor is connected to the first end of the second resistor, and the second end of the sampling resistor is connected to the first end of the third resistor; The in-phase end of the first operational amplifier is respectively connected to the first end of the first resistor and the second end of the second resistor, and the second end of the first resistor is used to connect to the VREF pin; the inverting end of the first operational amplifier is respectively connected to the second end of the third resistor and the first end of the fourth resistor, and the second end of the fourth resistor and the output end of the first operational amplifier are both connected to the input end of the detection protection unit.

6. The three-phase rectifier circuit according to claim 1, characterized in that: The detection protection unit includes a current detection protection unit, and the current detection protection unit includes three first comparators, three second comparators, three first AND gate elements, a second AND gate element, a fifth resistor, a sixth resistor, a seventh resistor and an eighth resistor; The output end of each of the amplifying sampling units and the current sampling end of the main control MCU are respectively connected to the in-phase end of one of the first comparators and the inverting end of the second comparator; the inverting end of each of the first comparators is connected to a first wiring terminal, and the first wiring terminal is also respectively connected to the first end of the fifth resistor and the first end of the sixth resistor; the in-phase end of each of the second comparators is connected to a second wiring terminal, and the second wiring terminal is also respectively connected to the first end of the seventh resistor and the first end of the eighth resistor; The output end of each first comparator and the corresponding output end of the second comparator are respectively connected to two input ends of one of the first AND gate elements, the output end of each first AND gate element is connected to the first input end of the second AND gate element, and the output end of the second AND gate element is connected to the input end of the execution unit; The second end of the fifth resistor, the second end of the seventh resistor and the second input end of the second AND gate element are all used to connect to the 5V pin; the second end of the sixth resistor and the second end of the eighth resistor are both grounded.

7. The three-phase rectifier circuit according to claim 1, characterized in that: The detection protection unit includes a voltage detection protection unit, and the voltage detection protection unit includes a third comparator, a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor; The in-phase terminal of the third operational amplifier is respectively connected to the first end of the ninth resistor and the first end of the tenth resistor, the inverting terminal of the third operational amplifier is respectively connected to the voltage sampling terminal of the main control MCU, the first end of the eleventh resistor and the first end of the twelfth resistor, and the output terminal of the third operational amplifier is connected to the input terminal of the execution unit; The second end of the twelfth resistor is used to connect to the first end of the bus capacitor; the second end of the ninth resistor is used to connect to the 5V pin; the second end of the tenth resistor and the second end of the eleventh resistor are both grounded.

8. The three-phase rectifier circuit according to claim 1, characterized in that: The three-phase rectifier circuit further includes an overvoltage protection unit, and the overvoltage protection unit includes a plurality of varistors; At least one varistor is connected between any two phases of the three-phase power supply.

9. The three-phase rectifier circuit according to claim 1, characterized in that: The three-phase rectifier circuit further includes a dummy load maintaining unit, and the dummy load maintaining unit includes a plurality of dummy loads; At least one dummy load is connected between any two phases of the three-phase power supply.

10. An intelligent device, comprising a frequency converter, characterized in that: The frequency converter comprises the three-phase rectifier circuit according to any one of claims 1 to 9.

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