CN113589128A - Short-circuit fault detection method for SiC MOSFET power module - Google Patents
Short-circuit fault detection method for SiC MOSFET power module Download PDFInfo
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Abstract
The invention relates to a short-circuit fault detection method of a SiC MOSFET power module, which utilizes a voltage division circuit and an integral circuit to obtain the detection values of drain-source voltage and drain current of the SiC MOSFET, inputs the detection values into a multiplier module, multiplies the detection values of the drain-source voltage and the drain current in the multiplier module to obtain the detection value proportional to instantaneous power consumption, compares the instantaneous power consumption detection value output by a high-speed multiplier with a preset threshold value by using a comparison and trigger holding module, and outputs a fault signal if the detection value is higher than the threshold value. By the short-circuit fault detection method, the SiC MOSFET can reliably judge whether the circuit has the short-circuit fault on line on the basis of not increasing excessive hardware loss and cost, so as to achieve the aim of accurately and quickly protecting the device.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a short-circuit fault detection method for a SiC MOSFET power module.
Background
Compared with the traditional Si material, the SiC material has excellent characteristics of high forbidden band width, high saturated electron drift rate, high thermal conductivity, high breakdown field strength and the like, so that the SiC device has the advantages of high switching frequency (higher than 20kHz), high voltage resistance, low conduction loss, high operation temperature and the like, but compared with the Si IGBT device of the same grade, the SiC MOSFET has the advantages of small chip area, large current density, low channel mobility and small conduction resistance, the current during short circuit can be increased to 8-10 times of a rated value, so the short circuit tolerance time is shorter, and the rapid and reliable detection and protection are needed. Therefore, the SiC MOSFET has higher requirements for the fast protection capability of the driver, and designing the SiC MOSFET driver with fast and reliable protection has important significance for promoting and accelerating the wide application of the SiC MOSFET.
Taking the driving application of the motor for electric traffic as an example, the SiC MOSFET is prone to two types of faults in the actual operation process, and the two types of faults can be divided into Hard Switching Fault (HSF) and Load short (full open Load) according to the inductance of a short circuit loop. The short-circuit current generated by the short circuit of the hard switch can generate very large heat in the power chip in a short time, so that the junction temperature is rapidly increased. If the protection circuit does not detect the short-circuit fault in time and quickly turns off the device, the chip is very easy to burn due to overhigh junction temperature or the gate oxide layer fails. Therefore, for SiC MOSFET modules, a hard-switched short is the most rapidly detected and responded to fault.
The load short circuit refers to the short circuit of the SiC MOSFET under the condition of being switched on, such as the phase short circuit or the ground short circuit of a load motor. After the load is short-circuited, the inductance of the power loop is greatly reduced, the drain current is rapidly increased, the loop inductance is directly communicated due to gradual saturation, the device exits from a saturation region and enters a short-circuit state, and the drain-source voltage is finally stabilized at the voltage value of the direct-current bus. Load shorts are also a more severe short-circuit fault and also require a fast shut-down.
The most important link in the short-circuit protection of the SiC MOSFET is short-circuit fault detection, and the detection of the short-circuit fault quickly and accurately is the premise of realizing quick and reliable protection. At present, methods for detecting short circuit of the SiC MOSFET mainly include a desaturation detection method, a di/dt detection method, a gate voltage detection method, and a gate charge detection method.
The desaturation detection method utilizes the characteristic that the drain voltage of the SiC MOSFET rises to the bus voltage when short circuit occurs, and triggers protection when the drain-source voltage is detected to be higher than a preset reference value; the di/dt detection method is to judge whether the short-circuit fault occurs by using induced electromotive force generated by rapid rise of drain current during short-circuit; the grid voltage detection method is characterized in that the principle that the electric charge amount in short circuit is smaller than that in normal driving when the driving voltage is the same is utilized, when the voltage reaches a reference value and the electric charge is smaller than the reference value, the short circuit fault is judged to occur, and the protection action is carried out; in the gate charge detection method, the amount of charge flowing through the gate is monitored, and when a short-circuit failure occurs, the amount of charge of the gate increases rapidly, and when the value exceeds the maximum value allowed by the detection circuit, a protection operation is triggered.
For example, patent CN 105445608B-SIC MOSFET overcurrent short circuit detection circuit and detection protection system "invented by the present invention realizes fast overcurrent detection by using a switching current-expanding device with faster switching speed than SIC MOSFET. The invention patent CN 111130518A-a SiC MOSFET rapid short-circuit protection circuit converts large current generated in short circuit into a voltage signal through a series resistor, thereby detecting short-circuit fault by monitoring voltage. The invention patent CN 111313874A-a current detection device and short-circuit protection method for SiC MOSFET uses the difference between the induced electromotive force generated by the drain and source current during short-circuit and the normal condition to detect the fault.
The short circuit detection method of the prior SiC MOSFET has the following defects:
1) the desaturation detection method has slow response and long time consumption when detection is carried out under the condition that the SiC MOSFET is short-circuited by a hard switch, and the short-circuit time is possibly beyond the endurable time, so that the device is damaged; and because of the lower on-resistance, the action threshold voltage of the SiC MOSFET is lower, which is easy to cause malfunction.
2) When a load short circuit occurs in the SiC MOSFET, the inductance of a loop is relatively large, and the di/dt value at the moment is not necessarily larger than the opening process, so that the induction voltage may not exceed a set protection action threshold value, and the di/dt detection method cannot quickly and reliably detect the load short circuit fault.
3) The gate voltage detection method and the gate charge detection method are similar, and have the advantage of fast response speed, but the topology for detecting the gate charge is too complex, the reliability is not high, and the algorithm is too cumbersome compared with other methods, which is not convenient for practical application, for example, patent CN 109061431A.
4) The detection circuit proposed in patent CN105445608B uses more resistance-capacitance devices and switch current-spreading devices, and although the detection circuit can increase the reaction rate, the topology is more complex than other methods, and the cost and power loss are increased; in the method of monitoring voltage through the series resistor in patent CN111130518A, since an additional series resistor is needed, a larger current causes higher heat generation when passing through the resistor, thereby increasing loss and reducing the working efficiency of the SiC MOSFET.
Therefore, it is urgently needed to design a short-circuit fault detection method for a SiC power module, so as to reliably judge whether a short-circuit fault occurs in a circuit on the basis of not increasing excessive hardware loss and cost, and achieve the purpose of accurately and quickly protecting devices.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a short-circuit fault detection method of a SiC MOSFET power module, which respectively detects drain current I of the SiC MOSFETDAnd drain-source voltage VDSThe instantaneous power consumption value with a certain proportion is obtained through the operation of the high-speed multiplier, and the detected instantaneous power consumption value is compared with the preset short-circuit fault loss power threshold value, so that whether the circuit has the short-circuit fault or not can be judged, the purpose of accurately and quickly protecting the device is achieved, and the hardware cost and the loss are low.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
the invention provides a short-circuit fault detection method of a SiC MOSFET power module, which realizes the hard short-circuit fault detection methodThe part comprising VDSDetection Module, IDA detection module, a multiplier module and a compare-and-trigger-hold module, said VDSOutput terminal and I of detection moduleDThe output end of the detection module is respectively connected with two input ends of the multiplier module, the output end of the multiplier module is connected with the input end of a comparison signal of the comparison and trigger holding module, and the instantaneous power consumption threshold value V is set manuallyPrefThe output end of the comparison and trigger holding module is connected with the input end of the other comparison signal of the comparison and trigger holding module, and the output end of the comparison and trigger holding module is connected with the grid electrode of the SiC MOSFET; the V isDSThe detection module is used for obtaining a voltage value V of a drain source of the SiC MOSFETDSProportional detection value VVds(ii) a Said IDThe detection module is used for obtaining the drain current value I of the SiC MOSFETDProportional detection value Vid(ii) a The multiplier module is used for processing the detection value VVdsAnd a detected value VidMultiplying and outputting a detected value V of instantaneous power consumptionploss(ii) a The comparison and trigger holding module is used for comparing the detection value V of the instantaneous power consumptionplossAnd instantaneous power consumption threshold VPrefAnd outputs a short-circuit fault signal.
Preferably, said VDSThe detection module is provided with a resistor R connected in series between the drain electrode and the Kelvin source electrode of the SiC MOSFET1And R2，R1One end of which is connected to the drain electrode of the SiC MOSFET, R1Another end of (1) and R2And VDSOutput end V of detection moduleVdsIs connected to R2Is connected to the Kelvin source of the SiC MOSFET, and R1、R2Two ends of the capacitor C are respectively connected in parallel1And C2。
Preferably, the IDThe detection module obtains a detection value V of the drain current of the SiC MOSFET by using a voltage division circuit and an integration circuit in sequenceidSpecifically, the method comprises the following steps: parasitic inductance L exists between Kelvin source S and main power source S of SiC MOSFETsSMain power source S and resistor R3Is connected to one end of R3The other end of each of the resistors R and R is connected with4And a resistor R5Is connected to one end of R4The other end of (A) is grounded, R5The other end of the first and second capacitors is respectively connected with the inverting terminal of the amplifier and the capacitor C3Is connected, the non-inverting terminal of the amplifier and the Kelvin source s are both grounded, C3Is connected with the output end of the amplifier to output the value I of the drain current of the SiC MOSFETDProportional detection value Vid。
Preferably, R is in series1And R2Common voltage dividing end and/or series-connected R3And R4The common voltage division end between the two ends is provided with a clamped series diode.
Preferably, two input ends of the multiplier module are respectively connected with VDSOutput terminal and I of detection moduleDDetecting the output of the module to obtain a detected value V of the instantaneous power consumptionploss(ii) a The digital function of the multiplier module is
W＝XY+Z
Wherein X, Y is input value, Z is initial bias voltage, and the output result is the detection value V of instantaneous power consumptionPloss。
Preferably, the comparison and trigger hold module comprises a voltage comparator and an RS latch, and the detection value V at the output of the multiplier modulePlossAnd a preset instantaneous power consumption threshold VPrefAnd as comparison signals of two input ends of the voltage comparator, the output end of the voltage comparator is connected with the S end of the RS latch, the inverted PWM driving signal is connected with the R end of the RS latch, and the Q end of the RS latch outputs a short-circuit fault signal.
(III) advantageous effects
According to the technical scheme, the invention has the following beneficial effects: when the SiC MOSFET power module is used for dealing with the hard switch short-circuit fault, the instantaneous power consumption detection method has higher response speed, and the response time and the detection time can be correspondingly shortened when the SiC MOSFET power module is used for dealing with the load short-circuit fault, so that the response speed of judging whether the circuit has the short-circuit fault or not by the SiC MOSFET is greatly improved comprehensively, the hardware cost and the loss are reduced while the action accuracy and the reliability are improved, and the practical applicability is strong.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:
FIG. 1 is an overall scheme of the short circuit fault detection method of the SiC MOSFET power module of the present invention;
FIG. 2 shows a view of a camera V in an embodiment of the present inventionDSA circuit diagram of a detection module;
FIG. 3 shows an embodiment I of the present inventionDA circuit diagram of a detection module;
FIG. 4 is a circuit diagram of a high speed multiplier module according to an embodiment of the present invention;
FIG. 5 is a circuit diagram of a compare and trigger hold module according to an embodiment of the present invention;
FIG. 6 is a waveform diagram illustrating the effect of the short-circuit fault detection method of the SiC MOSFET power module on the control of hard-switching short circuits;
FIG. 7 is a waveform diagram illustrating the control effect of the short-circuit fault detection method for the SiC MOSFET power module when the load is short-circuited;
fig. 8 is a flowchart of a short-circuit fault detection method of a SiC MOSFET of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in FIG. 1, the invention discloses a short-circuit fault detection method for a SiC MOSFET power module, wherein a hardware part comprises VDSDetection Module, IDA detection module, a multiplier module and a compare-and-trigger-hold module, said VDSOutput terminal and I of detection moduleDDetection ofThe output end of the multiplier module is connected with the two input ends of the multiplier module respectively, the output end of the multiplier module is connected with the input end of a comparison signal of the comparison and trigger holding module, and the instantaneous power consumption threshold value VPrefThe output end of the comparison and trigger holding module is connected with the input end of another comparison signal of the comparison and trigger holding module, and the output end of the comparison and trigger holding module outputs a short-circuit fault signal;
the specific functions of each module are as follows:
the V isDSThe detection module is used for obtaining a voltage value V of a drain source of the SiC MOSFETDSProportional detection value VVds；
Said IDThe detection module is used for obtaining the drain current value I of the SiC MOSFETDProportional detection value Vid；
The multiplier module is used for processing the detection value VVdsAnd a detected value VidMultiplying and outputting a detected value V of instantaneous power consumptionploss；
The comparison and trigger holding module is used for comparing the detection value V of the instantaneous power consumptionplossAnd instantaneous power consumption threshold VPrefAnd based on the inverted PWM drive signal and VplossAnd VPrefAnd outputting a short-circuit fault signal according to the comparison result so as to finally control the SiC MOSFET to be turned off in time.
It should be further noted that the present invention makes the above software and hardware design to solve the technical problem, mainly considering that the maximum instantaneous power of the SiC MOSFET is relatively small in the normal switching process and there is a corresponding instantaneous power consumption upper limit, and when a hard switching short circuit or a load short circuit occurs, the current flowing through the SiC MOSFET rapidly rises and greatly exceeds the rated value, and the device will generate instantaneous power consumption far higher than that in the normal switching process. The basic principle of the instantaneous power consumption detection method is that the loss power of the device is greatly different between the normal switching process and the short-circuit fault of the SiC MOSFET, so that a given threshold value is set properly by utilizing the difference (the threshold value is set according to a threshold value obtained by multiple experiments), and when the instantaneous power consumption of the power device is detected to be larger than the threshold value, the protection action can be triggered. By the short-circuit fault detection method, whether the circuit has the short-circuit fault or not can be reliably judged on line on the basis of not increasing excessive hardware loss and cost, so that the aim of accurately and quickly protecting the device is fulfilled, and the detection result does not influence the normal switching control of the SiC MOSFET when the circuit has no fault (namely, when the circuit has no short circuit, a signal output by a Q end can be used for the normal switching control of the SiC MOSFET).
The following detailed description of the hardware and software components and circuit effects of the present invention will be made with reference to the accompanying fig. 2-8, and the configuration of the sub-circuits of the present invention will not be limited to the best mode given by the following embodiments:
according to the idea of fig. 1, the instantaneous power detection and calculation are performed first, and the drain current I needs to be measured at this timeDAnd drain-source voltage VDSThe circuit topology for implementing the function of the present invention comprises three modules: vDSDetection Module, IDThe detection module and the multiplier module; performing instantaneous power consumption VplossAfter detection, the comparison and trigger holding module outputs a fault signal, so that the SiC MOSFET is finally controlled to be switched off when short circuit is completed by matching the fault signal with a corresponding protection circuit.
1)VDSDetection module
FIG. 2 is VDSA circuit diagram of the detection module, a series resistor R is arranged between the drain electrode and the Kelvin source electrode of the SiC MOSFET1And R2I.e. R1One end of which is connected to the drain electrode of the SiC MOSFET, R1Another end of (1) and R2Is connected to one end of R2Is connected to the Kelvin source of the SiC MOSFET, and R1、R2Two ends of the capacitor C are respectively connected in parallel1And C2，R1And the other end of (1) and R2One end of is VDSOutput end V of detection moduleVds。
Optionally, an output terminal VVdsCan also be provided with a clamping series diode, and the output end VVdsThe upper diode is connected with the VCC end, and the lower diode is grounded, thereby achieving the purpose of protecting the circuit.
Due to the drain-source voltage V at short circuitDSWill rise to a higher bus voltage and be less convenient to detect, so two resistors R are added between the source and drain of the SiC MOSFET1、R2Partial pressure is carried out. Meanwhile, in order to increase the accuracy and reliability of short circuit detection and prevent high frequency components from influencing the output detection value, R is1、R2Two ends of the capacitor C are respectively connected in parallel1、C2Thereby filtering the interference of high frequency, and then inputting the voltage signal obtained after voltage division to the multiplier. This is done to obtain a voltage V that is not the drain-source voltage VDSBut measured value and VDSProportional to the drain-source voltage V of SiC MOSFETDSProportional detection value VVdsCan be expressed as
VVds＝kvVDS
In the formula kv＝R2/(R1+R2)。
Of course, the drain-source voltage value V is realizedDSThe proportional voltage division measuring circuit can also be in other implementation manners, and the invention is not illustrated here.
2)IDDetection module
FIG. 3 is IDA circuit diagram of a detection module. The first one isDThe detection module obtains a detection value V of the drain current of the SiC MOSFET by using a voltage division circuit and an integration circuit in sequenceidSpecifically, the method comprises the following steps: parasitic inductance L exists between the Kelvin source S and the main power source S of the SiC MOSFETsSMain power source S and resistor R3Is connected to one end of R3The other end of each of the resistors R and R is connected with4And a resistor R5Is connected to one end of R4The other end of (A) is grounded, R5The other end of the first and second capacitors is respectively connected with the inverting terminal of the amplifier and the capacitor C3Is connected to the non-inverting terminal of the amplifier, C3Is connected with the output end of the amplifier to output the value I of the drain current of the SiC MOSFETDProportional detection value Vid。
Optionally, R3And R4Is divided intoThe voltage end A can also be provided with a clamped series diode, thereby achieving the purpose of protecting the circuit.
To measure the drain current IDCan first measure the parasitic inductance L between the Kelvin source S and the main power source S of the SiC MOSFETsSThe induced voltage is calculated to obtain the voltage value VlIs composed of
The voltage value is large during short circuit, which affects the drain current IDThe voltage at point A after voltage division is
In the formula ki1＝LsSR4/(R3+R4) If the drain current is to be derived from the voltage at point a, the voltage is integrated. Therefore, the detected value of the drain current can be obtained after the integrated circuit formed by the high-speed operational amplifier is finally passed
Vid＝-ki2∫VAdt＝kiID
In the formula ki2＝1/R5C3，ki＝ki1×ki2And inputs the signal to the multiplier. And VDSSame, this detection value VidIs also not equal to the drain current IDHowever, through the above analysis, the detection value and the drain current IDIs proportional and therefore directly reflects the magnitude of the current.
3) Multiplier module
Figure 4 is a schematic diagram of a multiplier module. Two input ends of the multiplier are respectively connected with VDSOutput terminal and I of detection moduleDOutput of the detection module to multiply the detection value VVdsAnd a detected value VidObtaining a detection value V of instantaneous power consumptionploss。
The invention adopts a high-speed multiplier to calculate the instantaneous power consumption of the SiC MOSFET. As shown in FIG. 3, the two input ports of the multiplier are respectively connected with the detection values V of the drain-source voltagesVdsAnd a detected value V of the drain currentidAfter processing, the result of the two values is output according to the digital function, and the digital function of the high-speed multiplier is
W＝XY+Z
Wherein X, Y is input value, Z is initial bias voltage, and the output result is the detection value V of instantaneous power consumptionPloss. From the above analysis, the detection value is not equal to the instantaneous power consumption, but may and sufficiently reflect the magnitude of the instantaneous power consumption.
4) Compare and trigger hold module
Fig. 5 is a circuit diagram comparing and triggering the hold module. The comparison and trigger holding module comprises a voltage comparator and an RS latch, and the output end of the multiplier module detects a value VPlossAnd a preset instantaneous power consumption threshold VPrefThe output end of the voltage comparator is connected with the S end (i.e. the SET end) of the RS latch as the input end of the voltage comparator to output a comparison result VctrlTo the input port of the trigger hold module, the inverted PWM driving signal is connected with the R end (namely the RESET end) of the RS latch, and the Q end of the RS latch outputs a short-circuit Fault signal Fault so as to detect a value V at the output endPlossGreater than a preset instantaneous power consumption threshold VPrefA fault signal is output.
In this circuit, the detected value V of instantaneous power consumption output by the multiplier is usedPlossThe input voltage comparator has a + input terminal and an instantaneous power consumption threshold V set at the-input terminalPrefA comparison is made. If the signal V isPlossExceeding a set threshold value VPrefThe high speed voltage comparator outputs a low level signal VctrlAnd the inverse PWM driving signal is matched to output a continuous low-level short-circuit Fault signal through the trigger, and the continuous low-level short-circuit Fault signal is output at the output end of the comparison and trigger holding module (of course, the short-circuit Fault signal Fault also outputs a continuous high-level signal through other circuits to complete alarm), so that the short-circuit Fault signal Fault can be detected at the output end of the comparison and trigger holding moduleFor controlling the SiC MOSFET to switch off during a short circuit, i.e. when S and R of the RS latch are 0 and 1, the original state Q of the output isnAnd new state Qn+1Are all low; when S and R are both 0, the original state QnAnd new state Qn+1Keeping unchanged to cooperate with a corresponding protection circuit to control the timely turn-off operation when the grid of the SiC MOSFET is in short circuit.
When the SiC MOSFET is in normal operation, the drain-source voltage VDSIn a lower state with a drain current IDAlso in the normal range, the instantaneous power consumption is low, so that the detected value V of the instantaneous power consumptionplossAnd is also lower. To avoid malfunction, a threshold value V is setPrefIt is ensured that the maximum value of the instantaneous power consumption during normal operation is less than the threshold value VPrefAnd a certain margin is reserved, so that the transient power fluctuation in the normal working state can not cause protection misoperation.
The protection principle of the circuit according to the invention based on fig. 1-5 will be described below using hard-switched short circuits and load short circuits as examples:
a) under the condition of hard switch short circuit, when the SiC MOSFET is switched on, the drain current rapidly rises due to small loop inductance, and the rapidly rising current can generate induced electromotive force to enable the drain-source voltage to generate certain voltage drop, but the working area of the device is transferred to a saturation area from a cut-off area, and the drain-source voltage rapidly rises back to the bus voltage. In the process, the drain-source voltage rises to enable the resistor voltage division to rise, and the drain-source voltage detection value transmitted to the multiplier rises; meanwhile, the drain current is rapidly increased, and a signal is transmitted to the integrating circuit, so that the detected value of the drain current obtained after integration is increased. The two detection values are simultaneously input to a high-speed multiplier module, and when the output quantity calculated by the digital function of the multiplier module, namely the detection value of the instantaneous power consumption, is increased and exceeds a set threshold value, a protection action is triggered.
b) The situation when the load short circuit occurs is similar to that when the hard switch short circuit occurs, and since the loop inductance at this time is larger than that when the hard switch short circuit occurs, the drain current rises at a speed slightly slower than that of the hard switch short circuit, but nevertheless, the rise of the current is far beyond the normal situation, and the detection value input to the high-speed multiplier also exceeds the normal value. With the rising of the current, the SiC MOSFET is out of the saturation working state, the drain-source voltage rises to the bus voltage, the voltage input into the high-speed multiplier is increased along with the voltage division of the resistor, and after the high-speed multiplier module processes the input data, the detection value of the output instantaneous power consumption is increased and exceeds the set threshold value, the protection action is triggered.
In addition, the driving method and the control strategy have the advantages by combining the simulation case. The simulation is carried out by using the SPICE building model, and the obtained results are shown in FIGS. 6 and 7. As can be seen from fig. 6 to 7, although the circuit of the present invention can increase the response speed and the fault determination accuracy of the hard switch short circuit and the load short circuit, the instantaneous power consumption detection method has a faster response speed when dealing with the hard switch short circuit fault, and has a longer response time when dealing with the load short circuit fault, and a larger drain current ratio during the operation, on one hand, the instantaneous power consumption rises more slowly under the load short circuit condition, the simulation condition is a zero current turn-on condition, but when the load short circuit occurs during the normal operation of the device, the instantaneous power consumption will increase more than the set value rapidly, and the detection time will also be shortened correspondingly; on the other hand, the action threshold value is set to be higher in simulation, and the power threshold value during action can be further reduced in practical application so as to improve the response speed.
The invention discloses a short-circuit fault detection method of a SiC MOSFET power module, the flow of which is shown in figure 8, and the method comprises the following specific steps:
1. determining the range of instantaneous power consumption values of the SiC MOSFET under normal working and short-circuit conditions by theory, simulation and experimental analysis, determining the threshold value of the instantaneous power consumption detection value of the SiC power module in a short-circuit state based on the range of the instantaneous power consumption values, and ensuring that the value is lower than the threshold value during normal working and higher than the threshold value during short-circuit;
2. the detection values of the drain-source voltage and the drain current of the SiC MOSFET are obtained by utilizing the voltage division circuit and the integrating circuit and are input into a high-speed multiplier;
3. multiplying the detected values of the drain-source voltage and the drain current in a high-speed multiplier to obtain a detected value proportional to the instantaneous power consumption;
4. and comparing the instantaneous power consumption detection value output by the high-speed multiplier with a preset threshold value by using a comparator. And if the detection value is higher than the threshold value, outputting a fault signal.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (6)
1. A short-circuit fault detection method of a SiC MOSFET power module is characterized in that a hardware part for realizing the short-circuit fault detection method comprises VDSDetection Module, IDA detection module, a multiplier module and a compare-and-trigger-hold module, said VDSOutput terminal and I of detection moduleDThe output end of the detection module is respectively connected with two input ends of the multiplier module, the output end of the multiplier module is connected with the input end of a comparison signal of the comparison and trigger holding module, and the instantaneous power consumption threshold value V is set manuallyPrefThe output end of the comparator is connected with the input end of the other comparison signal of the comparison and trigger holding module; the V isDSThe detection module is used for obtaining a voltage value V of a drain source of the SiC MOSFETDSProportional detection value VVds(ii) a Said IDThe detection module is used for obtaining the drain current value I of the SiC MOSFETDProportional detection value Vid(ii) a The multiplier module is used for processing the detection value VVdsAnd a detected value VidMultiplying and outputting a detected value V of instantaneous power consumptionploss(ii) a The comparison and trigger holding module is used for comparing the detection value V of the instantaneous power consumptionplossAnd instantaneous power consumption threshold VPrefAnd is in VplossGreater than VPrefAnd outputting a short-circuit fault signal.
2. The method of short circuit fault detection of SiC MOSFET power module of claim 1, characterized in thatIn that said VDSThe detection module is provided with a resistor R connected in series between the drain electrode and the Kelvin source electrode of the SiC MOSFET1And R2，R1One end of which is connected to the drain electrode of the SiC MOSFET, R1Another end of (1) and R2And VDSOutput end V of detection moduleVdsIs connected to R2Is connected to the Kelvin source of the SiC MOSFET, and R1、R2Two ends of the capacitor C are respectively connected in parallel1And C2。
3. The method of short-circuit fault detection of SiC MOSFET power module of claim 2, wherein said IDThe detection module obtains a detection value V of the drain current of the SiC MOSFET by using a voltage division circuit and an integration circuit in sequenceidSpecifically, the method comprises the following steps: parasitic inductance L exists between Kelvin source S and main power source S of SiC MOSFETsSMain power source S and resistor R3Is connected to one end of R3The other end of each of the resistors R and R is connected with4And a resistor R5Is connected to one end of R4The other end of (A) is grounded, R5The other end of the first and second capacitors is respectively connected with the inverting terminal of the amplifier and the capacitor C3Is connected, the non-inverting terminal of the amplifier and the Kelvin source s are both grounded, C3Is connected with the output end of the amplifier to output the value I of the drain current of the SiC MOSFETDProportional detection value Vid。
4. The method of short-circuit fault detection of SiC MOSFET power modules of claim 3, wherein R is connected in series1And R2Common voltage dividing end and/or series-connected R3And R4The common voltage division end between the two ends is provided with a clamped series diode.
5. The method for detecting the short-circuit fault of the SiC MOSFET power module as claimed in any one of claims 1 to 4, wherein two input terminals of the multiplier module are respectively connected to VDSOutput terminal and I of detection moduleDDetecting output of moduleOutput end to obtain the detection value V of instantaneous power consumptionplossThe digital function of the multiplier module is
W＝XY+Z
Wherein X, Y is input value, Z is initial bias voltage, and the output result is the detection value V of instantaneous power consumptionPloss。
6. The method of any of claims 1 to 4, wherein the comparison and trigger hold module comprises a voltage comparator and an RS latch, and the detection value V at the output of the multiplier module is detectedPlossAnd a preset instantaneous power consumption threshold VPrefAnd as comparison signals of two input ends of the voltage comparator, the output end of the voltage comparator is connected with the S end of the RS latch, the inverted PWM driving signal is connected with the R end of the RS latch, and the Q end of the RS latch is used for outputting a short-circuit fault signal.
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