CN115718247A - Non-contact thyristor working junction temperature online detection system and method - Google Patents
Non-contact thyristor working junction temperature online detection system and method Download PDFInfo
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- CN115718247A CN115718247A CN202211448007.0A CN202211448007A CN115718247A CN 115718247 A CN115718247 A CN 115718247A CN 202211448007 A CN202211448007 A CN 202211448007A CN 115718247 A CN115718247 A CN 115718247A
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Abstract
The invention discloses a non-contact thyristor working junction temperature online detection system and a non-contact thyristor working junction temperature online detection method, and belongs to the field of thyristor state detection. The power circuit unit is connected with the thyristor; the sampling unit is used for collecting direct current bus current, voltage at two ends of the thyristor, gate driving voltage of the thyristor and actual working junction temperature of the thyristor in the power loop unit; the temperature control unit is used for regulating and controlling the environmental temperature of the thyristor under the actual operation working condition and changing the actual working junction temperature of the thyristor; the driving unit is connected with the thyristor and is used for driving the thyristor to work; the junction temperature detection unit is used for measuring a thyristor gate pole current signal and extracting the integral of the gate pole current signal along with time to obtain the charge number input to the thyristor gate pole; extracting the peak value of the gate pole current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state; and obtaining the working junction temperature of the thyristor according to the working junction temperature calculation model of the thyristor, and realizing the non-contact measurement of the working junction temperature of the thyristor.
Description
Technical Field
The invention relates to the field of thyristor state detection, in particular to a thyristor working junction temperature online junction temperature detection technology.
Background
Since the invention of thyristors in bell laboratory in the united states in 1956, thyristors have been one of the switching devices widely used in the field of power electronics. Although many other types of semiconductor devices (such as MOSFET, IGBT, etc.) are available in applications of high frequency, medium and small power, etc., the thyristor has the advantages of high voltage resistance, low loss, small volume, high reliability, etc., and is widely used as a high voltage switch device in a power system, such as a Thyristor Switched Capacitor (TSC), a Thyristor Controlled Reactor (TCR), etc. in reactive power compensation technology. The rapid development of high voltage direct current transmission (HVDC) and high voltage Flexible Alternating Current Transmission Systems (FACTS) in recent years in particular has made the advantages of thyristor devices in high voltage application environments even more prominent. In addition, the thyristor device is also applied to the fields of high-voltage commutation equipment, high-voltage frequency converters and the like. Therefore, as a core element in a high voltage system, the reliability of the thyristor is related to the safe and efficient operation of the entire system. The junction temperature of the thyristor is a main factor for determining whether the relevant equipment can stably operate, and taking the converter valve under the actual operation condition as an example, the failure rate of the converter valve is doubled when the junction temperature of the thyristor rises by 10 ℃. The real-time monitoring of the junction temperature of the thyristor has important significance on the aspects of a series voltage-sharing mechanism of equipment, internal and external overvoltage, overcurrent, a control protection strategy and the like. By dynamically monitoring the junction temperature of the operating thyristor, a more scientific and accurate judgment basis can be provided for the overheating protection of relevant equipment, the operation adjustment can be carried out in time, and the operation risk can be reduced.
The current methods for detecting the on-line junction temperature of the thyristor can be divided into a contact type and a non-contact type. The contact temperature measurement method comprises a thermocouple method and an optical fiber temperature measurement method, temperature acquisition devices of the thermocouple method and the optical fiber temperature measurement method need to be in direct contact with a measured object, the structural design of an original device needs to be modified, and the insulation problem exists in high-voltage application. The non-contact temperature measurement can be realized by using an infrared thermometer or an infrared thermal imager, so that the operation of workers is facilitated. However, the related devices are highly integrated and limited by the problems of angle, distance and the like, and the junction temperature of the thyristor cannot be accurately monitored in real time. How to realize the non-contact real-time online junction temperature detection of the thyristor is full of challenges.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a thyristor working junction temperature online detection system and a thyristor working junction temperature online detection method.
The technical scheme adopted by the invention is as follows:
in a first aspect, the present invention provides an online detection system for operating junction temperature of a non-contact thyristor, including:
the power loop unit is connected with the thyristor to be tested;
the sampling unit is used for collecting direct current bus current, voltage at two ends of the thyristor, gate drive voltage of the thyristor and actual working junction temperature of the thyristor in the power loop unit;
the temperature control unit is used for regulating and controlling the environmental temperature of the thyristor under the actual operation working condition and changing the actual working junction temperature of the thyristor;
the driving unit is connected with the thyristor and is used for driving the thyristor to work;
the junction temperature detection unit is used for measuring a thyristor gate pole current signal and extracting the integral of the gate pole current signal along with time to obtain the charge number input to the thyristor gate pole; extracting the peak value of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state; and calculating to obtain an estimated value of the working junction temperature of the thyristor according to the thyristor gate electrode current signal, the number of charges input to the thyristor gate electrode, the peak value of the gate electrode current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state, and the direct-current bus current, the voltages at two ends of the thyristor and the thyristor gate electrode driving voltage which are obtained by combining the sampling unit.
Furthermore, the power loop unit comprises a direct-current voltage source, an electrolytic capacitor, a discharge resistor, an auxiliary diode, an auxiliary switching tube, an auxiliary inductor, a first switch and a second switch; the anode of the direct-current voltage source is connected with one end of a first switch, the other end of the first switch is connected with one end of an electrolytic capacitor, one end of a discharge resistor and the cathode of an auxiliary diode, the other end of the discharge resistor is connected with one end of a second switch, the anode of the auxiliary diode is connected with the collector of an auxiliary switch tube, the emitter of the auxiliary switch tube is connected with the anode of a thyristor, an auxiliary inductor is connected with the auxiliary diode in parallel, and the cathode of the direct-current voltage source is connected with the other end of the electrolytic capacitor, the other end of the second switch and the cathode of the thyristor.
Furthermore, the driving unit comprises a thyristor driving circuit and an auxiliary power supply, wherein the thyristor driving circuit is used for providing driving voltage for a gate pole of the thyristor so as to control the thyristor to be converted from a forward blocking state to a conducting state; the auxiliary power supply is used for supplying power to the driving circuit.
Furthermore, a thyristor working junction temperature calculation model is stored in the junction temperature detection unit, and is obtained by fitting a thyristor gate current signal, the number of charges input to the thyristor gate, the peak value of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state, the direct-current bus current, the voltages at two ends of the thyristor, the thyristor gate driving voltage and the thyristor working junction temperature.
Furthermore, the junction temperature detection unit comprises a thyristor gate pole current measurement module, a thyristor gate pole input charge amount detection module and a junction temperature calculation module;
the thyristor gate pole current measuring module obtains a differential signal of the thyristor gate pole current with respect to time through the Rogowski coil and reduces the differential signal to obtain a gate pole current signal;
the thyristor gate pole input charge quantity detection module integrates time by utilizing a differential signal of thyristor gate-level current extracted by the thyristor gate pole current measurement module, so as to obtain the charge quantity obtained by the gate pole in the transient process of switching the thyristor from a forward conduction state to a conduction state;
the junction temperature calculation module is used for extracting the peak value of a gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state and obtaining the working junction temperature of the thyristor according to the working junction temperature calculation model of the thyristor.
Furthermore, the thyristor gate pole current measuring module comprises a rogowski coil and a first lossy integrating circuit;
the Rogowski coil is an air coil, and a lead connected with the gate pole of the thyristor penetrates through the air coil and is used for obtaining a differential signal of the gate pole current of the thyristor relative to time;
the first lossy integrating circuit comprises a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor and a first operational amplifier; one end of the first resistor is connected with one end of the Rogowski coil, the other end of the first resistor is connected with one end of the first capacitor and the positive input end of the first operational amplifier, and the other end of the Rogowski coil and the other end of the first capacitor are grounded; the negative input end of the first operational amplifier is connected with one end of a second resistor, one end of a third resistor and one end of a second capacitor, the other end of the third resistor and the other end of the second capacitor are connected with the output end of the first operational amplifier, and the other end of the second resistor is grounded; one end of the first resistor is an input end of the first lossy integrating circuit, and an output end of the first operational amplifier is an output end of the first lossy integrating circuit, namely an output end of the thyristor gate current measuring module.
Furthermore, the thyristor gate pole input charge quantity detection module is composed of a second lossy integration circuit;
the second lossy integrating circuit comprises a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor and a second operational amplifier; one end of the fourth resistor is connected with the output end of the thyristor gate current measuring module, the other end of the fourth resistor is connected with the positive input end of the second operational amplifier, the negative input end of the second operational amplifier is connected with one end of the fifth resistor, one end of the sixth resistor and one end of the third capacitor, the other end of the sixth resistor and the other end of the third capacitor are connected with the output end of the second operational amplifier, and the other end of the fifth resistor is grounded; one end of the fourth resistor is the input end of the thyristor gate pole input charge quantity detection module, and the output end of the second operational amplifier is the output end of the thyristor gate pole input charge quantity detection module.
Further, the junction temperature calculation module adopts a Field Programmable Gate Array (FPGA).
In a second aspect, the present invention provides a method for detecting an online detection system of an operating junction temperature of a non-contact thyristor, including the following steps:
step 1, establishing a thyristor working junction temperature calculation model:
1.1 Setting an operation condition under the condition that the maximum working voltage, the maximum working current and the maximum working junction temperature of the thyristor to be tested are not exceeded; for any operation condition, in the transient process of switching the thyristor from the forward conduction state to the conduction state, acquiring a group of data of direct current bus current, voltage at two ends of the thyristor, thyristor gate electrode driving voltage, thyristor gate electrode current signals and thyristor working junction temperature, and calculating the number of charges input to the gate electrode of the thyristor under the corresponding operation condition and the peak value of the gate electrode current signals in the transient process of switching the thyristor from the forward conduction state to the conduction state according to the thyristor gate electrode current signals;
1.2 Traversing all the operating conditions, obtaining the charge number of the gate electrode of the input thyristor under each operating condition and the peak data of a gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state, and fitting to obtain a thyristor operating junction temperature calculation model by taking the direct-current bus current, the voltages at two ends of the thyristor, the gate electrode driving voltage of the thyristor, the charge number of the gate electrode of the input thyristor and the peak value of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state as independent variables and the actual operating junction temperature of the thyristor as a dependent variable;
step 2, detecting the working junction temperature of the thyristor on line:
detecting a thyristor gate current signal, and calculating the number of charges input to the thyristor gate and the peak value of the thyristor gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state; and simultaneously, collecting direct current bus current, voltage at two ends of the thyristor and gate driving voltage of the thyristor in the transient process of switching the thyristor from the forward conduction state to the conduction state, and calculating the estimated value of the working junction temperature of the thyristor by using a working junction temperature calculation model of the thyristor.
Under the condition that the application environment of the thyristor is relatively definite, the main power loop and the load object of the thyristor are relatively definite, so that the gate trigger current of the thyristor is only equal to the direct-current bus current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G And thyristor operating junction temperature T J The four physical quantities are related to real-time working conditions, so that the gate pole input current I of the thyristor is monitored in real time G With the direct bus current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G The four physical quantities can reversely deduce the working junction temperature of the thyristor. The Rogowski coil is adopted to realize non-contact current sampling, and the output voltage signal is convenient for a subsequent processing circuit to process, so that the Rogowski coil has higher usability, accuracy and instantaneity.
Drawings
Fig. 1 is a schematic structural diagram of an online detection system for operating junction temperature of a thyristor according to an embodiment of the present invention;
fig. 2 is a flowchart of a process of establishing a thyristor operating junction temperature calculation model and an actual detection method according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a thyristor structure;
FIG. 4 is a schematic diagram of a thyristor gate current measurement module, (a) a Rogowski coil structure, (b) a Rogowski coil equivalent circuit, and (c) a lossy integration circuit;
FIG. 5 is a block diagram of the thyristor gate input charge detection module;
FIG. 6 shows the invention in actual operating conditionsApplication example of (1), V AC Is a source of AC voltage, T 1 ～T 6 Is a thyristor, and is provided with three inductive loads;
FIG. 7 is a waveform diagram of various parameters of an application example, in which (a) is a bus voltage signal V AC Waveform, (b) is T in FIG. 5 5 Voltage signal V at both ends of thyristor under certain conduction angle T5 Waveform, (c) is the driving voltage signal V of the thyristor G Waveform, (d) is the driving current signal I of the thyristor G Wave form, I G_peak Peak value of gate current signal in transient state of switching thyristor from forward conducting state to conducting state, (e) charge quantity Q input for the thyristor G Wave form, Q G_max Obtaining the maximum charge quantity for carrying out one-time switching-on action on the thyristor;
fig. 8 is a timing diagram of test signals in a thyristor junction temperature calibration experiment.
Detailed Description
In order to describe the present invention more specifically, the following detailed description of the present invention is made with reference to the accompanying drawings and the detailed description of the present invention.
FIG. 3 is a schematic diagram of a thyristor structure, when a forward voltage is applied across the thyristor, i.e., V AK >0, J in three PN junctions 1 Knot and J 3 The junction is under slight forward bias, J 2 The junction is in the reverse blocking state, subject to almost all external voltages, with only a very small leakage current through the thyristor body. Applying a forward voltage, i.e. U, between G and K poles of the thyristor GK >At 0, T 2 The transistor is turned on and a main current flows from its collector to its emitter. T is a unit of 2 The current flowing out of the transistor collector to T 1 The transistor base provides the turn-on current to promote T 1 The transistor is turned on. And T is 1 Is turned on and current is taken from between AK, from T 1 Is injected into T, while the collector flows out 2 Base of (2) promoting T 2 Further opening of (3). This forms a positive feedback process. When the positive feedback proceeds to a certain extent, T 1 And T 2 When both transistors are in saturation, the thyristor is turned on. At this timeThe resistance between the thyristors AK is extremely low, which shows a low voltage and large current state. Because the positive feedback state of the two transistors is formed, after the thyristor is switched on, the G pole trigger voltage U is removed GK The thyristor can still maintain the conducting state. According to the related knowledge of semiconductor physics, the physical parameters inside the semiconductor power device are closely related to the temperature. For example, the intrinsic carrier concentration of a silicon-based material can be represented by the following formula:
wherein T is the thermodynamic temperature. This formula indicates that the intrinsic carrier concentration of silicon increases with increasing temperature. In addition, the semiconductor internal carrier concentration also exhibits a temperature dependence, with a mobility for electrons of
For holes, the mobility is
Wherein T is the thermodynamic temperature. This formula indicates that the mobility of electrons and holes decreases with increasing temperature. And the thyristor trigger current can be expressed as:
wherein, V bi The voltage threshold value born by the P-type base region resistor is V generated on the resistor when the grid current bi When the thyristor is triggered from the positive blocking state to enter the conducting state; w P Is the total width of the cathode region from the gate to the first short-circuited cathode, p PB Resistivity of the P-type base region, r K1 And r K2 Is the structural parameter of the thyristor. According to the related knowledgeSemiconductor internal resistivity
Therefore, the junction temperature of the thyristor can influence the output characteristic of the thyristor under the combined action of an electric field constructed by the driving voltage by influencing factors such as the concentration, the mobility and the like of carriers in the thyristor. Therefore, the peak value of the gate current signal and the input charge number of the thyristor have obvious correlation with the working junction temperature of the thyristor in the transient process of switching the thyristor from the forward conduction state to the conduction state.
Based on the characteristics of the thyristor, fig. 1 is a schematic diagram of an online detection system for the operating junction temperature of the thyristor according to an embodiment of the present invention. The whole test system comprises a DC voltage source V S Electrolytic capacitor C DC Discharge resistor R, thyristor to be tested and auxiliary diode D aux Auxiliary switch tube T aux And an auxiliary inductor L aux Switch K 1 K 2 The temperature control device comprises a power loop unit, a driving unit, a temperature control unit, a sampling unit and a junction temperature detection unit.
Wherein: in the power circuit unit, a DC voltage source V S Positive pole and switch K 1 Are connected to, K 1 The other end and an electrolytic capacitor C DC One terminal of the discharge resistor, one terminal of the auxiliary diode D aux The cathodes are connected, the discharge resistors are connected in series and connected with the switch K 2 Is connected to an auxiliary diode D aux Anode and auxiliary switch tube T aux The collector electrodes are connected with an auxiliary switch tube T aux The emitter is connected with the anode of the thyristor, and the DC voltage source V S Cathode of the electrolytic capacitor, the other end of the thyristor, and a switch K 2 The other end is connected with the auxiliary inductor which is connected with the auxiliary diode in parallel; v DC Is a DC bus voltage, I DC For current through the thyristor, V G For the gate drive voltage of the thyristor, I G For gate current of thyristor, T J The operating junction temperature of the thyristor. The discharge resistor can be one resistor or a series structure of two or more resistors.
A sampling unit for collecting DC busLine current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G And the operating junction temperature of the thyristor;
the temperature control unit is used for regulating and controlling the environmental temperature of the thyristor under the actual operation working condition; in this embodiment, the temperature control unit is in contact with the thyristor to be tested.
The driving unit is connected with the thyristor; the driving unit comprises a thyristor driving circuit and a corresponding auxiliary power supply; the thyristor driving circuit is used for providing a constant voltage and a large enough driving current for a gate pole of a thyristor so as to control the thyristor to be converted from a forward blocking state to a conducting state; the auxiliary power supply is a low-voltage power supply and is used for providing enough power for the driving circuit;
junction temperature detecting unit for collecting thyristor gate pole current signal I G And extracting the integral of the current signal over time, i.e. the number of charges Q input to the gate of the thyristor G And extracting the peak value I of the current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state G_peak (ii) a The junction temperature detection unit is internally stored with direct current bus current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G Input charge number Q of gate of thyristor G And the peak value I of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state G_peak And a data table of thyristor operating junction temperatures;
using the direct current bus current I under each operation condition in the data table DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G Input charge number Q of gate of thyristor G And the peak value I of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state G_peak And fitting to obtain a thyristor working junction temperature calculation model by taking the actual working junction temperature of the thyristor as a dependent variable, wherein the thyristor working junction temperature calculation model comprises but is not limited to a first-order equation, a second-order equation and a high-order equation. Further according to the DC bus current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G Charge number Q of input thyristor gate G And the peak value I of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state G_peak And the working junction temperature of the thyristor is obtained through the thyristor working junction temperature calculation model, and at the moment, the action of a temperature control unit is not needed, so that the non-contact on-line detection of the working junction temperature of the thyristor is realized.
Based on the thyristor working junction temperature online detection system, the process of establishing the thyristor working junction temperature calculation model through the junction temperature calibration experiment is shown in the left half part of fig. 2, and the following is specifically described: selecting the initial temperature, the initial current, the initial voltage and the gate drive voltage of the thyristor to be tested;
s1.1, setting the output voltage of the direct current voltage source as the initial voltage of the thyristor to be tested, and disconnecting the switch K 2 Closing switch K 1 Charging the electrolytic capacitor by a direct current voltage source;
s1.2, after the electrolytic capacitor is fully charged, the switch K is disconnected 1 Setting the output voltage of the driving unit as the initial driving voltage of the thyristor to be tested and starting to output, conducting the thyristor, and obtaining the current I of the direct current bus under the combined action of the sampling unit and the junction temperature detection unit DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G Charge number Q of input thyristor gate G And the peak value I of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state G_peak And actual operating junction temperature of the thyristor;
s1.3, resetting the environmental temperature of the thyristor by adjusting the temperature control unit so as to change the actual working junction temperature of the thyristor, gradually increasing the temperature to the highest set temperature at certain temperature intervals from the initial temperature of the thyristor to be tested as a starting point, keeping the initial current, the initial voltage and the initial driving voltage of the thyristor to be tested unchanged, repeating the steps S1.1 to S1.2, and recording peak values I corresponding to different working junction temperatures of the thyristor under the conditions of the initial voltage, the initial current and the initial driving voltage of the thyristor to be tested G_peak And number of charges Q G . Thereby, the device canEstablishing a peak value I under the initial voltage, the initial current and the initial drive voltage of the thyristor to be tested G_peak And number of charges Q G A database of corresponding thyristor operating junction temperatures;
s1.4, similarly, maintaining the direct current bus current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G Adjusting the value of the other physical quantity, repeating the steps S1.1 to S1.3, and establishing the complete thyristor working junction temperature and the direct current bus current I DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G Charge number Q of input thyristor gate G And the peak value I of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state G_peak And fitting to obtain a thyristor working junction temperature calculation model. In this embodiment, the voltage V at two ends of the thyristor is changed by adjusting the output voltage of the dc voltage source AK By varying the gate drive voltage V of the thyristor by adjusting the output voltage of the drive unit G The direct current bus current I is changed by adjusting the on-time of the auxiliary switch tube DC (i.e., the current through the thyristor).
Direct current bus current I DC The regulation principle of (2) is as follows: as shown in fig. 8, step S1.1 is performed, after which (1) the auxiliary IGBT gate and the thyristor gate are turned on at the same time by applying a high level to them at the same time, I DC Begin to increase at a rate of di/dt under the effect of the auxiliary inductance; (2) at t 1 Time of day, I DC The current value required by the experiment is achieved, and the auxiliary IGBT grid electrode and the thyristor gate electrode are simultaneously applied with low level to simultaneously turn off the two; (3) closed K 2 The capacitor was discharged and the single experiment was ended. From the above, adjusting the magnitude of the auxiliary inductor can adjust the current rising rate and t 1 -t 0 This period of time can be adjusted by I DC 。
FIG. 7 is a waveform diagram of various parameters extracted in this embodiment, where (a) is a bus voltage signal V AC Wave form, (b) is the thyristor T in figure 6 5 Voltage signal at both ends of the conductor under a certain conduction angleV T5 Waveform, (c) is the driving voltage signal V of the thyristor G Waveform, (d) is the driving current signal I of the thyristor G Wave form, I G_peak Peak value of gate current signal in transient state of switching thyristor from forward conducting state to conducting state, (e) charge quantity Q input for the thyristor G Wave form, Q G_max The maximum charge amount obtained by one-time switching-on action of the thyristor.
The working junction temperature online detection process is shown in the right half part of fig. 2, and is described in detail as follows:
s2.1, detecting a thyristor gate electrode current signal, and calculating the charge number input to the thyristor gate electrode and the peak value of the gate electrode current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state; simultaneously, collecting direct current bus current, voltage at two ends of the thyristor and gate drive voltage of the thyristor in the transient process of switching the thyristor from the forward conduction state to the conduction state;
and S2.2, obtaining an estimated value of the working junction temperature of the thyristor by using the working junction temperature calculation model of the thyristor.
In one embodiment of the present invention, the junction temperature detecting unit includes a thyristor gate current measuring module, a thyristor gate input charge amount detecting module, and a junction temperature calculating module; wherein:
the thyristor gate pole current measuring module has the functions of obtaining a differential signal of the thyristor gate pole current with respect to time through the Rogowski coil, obtaining a gate pole current signal through the reduction of a subsequent integrating circuit, and extracting peak information of the gate pole current signal through the processing of the junction temperature calculating module.
As shown in (a) of fig. 4, the thyristor gate current measurement module includes a rogowski coil and a first lossy integration circuit; the Rogowski coil is a circular sensor made of a PCB, is formed by repeatedly folding and winding a wire on the PCB, is similar to an air-core coil in nature, and a current to be measured passes through the circular ring; according to Faraday's law of electromagnetic induction, the output signal is a voltage signal proportional to the integral of the measured current
However, due to mutual influence among the wires, certain parasitic parameters can be generated, so that the output signal of the parasitic parameters is no longer a voltage signal which is proportional to the integral of the measured current after a certain frequency; as shown in (c) of fig. 4, the first lossy integration circuit includes three resistors R 1 、R 2 、R 3 Two capacitors C 1 、C 2 And a first operational amplifier; wherein R is 1 One end of which is connected to one end of the Rogowski coil, R 1 The other end is connected with C 1 One end of the first operational amplifier is connected with the positive input end of the first operational amplifier, and the negative input end of the first operational amplifier is connected with the R 2 、R 3 、C 2 Are connected at one end to R 3 、C 2 The other end is connected with the output end of the first operational amplifier, R 2 Another terminal, a capacitor C 1 The other end of the Rogowski coil is grounded, namely the input end of the lossy integrating circuit is R 1 One end, the output end is the output end of the first operational amplifier. Wherein the equivalent circuit of the Rogowski coil is shown as (b) in FIG. 4, R R 、L R 、C R The different structures can influence the size of each parameter and further influence the bandwidth of the Rogowski coil; and the subsequent first lossy integrating circuit adjusts R 1 、R 2 、R 3 And C 1 、C 2 The bandwidth of the integrator is adjusted by a numerical value to realize the fit with the bandwidth of the Rogowski coil, so that the reduction of the current signal is completed, and the extraction of a gate current peak value and the further processing of the current signal by a subsequent circuit are facilitated.
In one embodiment of the invention, V is shown in FIG. 6 AC Is an AC voltage source, T 1 ～T 6 Is a thyristor, and is provided with three inductive loads; the Rogowski coil of the junction temperature detection unit is arranged at the position shown in the figure and is connected with other parts of the junction temperature detection unit through connecting wires. When a high level is applied to the thyristor gate, the thyristor gate will flow a current signal I as shown in the figure G The junction temperature detection unit extracts I through the Rogowski coil G Obtaining the driving current peak value I under the operating condition through the thyristor gate pole current measuring module and the thyristor gate pole input charge quantity detecting module G_peak And number of charges input to gate Q G 。
The thyristor gate pole input charge quantity detection module has the function of integrating time by utilizing differential signals of thyristor gate level current extracted by the thyristor gate pole current measurement module, so as to obtain the charge quantity Q obtained by the gate pole in the transient process of switching the thyristor from the forward conduction state to the conduction state G 。
As shown in fig. 5, the thyristor gate input charge amount detection module is formed by a second lossy integration circuit and comprises three resistors R 4 、R 5 、R 6 A capacitor C 3 And a second operational amplifier; wherein R is 4 One end of the output end is connected with the output end of the thyristor gate pole current measuring module, R 4 The other end is connected with the positive input end of a second operational amplifier, and the negative input end of the second operational amplifier is connected with R 5 、R 6 、C 3 Are connected to one end of R 6 、C 3 The other end is connected with the output end of a second operational amplifier, R 5 The other end of the Rogowski coil is grounded. The input end of the second lossy integrating circuit is R 4 One end, the output end is the output end of the second operational amplifier. The module can adjust the proportion of the output signal by adjusting R 5 、R 6 The ratio can be adjusted.
Because the Rogowski coil is not connected with the thyristor drive circuit, the junction temperature detection unit does not need to take isolation measures. Current signal I output by thyristor gate pole current measuring module G Input charge number Q of gate of thyristor G And the direct current bus current I extracted by the acquisition module DC Voltage V at two ends of thyristor AK Thyristor gate drive voltage V G The equal signal can be sent to a junction temperature calculation unit (FPGA), the real-time working junction temperature of the thyristor is calculated and obtained through a relevant physical quantity data table and a function model stored in the FPGA, and the junction temperature calculation unit also has a function of extracting the peak value I of a gate current signal in the transient process of switching the thyristor from a forward conduction state to a conduction state G_peak The function of (c). In order to realize the on-line detection of the operating junction temperature of the thyristor, the junction temperature detection unit and the driving unit can be integrated together.
The foregoing lists merely exemplary embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by the person skilled in the art from the present disclosure are to be considered within the scope of the present invention.
Claims (9)
1. An on-line detection system for the operating junction temperature of a non-contact thyristor, which is characterized by comprising:
the power loop unit is connected with the thyristor to be tested;
the sampling unit is used for collecting direct current bus current, voltage at two ends of the thyristor, gate driving voltage of the thyristor and actual working junction temperature of the thyristor in the power loop unit;
the temperature control unit is used for regulating and controlling the environmental temperature of the thyristor under the actual operation working condition and changing the actual working junction temperature of the thyristor;
the driving unit is connected with the thyristor and is used for driving the thyristor to work;
the junction temperature detection unit is used for measuring a thyristor gate pole current signal and extracting the integral of the gate pole current signal along with time to obtain the charge number input to the thyristor gate pole; extracting the peak value of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state; and calculating to obtain an estimated value of the working junction temperature of the thyristor according to the thyristor gate current signal, the charge number input to the thyristor gate, the peak value of the thyristor current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state, and the direct-current bus current, the voltage at two ends of the thyristor and the thyristor gate driving voltage obtained by the sampling unit.
2. The system for on-line detection of operating junction temperature of a non-contact thyristor according to claim 1, wherein the power loop unit comprises a direct-current voltage source, an electrolytic capacitor, a discharge resistor, an auxiliary diode, an auxiliary switch tube, an auxiliary inductor, a first switch and a second switch; the anode of the direct-current voltage source is connected with one end of a first switch, the other end of the first switch is connected with one end of an electrolytic capacitor, one end of a discharge resistor and the cathode of an auxiliary diode, the other end of the discharge resistor is connected with one end of a second switch, the anode of the auxiliary diode is connected with the collector of an auxiliary switch tube, the emitter of the auxiliary switch tube is connected with the anode of a thyristor, an auxiliary inductor is connected with the auxiliary diode in parallel, and the cathode of the direct-current voltage source is connected with the other end of the electrolytic capacitor, the other end of the second switch and the cathode of the thyristor.
3. The system as claimed in claim 1, wherein the driving unit includes a thyristor driving circuit and an auxiliary power supply, the thyristor driving circuit is configured to provide a driving voltage to the gate of the thyristor to control the thyristor to switch from the forward blocking state to the conducting state; the auxiliary power supply is used for supplying power to the driving circuit.
4. The system of claim 1, wherein a thyristor operating junction temperature calculation model is stored in the junction temperature detection unit, and the thyristor operating junction temperature calculation model is obtained by fitting a thyristor gate current signal, a number of charges input to a thyristor gate, a peak value of the thyristor current signal in a transient process in which the thyristor switches from a forward conduction state to a conduction state, a direct current bus current, a voltage across the thyristor, a thyristor gate drive voltage, and the thyristor operating junction temperature.
5. The system as claimed in claim 4, wherein the junction temperature detecting unit comprises a thyristor gate current measuring module, a thyristor gate input charge amount detecting module, and a junction temperature calculating module;
the thyristor gate pole current measuring module obtains a differential signal of the thyristor gate pole current with respect to time through the Rogowski coil and reduces the differential signal to obtain a gate pole current signal;
the thyristor gate pole input charge quantity detection module integrates time by using a differential signal of thyristor gate-level current extracted by the thyristor gate pole current measurement module with respect to time to obtain the charge quantity obtained by the gate pole in the transient process of switching the thyristor from a forward conduction state to a conduction state;
the junction temperature calculation module is used for extracting the peak value of a gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state and obtaining the working junction temperature of the thyristor according to the working junction temperature calculation model of the thyristor.
6. The system as claimed in claim 5, wherein the thyristor gate current measurement module comprises a rogowski coil and a first lossy integration circuit;
the Rogowski coil is an air coil, and a lead connected with the gate pole of the thyristor penetrates through the air coil and is used for obtaining a differential signal of the gate pole current of the thyristor relative to time;
the first lossy integration circuit comprises a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor and a first operational amplifier; one end of the first resistor is connected with one end of the Rogowski coil, the other end of the first resistor is connected with one end of the first capacitor and the positive input end of the first operational amplifier, and the other end of the Rogowski coil and the other end of the first capacitor are grounded; the negative input end of the first operational amplifier is connected with one end of a second resistor, one end of a third resistor and one end of a second capacitor, the other end of the third resistor and the other end of the second capacitor are connected with the output end of the first operational amplifier, and the other end of the second resistor is grounded; one end of the first resistor is an input end of the first lossy integrating circuit, and an output end of the first operational amplifier is an output end of the first lossy integrating circuit, namely an output end of the thyristor gate current measuring module.
7. The system as claimed in claim 5, wherein the thyristor gate input charge amount detection module comprises a second lossy integration circuit;
the second lossy integration circuit comprises a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor and a second operational amplifier; one end of the fourth resistor is connected with the output end of the thyristor gate current measuring module, the other end of the fourth resistor is connected with the positive input end of the second operational amplifier, the negative input end of the second operational amplifier is connected with one end of the fifth resistor, one end of the sixth resistor and one end of the third capacitor, the other end of the sixth resistor and the other end of the third capacitor are connected with the output end of the second operational amplifier, and the other end of the fifth resistor is grounded; one end of the fourth resistor is the input end of the thyristor gate pole input charge quantity detection module, and the output end of the second operational amplifier is the output end of the thyristor gate pole input charge quantity detection module.
8. The system for on-line detection of operating junction temperature of a non-contact thyristor according to claim 5, wherein the junction temperature calculation module employs a Field Programmable Gate Array (FPGA).
9. A detection method of a non-contact thyristor working junction temperature online detection system is characterized by comprising the following steps:
step 1, establishing a thyristor working junction temperature calculation model:
1.1 Setting an operation condition under the condition that the maximum working voltage, the maximum working current and the maximum working junction temperature of the thyristor to be tested are not exceeded; for any operation condition, in the transient process of switching the thyristor from the forward conduction state to the conduction state, acquiring a group of data of direct current bus current, voltage at two ends of the thyristor, thyristor gate drive voltage, thyristor gate current signals and thyristor working junction temperature, and calculating the charge number input to the thyristor gate under the corresponding operation condition and the peak value of the thyristor current signals in the transient process of switching the thyristor from the forward conduction state to the conduction state according to the thyristor gate current signals;
1.2 Traversing all the operating conditions, obtaining the charge number of the gate electrode of the input thyristor under each operating condition and the peak data of a gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state, and fitting to obtain a thyristor operating junction temperature calculation model by taking the direct-current bus current, the voltages at two ends of the thyristor, the gate electrode driving voltage of the thyristor, the charge number of the gate electrode of the input thyristor and the peak value of the gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state as independent variables and the actual operating junction temperature of the thyristor as a dependent variable;
step 2, detecting the working junction temperature of the thyristor on line:
detecting a thyristor gate current signal, and calculating the charge number input to the thyristor gate and the peak value of the thyristor gate current signal in the transient process of switching the thyristor from the forward conduction state to the conduction state; and simultaneously, collecting direct current bus current, voltage at two ends of the thyristor and gate driving voltage of the thyristor in the transient process of switching the thyristor from the forward conduction state to the conduction state, and calculating the estimated value of the working junction temperature of the thyristor by using a working junction temperature calculation model of the thyristor.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116008768A (en) * | 2023-03-24 | 2023-04-25 | 杭州飞仕得科技股份有限公司 | Conduction voltage drop test circuit and junction temperature tester |
| CN117176121A (en) * | 2023-11-02 | 2023-12-05 | 成都沃飞天驭科技有限公司 | Electronic switch driving circuit, control method and electric aircraft |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116008768A (en) * | 2023-03-24 | 2023-04-25 | 杭州飞仕得科技股份有限公司 | Conduction voltage drop test circuit and junction temperature tester |
| CN117176121A (en) * | 2023-11-02 | 2023-12-05 | 成都沃飞天驭科技有限公司 | Electronic switch driving circuit, control method and electric aircraft |
| CN117176121B (en) * | 2023-11-02 | 2024-02-23 | 成都沃飞天驭科技有限公司 | Electronic switch driving circuit, control method and electric aircraft |
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