Hybrid DC relay topology circuit switch transient characteristic analysis method

Abstract

The invention relates to the technical field of hybrid direct-current relays, and discloses a hybrid direct-current relay topology circuit switch transient characteristic analysis method. The method comprises the steps of obtaining circuit parameters corresponding to a topological circuit of the hybrid direct-current relay, establishing a transient characteristic equivalent mathematical model of a switch of the topological circuit of the direct-current relay according to the circuit parameters, and carrying out transient characteristic analysis on a conduction process and a turn-off process of the hybrid direct-current relay according to the transient characteristic equivalent mathematical model. Therefore, the transient characteristic analysis process of multiple segments on the topological circuit of the hybrid direct current relay can be realized, and the technical problem that the transient analysis method for the hybrid direct current relay in the prior art is insufficient in accuracy is solved.

Description

Technical Field

[0001] The invention relates to the technical field of direct current relays, and in particular to a method for analyzing transient characteristics of a hybrid direct current relay topology circuit switch. Background Art

[0002] As a mechanical switch, electromagnetic relays have low contact resistance and low conduction loss during operation. They are widely used in the industrial field and are one of the most important control components. The contacts of relays are the most important and most prone to failure in the contact system. Arc erosion is one of the main causes of relay contact failure. In DC systems, arc extinguishing is difficult due to the lack of current zero crossing. There is an urgent need for arc suppression technology to ensure the reliability of DC systems and improve the electrical life of relays.

[0003] The hybrid switch includes mechanical switches and power electronic devices. It combines the advantages of mechanical switches and solid-state relays, using mechanical switches to conduct normal load current and solid-state switches to provide commutation branches during the breaking process. It can reduce the arcing time of relay contacts and suppress the impact of arc on contacts while ensuring breaking capacity and action speed. However, the traditional hybrid switch analysis method cannot fully and accurately quantitatively characterize the transient characteristics of relay load switch circuits, and thus cannot reflect the true switching characteristics of hybrid DC relays. Summary of the invention

[0004] In view of the above problems, an embodiment of the present invention provides a method for analyzing the transient characteristics of a hybrid DC relay switch.

[0005] According to a first aspect of an embodiment of the present invention, a method for analyzing transient characteristics of a switch based on a hybrid DC relay topology circuit is provided, wherein the topology circuit includes a main branch, a commutation branch, an energy absorption branch and a drive circuit, and specifically includes: Obtaining circuit parameters of the hybrid DC relay topology circuit; Establishing an equivalent mathematical model of the switching transient characteristics of the hybrid DC relay topology circuit according to the circuit parameters; Performing transient characteristic analysis of the conduction process of the hybrid DC relay according to the mathematical model; The transient characteristics of the hybrid DC relay during the shutoff process are analyzed according to the mathematical model.

[0006] In a possible implementation manner of the first aspect, obtaining the circuit parameters of the hybrid DC relay topology circuit includes: Obtaining PCB three-dimensional models corresponding to the main branch, the commutation branch, and the energy absorption branch respectively; Construct PCB finite element simulation model and extract PCB parasitic parameters; Calculate the dynamic characteristic parameters of the varistor MOV; The equivalent inductance of each branch connecting wire in the PCB three-dimensional model is calculated.

[0007] In a possible implementation manner of the first aspect, before the step of analyzing the transient characteristics of the hybrid DC relay during the conduction process according to the mathematical model, the step of receiving a drive signal sent by the drive circuit and controlling the hybrid DC relay to conduct based on the drive signal specifically includes: Step 1, the first driving signal of the driving circuit outputs a high level, and after the gate of the first MOS tube of the main branch receives the high level, it is turned on when a preset condition is met, and the first coil of the DC relay is powered on; Step 2: After the first coil is powered on for a first preset time, the second drive signal of the drive circuit outputs a high level, and after receiving the high level, the gate of the second MOS transistor of the commutation branch is turned on when a preset condition is met, and the commutation branch is turned on; Step 3: After the first coil is powered on for a second preset time, the contacts of the first switch of the DC relay begin to close, and are completely closed after multiple bounces, and the main branch is turned on; after the second MOS tube is turned on for a third preset time, the second drive signal of the drive circuit outputs a low level, and the gate of the second MOS tube is turned off after receiving the low level, and the commutation branch is turned off; wherein, the first preset time is greater than or equal to 0 and less than the second preset time, and the third preset time is greater than or equal to the pull-in action time of the DC relay.

[0008] In a possible implementation manner of the first aspect, before the step of analyzing the transient characteristics of the hybrid DC relay during the shutdown process according to the mathematical model, the step of receiving a drive signal sent by the drive circuit and controlling the hybrid DC relay to shut down based on the drive signal specifically includes: Step 5, the first driving signal of the driving circuit outputs a low level, the gate of the first MOS tube is turned off after receiving the low level, and the first coil is powered off; Step 6: After the first coil is powered off for a fourth preset time, the second drive signal of the drive circuit outputs a high level, and after receiving the high level, the gate of the second MOS transistor of the commutation branch is turned on when a preset condition is met, and the commutation branch is turned on; Step 7: After the first coil is powered off for the fifth preset time, the contacts of the first switch begin to release and are completely disconnected after multiple bounces, and the main branch is turned off; after the second MOS tube is turned on for the sixth preset time, the second drive signal of the drive circuit outputs a low level, the second MOS tube is turned off, and the commutation branch is turned off; wherein the fourth preset time is greater than or equal to 0 and less than the fifth preset time, and the sixth preset time is greater than or equal to the release action time of the DC relay.

[0009] In a possible implementation manner of the first aspect, the method further includes a step of analyzing transient characteristics of a conduction process of the hybrid DC relay according to the mathematical model; In a possible implementation manner of the first aspect, the method further includes a step of analyzing transient characteristics of a switching-off process of the hybrid DC relay according to the mathematical model.

[0010] In a possible implementation of the first aspect, the topology circuit further includes: a positive terminal and a negative terminal; Wherein, the main branch, the commutation branch, and the energy absorption branch are connected in parallel between the positive terminal and the negative terminal; wherein the input end of the main branch, the input end of the commutation branch, and the input end of the energy absorption branch are respectively connected to the positive terminal, and the output end of the main branch, the output end of the commutation branch, and the output end of the energy absorption branch are respectively connected to the negative terminal; The driving circuit is connected to the main branch and the commutation branch respectively.

[0011] In a possible implementation of the first aspect, the topology circuit also includes a DC power supply and a load resistor; wherein the load resistor is connected in series between the positive electrode of the DC power supply and the positive terminal, and the negative electrode of the DC power supply is connected to the negative terminal and to the ground.

[0012] In a possible implementation manner of the first aspect, the main branch includes a first switch, a first coil, and a first MOS transistor; wherein a first end of the first switch is connected to the positive terminal as an input end of the main branch, a second end of the first switch is connected to the negative terminal as an output end of the main branch, a first end of the first coil is connected to VCC, a second end of the first coil is connected to a drain of the first MOS transistor, and a source of the first MOS transistor is connected to VEE; The commutation branch includes a second MOS transistor, a first diode, a second diode, a third diode and a fourth diode; wherein the anode of the first diode is connected to the cathode of the fourth diode and is connected to the anode terminal as the input end of the commutation branch, the anode of the second diode is connected to the cathode of the third diode and is connected to the cathode terminal as the output end of the commutation branch, the cathode of the first diode and the cathode of the second diode are commonly connected to the drain of the second MOS transistor, and the anode of the third diode and the anode of the fourth diode are commonly connected to the source of the second MOS transistor; The energy absorption branch comprises a first varistor, and two ends of the first varistor are respectively connected to the positive terminal and the negative terminal; The driving circuit includes a first driving signal and a second driving signal; the first driving signal is connected to the gate of the first MOS tube, and the second driving signal is connected to the gate of the second MOS tube.

[0013] The present invention provides a hybrid DC relay topology circuit switch transient analysis method, which obtains circuit parameters corresponding to the hybrid DC relay topology circuit, establishes an equivalent mathematical model of the transient characteristics of the relay topology circuit switch according to the circuit parameters, and performs transient characteristics analysis of the hybrid DC relay during a conduction process and a shutdown process according to the transient characteristics equivalent mathematical model, thereby realizing a plurality of segmented transient characteristics analysis processes for the topology circuit of the hybrid DC relay, so as to solve the technical problems of incomplete transient analysis methods for hybrid DC relays and insufficient accuracy in the prior art.

[0014] The above description is only an overview of the technical solution of the embodiment of the present invention. In order to more clearly understand the technical means of the embodiment of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are only used to illustrate the embodiments and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings: Figure 1 A flow chart of a method for analyzing transient characteristics of a hybrid DC relay topology circuit switch provided by the present invention is shown; FIG. 2( a ) shows a schematic diagram of a structure block diagram of a hybrid DC relay topology circuit provided by the present invention; FIG. 2( b ) shows a schematic diagram of the connection relationship of the hybrid DC relay topology circuit provided by the present invention; Figure 3A schematic diagram of parasitic parameter extraction of a hybrid DC relay topology circuit provided by the present invention is shown; Figure 4 A schematic diagram of a first conduction process of a hybrid DC relay topology circuit provided by the present invention is shown; Figure 5 A schematic diagram showing a second conduction process of the hybrid DC relay topology circuit provided by the present invention is shown; Figure 6 A schematic diagram showing a third conduction process of the hybrid DC relay topology circuit provided by the present invention is shown; Figure 7 A schematic diagram showing a first shut-down process of the hybrid DC relay topology circuit provided by the present invention is shown; Figure 8 A schematic diagram showing a second shut-down process of the hybrid DC relay topology circuit provided by the present invention is shown; Fig. 9 A schematic diagram of the conduction process waveform of the hybrid DC relay topology circuit provided by the present invention is shown; Fig.10 A schematic diagram of the conduction process waveform of the hybrid DC relay topology circuit provided by the present invention is shown; Fig.11 A schematic diagram of the waveform of the shut-down process of the hybrid DC relay topology circuit provided by the present invention is shown; Fig.12 A schematic diagram of the waveform of the shut-down process of the hybrid DC relay topology circuit provided by the present invention is shown; Fig.13 A schematic diagram of a driving control signal waveform of a hybrid DC relay topology circuit provided by the present invention is shown; Fig.14 A schematic diagram of transient waveforms of the conduction process of the hybrid DC relay topology circuit provided by the present invention is shown; Fig.15 A schematic diagram of transient waveforms during the shut-off process of the hybrid DC relay topology circuit provided by the present invention is shown. DETAILED DESCRIPTION

[0016] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0017] In the exemplary technology, the traditional analysis method cannot accurately characterize the transient characteristics of the load switch circuit, and will increase the cost and affect the switching speed, thereby failing to reflect the real switching characteristics of the hybrid DC relay.

[0018] Based on the above technical problems, the present invention proposes a hybrid DC relay topology circuit switch transient characteristics analysis method, such as Figure 1 As shown, the hybrid DC relay topology circuit includes four parts, namely a main branch 10, a commutation branch 20, an energy absorption branch 30 and a drive circuit 40. The switching transient characteristic analysis method specifically includes the following specific steps: Step S1, obtaining circuit parameters of a hybrid DC relay topology circuit; Step S1.1, respectively obtaining PCB three-dimensional models corresponding to the main branch 10, the commutation branch 20, and the energy absorption branch 30; The PCB 3D model of each branch is established through electronic product design software and the technical parameters of each device are obtained; the electronic product design software can be Allegro, Altium Designer, etc., and the corresponding topological design structure of each branch can be input to generate the PCB 3D model of the corresponding branch. Preferably, the time parameters of the DC relay and the relevant parameters of the MOSFET device such as the gate-source capacitance , gate-drain capacitance , drain-source capacitance , transconductance It can be found in the technical manual.

[0019] Step S1.2, constructing a PCB finite element simulation model and extracting PCB parasitic parameters; The selected simulation software may be finite element simulation software such as Ansys Q3D Extractor. By inputting each branch circuit topology, a PCB finite element simulation model can be established to extract the parasitic parameters of the PCB. The schematic diagram of PCB parasitic parameter extraction is shown in FIG. Figure 3 shown.

[0020] Step S1.3, calculating the dynamic characteristic parameters of the varistor MOV; Specifically, the static resistance value of the metal oxide varistor in the energy absorption branch is calculated according to the VI characteristic curve, and the dynamic characteristic parameter is calculated according to the experimental data of the energy absorption branch obtained; wherein the VI characteristic curve can be obtained from the manufacturer's data sheet provided by the metal oxide varistor. At this time, the dynamic resistance of the metal oxide varistor It can be expressed as:

[0021] in, is the peak value of the dynamic current of MOV, The current is The corresponding voltage value at the moment. MOV internal equivalent inductance It can be calculated as:

[0022] in, is the voltage drop value during the energy absorption stage, is the dynamic current value.

[0023] Step S1.4, calculating the equivalent inductance of each conductor in the PCB three-dimensional model; Among them, the equivalent inductance can be expressed as:

[0024] in, is the magnetic permeability of the material, Represents the wire length, is the wire diameter.

[0025] Step S2, establishing an equivalent mathematical model of transient characteristics of the relay topology circuit according to the circuit parameters; Step S3, analyzing the transient characteristics of the hybrid DC relay during the conduction process according to the mathematical model; Step S4, analyzing the transient characteristics of the hybrid DC relay during a shutoff process according to the mathematical model.

[0026] As an optional embodiment of the first aspect, a hybrid DC relay topology circuit is provided, the structural block diagram of which is shown in FIG2(a), and mainly includes: a positive terminal 1, a negative terminal 2, a main branch 10, a commutation branch 20, an energy absorption branch 30 and a drive circuit 40; further, FIG2(b) shows the specific connection relationship between each branch in the topology circuit, as well as a DC power supply and a load resistor used for testing.

[0027] Among them, the main branch 10, the commutation branch 20, and the energy absorption branch 30 are connected in parallel between the positive terminal 1 and the negative terminal 2; the input end of the main branch 10, the input end of the commutation branch 20, and the input end of the energy absorption branch 30 are respectively connected to the positive terminal 1, and the output end of the main branch 10, the output end of the commutation branch 20, and the output end of the energy absorption branch 30 are respectively connected to the negative terminal 2; the drive circuit 40 is respectively connected to the main branch 10 and the commutation branch 20, and provides a first drive signal S1 and a second drive signal S2 respectively to realize the conduction and shutdown of the main branch 10 and the commutation branch 20.

[0028] The main branch 10 includes a first switch K1, a first coil Coil, and a first MOS tube T1; wherein the first switch K1 and the first coil Coil together constitute the body of the relay, and the specific circuit topology can be divided into the first switch K1 and the first coil Coil; one end of the first switch K1 is connected to the positive terminal 1, the other end of the first switch K1 is connected to the negative terminal 2, one end of the first coil Coil is connected to the power supply voltage VCC, the other end of the first coil Coil is connected to the drain of the first MOS tube T1, and the source of the first MOS tube T1 is connected to VEE, which is usually a negative voltage equal to the voltage value of VCC; after the gate of the first MOS tube receives a high level, it is turned on when the preset conditions are met, and the first switch is controlled to be closed, otherwise, the first MOS tube is turned off after receiving a low level, and the first switch is controlled to be opened.

[0029] The commutation branch 20 includes a second MOS transistor T2, a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4; wherein the four diodes form a full-bridge structure, the cathode of the first diode D1 and the cathode of the second diode D2 are commonly connected to the drain D of the second MOS transistor T2, the anode of the third diode D3 and the anode of the fourth diode D4 are commonly connected to the source of the second MOS transistor T2; the anode of the first diode D1 and the cathode of the fourth diode D4 are commonly connected to the anode terminal 1 as the input end of the commutation branch, the anode of the second diode D2 and the cathode of the third diode D3 are commonly connected to the cathode terminal 2 as the output end of the commutation branch; when the second MOS transistor T2 is turned on, the first diode D1, the second MOS transistor T2, and the third diode D3 serve as the current path of the commutation branch; The energy absorption branch 30 includes a first varistor MOV, two ends of which are connected in parallel between the positive terminal 1 and the negative terminal 2; the varistor MOV is used to absorb the energy of the DC relay system during the shutdown process. Preferably, the varistor can be a metal oxide varistor MOV.

[0030] The driving circuit 40 includes a first driving signal S1 and a second driving signal S2, which are respectively used to connect to the gate of the first MOS transistor T1 and the gate of the second MOS transistor T2, and are used to control the conduction and shutdown of the MOS transistors, thereby realizing the conduction and shutdown of the main branch 10 and the commutation branch in the DC relay system.

[0031] As a preferred embodiment, it also includes a DC power supply and a load resistor R DC; Used for testing hybrid DC relay topology circuits; wherein the load resistor is connected in series between the positive pole of the DC power supply and the positive terminal 1, and the negative pole of the DC power supply is connected to the negative terminal 2 and then connected to the ground GND. The DC power supply, the load resistor and the DC relay system form a current loop, and the circuit switching characteristics are tested and analyzed based on the current and voltage waveforms.

[0032] Preferably, the first MOS tube and the second MOS tube are N-channel MOSFETs, or P-channel MOSFETs, and the corresponding control logic can be determined according to different types of MOSFETs.

[0033] The present invention provides a hybrid DC relay topology circuit switch transient characteristic analysis method, which obtains circuit parameters corresponding to the hybrid DC relay topology circuit, establishes a DC relay topology circuit switch transient characteristic equivalent mathematical model according to the circuit parameters, and performs transient characteristic analysis of the hybrid DC relay during a conduction process and a shutdown process according to the transient characteristic equivalent mathematical model, thereby realizing a plurality of segmented transient characteristic analysis processes for the hybrid DC relay topology circuit, so as to solve the technical problem of insufficient accuracy of the transient analysis method for the hybrid DC relay in the prior art.

[0034] In a possible implementation of the first aspect, step S2, establishing an equivalent mathematical model of transient characteristics of the DC relay topology circuit according to the circuit parameters, specifically includes: Connect the DC power supply and load resistor to the hybrid DC relay circuit to build a test system; Obtain the timing parameters of DC relays and related parameters of MOSFET devices, including gate-source capacitance , gate-drain capacitance , drain-source capacitance , transconductance ; Extract the parasitic parameters of each branch PCB, including the equivalent stray inductance of the commutation branch , Parasitic resistance of commutation branch , stray inductance in the energy absorption branch ; Copper conductors are preferred. Based on the length and cross-sectional area of ​​the conductors, the equivalent inductance of the conductors in the main branch and the commutation branch is calculated. L DC , ; Based on the above parameters, an equivalent mathematical model of the transient characteristics of the DC relay topology circuit can be established.

[0035] In a possible implementation manner of the first aspect, before step S3, the method further includes receiving a drive signal sent by the drive circuit, and controlling the hybrid DC relay to be turned on based on the drive signal, specifically including: Step 1: The first driving signal of the driving circuit outputs a high level, the first MOS tube of the main branch is turned on when a preset condition is met, and the first coil of the DC relay is powered on; The driving circuit usually controls the on and off of the MOS tube by sending PWM high and low level signals from FPGA. When the gate of the first MOS tube receives a high level, the conduction condition is met when its gate-source voltage is greater than or equal to the gate-source threshold voltage. At this time, the coil of the DC relay is powered on. Due to the delay caused by the inductance effect, the contacts of the DC relay are not attracted.

[0036] Step 2: After the first coil is powered on for a first preset time, the second drive signal of the drive circuit outputs a high level, and after receiving the high level, the gate of the second MOS tube of the commutation branch is turned on when a preset condition is met, and the commutation branch is turned on; Preferably, after a predetermined time has passed since the coil of the DC relay was powered on, the second drive signal of the drive circuit 40 outputs a high-level signal. The specific duration of the predetermined time may be 0, that is, the second drive signal is sent synchronously with the first drive signal. The specific delay duration may be determined based on actual conditions and is not specifically limited here.

[0037] Step 3: After the first coil of the DC relay is powered on for a second preset time, the contacts of the first switch of the DC relay begin to close, and are completely closed after multiple bounces, and the main branch is turned on; after the second MOS tube is turned on for a third preset time, the second drive signal of the drive circuit outputs a low level, and the gate of the second MOS tube is turned off after receiving the low level, and the commutation branch is turned off; wherein the first preset time is greater than or equal to 0 and less than the second preset time, and the third preset time is greater than or equal to the pull-in action time of the DC relay.

[0038] Preferably, after delaying for the second preset time, the switch contact of the DC relay begins to close. Due to the influence of the switching characteristics of the DC relay, the contact needs to bounce multiple times before it can be completely closed. There is an arc during the multiple bounces, so the main circuit current is commutated to the commutation branch under the action of the arc voltage. After multiple commutations, the first switch K1 is completely closed and the main branch is turned on. Since the switch delay characteristics of the DC relay need to be considered, the conduction time of the second MOS tube needs to be greater than the conduction time of the DC relay. Specifically, the third preset time is greater than or equal to the closure action time of the DC relay.

[0039] After receiving the driving control signal sent by the driving circuit, the first and second MOS tubes are turned on and off according to the different high and low levels of the driving signal. During the conduction process, the transient characteristics of the hybrid DC relay are analyzed according to the mathematical model of the topological circuit. Fig.14 The transient waveform diagram of the conduction process is shown in FIG. 1 , wherein the first drive signal S1 and the second drive signal S2 are synchronously issued at time t0. The transient analysis process specifically includes the following stages: Phase 1 (t0-t1): After the second MOS transistor T2 of the commutation branch 20 receives the high level of the drive signal S2, the gate voltage from Jumped to , Through the gate drive resistor Applied to the second MOS tube and to the input capacitor and Charging, gate-source voltage Start rising to , now entering stage 2; in this stage, although the first MOS tube T1 receives a high-level signal, due to the delay caused by the inductance effect, the coil of the DC relay is only powered on, and the switch is not closed; Phase 2 (t1-t2): When Exceeding the threshold After that, the second MOS tube of the commutation branch starts to conduct, and the drain-source current Starting from zero, the diode of the commutation branch is turned on. The schematic diagram of the first conduction process is as follows Figure 4 As shown, the equations of this process are expressed as:

[0040] in is the time when the stage 2 starts, is the drain-source voltage of the second MOS tube, is the DC power supply voltage, is the diode conduction voltage in the commutation branch, is the equivalent stray inductance in the commutation branch, L DC is the equivalent inductance, is the parasitic resistance of the commutation branch, is the load resistance, the drain-source current It is expressed as:

[0041] in, , , , , is the steady-state voltage of the second MOS tube when it is turned on, , , g m , R g , V gs(th) They are gate-source parasitic capacitance, gate-drain parasitic capacitance, transconductance, gate resistance, and gate threshold voltage; During this phase, the drain current It rises rapidly and approaches the theoretical load current value. When the loop stray inductance is large or the load is heavy, the drain current During the rising process, the drain-source voltage The value has dropped to less than , the drain-source voltage Drop to drain-source on-state voltage , the second MOS tube will work in the variable resistance area, and then enter stage 3; Phase 3 (t2-t3): The second MOS tube works in the variable resistance area, and the drain-source current of the commutation branch Continue to rise, the equations of this process are:

[0042] in, is the time when the stage 3 starts, for The initial value at the beginning of this phase, represents the sum of the equivalent resistance and parasitic resistance of the commutation switch, then the drain-source current It is expressed as:

[0043] When the drain-source current Rising to system load current , then enter stage 4; Phase 4 (t3-t4): When the gate-source voltage of the second MOS tube Rise to V g1 , the conduction process of the commutation branch is completed, and the stage 5 is entered; Phase 5 (t4-t5): The contact of the first switch K1 of the DC relay begins to close, and the load current is commutated from the commutation branch to the main branch. The system load current for and i relay The sum of the drain-source current and remains unchanged Gradually decreases, while the current in the main branch i relayThe second conduction process diagram is shown in Figure 5 As shown, the equations of this process are expressed as:

[0044] in, The moment when stage 5 begins. The loop inductance caused by the wires and terminals in the main branch, then the leakage current It is expressed as:

[0045] according to Fig.14 as well as As shown in the formula, the drain-source current It may drop to 0 and become negative. At this time, it can be considered that the commutation branch is charging the main branch in reverse. It returns to 0 and does not change any more, and then enters stage 6; Stage 6: The contact of the first switch K1 bounces, and an arc exists during the contact separation process. Under the action of the arc voltage, the main branch current is commutated to the commutation branch. During the commutation process, the system load current for and i relay The sum of the drain-source current and remains unchanged Gradually increases, while the current in the main branch i relay The corresponding reduction is shown in the schematic diagram of the third conduction process. Figure 6 As shown, the equations of this process are expressed as:

[0046] in, is the arc voltage when the contacts of the first switch are separated, At the beginning of phase 6, the drain-source current for:

[0047] When the drain-source current Rising as load current And it no longer changes, and then enters stage 7; Stage 7: The contacts of the first switch of the DC relay bounce and then close, repeating the commutation process of stages 5 and 6. After multiple bounces, the contacts of the first switch of the DC relay are completely closed, and the main branch is fully conductive.

[0048] In a possible implementation manner of the first aspect, the method further includes receiving a drive signal sent by a drive circuit, and controlling the hybrid DC relay to shut down based on the drive signal, specifically including: Step 5, the first driving signal of the driving circuit outputs a low level, the gate of the first MOS tube is turned off after receiving the low level, and the first coil is powered off; after the MOS tube is turned off, the coil of the DC relay is immediately powered off, and the switch of the relay needs to be delayed due to the inductance effect.

[0049] Step 6: After the first coil of the DC relay is powered off for a fourth preset time, the second drive signal of the drive circuit outputs a high level, and after receiving the high level, the gate of the second MOS tube of the commutation branch is turned on when a preset condition is met, and the commutation branch is turned on; Preferably, the specific duration of the fourth preset duration can be set to 0, that is, the first MOS tube and the second MOS tube can synchronously receive the driving signal, which can be specifically set and selected according to the actual application scenario.

[0050] Step 7: After the first coil of the DC relay is de-energized for the fifth preset time, the contacts of the first switch of the DC relay begin to release and are completely disconnected after multiple bounces, and the main branch is turned off; after the second MOS tube is turned on for the sixth preset time, the second drive signal of the drive circuit outputs a low level, the second MOS tube is turned off, and the commutation branch is turned off; wherein the fourth preset time is greater than or equal to 0 and less than the fifth preset time, and the sixth preset time is greater than or equal to the release action time of the DC relay.

[0051] Preferably, after the fifth preset delay time, the switch contact of the DC relay begins to release. Due to the influence of the DC relay switch characteristics, the contact needs to bounce multiple times before it can be completely disconnected. There is an arc during the multiple bounces, so the main circuit current is commutated to the commutation branch under the action of the arc voltage. After multiple commutations, the first switch K1 is completely disconnected and the main branch is turned off. Since the switch delay characteristics of the DC relay need to be considered, the conduction time of the second MOS tube needs to be greater than the turn-off time of the DC relay. Specifically, the sixth preset time is greater than or equal to the release action time of the DC relay.

[0052] Preferably, after receiving the driving control signal sent by the driving circuit, the first and second MOS tubes are turned on and off according to the different high and low levels of the driving signal. During the shutdown process, the transient characteristics of the hybrid DC relay during the shutdown process are analyzed according to the mathematical model of the topological circuit. Specifically, Fig.15 The transient waveform diagram of the shutdown process is shown in the figure, wherein the first drive signal S1 and the second drive signal S2 are synchronously sent out at time t0, and the transient analysis process specifically includes the following stages: Phase 1 (t0-t1): The gate of the first MOS tube of the main branch is turned off after receiving a low level, and the first coil of the DC relay is de-energized; the gate of the second MOS tube of the commutation branch is turned off after receiving a high level. from Gradually increasing, drain-source current Keep it at 0; Phase 2 (t1-t2): After the first coil of the DC relay is deenergized for the fifth preset time, the contacts of the first switch K1 begin to release. There is an arc in the process of the contacts bouncing and separating. Under the action of the arc voltage, the main branch current is commutated to the commutation branch, and the drain-source current The moment when the voltage starts to increase from 0 is t1. The second MOS tube needs to be turned on with load for a period of time to ensure that there is enough gap between the contacts of the DC relay. The transient process is the same as stage 6 in the turn-on transient characteristic, and will not be repeated here.

[0053] Phase 3 (t2-t3): The second MOS tube is due to the Miller effect. , Both remain unchanged, and the initial value of the gate-source voltage is , Starts to rise, the gate leakage current It is expressed as:

[0054] at the same time, satisfy:

[0055] The drain-source voltage at this stage is:

[0056] Where t2 is the moment when the Miller effect starts; since the hybrid DC relay is connected in parallel with the varistor MOV, when the voltage of the commutation branch exceeds its varistor voltage, the MOV device starts to work, and the branch voltage jumps to the clamping voltage, which is greater than Therefore, during the voltage rise, it is considered that the MOV charges the commutation branch, which makes Increase.

[0057] Phase 4 (t3-t4): After the Miller effect ends, the current in the commutation branch begins to decrease, and the current is commutated to the energy absorption branch. The schematic diagram of the first shutdown process is shown in FIG. Figure 7 As shown, the equivalent resistance of the varistor MOV quickly decreases to the dynamic resistance. The equation group of this process is expressed as:

[0058] in, is the equivalent dynamic inductance inside the varistor MOV, is the equivalent nonlinear resistance inside the varistor MOV, is the current of the energy absorbing branch, is the stray inductance in the energy absorption branch, is the voltage of the energy absorption branch after the Miller effect ends, and is the voltage slope and fall time variable, is the moment when the Miller effect ends, and the current in the energy absorption branch is:

[0059] For the second MOS tube of the commutation branch, the equations of this process are:

[0060] in, , , then the drain-source current for:

[0061] Phase 5 (t4-t5): The current in the commutation branch continues to decrease, and the drain-source current Reduced to 0, the current of the varistor MOV reaches its peak value , which then absorbs the stored energy, and the current in the energy absorbing branch Gradually decreases, the second shutdown process schematic diagram is as follows Figure 8 As shown, the equations of this process are expressed as:

[0062] is the moment when the current of the varistor MOV reaches its peak value, then the current of the energy absorption branch for:

[0063] Current in the energy absorbing branch When it drops to 0, the shut-down process of the hybrid DC relay is completed.

[0064] Among them, those skilled in the art can understand that for Figure 4-Figure 8 The direction of the arrow in the figure indicates the direction of current flow, and the path where the arrow is located represents the path that the current passes through in the current on or off state.

[0065] As a further embodiment, the present invention also proposes a method for verifying the dynamic analysis method of the transient characteristics of a hybrid DC relay topology circuit by measuring the voltage and current method; the voltage and current measurement method is to measure the current and voltage of the hybrid DC relay port during the switching process, test the transient process time of the hybrid DC relay switch, and compare it with the waveform and process time of the transient calculation analytical formula, so as to verify the transient characteristics analysis method proposed by the present invention.

[0066] For a certain type of DC electromagnetic relay, a hybrid DC relay is constructed, a transient mathematical model is established, and the transient characteristic calculation of the switch segment analysis is completed. The hybrid DC relay prototype is connected to a resistive load, and the waveform diagram of the drive control signal is shown in the figure. Fig.13 As shown, it is controlled by the multi-channel pulse signal output by the FPGA, and the IC driver chip ensures the driving power of the MOSFET. The DC voltage source is 28V, and the resistive load 1.4 , that is, the load current The gate-source capacitance of the MOSFET is 20A. The conduction voltage of the diode is 1.1V. The gate-drain capacitance is 4.7uF 300pF, drain-source capacitance 500 pF, transconductance It is 189S.

[0067] According to the hybrid DC relay topology circuit, a PCB 3D model is established, and a finite element simulation model is generated to extract the parasitic parameters of each branch PCB. The 3D PCB model corresponding to each branch is designed using Altium Designer. It is imported into Ansys Q3D Extractor to generate a finite element simulation model and extract the parasitic parameters of each branch PCB. , , .

[0068] Determine the equivalent inductance of the conductors in the main branch and the commutation branch; select copper conductors and calculate the equivalent inductance based on the conductor length and cross-sectional area , .

[0069] Carry out the hybrid DC relay on-load on-off test, use the voltage and current measurement method to record the waveform during the experiment, and record the duration of each transient process, refer to Figure 9-12 The waveform diagram of the conduction process and the shutdown process is shown, and the dynamic characteristic parameters of the metal oxide varistor MOV are calculated based on the transient experimental data of the shutdown.

[0070] Input the parasitic parameters, equivalent inductance and dynamic characteristic parameters into the formulas of each on state and each off state in the transient characteristic analysis method of the hybrid relay as described above to obtain the analytical expression of the current in each state, thereby drawing a function graph and measuring the duration of each stage; Calculate the relative error between the test value and the calculated value, specifically:

[0071] Table 1 Comparison of transient calculated values ​​and experimental results of hybrid DC relay of the present invention

[0072] Beneficial effects of the present invention: The calculation results of the segmented analytical transient characteristics of the hybrid DC relay provided by the present invention are basically consistent with the measured results, and can accurately reflect the transient characteristics and duration of the current during the switching process, with an error within 24%. The minimum error of the MOV transient current characteristics calculated by the dynamic parameter determination method of the present invention is 6%. For the subsequent study of the influence of the relevant parameters of the hybrid relay on its switching characteristics, a reliable and convenient dynamic characteristic analysis and calculation method is provided.

[0073] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. Similarly, in order to simplify the present invention and help understand one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Wherein, the claims that follow the specific embodiment are hereby expressly incorporated into the specific embodiment, wherein each claim itself is a separate embodiment of the present invention.

[0074] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and further may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive.

[0075] It should be noted that the above embodiments illustrate the present invention rather than limit it, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets shall not be construed as a limitation on the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention may be implemented by means of hardware comprising a number of different elements and by means of a suitably programmed computer. In a unit claim enumerating a number of devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be understood as limitations on the order of execution.

Claims

1. A method for analyzing the transient characteristics of a hybrid DC relay topology circuit switch, wherein the topology circuit comprises a main branch, a commutation branch, an energy absorption branch and a drive circuit, characterized in that: The method comprises: Obtaining circuit parameters of the hybrid DC relay topology circuit; Establishing an equivalent mathematical model of the switching transient characteristics of the hybrid DC relay topology circuit according to the circuit parameters; Performing transient characteristic analysis of the conduction process of the hybrid DC relay according to the mathematical model; The transient characteristics of the hybrid DC relay during the shutoff process are analyzed according to the mathematical model.

2. The switch transient characteristic analysis method according to claim 1, characterized in that: The obtaining of the circuit parameters of the hybrid DC relay topology circuit comprises: Obtaining PCB three-dimensional models corresponding to the main branch, the commutation branch, and the energy absorption branch respectively; Construct PCB finite element simulation model and extract PCB parasitic parameters; Calculate the dynamic characteristic parameters of the varistor MOV; The equivalent inductance of each branch connecting wire in the PCB three-dimensional model is calculated.

3. The switch transient characteristic analysis method according to claim 1, characterized in that: Before the step of analyzing the transient characteristics of the hybrid DC relay during the conduction process according to the mathematical model, the method further includes receiving a drive signal sent by the drive circuit, and controlling the hybrid DC relay to conduct based on the drive signal, which specifically includes: Step 1, the first driving signal of the driving circuit outputs a high level, and after the gate of the first MOS tube of the main branch receives the high level, it is turned on when a preset condition is met, and the first coil of the DC relay is powered on; Step 2: After the first coil is powered on for a first preset time, the second drive signal of the drive circuit outputs a high level, and after receiving the high level, the gate of the second MOS transistor of the commutation branch is turned on when a preset condition is met, and the commutation branch is turned on; Step 3: After the first coil is powered on for a second preset time, the contacts of the first switch of the DC relay begin to close, and are completely closed after multiple bounces, and the main branch is turned on; after the second MOS tube is turned on for a third preset time, the second drive signal of the drive circuit outputs a low level, and the gate of the second MOS tube is turned off after receiving the low level, and the commutation branch is turned off; wherein, the first preset time is greater than or equal to 0 and less than the second preset time, and the third preset time is greater than or equal to the pull-in action time of the DC relay.

4. The switch transient characteristic analysis method according to claim 3, characterized in that: The transient characteristic analysis of the conduction process of the hybrid DC relay according to the mathematical model includes the following stages: Phase 1: After the second MOS tube of the commutation branch receives the high level, the gate voltage from Jumped to , Through the gate drive resistor applied to the second MOS tube, to the input capacitor and Charging, gate-source voltage Start rising to , now enter stage 2; Phase 2: When Exceeding the threshold After that, the second MOS tube of the commutation branch starts to conduct, and the drain-source current Starting from zero, the diode of the commutation branch is turned on, and the equation group of this process is expressed as: in is the time when the stage 2 starts, is the drain-source voltage of the second MOS tube, is the DC power supply voltage, is the diode conduction voltage in the commutation branch, is the equivalent stray inductance in the commutation branch, L DC is the equivalent inductance, is the parasitic resistance of the commutation branch, is the load resistance, the drain-source current It is expressed as: in, , , , , is the steady-state voltage of the second MOS tube when it is turned on, , , g m , R g , V gs(th) They are gate-source parasitic capacitance, gate-drain parasitic capacitance, transconductance, gate resistance, and gate threshold voltage; Drain Current Rapidly rising drain-source voltage Drop to drain-source on-state voltage , now enter stage 3; Phase 3: The drain-source current of the commutation branch continues to rise, and the second MOS tube operates in the variable resistance region. The equation group of this process is: in, is the time when the stage 3 starts, for The initial value at the beginning of this phase, represents the sum of the equivalent resistance and parasitic resistance of the commutation switch, then the drain-source current It is expressed as: When the drain-source current Rising to system load current , then enter stage 4; Phase 4: When the gate-source voltage of the second MOS tube Rise to V g1 , the conduction process of the commutation branch is completed, and the process enters stage 5; Phase 5: The contact of the first switch of the relay begins to close, the load current is commutated from the commutation branch to the main branch, and the drain-source current Gradually decreasing, the equations of this process are expressed as: in, The moment when stage 5 begins. The loop inductance caused by the wires and terminals in the main branch, then the leakage current It is expressed as: When the drain-source current It decreases to 0 and does not change any more, and then enters stage 6; Stage 6: The contacts of the first switch bounce, and an arc exists during the contact separation process. Under the action of the arc voltage, the main branch current is commutated to the commutation branch. During the commutation process, the system load current The equations of this process are expressed as: in, is the arc voltage when the contacts of the first switch are separated, At the beginning of phase 6, the drain-source current for: When the drain-source current Rising as load current And it no longer changes, and then enters stage 7; Stage 7: The contacts of the first switch are closed after bouncing, and the commutation process of stages 5 and 6 is repeated. After multiple bounces, the contacts of the first switch are completely closed, and the main branch is turned on.

5. The switch transient characteristic analysis method according to claim 1, characterized in that: Before the step of analyzing the transient characteristics of the hybrid DC relay during the shutoff process according to the mathematical model, the step of receiving a drive signal sent by the drive circuit and controlling the hybrid DC relay to shut off based on the drive signal specifically includes: Step 5, the first driving signal of the driving circuit outputs a low level, the gate of the first MOS tube is turned off after receiving the low level, and the first coil of the DC relay is powered off; Step 6: After the first coil is powered off for a fourth preset time, the second drive signal of the drive circuit outputs a high level, and after receiving the high level, the gate of the second MOS transistor of the commutation branch is turned on when a preset condition is met, and the commutation branch is turned on; Step 7: After the first coil is powered off for the fifth preset time, the contacts of the first switch of the DC relay begin to release and are completely disconnected after multiple bounces, and the main branch is turned off; after the second MOS tube is turned on for the sixth preset time, the second drive signal of the drive circuit outputs a low level, the second MOS tube is turned off, and the commutation branch is turned off; wherein the fourth preset time is greater than or equal to 0 and less than the fifth preset time, and the sixth preset time is greater than or equal to the release action time of the DC relay.

6. The switch transient characteristic analysis method according to claim 5, characterized in that: The transient characteristic analysis of the hybrid DC relay during the shut-off process according to the mathematical model includes the following stages: Phase 1: After the gate of the first MOS tube of the main branch receives the low level, it is turned off, and the first coil is powered off; after the gate of the second MOS tube of the commutation branch receives the high level, the gate-source voltage V gs from- V g2 Gradually rising, drain-source current Keep it at 0; Stage 2: After the first coil is powered off for a fifth preset time, the contacts of the first switch begin to release, an arc exists during the process of the contacts bouncing and separating, and the main branch current is commutated to the commutation branch under the action of the arc voltage; Stage 3: The second MOS tube has a Miller effect. , Both remain unchanged, and the initial value of the gate-source voltage is , Starts to rise, the gate leakage current It is expressed as: at the same time, satisfy: The drain-source voltage at this stage is: Phase 4: After the Miller effect ends, the current of the commutation branch begins to decrease, and the current is commutated to the energy absorption branch. The equivalent resistance of the varistor MOV of the energy absorption branch is rapidly reduced to the dynamic resistance. The equation group of this process is expressed as: in, is the equivalent dynamic inductance inside the MOV varistor, is the equivalent nonlinear resistance inside the varistor MOV, is the current of the energy absorbing branch, is the stray inductance in the energy absorption branch, is the voltage of the energy absorption branch after the Miller effect ends, and is the slope and fall time variable of the branch voltage, is the moment when the Miller effect ends, and the current of the energy absorption branch is obtained as: For the second MOS transistor of the commutation branch, the equation group of the process is: in, , , then the drain-source current for: Phase 5: The current in the commutation branch continues to decrease, and the drain-source current decreases to 0, the current of the varistor MOV reaches its peak , which then absorbs the stored energy, which absorbs the current of the branch Gradually decreasing, the equations of this process are expressed as: is the moment when the current of the varistor MOV reaches its peak value, then the current of the energy absorption branch for: The current of the energy absorption branch When it drops to 0, the shut-down process of the hybrid DC relay is completed.

7. The switch transient characteristic analysis method according to claim 1, characterized in that: The topological circuit further includes: a positive terminal and a negative terminal; Wherein, the main branch, the commutation branch, and the energy absorption branch are connected in parallel between the positive terminal and the negative terminal; wherein the input end of the main branch, the input end of the commutation branch, and the input end of the energy absorption branch are respectively connected to the positive terminal, and the output end of the main branch, the output end of the commutation branch, and the output end of the energy absorption branch are respectively connected to the negative terminal; The driving circuit is connected to the main branch and the commutation branch respectively.

8. The switch transient characteristic analysis method according to claim 7, characterized in that: Also included is a DC power supply and a load resistor for testing the hybrid DC relay; The load resistor is connected in series between the positive electrode of the DC power supply and the positive terminal, and the negative electrode of the DC power supply is connected to the negative terminal and to the ground.

9. The switch transient characteristic analysis method according to claim 7, characterized in that: The main branch includes a first switch, a first coil and a first MOS tube; The first end of the first switch is connected to the positive terminal as the input end of the main branch, the second end of the first switch is connected to the negative terminal as the output end of the main branch, the first end of the first coil is connected to VCC, the second end of the first coil is connected to the drain of the first MOS transistor, and the source of the first MOS transistor is connected to VEE; The commutation branch includes a second MOS tube, a first diode, a second diode, a third diode and a fourth diode; Wherein, the anode of the first diode is connected to the cathode of the fourth diode and is connected to the anode terminal as the input end of the commutation branch, the anode of the second diode is connected to the cathode of the third diode and is connected to the cathode terminal as the output end of the commutation branch, the cathode of the first diode and the cathode of the second diode are commonly connected to the drain of the second MOS transistor, and the anode of the third diode and the anode of the fourth diode are commonly connected to the source of the second MOS transistor; The energy absorption branch comprises a first varistor, and two ends of the first varistor are respectively connected to the positive terminal and the negative terminal; The driving circuit includes a first driving signal and a second driving signal; the first driving signal is connected to the gate of the first MOS tube, and the second driving signal is connected to the gate of the second MOS tube.

Images