RU121374U1 - DEVICE FOR ACCELERATED CONTROL OF HEAT RESISTANCE OF POWER SEMICONDUCTOR TABLET CONSTRUCTION DEVICES - Google Patents

Abstract

A device for accelerated monitoring of the thermal resistance of power semiconductor devices of a tablet design, in which there is a power heating current block and a measuring unit, characterized in that the tested device (MT) is placed in a clamping assembly, in which a water-cooled cooler, MT, the first power copper bus, a tablet-type diode with known parameters, calibrated according to a temperature-sensitive parameter (TCHP), a second power copper bus, a thermal insulator, while the thermal resistance of the MT with two-sided cooling Rtjc is determined by the relationship of the measured deviation of the TCHP calculated for this assembly with the thermal parameters of the device through the coefficient asymmetry n = Rta / Rtjc, where Rta is the thermal resistance of the device under test from the anode side:! ,! where R is the thermal resistance of the MT in the assembly; n - coefficient of unbalance, constant for devices of this design.

Description

The utility model relates to the field of electrical engineering, namely to power semiconductor converters and specifically to power semiconductor devices (SPP) - thyristors and diodes of tablet design.

NGN, which are the main functional elements of converters, mainly determine their reliability.

A device for measuring thermal resistance pn junction-case of semiconductor diodes (hereinafter _{referred to as} thermal resistance, R _tjc ) is described in [1] (Patent RU 2087919, class G01R 31/26, claims), containing, in particular, a heating current source in the form of a source of pulses modulated according to a harmonic law with a period an order of magnitude greater than the thermal time constant of the transition-case τ of the diode under study. However, the value of m is the product of the heat capacity and R _th, and before the measurement of R _{th is} unknown. Therefore, in the solution [1], a certain value of τ is adopted, which is typical for this type of diode. All devices are measured in one mode, while the values of τ can vary by an order of magnitude or more from device to device. This leads to measurement error.

The closest in technical essence to the proposed utility model and selected as a prototype is a device for determining the thermal resistance of power semiconductor devices, given in [2] (GOST 24461-80. Power semiconductor devices. Methods of measurement and testing. The term of introduction is set from 01.01. 1982 g).

The circuit of the device [2] includes: a source of power heating direct current; adjustable source of measuring stabilized direct current; a source of control pulses (for thyristors), providing current pulses with an amplitude and duration sufficient to fully turn on the thyristor under test; an adjustable source of stabilized constant voltage for measuring, by the compensation method, the voltage in the open state on the device under test (IP), due to the measuring current; thermocouple and DC potentiometer for measuring the temperature of the instrument housing.

The thermosensitive parameter (TJP) for measuring the pn junction temperature T _j is the voltage in the open state U, due to the current in the open state I. In the case of thyristors containing 3 pn junctions, due to the small thickness of the semiconductor structure, the temperature of all three pn junctions can be considered the same , therefore, for thyristors, T _j means the temperature of the semiconductor structure.

According to [2], the measurement of thermal resistance of devices is carried out as follows:

1) carry out the calibration of the tested device, i.e. a calibration curve is constructed on the basis of open voltage measurements at a selected value of the measuring current as a function of the transition temperature, which changes under the influence of an external heat source (usually the device is placed in a thermostat). The devices of the tablet design must be graduated assembled with coolers or devices providing equivalent pressure conditions;

2) turn on the test thyristor by a control pulse *;

3) establish from the source of the measured stabilized direct current measuring current through the device, equal to the current used in the calibration;

4) establish the cooling conditions of the device in accordance with the requirements of technical conditions (TU);

5) establish a constant heating current from the power heating direct current source through the device in accordance with the requirements of the technical specifications for the devices and heat the device to a steady state of heat (The steady state of heat is fixed by setting the temperature of the case, measured with a thermocouple and a direct current potentiometer;

6) measure the current I through the device using an ammeter and the voltage U on the device using a voltmeter;

7) measure the temperature of the casing T _c (with one-sided cooling) or T _cA and T _cK (with two-sided cooling, respectively, on the side of the anode and cathode) using a thermocouple and a DC potentiometer;

8) turn off the heating current;

9) measure the voltage on the device in the open state by the compensation method using a stabilized constant voltage source, a voltmeter and an oscilloscope;

10) transfer the measured voltage on the device to the transition temperature using a calibration curve;

11) calculate R _tjc :

where R _tA is the thermal resistance of the device from the side of the anode; R _tK is the thermal resistance of the device from the cathode side; T _j is the pn junction temperature.

The total thermal resistance of the transition-case of the device:

It is believed that the device has passed the test if the thermal resistance of the junction-case R _tjc does not exceed the established norm.

The disadvantages of the prototype are:

- significant time costs associated with calibrating the tested device by TCHP, as well as bringing the IP-cooler system to a steady thermal state both during the period of heating it from the source of the heating power supply and during cooling.

- for thyristors - the occurrence of an additional error in measuring the temperature of the semiconductor structure due to the presence of jumps in the calibration dependence due to the instability of the semiconductor structure being turned on both during calibration-heating from an external source and when the thyristor cools after the heating current has ceased.

The complexity of measuring thermal resistance according to [2] (at least 2 hours per device) does not allow continuous monitoring of this parameter in the production environment, therefore, thermal resistance is checked selectively during type tests of 10 pcs. devices, which can lead to the commissioning of devices with thermal resistance that do not meet the requirements established in TU.

The technical task of the utility model is to create a device for accelerated and more accurate control of the thermal resistance of power semiconductor devices (thyristors, diodes) of a tablet design.

The technical result of using the utility model is to increase the accuracy of the control results of power semiconductor devices with respect to the thermal resistance parameter and significantly reduce the control time, which ensures continuous monitoring of products and eliminates the commissioning of power semiconductor devices with thermal resistance that do not meet technical requirements.

The technical result is achieved by the fact that in the device for accelerated thermal resistance control of power semiconductor devices of tablet design, in which there is a power heating current unit and a measuring unit, according to the proposed solution, the IP is placed in the clamping assembly, in which the water-cooled chiller, IP, the first power copper bus, a diode of a tablet design with known parameters (calibrated by TCHP), the second power copper bus and thermal insulator, in orc compression force is provided in accordance with the specification for the diode type and SP. The thermal resistance of the IP is determined by the calculated for this assembly connection of the measured deviation of the PST with the thermal parameters of the device through the asymmetry coefficient, which reflects the difference R _tA and R _{tK of the} tested device.

No technical solutions with the indicated features were found

In the proposed device, the power heating current and the measuring current flow only through the diode, calibrated by a temperature-sensitive parameter. IP is in the heat flow between the diode and the water cooler. The thermal resistance of the IP determines the deviation of the PMT of the diode and is calculated according to the proposed formulas through the asymmetry coefficient.

The advantage of the proposed solution is a significant reduction in the monitoring time R _tjc , since the calibration of the IP is not performed. In addition, the measurement takes place in a transient thermal regime and, therefore, eliminates the need to heat the test device to a steady thermal regime.

There is also an advantage in the absence of a source of control pulses for both diodes and thyristors.

The essence of the proposed technical solution is illustrated in the figure.

Marked with:

TP (test device) - a diode of a tablet design, calibrated by a thermosensitive parameter;

IP (device under test) - a device of tablet design, the thermal resistance of which is subject to control;

1 - thermal insulator;

2 - water-cooled chiller;

3 - power copper busbars;

4 - power heating current block;

5 - measuring unit for measuring the temperature of the semiconductor structure of TP according to the PPP;

K1 and K2 are switches.

Work sequence:

1) turn on the power heating current from unit 4 for a time interval during which the heat flux from the semiconductor structure of the TP reaches cooler 2;

2) after turning off the power heating current through 150 μs, the measuring unit 5 measures the PMT, the value of which determines the temperature of the semiconductor structure of the TP;

3) the thermal resistance of the assembly “1-TP-IP-2” is calculated similarly to the thermal resistance of the structure-casing in the prototype circuit;

4) calculations of the thermal resistance of the PI from the side of the anode and from the side of the cathode R _tK and R _tA are based on the thermal resistance of the assembly, taking into account the asymmetry coefficient n = R _ta / R _tjc :

where R is the thermal resistance of the IP in the assembly; n is the asymmetry coefficient constant for devices of this design;

5) the calculation of the thermal resistance of the PI during two-sided cooling R _{tjc is} carried out according to the formula

The device passed the test if the thermal resistance pn junction-case R _tjc does not exceed the norm established in the technical specifications.

Claims (1)

An accelerated control device for the thermal resistance of power semiconductor devices of a tablet design, in which there is a power heating current unit and a measuring unit, characterized in that the device under test (IP) is placed in the clamping assembly, in which a water-cooled chiller, IP, is installed in the stack, the first power a copper bus, a tablet design diode with known parameters, calibrated by a temperature-sensitive parameter (TCH), a second power copper bus, a thermal insulator, while m the thermal resistance of the PI during two-sided cooling R _tjc is determined by the relationship calculated for the assembly of the measured deviation of the PST with the thermal parameters of the device through the asymmetry coefficient n = R _ta / R _tjc , where R _ta is the thermal resistance of the tested device from the anode side:

, where R is the thermal resistance of the IP in the assembly; n is the asymmetry coefficient constant for devices of this design.