Three-phase rectifying circuit and intelligent equipment

Abstract

The utility model 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 utility model, the execution unit receives the fault signal sent by the detection protection unit, and controls the rectification unit to break circuit and discharge excess energy of a bus capacitor in the load, thereby protecting the safety of the load and the rectification unit, and improving the stability and reliability of the three-phase rectification circuit.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of power transformation, especially to a three-phase rectifier circuit and intelligent equipment. BACKGROUND

[0002] In the traditional frequency conversion drive circuit, the rectifier bridge (rectifier unit) is one of the most important power devices, one side of which is directly connected to the main power supply or directly connected to the power grid, and the other side is connected to the circuit load, that is, the rectifier bridge is located between the circuit load and the power supply, so the rectifier bridge as an intermediate bridge is easily affected by overcurrent and overvoltage and other impacts, causing the rectifier bridge to be damaged.

[0003] And it is difficult to analyze the specific damage reason of the damaged rectifier bridge, because whether the front-end power supply or the rear-end load is abnormal, the rectifier bridge may be directly damaged. On the other hand, the damage of the rectifier bridge caused by unstable power supply also easily leads to the damage of the rear-end load, causing a series of accidents or equipment loss.

[0004] Therefore, how to provide a three-phase rectifier circuit that can protect the safety of the rectifier unit and the safety of the load on the bus at the same time is a technical problem to be solved. INVENTION CONTENTS

[0005] The utility model provides a three-phase rectifier circuit and intelligent equipment for solving the problem that the three-phase rectifier circuit in the prior art cannot protect the rectifier unit and the load on the bus at the same time.

[0006] The technical scheme of the utility model is a three-phase rectifier circuit, which comprises a three-phase power supply, a load and a rectifier unit located between the two; further comprising:

[0007] A 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 rectifier circuit fails and generating a fault signal when a failure occurs;

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

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

[0010] The rectifier unit comprises a plurality of bridge arms, the middle point of each bridge arm is connected with the collector of the corresponding first IGBT, and the upper bridge arm of each bridge arm is connected with the emitter of the corresponding first IGBT.

[0011] The base of the triode is connected with the output end of the detection protection unit, the collector of the triode is used for connecting the 15V pin, the base of the triode is connected with the gate of all the first IGBTs and the gate of the second IGBT respectively, the emitter of the second IGBT is also connected with the upper bridge arm of all the bridge arms respectively, and the collector of the second IGBT is grounded.

[0012] Further, the three-phase rectifier circuit further comprises a cut-off diode, the anode of the cut-off diode is connected with the emitter of the second IGBT, and the anode of the cut-off diode is connected with the first end of the bus capacitor.

[0013] Further, the three-phase rectifier circuit further comprises a plurality of amplification sampling units.

[0014] Each phase of the three-phase power supply is connected in series with one of the sampling resistors, and the two ends of each sampling resistor are connected with two input ends of the corresponding amplification sampling unit.

[0015] Further, each amplification sampling unit comprises 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 with the first end of the second resistor, and the second end of the sampling resistor is connected with the first end of the third resistor.

[0017] The non-inverting input terminal of the first operational amplifier is connected with the first end of the first resistor and the second end of the second resistor respectively, the second end of the first resistor is used for connecting the VREF pin, the inverting input terminal of the first operational amplifier is connected with the second end of the third resistor and the first end of the fourth resistor respectively, and the second end of the fourth resistor and the output terminal of the first operational amplifier are connected with the input terminal of the detection protection unit.

[0018] Further, the detection protection unit comprises a current detection protection unit, the current detection protection unit comprises 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 terminal of each amplification sampling unit and the current sampling end of the master control MCU are connected with the non-inverting input terminal of one first comparator and the inverting input terminal of one second comparator respectively, the inverting input terminal of each first comparator is connected with a first wiring terminal, the first wiring terminal is also connected with the first end of the fifth resistor and the first end of the sixth resistor respectively, the non-inverting input terminal of each second comparator is connected with a second wiring terminal, and the second wiring terminal is also connected with the first end of the seventh resistor and the first end of the eighth resistor respectively.

[0020] The output of each of the first comparators and the corresponding output of the second comparator are respectively connected to the two inputs of a first AND gate element, the output of each of the first AND gate elements is connected to the first input of the second AND gate element, and the output of the second AND gate element is connected to the input of the execution unit.

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

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

[0023] The non-inverting input of the third comparator is connected to the first terminals of the ninth resistor and the tenth resistor, respectively. The inverting input of the third comparator is connected to the voltage sampling terminal of the main control MCU, the first terminal of the eleventh resistor, and the first terminal of the twelfth resistor, respectively. The output terminal of the third comparator 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 ends of the tenth resistor and the eleventh resistor are both grounded.

[0025] Furthermore, the three-phase rectifier circuit also includes an overvoltage protection unit, which includes multiple 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 also includes a dummy load sustaining unit, which includes multiple dummy loads;

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

[0029] This utility model also proposes 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 this invention, the execution unit receives a fault signal from the detection and protection unit, controls the rectifier unit to open the circuit, discharges excess energy from the bus capacitor in the load, thereby protecting the load and the safety of the rectifier unit, and improving the stability and reliability of the three-phase rectifier circuit. Attached Figure Description

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this invention are used to distinguish different objects and not to describe a particular order.

[0033] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a block diagram of the three-phase rectifier circuit proposed in this utility model;

[0035] Figure 2 The circuit diagram is for the three-phase rectifier circuit proposed in this utility model.

[0036] Figure label:

[0037] 1. Three-phase power supply;

[0038] 2. Load;

[0039] 3. Rectifier unit;

[0040] 4. Amplified sampling unit; 41. First amplified sampling unit; 42. Second amplified sampling unit

[0041] Yuan; 43. Third amplification sampling unit;

[0042] 5. Current detection and protection unit;

[0043] 6. Execution unit;

[0044] 7. Voltage detection and protection unit;

[0045] 8. Overvoltage protection unit;

[0046] 9. dummy load maintaining unit;

[0047] 10. master MCU. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions and beneficial effects of the present application more clear, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. Thus, the features described in the specification are used to explain one of the embodiments of the present application, but do not imply that each embodiment of the present application must have the features described. In addition, it should be noted that the specification describes many features. Although certain features can be combined together to show 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 principles and structures of the present application will be described in detail below in combination with the drawings and embodiments.

[0050] Embodiment 1

[0051] In a conventional variable frequency drive circuit, the rectifier bridge (rectifier unit) is one of the most important power devices. One side is directly connected to the main power supply or directly connected to the power grid, and the other side is connected to the circuit load, that is, the rectifier bridge is located between the circuit load and the power supply. Therefore, the rectifier bridge as an intermediate bridge is easily affected by overcurrent and overvoltage, causing the rectifier bridge to be damaged.

[0052] The damage of the rectifier bridge is difficult to analyze the specific damage reason, because whether the front-end power supply or the rear-end load appears abnormal, it is possible to directly damage the rectifier bridge. On the other hand, the damage of the rectifier bridge caused by unstable power supply is also easy to cause the damage of the rear-end load, causing a series of accidents or equipment loss.

[0053] Therefore, in order to solve the above problems, with reference to the accompanying drawings Figure 1 The present application provides a three-phase rectifier circuit which can protect the safety of the rectifier unit and the safety of the load on the bus, comprising a three-phase power supply 1, a load 2 and a rectifier unit 3 located between the two; further comprising:

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

[0055] An executing unit 6 is connected with the rectifying unit 3, the detecting and protecting unit and the load 2 respectively, and is used for receiving the 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 rectifying circuit in the embodiment includes overvoltage fault and / or overcurrent fault, and the corresponding fault signal includes overvoltage signal and / or overcurrent signal.

[0057] Therefore, when the three-phase rectifying circuit is faulty, i.e. the three-phase power supply 1 and / or the load 2 is overvoltage and / or overcurrent, the detecting and protecting unit detects the fault and generates the corresponding overvoltage signal and / or overcurrent signal, and the executing unit 6 receives the corresponding overvoltage signal and / or overcurrent signal, the executing unit 6 controls the rectifying unit 3 to be tripped, and discharges the excess energy of the bus capacitor C1 in the load 2, thereby protecting the safety of the load 2 and the rectifying unit 3 and improving the stability and reliability of the three-phase rectifying circuit; when the excess energy of the bus capacitor C1 is discharged and the current and / or voltage in the three-phase rectifying circuit is normal, the executing unit 6 controls the rectifying unit 3 to be reset, so that the three-phase rectifying circuit works normally.

[0058] In the embodiment, the rectifying unit 3, the detecting and protecting unit and the load 2 are connected with each other, and the three-phase power supply 1 is connected with the rectifying unit 3. Figure 2 The executing unit 6 includes a plurality of first IGBTs, a second IGBT M4 and a triode M5.

[0059] It should be noted that the number of the first IGBTs in the embodiment is preferably three, which are the first IGBT M1, the first IGBT M2 and the first IGBT M3.

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

[0061] The middle point of the first bridge arm is connected with the collector of the first IGBT M1, and the anode of the diode D1 is connected with the emitter of the first IGBT M1; the middle point of the second bridge arm is connected with the collector of the first IGBT M2, and the anode of the diode D3 is connected with the emitter of the first IGBT M2; the middle point of the third bridge arm is connected with the collector of the first IGBT M3, and the anode of the diode D5 is connected with the emitter of the first IGBT M3.

[0062] The base of the triode M5 is connected with the output of the detection protection unit, the collector of the triode M5 is used for connecting the 15V pin, the base of the triode M5 is connected with the gate of the first IGBT M1, the gate of the first IGBT M2, the gate of the first IGBT M3 and the gate of the second IGBT M4 respectively, the collector of the second IGBT M4 is grounded, and the emitter of the second IGBT M4 is also connected with the upper bridge arm of all the bridge arms (namely, the emitter of the second IGBT M4 is connected with the first end P of the bus capacitor C1).

[0063] It should be noted that the collector of the second IGBT M4 in the embodiment is connected with the PE ground; the first IGBT M1, the first IGBT M2 and the first IGBT M3 are all N-type IGBTs, the second IGBT M4 is a P-type IGBT, and the triode M5 is an N-type triode.

[0064] Therefore, when the detection protection unit detects that the three-phase rectifier circuit fails and generates a corresponding overvoltage signal and / or overcurrent signal, the triode M5 is turned off, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned off accordingly, resulting in that the first bridge arm, the second bridge arm and the third bridge arm are disconnected, and the second IGBT M4 is 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; 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 level output by the second AND element G2 is reversed (namely, the second AND element G2 outputs a low level), resulting in that the triode M5 is turned on, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned on accordingly, resulting in that the first bridge arm, the second bridge arm and the third bridge arm are not disconnected, and the second IGBT M4 is turned off, so that the three-phase rectifier circuit works normally.

[0065] If the three-phase rectifier circuit does not have overvoltage failure and / or overcurrent failure, the triode M5 is turned on, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned on accordingly, resulting in that the first bridge arm, the second bridge arm and the third bridge arm are not disconnected, the second IGBT M4 is turned off, and the rectifier unit 3 or the three-phase rectifier circuit works normally.

[0066] In order to prevent the energy of the load 2 or the bus capacitor C1 from being back-feeding, referring to the attached drawings, Figure 2 The three-phase rectifier circuit further comprises a cutoff diode D7, the anode of the cutoff diode D7 is connected with the emitter of the second IGBT M4, and the anode of the cutoff diode D7 is connected with the first end P of the bus capacitor C1.

[0067] In order to ensure that the current signal change of the three-phase power supply 1 is detected and amplified, and the common-mode signal is suppressed, referring to the attached drawings, Figure 2The three-phase rectifier circuit further comprises a plurality of amplification sampling units 4; each phase of the three-phase power supply 1 is connected in series with a sampling resistor, and the two ends of each sampling resistor are connected with the two input ends of the corresponding amplification sampling unit 4.

[0068] It should be noted that the three-phase power supply 1 comprises three phases, namely L1 phase, L2 phase and L3 phase; therefore, the sampling resistors in the embodiment comprise three sampling resistors, namely sampling resistor RS1, sampling resistor RS2 and sampling resistor RS3; correspondingly, the amplification sampling units 4 also comprise three amplification sampling units, namely first amplification sampling unit 41, second amplification sampling unit 42 and third amplification sampling unit 43.

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

[0070] Specifically, in order to ensure detection and amplification of the current signal change of the three-phase power supply 1 and suppression of the common-mode signal, reference is made to the attached drawings Figure 2 The embodiment provides a circuit structure of the amplification sampling unit 4:

[0071] The first amplification sampling unit 41 comprises a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; the second amplification sampling unit 42 comprises a first operational amplifier U1', a first resistor R1', a second resistor R2', a third resistor R3' and a fourth resistor R4'; and the third amplification sampling unit 43 comprises a first operational amplifier U1'', a first resistor R1'', a second resistor R2'', a third resistor R3'' and a fourth resistor R4''.

[0072] The first end of the sampling resistor RS1 is connected with the first end of the second resistor R2, and the second end of the sampling resistor RS1 is connected with the first end of the third resistor R3;

[0073] The non-inverting terminal of the first operational amplifier U1 is connected with the first end of the first resistor R1 and the second end of the second resistor R2, respectively, and the second end of the first resistor R1 is used for connecting the VREF pin; the inverting terminal of the first operational amplifier U1 is connected with the second end of the third resistor R3 and the first end of the fourth resistor R4, respectively, and the second end of the fourth resistor R4 and the output end of the first operational amplifier U1 are both connected with 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] A non-inverting terminal of the first operational amplifier U1 is connected to a first end of the first resistor R1' and a second end of the second resistor R2', and a second end of the first resistor R1' is connected to the VREF pin; an inverting terminal of the first operational amplifier U1 is connected to a second end of the third resistor R3' and a first end of the fourth resistor R4', and a second end of the fourth resistor R4' and an output terminal of the first operational amplifier U1 are both connected to a second input terminal of the detection protection unit.

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

[0077] A non-inverting terminal of the first operational amplifier U1" is connected to a first end of the first resistor R1" and a second end of the second resistor R2", and a second end of the first resistor R1" is connected to the VREF pin; an inverting terminal of the first operational amplifier U1" is connected to a second end of the third resistor R3" and a first end of the fourth resistor R4", and a second end of the fourth resistor R4" and an output terminal of the first operational amplifier U1" are both connected to a third input terminal of the detection protection unit.

[0078] It should be noted that R2=R3=R2'=R3'=R2"=R3", R4=R1=R4'=R1'=R4"=R1".

[0079] The calculation formula of the sampling output VOUT of the first operational amplifier U1, the first operational amplifier U1', and the first operational amplifier U1" is:

[0080]

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

[0082] Among them, refer to the attached Figure 2 The detection protection unit includes a current detection protection unit 5, and 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 master MCU 10 are connected with the non-inverting terminal of the first comparator U2 and the inverting terminal of the second comparator U3 respectively; the output end of the first operational amplifier U1' and the second current sampling end of the master MCU 10 are connected with the non-inverting terminal of the first comparator U2' and the inverting terminal of the second comparator U3' respectively; the output end of the first operational amplifier U1" and the third current sampling end of the master MCU 10 are connected with the non-inverting terminal of the first comparator U2" and the inverting terminal of the second comparator U3" respectively;

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

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

[0086] The second terminal of the fifth resistor R5, the second terminal of the seventh resistor R7 and the second input end of the second AND gate element G2 are all used for connecting the 5V pin; the second terminal of the sixth resistor R6 and the second terminal of the eighth resistor R8 are all 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 several cases:

[0088] 1. When the three-phase rectifier circuit is normal, the voltage at the non-inverting terminal of the first comparator U2, the first comparator U2', and the first comparator U2" is lower than the voltage at the inverting terminal of the first comparator U2, the first comparator U2', and the first comparator U2", so that the first comparator U2, the first comparator U2', and the first comparator U2" output high level; the voltage at the inverting terminal of the second comparator U3, the second comparator U3', and the second comparator U3" is lower than the voltage at the non-inverting terminal of the second comparator U3, the second comparator U3', and the second comparator U3", so that the second comparator U3, the second comparator U3', and the second comparator U3" output high level, and then the first AND gate element G1, the first AND gate element G1', and the first AND gate element G1" output high level, so that the second AND gate element G2 outputs high level, the triode M5 is turned on, and the first IGBT M1, the first IGBT M2, and the first IGBT M3 are also turned on, so that the first bridge arm, the second bridge arm, and the third bridge arm are not disconnected, and the second IGBT M4 is disconnected, so that the rectifier unit 3 or the three-phase rectifier circuit works normally.

[0089] 2. When the three-phase rectifier circuit has forward current overcurrent, the voltage at the inverting terminal of the first comparator U2, the first comparator U2', and the first comparator U2" is higher than the voltage at the non-inverting terminal of the first comparator U2, the first comparator U2', and the first comparator U2", so that the first comparator U2, the first comparator U2', and the first comparator U2" output high level; the voltage at the non-inverting terminal of the second comparator U3, the second comparator U3', and the second comparator U3" is higher than the voltage at the inverting terminal of the second comparator U3, the second comparator U3', and the second comparator U3", so that the second comparator U3, the second comparator U3', and the second comparator U3" output low level; then the first AND gate element G1, the first AND gate element G1', and the first AND gate element G1" output low level, so that the second AND gate element G2 outputs low level, the triode M5 is turned off, and the first IGBT M1, the first IGBT M2, and the first IGBT M3 are also turned off, so that the first bridge arm, the second bridge arm, and the third bridge arm are disconnected, and the second IGBT M4 is turned on to discharge the excess energy of the bus capacitor C1 to the PE ground, so as to protect the safety of the load 2 and the rectifier unit 3; and when the excess energy of the bus capacitor C1 is discharged and the current in the three-phase rectifier circuit is within the safety threshold, the level output by the second AND gate element G2 is reversed (i.e. the second AND gate element G2 outputs low level), so that the triode M5 is turned on, the first IGBT M1, the first IGBT M2, and the first IGBT M3 are also turned on, so that the first bridge arm, the second bridge arm, and the third bridge arm are not disconnected, and the second IGBT M4 is disconnected, so that the three-phase rectifier circuit works normally.

[0090] 3, when the three-phase rectifier circuit generates reverse current overcurrent, the voltage at the non-inverting 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 non-inverting 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; in turn, 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, causing the second AND gate element G2 to output a low level, causing the triode M5 to be turned off, causing the first IGBT M1, the first IGBT M2 and the first IGBT M3 to be turned off, causing the first bridge arm, the second bridge arm and the third bridge arm to be disconnected, causing the second IGBT M4 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 and 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 (i.e. the second AND gate element G2 outputs a low level), causing the triode M5 to be turned on, causing the first IGBT M1, the first IGBT M2 and the first IGBT M3 to be turned on, causing the first bridge arm, the second bridge arm and the third bridge arm to be connected, causing the second IGBT M4 to be turned off, so that the three-phase rectifier circuit works normally.

[0091] 4, When the forward current overflows and the reverse current overflows occur in the three-phase rectifier circuit, the first comparator U2 and / or the first comparator U2' and / or the first comparator U2" output low level to the outside, the second comparator U3, the second comparator U3' and the second comparator U3" output low level to the outside, and then the corresponding first AND gate element G1 and / or the first AND gate element G1' and / or the first AND gate element G1" output low level, the second AND gate element G2 outputs low level, the triode M5 is turned off, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned off, the first bridge arm, the second bridge arm and the third bridge arm are disconnected, and the second IGBT M4 is 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 and 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 (i.e. the second AND gate element G2 outputs low level), the triode M5 is turned on, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned on, the first bridge arm, the second bridge arm and the third bridge arm are not disconnected, and the second IGBT M4 is turned off, so that the three-phase rectifier circuit works normally.

[0092] Further, in order to ensure that the three-phase rectifier circuit can still continuously sample the current when the rectifier unit 3 is disconnected, with reference to the accompanying drawings Figure 2 The three-phase rectifier circuit further comprises a dummy load maintaining unit 9, and the dummy load maintaining unit 9 comprises a plurality of dummy loads.

[0093] The three-phase power supply 1 is connected with at least one dummy load between any two phases.

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

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

[0096] The three-phase rectifier circuit further comprises a detection protection unit 8, and the detection protection unit 8 comprises a current detection protection unit 6 and a voltage detection protection unit 7. Figure 2 The detection protection unit comprises a voltage detection protection unit 7, and the voltage detection protection unit 7 comprises a third comparator U4, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a twelfth resistor R12.

[0097] The non-inverting terminal of the third comparator U4 is connected with the first end of the ninth resistor R9 and the first end of the tenth resistor R10 respectively, the inverting terminal of the third comparator U4 is connected with the voltage sampling terminal of the master MCU 10, the first end of the eleventh resistor R11 and the first end of the twelfth resistor R12 respectively, and the output terminal of the third comparator U4 is also connected with the base of the triode M5.

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

[0099] In this way, when the three-phase rectifier circuit works normally, the voltage of the inverting terminal of the third comparator U4 is lower than the voltage of the non-inverting terminal of the third comparator U4, so that the third comparator U4 outputs high level to the outside, the triode M5 is turned on, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned on accordingly, so that the first bridge arm, the second bridge arm and the third bridge arm do not break, and the second IGBT M4 is turned off, so that the rectifier unit 3 or the three-phase rectifier circuit works normally.

[0100] When the three-phase rectifier circuit overvoltage occurs, the voltage of the inverting terminal of the third comparator U4 is higher than the voltage of the non-inverting terminal of the third comparator U4, so that the third comparator U4 outputs low level to the outside, the triode M5 is turned off, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned off accordingly, so that the first bridge arm, the second bridge arm and the third bridge arm break, and the second IGBT M4 is turned on, so that the excess energy of the bus capacitor C1 is discharged to the PE ground, thereby protecting the safety of the load 2 and the rectifier unit 3; and when the voltage of the bus capacitor C1 drops to within the safety threshold after the excess energy of the bus capacitor C1 is discharged, the level output by the third comparator U4 is reversed (i.e. the third comparator U4 outputs low level), so that the triode M5 is turned on, the first IGBT M1, the first IGBT M2 and the first IGBT M3 are also turned on accordingly, so that the first bridge arm, the second bridge arm and the third bridge arm do not break, and the second IGBT M4 is turned off, so that the three-phase rectifier circuit works normally.

[0101] In this embodiment, the three-phase rectifier circuit further comprises an overvoltage protection unit 8, and the overvoltage protection unit 8 comprises a plurality of voltage-dependent resistors. Figure 2

[0102] At least one voltage-dependent resistor 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 comprises three voltage-dependent resistors, which are the voltage-dependent resistor Z1, the voltage-dependent resistor Z2 and the voltage-dependent resistor Z3.

[0104] ​Specifically, a pressure-sensitive resistor Z1 is connected between the L1 phase and the L2 phase, a pressure-sensitive resistor Z2 is connected between the L1 phase and the L3 phase, and a pressure-sensitive resistor 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 the pressure-sensitive resistors in the overvoltage protection unit 8 can absorb part of the voltage, effectively preventing the excessively high voltage from damaging other sensitive elements in the three-phase rectifier circuit, reducing the overvoltage-induced faults of the three-phase rectifier circuit, and improving the stability and reliability of the three-phase rectifier circuit.

[0106] The main control MCU 10 is further connected to a display module (not shown, the same throughout the text). The main control MCU 10 collects the voltage signals and current signals in the three-phase rectifier circuit, calculates the actual current value and voltage value through an 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, thereby facilitating the detection of the three-phase rectifier circuit.

[0107] Embodiment 2

[0108] The utility model further provides a kind of intelligent equipment, and the intelligent equipment includes frequency converter, and 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 frequency converter, the detection protection unit detects the fault and generates a corresponding overvoltage signal and / or overcurrent signal, and after the execution unit 6 receives the corresponding overvoltage signal and / or overcurrent signal, the execution unit 6 controls the rectifier unit 3 to trip 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; after the excess energy of the bus capacitor C1 is discharged and the current and / or voltage in the three-phase rectifier circuit is normal, the execution unit 6 controls the rectifier unit 3 to reset, so that the three-phase rectifier circuit and the frequency converter work normally.

[0110] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments, and the preferred embodiments of the present application are given in the drawings, but do not limit the patent scope of the present application. The present application can be realized in many different forms, and conversely, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing specific embodiments, or equivalently replace some of the technical features. Any equivalent structure made by using the content of the present application specification and drawings, directly or indirectly used in other related technical fields, is also within the patent protection scope of the present application.

Claims

1. A three-phase rectifier circuit comprising a three-phase power supply, a load and a rectifier unit located therebetween; characterized in that, Also include: A detection protection unit connected with the three-phase power supply and the load respectively, the detection protection unit is used for detecting whether the three-phase rectifier circuit fails, and generating a fault signal when the failure occurs; An execution unit connected with the rectifier unit, the detection protection unit and the load respectively, the execution unit is used for receiving 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 includes a plurality of bridge arms, the middle point of each bridge arm is connected with the collector of the corresponding first IGBT, and the upper bridge arm of each bridge arm is connected with the emitter of the corresponding first IGBT; The base of the triode is connected with the output end of the detection protection unit, the collector of the triode is used for connecting the 15V pin, the base of the triode is connected with the gate of all the first IGBTs and the gate of the second IGBT respectively, the emitter of the second IGBT is also connected with the upper bridge arm of all the bridge arms respectively, and the collector of the second IGBT is grounded.

3. The three-phase rectifier circuit of claim 2, characterized in that The three-phase rectifier circuit further includes a cutoff diode, the anode of the cutoff diode is connected with the emitter of the second IGBT, and the anode of the cutoff diode is connected with the first end of the bus capacitor.

4. The three-phase rectifier circuit of claim 1, wherein The three-phase rectifier circuit further includes a plurality of amplification sampling units; Each phase of the three-phase power supply is connected with a sampling resistor in series respectively, and the two ends of each sampling resistor are connected with two input ends of the corresponding amplification sampling unit respectively.

5. The three-phase rectifier circuit of claim 4, characterized in that Each amplification sampling unit 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 with the first end of the second resistor, and the second end of the sampling resistor is connected with the first end of the third resistor; The non-inverting input terminal of the first operational amplifier is connected with the first end of the first resistor and the second end of the second resistor respectively, the second end of the first resistor is used for connecting the VREF pin, the inverting input terminal of the first operational amplifier is connected with the second end of the third resistor and the first end of the fourth resistor respectively, and the second end of the fourth resistor and the output terminal of the first operational amplifier are connected with the input terminal of the detection protection unit.

6. The three-phase rectifier circuit of claim 4, wherein, 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 terminal of each amplification sampling unit and the current sampling end of the master control MCU are connected with the non-inverting input terminal of the first comparator and the inverting input terminal of the second comparator respectively; the inverting input terminal of each first comparator is connected with a first wiring terminal, and the first wiring terminal is also connected with the first end of the fifth resistor and the first end of the sixth resistor respectively; the non-inverting input terminal of each second comparator is connected with a second wiring terminal, and the second wiring terminal is also connected with the first end of the seventh resistor and the first end of the eighth resistor respectively; The output end of each of the first comparators and the output end of the corresponding second comparator are connected to two input ends of a first AND gate element respectively, the output end of each of the first AND gate elements is connected to a first input end of a second AND gate element, and the output end of the second AND gate element is connected to an 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 connected to a 5V pin; the second end of the sixth resistor and the second end of the eighth resistor are grounded.

7. The three-phase rectifier circuit of claim 1, wherein The detection protection unit comprises a voltage detection protection unit, and the voltage detection protection unit comprises a third comparator, a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor; The non-inverting input end of the third comparator is connected to the first end of the ninth resistor and the first end of the tenth resistor respectively, the inverting input end of the third comparator is connected to a voltage sampling end of a master control MCU, the first end of the eleventh resistor and the first end of the twelfth resistor respectively, and the output end of the third comparator is connected to an input end of the execution unit; The second end of the twelfth resistor is connected to the first end of the bus capacitor, the second end of the ninth resistor is connected to a 5V pin, and the second end of the tenth resistor and the second end of the eleventh resistor are grounded.

8. The three-phase rectifier circuit of claim 1, wherein, The three-phase rectifier circuit further comprises an overvoltage protection unit, and the overvoltage protection unit comprises a plurality of voltage-dependent resistors; At least one voltage-dependent resistor is connected between any two phases of the three-phase power supply.

9. The three-phase rectifier circuit of claim 1, wherein, The three-phase rectifier circuit further comprises a dummy load maintaining unit, and the dummy load maintaining unit comprises a plurality of dummy loads. At least one dummy load is connected between any two phases of the three-phase power supply.

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

Images