FR3084467A1 - TEMPERATURE CONTROL METHOD AND CORRESPONDING CONTROL CIRCUIT - Google Patents

Abstract

The invention relates to a method for controlling the temperature of a high voltage transistor (Q1; Q1 '). According to the invention, said method comprises the following steps: - the voltage (VCE_sat; VDS) at the terminals of the transistor (Q1; Q1 ') is measured when it is on, - the current (IC; ID) flowing through is noted transistor (Q1; Q1 '), and from the voltage (VcE_sat; VDS) measured and the current (IC; ID) read, the junction temperature (TJ) of the transistor (Q1; Q1') is estimated. The invention also relates to a temperature control circuit of a high voltage transistor (Q1; Q1 ') for the implementation of such a method.

Description

Temperature control method and corresponding control circuit

The invention relates to the control of the junction temperature of a high voltage transistor. These are in particular bipolar transistors, such as insulated gate bipolar transistors called IGBT transistors for "Insulated Gate Bipolar Transistor" in English, or insulated gate field effect transistors called MOSFET transistors for "Metal Oxide Semiconductor Field Effect Transistor ”in English.

High voltage transistors are used to modulate energy in high voltage products or equipment. Such high voltage transistors can be provided in high voltage converters, for example in certain electrical equipment of electric motor vehicles. Mention may in particular be made in a non-exhaustive manner of equipment for heating, compressors, converters such as inverters or choppers, or even batteries.

In operation of such high voltage transistors, a high loss of energy is dissipated in the form of heat. This heat can be quantified from the measurement of the junction temperature. However, if the junction temperature exceeds a predefined threshold, this can cause the transistor to fail. In order to ensure proper operation of the electrical product or equipment, it is necessary to provide an effective thermal protection in order to protect against possible transistor failures.

To do this, according to a known solution, analog temperature sensors are provided, such as negative temperature coefficient (CTN), or positive temperature coefficient (PTC) sensors.

For surface mounted transistors, for example soldered on a printed circuit board, such sensors are placed near the transistors.

However, for through transistors, that is to say the pins of which pass through the support of such transistors, the temperature sensors cannot be mounted directly near the transistors but are mounted on a heat sink near the sole. , which can present difficulties related to integration and prove to be expensive, in particular in terms of manufacturing process and components

-2 additional mechanics. In addition, if the transistor is incorrectly attached to the heat sink, the temperature sensor may return erroneous temperature information from the transistor. If overheated, this can destroy the component.

The object of the invention is to at least partially overcome these drawbacks of the prior art by proposing an alternative solution making it possible to monitor and control the junction temperature of a high voltage transistor.

To this end, the invention relates to a process for controlling the temperature of a high voltage transistor. According to the invention, said method comprises the following steps:

- we measure the voltage across the transistor when it is on,

- the current flowing through the transistor is noted, and

- From the measured voltage and the current read, the junction temperature of the transistor is estimated.

Such a solution no longer requires the arrangement of temperature sensors near the transistors, but allows an indirect measurement of the junction temperature of the transistors based on their heat-sensitive parameters. Such parameters, such as the current flowing through the transistor and the voltage between the collector and the emitter if it is bipolar transistors with an insulated gate, or the voltage between the drain and the source if it is of an insulated gate field effect transistor, vary as a function of the junction temperature, which makes it possible to estimate the junction temperature.

Thus, by taking into account only the heat-sensitive electrical parameters, it is possible to estimate the junction temperature of the transistor in order to guard against possible overheating of the transistor.

According to a first embodiment, it is a process for controlling the temperature of an insulated gate bipolar transistor, in which:

- we measure the voltage from the collector to the emitter when the transistor is saturated,

- we collect the current from the collector to the transmitter,

- we model a linear approximation of the evolution of the emitter collector voltage as a function of the junction temperature for the measured current, from

-3 at least two voltage reference values between the collector and the emitter of the transistor at two predefined junction temperatures, and

- from the modeled approximation, the junction temperature of the transistor is estimated for the measured emitter collector voltage.

The predefined junction temperatures are for example 25 ° C and 175 ° C.

The voltage reference values between the collector and the emitter of the transistor at two predefined temperatures can be determined as a function of the value of the predefined emitter gate voltage in the specifications.

According to a second embodiment, it is a process for controlling the temperature of an insulated gate field effect transistor, in which:

- the voltage between the drain and the source is measured when the transistor is on,

- the drain current is noted,

- from the voltage between the drain, the measured source and the drain current, we determine the resistance of the transistor when it is on, and

- from the determined resistance, the junction temperature is estimated using at least one memorized correspondence table.

Said method can also include one or more of the following characteristics, taken separately or in combination:

- Said method comprises the following steps: the estimated junction temperature of the transistor is compared to a predefined temperature threshold, and if the estimated junction temperature of the transistor exceeds a predefined temperature threshold, the transistor is switched from the state passing to blocked state;

- measuring the voltage across a measurement resistor arranged in series with the transistor so as to determine the current passing through said resistance and passing through the transistor;

- the measurement resistor is a measurement shunt;

- the measurement resistor comprises a terminal electrically connected to the emitter of the insulated gate bipolar transistor or to the source of the insulated gate field effect transistor;

- the measurement resistor has another terminal electrically connected to ground.

The invention also relates to a temperature control circuit of a high voltage transistor, configured to implement the method as defined above. Said circuit includes:

- a high voltage transistor, a voltage measuring device mounted across the transistor and configured to measure the voltage of the transistor when it is on,

- a current acquisition device electrically connected to an electrode of the transistor and configured to take a current flowing through the transistor, and

- at least one processing means configured to receive at input at least one voltage information coming from the voltage measurement device and at least one current information coming from the current acquisition device, and configured to estimate the temperature of junction of the transistor, from the voltage of the transistor when it is on and the current passing through it.

Said circuit can also include one or more of the following characteristics, taken separately or in combination:

- the transistor is electrically connected to a high voltage source for example by means of a load;

- The transistor is a bipolar transistor with insulated gate whose collector is electrically connected to the high voltage source or a field effect transistor with insulated gate whose drain is electrically connected to the high voltage source;

- the voltage measurement device comprises an operational amplifier;

- the operational amplifier has an input electrically connected to said transistor;

- Said circuit further comprises a voltage measurement control module electrically connected to the transistor and to the voltage measurement device;

- the voltage measurement control module includes:

• at least one resistive element electrically connected to a supply voltage and • at least a first and a second switch, such as transistors,

-5respectively connected on the one hand to ground and on the other hand to an electrode different from the transistor, and such that the second switch is arranged in series with the resistive element and the first switch is electrically connected to the node between the element resistive and the second switch;

- Said circuit comprises at least one voltage divider bridge, said at least one divider point comprises two resistors in series;

- said circuit comprises a first voltage divider bridge and the operational amplifier has another input electrically connected to the node between the two resistors in series of the first divider bridge;

- the voltage measurement control module has an input electrically connected to the output of the first divider bridge;

- The circuit includes a second divider bridge and the voltage measurement control module has an output electrically connected to the node between the two resistors in series of the second divider bridge;

- the acquisition device is configured to measure the voltage across a measurement resistor arranged in series with the transistor;

- Said at least one processing means configured to estimate the junction temperature of the transistor is chosen from a microcontroller or a discrete circuit module;

- Said at least one processing means is configured to estimate the junction temperature of the transistor is configured to emit a switching control signal of the transistor as a function of the estimated junction temperature of the transistor;

- Said circuit comprises a control module configured to switch the transistor between the on state and the off state;

- The control module is configured to receive a switching control signal of the transistor emitted by said at least one processing means such as the microcontroller or the discrete circuit module.

Other features and advantages of the invention will become more apparent

On reading the following description, given by way of illustrative and nonlimiting example, and of the appended drawings among which:

- Figure la shows schematically a first variant of an assembly of a temperature control circuit of a bipolar transistor with insulated gate,

FIG. 1b schematically represents a second variant of an assembly of a temperature control circuit of a bipolar transistor with an insulated gate,

FIG. 2a is a graph showing curves of evolution of the voltage between the collector and the emitter of a bipolar transistor with insulated gate as a function of the collector current at a first predefined temperature,

FIG. 2b is a graph showing curves of evolution of the voltage between the collector and the emitter of a bipolar transistor with an insulated gate as a function of the collector current at a second predefined temperature,

FIG. 2c is a graph showing curves of evolution of the voltage between the collector and the emitter as a function of the junction temperature,

FIG. 3 schematically represents an assembly of a temperature control circuit of an insulated gate field effect transistor, and

- Figure 4 is a graph showing an evolution curve of the resistance to the on state of an insulated gate field effect transistor as a function of the junction temperature.

In these figures, identical elements have the same references.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply only to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments.

In the description, it is possible to index certain elements, such as for example first element or second element. In this case, it is a simple indexing to differentiate and name similar but not identical elements. This indexing does not imply a priority of one element over another and we can easily

Interchange such names without departing from the scope of this description. This indexing does not imply an order in time either.

The invention relates to monitoring the junction temperature of a high-voltage transistor, more particularly of an insulated gate bipolar transistor called IGBT or an insulated gate field effect transistor called MOSFET. "High voltage" means a voltage in the range of 100V to 6500V, for example of the order of 400V or 800V. Such high voltage transistors are used for power electronics.

Temperature control process

Referring to all of FIGS. 1 to 5, a method for controlling the temperature of a high voltage transistor is described.

Figures 1a to 2c refer to monitoring the junction temperature of an insulated gate bipolar transistor, hereinafter designated IGBT transistor Ql.

Figures 3 and 4 refer to monitoring the junction temperature of an insulated gate field effect transistor hereinafter referred to as MOSFET transistor Ql ’.

The process, the steps of which are shown diagrammatically in a simplified manner in the diagram of FIG. 5, for monitoring the junction temperature of one or other of the transistors Ql, Ql ', can be started at a starting step E0 .

The method generally comprises the steps described below. During a step E1, the voltage across the terminals of the transistor Q1 is measured; Ql ’when passing, as shown by Ql ON and Ql’ ON in Figure 5.

In step E2, the current flowing through the transistor Ql is noted; Ql. Then in step E3, the junction temperature Tj of the transistor Ql is estimated; Ql 'from the measured voltage and the current read.

IGBT transistor case

In the case of an IGBT transistor Ql, in step El, the voltage between the

-8 collector and emitter, hereinafter referred to as collector-emitter voltage VcE_sat, when the transistor Q1 is saturated. In particular, a differential measurement of the collector-emitter voltage VcE_sat is carried out. At least one step of processing the measured collector-emitter voltage VcE_sat can be provided, for example an amplification step.

The current which is read in step E2 is the current from the collector to the transmitter le. To do this, according to the examples illustrated in FIGS. 1a, 1b, it is possible to measure the voltage Vshunt across the terminals of a measurement resistor, in particular a measurement shunt S arranged in series with the IGBT transistor Ql. The measurement resistor such as the measurement shunt S has a terminal electrically connected to the emitter of the IGBT transistor QL The other terminal is electrically connected to ground. From the measured voltage Vshunt, it is possible to determine the current passing through the measurement resistor such as the measurement shunt S, and thus the current from the collector to the transmitter le.

For the estimation of the junction temperature Tj of the IGBT transistor Ql, the method can comprise at least one substep, in which a linear approximation of the evolution of the collector-emitter voltage VcE_sat is modeled as a function of the temperature of Tj junction. From this linear approximation, the junction temperature Tj of the transistor Ql can be estimated for the collector-emitter voltage VcE_sat which is measured.

The linear approximation of the evolution of the collector-emitter voltage can be done from at least two collector-emitter voltage reference values Vce_25, Vce_175 of the IGBT transistor QL The reference values Vce_25, Vce_175 of the IGBT transistor Ql are defined at two predefined junction temperatures and for a current from the collector to the emitter the given which is less than a predefined maximum system current. The predefined junction temperatures are for example 25 ° C and 175 ° C. The collector-emitter voltage reference values Vce_25, Vce_175 of the IGBT transistor Ql at the two predefined temperatures are determined as a function of the value of the voltage between the gate and the emitter designated below by the gate-emitter voltage Vge predefined for example in the notebook charges.

To this end, the method may include a preliminary step in which a mapping or mapping is carried out in English, for example using a

-9microcontroller, so as to obtain a table of collector-emitter voltage values Vce based on the heat-sensitive parameters of the IGBT transistor Q1 provided in the specifications, by the manufacturer of the IGBT transistor Ql. In other words, the collector-emitter voltage values Vce are noted as a function of the current and for known values of gate-emitter voltage Vge.

FIG. 2a schematically represents a graph showing the evolution of the collector-emitter voltage reference value Vce_25, for a junction temperature of 25 ° C, as a function of the current from the collector to the emitter le and for different values of grid-emitter voltage Vge, for example from 5V to 20V.

Similarly, FIG. 2b schematically represents a graph showing the evolution of the collector-emitter voltage reference value Vce_175, for a junction temperature of 175 ° C., as a function of the current from the collector to the emitter and for different values of gate-emitter voltage Vge, for example from 5V to 20V.

FIG. 2c is a graph schematically representing different curves of evolution of the collector-emitter voltage Vce according to the value of the current from the collector to the emitter le and for a predefined gate-emitter voltage value Vge. By way of nonlimiting example, one places oneself for example in the case of an IGBT transistor Ql having a predefined gate-emitter voltage Vge of the order of 15V. In this FIG. 2c, various examples of curves of evolution of the collector-emitter voltage Vce have been represented, value of the current from the collector to the emitter le. For example :

the dashed curve shows the evolution of the collector-emitter voltage Vce for a value of the current from the collector to the emitter le of 60A, the dashed curve shows the evolution of the collector-emitter voltage Vce for a current value from the collector to the emitter le of 30A, and the curve in solid lines with triangles shows the evolution of the collector emitter voltage Vce for a value of the current from the collector to the emitter le of 15A.

By way of nonlimiting illustrative example, in the case of an IGBT transistor Ql of gate-emitter voltage Vge of the order of 15V, and for which a current of the

-10 collector to the transmitter on, for example in step E2, of the order of 20A, it is possible to determine from the data represented schematically on the graphs of FIGS. 2a and 2b at least one voltage reference value collector-emitter Vce_25, for a junction temperature of 25 ° C and another voltage reference value collector-emitter Vce_175 for a junction temperature of 175 ° C.

It is possible to provide a substep for storing these reference values VcE_25, VcE_175.

From the reference values Vce_25, Vce_175, we model the linear approximation of the evolution of the collector-emitter voltage VcE_sat as a function of the junction temperature Tj, as shown schematically by the straight line in solid lines with circles. This linear approximation corresponds to the following equation (a):

(a) V _C e = a X Tj + b, with a, b corresponding to variable coefficients.

Depending on the collector-emitter voltage VcE_sat which is measured in step El, we can then estimate the junction temperature Tj of the IGBT transistor Q1 from this linear approximation in step E3. In other words, we can determine the junction temperature Tj from the following equation (b):

(b) T, = - - - ^J aa with a, b corresponding to variable coefficients, and by replacing Vce by the value VcE_sat measured in step El.

MQSFET transistor case

Referring to FIGS. 3 to 5, in the case of a MOSFET transistor Ql ′, the voltage between the drain and the source, hereinafter referred to as drain-source voltage Vds, is measured in step E1, when the transistor MOSFET Q 'is passing. In particular, a differential measurement of the drain-source voltage Vds is carried out. Similarly to the case of the IGBT transistor Ql, it is possible to provide at least one processing step, for example of amplification, of the drain-source voltage Vds measured at the terminals of the MOSFET transistor Ql ’.

The current which is recorded in step E2 is the drain current Id. As described

Previously, this can be done by measuring the voltage Vshunt across the terminals of a measurement resistor, such as a measurement shunt arranged in series with the MOSFET transistor Ql ′ by having a terminal electrically connected to the source of the MOSFET transistor Ql 'and the other terminal electrically connected to ground.

For the estimation of the junction temperature Tj of the MOSFET transistor Ql ’, in step E3, the method can include the following substeps:

from the drain-source voltage Vds measured and the drain current Id noted, the resistance Rdsoii of the MOSFET transistor Ql 'is determined when it is on, and from the resistance Rdsoii determined, the junction temperature Tj is estimated using at least one memorized correspondence table.

The resistance Rdsoii of the MOSFET transistor Ql ′ in the on state is defined as a function of the drain-source voltage Vds and of the drain current Id according to the following equation (c):

(c) RüSon - * D

Its value is conventionally determined for a voltage between the gate and the source, hereinafter referred to as gate-source voltage or gate voltage Vgs of 10V.

The method may include a preliminary step in which a mapping is carried out, so as to obtain a table of values of the resistance Rdsoii of the MOSFET transistor Ql 'in the on state based on the thermosensitive parameters of the MOSFET transistor Ql' supplied in the specifications, by the manufacturer of the transistor, such as the drain-source voltage Vds and the drain current Id, as a function of the junction temperature.

There is shown schematically in FIG. 4, an evolution curve of the resistance Rdsoii of the MOSFET transistor Ql ’as a function of the junction temperature Tj. These values, for example provided by the manufacturer, are given for a gate voltage Vgs and for a particular drain current Id. In the example of FIG. 4, the MOSFET transistor Q1 ’has a gate voltage Vgs of 10V and the drain current Id is of the order of 1.25A.

From this table, according to the drain-source voltage Vds and the drain current Id recorded in steps El and E2, the resistance Rdsoii of the MOSFET transistor can be calculated.

-12Ql ’and deduce the junction temperature Tj of the MOSFET transistor Ql’ in step E3.

Furthermore, by referring again to FIG. 5, according to one or other of the variants, that is to say for an IGBT transistor Ql or MOSFET Ql ', after having estimated the junction temperature Tj at step E3, the method may include the following steps.

During a step E4, the junction temperature Tj of the IGBT transistor Ql, respectively of the MOSFET transistor Ql ', is compared to a predefined temperature threshold TL The predefined temperature threshold Tl for the IGBT transistor Ql or MOSFET Ql' is in particular chosen lower than the maximum admissible junction temperature Tj _m ax of the IGBT transistor Ql, respectively MOSFET Ql '. Such a predefined temperature threshold Tl depends in particular on the specifications and the application.

If the estimated junction temperature Tj of the IGBT transistor Ql, respectively of the MOSFET transistor Ql ’, is lower, more precisely less than or equal, to the predefined temperature threshold Tl, the steps of the method can again be iterated from the start.

On the contrary, if the estimated junction temperature Tj of the IGBT transistor Ql, respectively of the MOSFET transistor Ql ', exceeds the predefined temperature threshold Tl, in step E5, the IGBT transistor Ql, respectively of the MOSFET transistor Ql', is switched on, from the state passing to the blocked state, as shown diagrammatically by Ql OFF and Ql 'OFF in FIG. 5.

Cooling can then take place naturally. We can continue to monitor the junction temperature Tj of the IGBT transistor Ql, respectively of the MOSFET transistor Ql ’. To do this, it is possible to initiate a step E6 of switching strategy in the transient passing state of the IGBT transistor Ql, respectively of the MOSFET transistor Ql ’. For example, the IGBT transistor Ql, respectively the MOSFET transistor Ql ’, can be switched to the on state during a predefined period, at a time interval which can be regular. Without limitation, an example of a monitoring strategy is the switching of the IGBT transistor Q1,

-13respectively of the MOSFET transistor QI ’in the passing state during 50ms every 5s.

During the switching states of the IGBT transistor QI, respectively of the MOSFET transistor QI ’, the junction temperature Tj can be estimated as explained above with reference to steps E1 to E3.

The junction temperature Tj estimated during these transient periods of switching to the on state can be compared in step E7 with another predefined temperature threshold T2 different from the predefined temperature threshold Tl used during the comparison step E4. In this case, the predefined temperature threshold Tl of step E4 is called the first temperature threshold and the predefined temperature threshold T2 of step E6 is called the second temperature threshold. The second temperature threshold T2 is lower than the first temperature threshold Tl. The second temperature threshold T2 is chosen according to the application.

As long as the junction temperature Tj is greater than or equal to the second temperature threshold T2, the transient switching in the on state of the IGBT transistor Ql, respectively MOSFET Ql ’, according to the strategy defined in step E6 can continue.

When the junction temperature Tj is lower, more precisely strictly lower, than the second temperature threshold T2, the switching on of the IGBT transistor Ql, respectively MOSFET Ql ’, is restarted. In other words, the IGBT transistor Ql, respectively MOSFET Ql ’, is in the on state and the process begins again at the start so as to continue monitoring the junction temperature Tj.

Control circuit

The implementation of the method as described above can be done by a circuit 1 for controlling the temperature of a high voltage transistor Ql, Ql ', of which mounting examples are shown schematically in Figures la, 1b and 3.

The temperature control circuit 1 includes a high voltage transistor, such as an IGBT transistor Ql or a MOSFET transistor Ql '. According to the examples illustrated, the transistor Q1; Ql 'is electrically connected to a voltage source which may be a high voltage HV, for example by means of a load Rl.

-14 In the case of an IGBT transistor Ql, it is the collector which is electrically connected to the voltage source HV for example by means of the load Rl. In the case of a MOSFET transistor Ql ’, it is the drain which is electrically connected to the voltage source HV for example by means of the load Rl.

In addition, according to the mounting examples illustrated in FIGS. 1a, 1b and 3, the IGBT transistor Ql or MOSFET Ql 'is arranged in series with the load Rl and a measurement resistor, such as a measurement shunt S. In the case of an IGBT transistor Ql, it is the emitter which is electrically connected to the measurement shunt S. In the case of a MOSFET transistor Ql ', it is the source which is electrically connected to the measurement shunt

S.

In general, the control circuit 1 also includes:

a voltage measurement device 3, a current acquisition device 5, and at least one processing means 7 configured to receive at input at least one voltage information coming from the voltage measurement device 3 and at least one information current from the current acquisition device 5.

The voltage measuring device 3 is mounted across the terminals of the transistor Q1; Ql 'and is configured to measure the voltage VcE_sat; Vds of transistor Ql; Ql when he is passing. More specifically, the voltage measurement device 3 makes it possible to measure the collector-emitter voltage VcE_sat of the saturated IGBT transistor Ql or the drainsource voltage Vds of the MOSFET transistor Ql ’.

In particular, the voltage measurement device 3 allows a differential measurement of the voltage VcE_sat, respectively Vds, between the electrodes of the IGBT transistor Ql, respectively of the MOSFET transistor Ql ', electrically connected on one side to the voltage source HV by example via the load Rl and on the other side to the measurement shunt S.

By way of example, the voltage measuring device 3 comprises an operational amplifier Al. The operational amplifier Al is mounted in parallel

-15 from the IGBT QI or MOSFET QI transistor. More specifically, the operational amplifier A1 has an input ei electrically connected to the transmitter in the case of an IGBT transistor Ql, or to the source in the case of a MOSFET transistor Ql ’. The operational amplifier A1 has another input 62 electrically connected to the collector in the case of an IGBT transistor Ql, or to the drain in the case of a MOSFET transistor Ql ’.

The current acquisition device 5 is electrically connected to an electrode of the transistor Ql, Ql ’and is configured to take a current le; Id traversing the transistor Ql; Ql. More specifically, the current acquisition device 5 makes it possible to read the current from the collector to the emitter 1a when it is an IGBT transistor Ql or the drain current lol when it is a transistor MOSFET Ql '.

In particular, the current acquisition device 5 may include a voltage measurement device A2 configured to measure the voltage Vshunt across a measurement resistance S arranged in series with the transistor Ql; Ql. The voltage measurement device A2 can be configured to deduce the current passing through the MOSFET transistor Ql ’from the voltage Vshunt measured across the terminals of the measurement shunt S.

The processing means 7 is / are configured to estimate the junction temperature Tj of the transistor Ql; Ql ', from:

of the voltage VcE_sat; Vds of transistor Ql; Ql 'when it is passing and current, Id crossing it.

This is for example a microcontroller or a discrete circuit module. The processing means (s) 7 can be configured for digital processing. It can also be a hardware device, for example of the hysteresis comparator type with non-inverting summator, and for example with threshold detection.

The processing means 7 is / are configured to receive the voltage information VcE_sat; Vds and current le, Id recorded by the voltage measurement devices 3 and current acquisition devices 5.

The processing means 7 is / are configured to transmit a signal

-16 for switching control of the QI transistor; QI ’as a function of the estimated junction temperature Tj of the transistor QI; IQ 'or if a temperature threshold has been exceeded.

The control circuit 1 may further comprise a module 9 for controlling the voltage measurement which makes it possible to manage the measurement of the high voltage of the transistor QI; IQ '. The voltage measurement control module 9 is electrically connected to the transistor QI; QI ’whose junction temperature and the voltage measurement device 3 are monitored. Such a module 9 is configured to control which voltage is measured by the voltage measurement device 3, as explained below.

The voltage measurement control module 9 comprises at least one resistive element R3 electrically connected to a supply voltage Vcc.

The module 9 for controlling the voltage measurement further comprises at least two switches such as transistors. For example, at least a first transistor Q2 and a second transistor Q3 are provided. The transistors Q2, Q3 are respectively connected on the one hand to the ground and on the other hand to an electrode different from the IGBT transistor Ql, respectively MOSFET QI ’. As a specific example, it can be bipolar transistors Q2, Q3.

The first transistor Q2 is electrically connected on the one hand to ground and on the other hand to the IGBT transistor Ql, respectively MOSFET Ql ', and to the voltage measurement device 3. The first transistor Q2 is also electrically connected to the node between the resistive element R3 and the second transistor Q3. More precisely, if it is a first bipolar transistor Q2, its emitter is electrically connected to ground and its collector is electrically connected to the IGBT transistor Ql, respectively MOSFET Ql ’, and to the voltage measurement device 3.

The second transistor Q3 is arranged in series with the resistive element R3.

The base of the first bipolar transistor Q2 is electrically connected to the node between the resistive element R3 and the second transistor Q3.

In addition, the second transistor Q3 is electrically connected on the one hand to ground and on the other hand to the IGBT transistor Ql, respectively MOSFET Ql ’. More precisely,

-17 if it is a second bipolar transistor Q3, its emitter is electrically connected to ground, its collector is electrically connected to the resistive element R3 and its base is electrically connected to the IGBT transistor Ql, respectively MOSFET Ql ' .

In addition, in the case of an IGBT transistor Ql (FIGS. 1a, 1b), the first transistor Q2 of the module 9 for controlling the voltage measurement can be electrically connected to the collector of the IGBT transistor Ql while the second transistor Q3 of the module 9 for controlling the voltage measurement can be electrically connected to the gate of the IGBT transistor Ql.

In the case of a MOSFET transistor Ql '(FIG. 3), the first transistor Q2 of the module 9 for controlling the voltage measurement can be electrically connected to the drain of the MOSFET transistor Ql' while the second transistor Q3 of the module 9 of control of the voltage measurement can be electrically connected to the gate of the MOSFET transistor Ql '.

The IGBT transistor Ql, respectively MOSFET Ql ’, and the second transistor Q3 can be driven at the same time and the second transistor Q3 can drive the first transistor Q2.

When the IGBT transistor Ql, respectively MOSFET Ql ', is in the off state, the second transistor Q3 of said control module 9 is switched off and the first transistor Q2 of said control module 9 is switched on. passing state. In this case, the voltage measured by the voltage measuring device 3 corresponds to the low voltage of the IGBT transistor Ql, respectively MOSFET Ql ’in the off state.

When the IGBT transistor Ql, respectively MOSFET Ql 'is in the on state, the second transistor Q3 of the said control module 9 is switched on and the first transistor Q2 of the said control module 9 is switched on. blocked state. In this case, the voltage measured by the voltage measuring device 3 corresponds to the high voltage of the IGBT transistor Ql, respectively MOSFET Ql ’, in the on state.

The control circuit 1 may include one or more dividing bridges

-18 voltage 11, 13. In the example of FIG. 1a, the control circuit 1 comprises a voltage divider bridge 11. In the examples of FIGS. 1b and 3, the control circuit 1 comprises two voltage divider bridges 11 and 13.

The dividing bridge (s) 11, 13 make it possible to attenuate the high voltage. The dividing bridge (s) 11, 13 also make it possible to protect or limit the propagation of the high voltage on the low voltage devices, in particular the module 9 for controlling the voltage measurement or the operational amplifier A1, for example in the event of failure of the IGBT transistor Ql, respectively MOSFET Ql '.

Each dividing point 11, respectively 13, has two resistors RI, R2, respectively R4, R5, in series.

A voltage divider bridge 11 (FIG. 1a) or a first voltage divider bridge 11 (FIGS. 1b, 3) can be provided between the IGBT transistor Ql, respectively MOSFET Ql ’, and the voltage measurement control module 9. More specifically, the voltage divider bridge or first bridge 11 can be provided between the collector of the IGBT transistor Ql, or the drain of the MOSFET transistor Ql ’, and the first transistor Q2 of the voltage measurement control module 9.

The voltage divider bridge 11 or first voltage divider bridge 11 includes a first resistor RI and a second resistor R2 in series.

The voltage measurement control module 9 can include an input electrically connected to the output of the first or single divider bridge 11. In particular, the input of the voltage measurement control module 9 can be electrically connected to the second resistor R2. The first resistor RI can be electrically connected to the collector of the IGBT transistor Ql, respectively to the drain of the MOSFET transistor Ql ’.

According to the embodiment of the voltage measurement device 3 with an operational amplifier Al, one of the inputs 62 of the operational amplifier Al can be electrically connected to the node between the two resistors RI, R2 in series of the first divider bridge or single bridge divider 11. The divider bridge (FIG. 1a) or first divider bridge 11 (FIGS. 1b, 3) makes it possible to adapt the voltage for the measurement by

-19Γ operational amplifier Al which is a low voltage processing device. Such a divider bridge 11 also makes it possible to protect from the propagation of high voltage on low voltage devices.

A second divider bridge 13 can be provided (see FIGS. 1b and 3) between the IGBT transistor Ql, respectively MOSFET QU, and the voltage measurement control module 9. More precisely, the second voltage divider bridge 13 can be provided between the gate of the IGBT transistor Ql, respectively MOSFET Ql ’, and the second transistor Q3 of the voltage measurement control module 9.

The second voltage divider bridge 13 includes a first resistor R4 and a second resistor R5 in series. The first resistor R4 can be electrically connected to the gate of the IGBT transistor Ql, respectively MOSFET Ql ’. The second resistor R5 can be electrically connected to ground.

The module 9 for controlling the voltage measurement may include an output electrically connected to the node between the two resistors R4, R5 in series of the second divider bridge 13.

The second divider bridge 13 makes it possible to limit the propagation of the high voltage, in particular on the module 9 for controlling the voltage measurement in the event of failure of the IGBT transistor Ql, respectively MOSFET Ql ’. In addition, the second divider bridge makes it possible to adapt the control voltage of the gate of the IGBT transistor Ql, respectively MOSFET Ql ’, for controlling the module 9 for controlling the voltage measurement.

Finally, the control circuit 1 advantageously comprises a control module 15 configured to switch the IGBT transistor Ql, respectively MOSFET Ql ’, between the on state and the off state.

Advantageously, the control module 15 is also configured to drive the second transistor Q3 of the module 9 for controlling the voltage measurement, which in turn drives the first transistor Q2 of said module 9. In particular, the control module 15 can drive at the same time the IGBT transistor Ql, respectively

-20MOSFET Ql ’, and the second transistor Q3 of said module 9.

The control module 15 is for example configured to receive a switching control signal from the IGBT transistor Ql, respectively MOSFET Ql ’, emitted by the processing means or means 7.

A method as described above, for example implemented by the control circuit 1, makes it possible to estimate and monitor the junction temperature of high voltage transistors or power transistors, for example IGBT and MOSFET, based on their parameters. heat-sensitive electrics which vary as a function of the junction temperature Tj. In this case, we use the current Id or passing through the IGBT transistor Ql or MOSFET Ql 'and the collector-emitter voltage VcE_sat for an IGBT transistor Ql or the drain-source voltage Vds for the MOSFET transistor Ql', to determine the junction temperature Tj.

In the case of the IGBT transistor Ql, a linear approximation can be made from stored collector-emitter voltage reference values for at least two predefined junction temperatures, and deduct the junction temperature for the collector-emitter voltage value VcE_sat measured.

In the case of the MOSFET transistor Ql ′, it is possible to calculate the resistance in the passing state Rdsoii and to deduce the junction temperature Tj from a correspondence table between the resistance in the passing state Rdsoii and the junction temperature Tj stored.

In either case, it is no longer necessary, as in the solutions of the prior art, to provide a temperature sensor to be arranged near the transistor. When the deduced junction temperature exceeds a predefined threshold, the IGBT transistor Ql or MOSFET Ql 'can be switched to the off state in order to protect the electrical equipment.

Claims (10)

1. Method for controlling the temperature of a high voltage transistor (Q1; Ql ’), characterized in that said method comprises the following steps: - the voltage (VcE_sat; Vds) at the terminals of the transistor (Ql; Ql ’) is measured when it is on, - the current (le; Id) flowing through the transistor (Ql; Ql ’) is noted, and - from the measured voltage (VcE_sat; Vds) and the current (le; Id) noted, the junction temperature (Tj) of the transistor (Ql; Ql ’) is estimated. 2. Method according to claim 1 for controlling the temperature of an insulated gate bipolar transistor (Ql), in which: - we measure the voltage from the collector to the emitter (VcE_sat) when the transistor (Ql) is saturated, - the current from the collector to the transmitter (the) is noted, - we model a linear approximation of the evolution of the emitter collector voltage (VcE_sat) as a function of the junction temperature (Tj) for the current (le) measured, from at least two voltage reference values between the collector and the emitter (Vce_25, Vce_17s) of the transistor (Ql) at two predefined junction temperatures, and - from the modeled approximation, the junction temperature (Tj) of the transistor (Ql) is estimated for the emitter collector voltage (VcE_sat) measured. 3. Method according to claim 1 for controlling the temperature of an insulated gate field effect transistor (Ql ’), in which: - the voltage between the drain and the source (Vds) is measured when the transistor (Ql ’) is on, - the drain current (Id) is noted, - from the voltage between the source drain (Vds) measured and the drain current (Id) noted, the resistance (Rdsou) of the transistor (Ql ') is determined when it is on, and - from the resistance (Rdsoii) determined, the junction temperature is estimated -22 (Tj) using at least one memorized correspondence table. 4. Method according to any one of the preceding claims, comprising the following steps: - the estimated junction temperature (Tj) of the transistor (Q1; Q1 ’) is compared to a predefined temperature threshold (Tl), and - if the estimated junction temperature (Tj) of the transistor (Q1; Ql ’) exceeds a predefined temperature threshold, the transistor (Ql; Ql’) is switched from the state going to the off state. 5. Method according to any one of the preceding claims, in which the voltage (Vshunt) is measured across a measurement resistor arranged in series with the transistor (Ql; Ql ') so as to determine the current passing through said resistor and traversing the transistor (Ql; Ql '). 6. A circuit for controlling the temperature of a high voltage transistor (Ql; Ql ’), characterized in that it is configured to carry out said method according to any one of the preceding claims and comprises: - a high voltage transistor (Ql; Ql ’), - a voltage measurement device (3) mounted at the terminals of the transistor (Ql; Ql ’) and configured to measure the voltage (VcE_sat; Vds) of the transistor (Ql; Ql’) when it is on, - a current acquisition device (5) electrically connected to an electrode of the transistor (Ql, Ql ’) and configured to take a current (le; Id) flowing through the transistor (Ql; Ql’), and - at least one processing means (7) configured to receive as input at least one voltage information coming from the voltage measurement device (3) and at least one current information coming from the current acquisition device (5 ), and configured to estimate the junction temperature (Tj) of the transistor (Ql; Ql '), from the voltage (VcE_sat; Vds) of the transistor (Ql; Ql') when it is on and the current (the , Id) crossing it. 7. The circuit of claim 6, further comprising a module for controlling the -23 voltage measurement electrically connected to the transistor (Ql, Ql ’) and to the voltage measurement device (3). 8. Circuit according to one of claims 6 or 7, in which the acquisition device (A2) is configured to measure the voltage (Vshunt) across a resistor. 5 measure (S) arranged in series with the transistor (Ql; Ql ’). 9. Circuit according to any one of claims 6 to 8, in which said at least one processing means (7) configured to estimate the junction temperature (Tj) of the transistor (Ql; Ql ') is configured to emit a signal for switching the transistor (Ql; Ql ') as a function of the junction temperature (Tj) 10 estimated transistor (Ql; Ql ’). 10. Circuit according to any one of claims 6 to 9, comprising a control module (15) configured to switch the transistor (Ql; Ql ’) between the on state and the off state.