EP3797471A1

EP3797471A1 - Half-bridge electronic device comprising two systems for optimising dead-time between the switching operations of a high level switch and of a low level switch

Info

Publication number: EP3797471A1
Application number: EP19732078.1A
Authority: EP
Inventors: Laurent Guillot; Thierry SUTTO; Gérald AUGUSTONI
Original assignee: Exagan SAS
Current assignee: STMicroelectronics France SAS
Priority date: 2018-05-22
Filing date: 2019-05-14
Publication date: 2021-03-31
Also published as: FR3081633B1; CN112154594A; US20210159774A1; CN112154594B; FR3081633A1; US11695326B2; WO2019224451A1

Abstract

The invention relates to a half-bridge electronic device (100) comprising, in series, a low level switch (1) and a high level switch (2) connected at a central point (3), and respectively controlled by a first (SLS) and a second (SHS) activation/deactivation signal. The device (100) comprises: • a first (10) and a second (20) synchronisation system configured to interpret a variation in the voltage (Vm) at the central point (3), respectively following a falling edge and following a rising edge, and to respectively generate a first (ATON-LS) and a second (ATON-HS) synchronisation signal separate from the first; • a first (18) and a second (28) AND type logic gate respectively combining the first synchronisation signal (ATON-LS) with a first control signal (PWM-LS) and the second synchronisation signal (ATON-HS) with a second control signal (PWM-HS), in order to respectively form the first (SLS) and second (SHS) activation/deactivation signals.

Description

SEMI-BRIDGE ELECTRONIC DEVICE COMPRISING TWO SYSTEMS FOR OPTIMIZING DEAD TIMES BETWEEN THE SWITCHES OF A HIGH LEVEL SWITCH AND A LOW LEVEL SWITCH

FIELD OF THE INVENTION

The present invention relates to the field of power electronics. It relates in particular to a half-bridge electronic device comprising two synchronization systems making it possible to optimally optimize dead times between the alternating activation of a high level switch and a low level switch, the device being notably used in a DC-DC converter.

BACKGROUND OF THE INVENTION

Electronic devices called "half-bridge" ("half-bridge" according to the English terminology), composed of a high-side switch and a low-level switch ("low-side"). ") Are commonly used in DC-DC converters to convert a DC voltage to another DC voltage of lower value.

In these half bridge devices, the two switches, formed by transistors, are connected in series at a midpoint to which a load is connected. As already known in the field of DC-DC converters, the load is selectively coupled to either the DC voltage source, by activation (put in passing mode) of the "high-side" switch, or to the ground, by activation the "low-side" switch. A DC-DC converter may suffer significant electrical losses due to idle time between deactivation (switching off) of the high-side switch and activation of the "low-side" switch, and between deactivation of the "low-side" switch and activation of the "high-side" switch.

To maximize the efficiency of the converter, it is therefore desirable to minimize these dead time switching, while avoiding simultaneous conduction switches "high-side" and "low-side" which would cause a short circuit between the voltage source and the mass.

In the prior art there are control systems implemented in half-bridge electronic devices to optimize switching dead times. Document US6396250 and US6861826, which provide control systems for the synchronization of the activation and deactivation of the "high-side" and "low-side" switches in a converter, using the measurement of the voltage at the point in point, are particularly known. middle .

With the implementation of fast switching switches (in particular, formed from GaN transistors) in half-bridge electronic devices, an additional constraint appears: the typical switching times of said switches from a hundred nanoseconds to ten nanoseconds, the measurement time, analysis and response of the control system must be of the same order of magnitude, to effectively optimize the dead time between switching switches. OBJECT OF THE INVENTION

An object of the present invention is to propose an alternative solution to the solutions of the state of the art. An object of the invention is in particular to provide a half-bridge electronic device comprising two synchronization systems for efficiently and effectively minimizing the dead time between the successive commutations of the switches.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a half-bridge electronic device, comprising in series a high level switch and a low level switch, connected at a midpoint, the low level switch and the high level switch being respectively controlled by a first and a second activation / deactivation signal.

The device comprises:

A first synchronization system configured to interpret a variation, along a falling edge, of the voltage at the mid-point, and to generate a first synchronization signal;

A second synchronization system configured to interpret a variation, according to a rising edge, of the voltage at the mid-point, and to generate a second synchronization signal, distinct from the first synchronization signal;

A first AND-type logic gate combining the first synchronization signal with a first control signal, to form, at the output of said first logic gate, the first activation / deactivation signal; A second AND-type logic gate combining the second synchronization signal with a second control signal, to form, at the output of said second logic gate, the second activation / deactivation signal.

According to other advantageous and nonlimiting features of the invention, taken alone or in any technically feasible combination: each synchronization system comprises a detection circuit and a processing circuit;

each detection circuit comprises a capacitive element for generating a transient current depending on the variations of the mid-point voltage;

each detection circuit comprises, in series with the capacitive element, a diode and a shunt resistor, for measuring a voltage proportional to the transient current;

each processing circuit is configured to generate, from measurements of the detection circuit, the synchronization signal;

each processing circuit comprises a voltage comparator and a memory point;

each processing circuit comprises an OR logic gate, between the voltage comparator and the memory point, combining an output signal of the comparator and a control signal delayed by a defined delay;

the second detection circuit is configured to interpret a variation, along a falling edge, of the voltage resulting from the difference between the input voltage of the high-level switch and the mid-point voltage; The first synchronization system and the second synchronization system are formed of identical detection and processing circuits;

At least one of the switches comprises a high voltage transistor;

The high voltage transistor is formed based on GaN;

At least one of the switches comprises a high voltage transistor in depletion mode in series with a low voltage transistor in enrichment mode.

1 / invention also relates to a method for synchronizing the alternating activation of a low level switch and a high level switch in a half-bridge electronic device. It includes the following steps:

a) deactivation of the low level switch when a first control signal goes to 0, b) interpretation of a variation along a rising edge of the voltage at the midpoint, to generate a second signal of synchronization,

c) the activation of the high level switch, by a second activation / deactivation signal resulting directly from the combination of the second synchronization signal with a second control signal in an AND type logic gate,

d) disabling the high level switch when the second control signal changes to state 0,

e) interpreting a variation along a falling edge of the mid-point voltage to generate a first synchronization signal, distinct from the second synchronization signal,

f) the activation of the low level switch, by a first activation / deactivation signal resulting directly from the combination of the first signal of synchronization with the first control signal in an AND type logic gate.

According to other advantageous and nonlimiting features of the invention, taken alone or in any technically feasible combination: steps a) to f) are repeated for each new cycle of alternating switching of the low level switch and the switch high level ;

step b) is performed by interpreting a variation, along a falling edge, of the voltage resulting from the difference between the input voltage of the high-level switch and the voltage at the mid-point; the method comprises a step b ') operated in case of failure in step b) in the interpretation of a variation along a rising edge of the voltage at the mid-point, making it possible to generate the second synchronization signal at the end of a definite time;

the method comprises a step e ') operated in case of failure in step e) in the interpretation of a variation along a falling edge of the voltage at the midpoint, for generating the first synchronization signal at the end of a defined time.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge from the detailed description which follows with reference to the appended figures in which: FIGS. 1a and 1b respectively show a block diagram and a chronogram of a half-bridge electronic device according to the state of the art; Figures 2a and 2b show schematic diagrams of a half-bridge electronic device according to a first and a second embodiment of the invention;

FIG. 3 presents a timing diagram of the control signals, the synchronization signals and the activation / deactivation signals of the switches of the half-bridge electronic device according to the invention;

FIGS. 4a and 4b show synchronization systems for a half-bridge electronic device according to a first embodiment of the invention; FIGS. 5a and 5b show synchronization systems for a half-bridge electronic device according to a second embodiment of the invention;

FIG. 6 shows a synchronization system for a half-bridge electronic device according to a variant of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the descriptive part, the same references in the figures can be used for elements of the same nature.

The invention relates to an electronic half - bridge device 100, comprising in series a high level switch 2 and a low level switch 1. Conventionally, in such a device, the two switches 1,2 are connected together at a midpoint 3 (Figure la). The high level switch 2 is also connected to a voltage source V, which can be a high voltage source (from a few volts to a few hundred volts); the low level switch 1 is also connected to ground. A load 200, as for example shown in Figure la, is intended to be connected to the midpoint 3.

According to a standard operating mode, a PWM ("pulse width modulation") input signal is sent to the low level 1 and high 2 level switches, through the intermediate respectively a first control circuit 19 and a second control circuit 29. The PWM input signal is reflected by pulses to activate and deactivate the high level switch 2 and alternately, disable and enable the low level switch 1.

By activating, we mean the action of closing the switch to make it passing; by deactivating, we mean the action of opening the switch to make it blocking.

To avoid any short circuit related to an activation of the two switches 1,2 simultaneously, it is necessary to provide dead times T _M between the deactivation of a switch and the activation of the other (Figure lb).

A delay generating device 40 (FIG. 1a), receiving the PWM input signal, usually generates a PWM-LS control signal (called the first control signal), of the same polarity as the PWM input signal, and whose the pulses (active state 1) are shifted by a time T _M with respect to the input signal PWM. The delay generation device 40 also generates a control signal PWM-HS (called a second control signal), of inverted polarity with respect to the PWM input signal, and whose pulses (activated state 1) are also shifted by a time T _M with respect to the PWM input signal. The first control circuit 19 receives as input the first control signal PWM-LS, which will control the activation / deactivation of the low level switch 1. The second control circuit 29 receives as input the second control signal PWM. HS (of reversed polarity with respect to the first control signal PWM-LS), which will control the activation / deactivation of the high level switch 2.

Of course, as previously stated, it is important to minimize the induced dead times T _M (FIG. 1a) to avoid significant electrical losses in a converter that would include the device.

The device 100 according to the invention comprises a first 10 and a second 20 synchronization system respectively intended to send an ATON-LS synchronization signal ("Automatic Turn ON - Low Side") to enable activation of the level switch. bottom 1, and an ATON-HS synchronization signal ("Automatic Turn ON - High Side") to enable the activation of the high level switch 2 (FIGS. 2a, 2b).

The first synchronization system 10 is configured to interpret a variation, along a falling edge, of the voltage Vm at the midpoint 3, and to generate the first synchronization signal ATON-LS; the second synchronization system 20 is configured to interpret a variation, according to a rising edge, of the voltage Vm at the midpoint 3, and to generate the second synchronization signal ATON-HS, distinct from the first synchronization signal ATON-LS.

A first AND type logic gate 18 combines the first ATON-LS synchronization signal with a first PWM-LS control signal, to form, directly at the output of said first logic gate 18, a first SLS on / off signal, which, sent in entry of the first control circuit 19, will control the activation / deactivation of the low level switch 1.

A second AND logic gate 28 combines the second synchronization signal ATON-HS with the second control signal PWM-HS, to form, directly at the output of said second logic gate 28, the second activation / deactivation signal S _HS. , which, sent to the input of the second control circuit 29, will control the activation / deactivation of the high level switch 2.

The fixed dead time TM implemented on the first PWM-LS and the second PWM-HS control signal can be minimized to the maximum, or even zero; in fact, the first and second synchronization signals ATON-LS, ATON-HS make it possible to activate respectively the low level switch 1 and the high level switch 2 at the earliest after the deactivation of the high level switch 2 respectively. and the low level switch 1, by observing the voltage variation at the midpoint 3.

The AND logic gates 18,28 require that the synchronization signal ATON-LS, ATON-HS and the control signal PWM-LS, PWM-HS of each switch 1,2 are in the activated state 1, to generate the activation signal S _LS , S _HS , which avoids simultaneous conduction of the two switches 1,2. The combination of the synchronization signal (ATON-LS or ATON-HS) with the control signal (PWM-LS or PWM-HS) in the logic gate (18 or 28) of the ET type also makes it possible to secure any unwanted switchover. which would be related to a failure of the associated synchronization system 10,20. To compensate for a failure of the first and second synchronization systems 10, 20 (non-generation respectively of the first synchronization signal ATON-LS and the second synchronization signal ATON-HS), the first activation / deactivation signal S _LS and the second activation / deactivation signal S _HS for activating respectively the low level switch 1 and the high level switch 2 are formed after a defined time _T t o. For example, t _T o will be defined in a range of 20ns to 50ns.

The presence of two synchronization systems 10, 20 dedicated respectively to the low level switch 1 and the high level switch 2, which generate two separate independent ATON-LS, ATON-HS synchronization signals, allows optimized control. and independent for each of the switches and not an identical dead time prediction for either of the switches or depending on the one and the other of the switches.

The two synchronization systems 10, 20 thus make it possible to efficiently and securely optimize the dead times between the alternating activation of a high level switch 2 and a low level switch 1.

Each synchronization system 10, 20 comprises a detection circuit 11, 21 for interpreting the variation over time (dVm / dt) of the voltage Vm at the midpoint 3. As illustrated in the timing diagram of FIG. 3, the voltage Vm at middle point 3 will vary over time, depending on whether the high level switch 2 or the low level switch 1 will respectively be activated (closed) or deactivated (open). In practice, the voltage Vm at the midpoint 3 will decrease as soon as the high level switch 2 will open (deactivation); it will increase as soon as the low level switch 1 will open (deactivation).

The first detection circuit 11, included in the first synchronization system 10, aims to detect the falling edges of the voltage Vm at the midpoint 3. The second detection circuit 21, included in the second synchronization system 20 is meanwhile detecting the rising edges of the voltage Vm at the midpoint 3. According to a first embodiment (FIG. 2a), each detection circuit 11, 21 comprises a capacitive element 12, 22 directly connected to the midpoint 3 (FIGS. 4a, 4b). This capacitive element 12,22 will generate a transient current i depending on the temporal variation of the voltage Vm at the middle point 3. The capacitive element 12,22 must be compatible with the maximum level that can reach the voltage Vm at the midpoint 3 at least the voltage V of the voltage source connected to the input of the high level switch 2. The use of a capacitive element 12, 22 makes it possible to overcome the detection circuit 11, 21, an active measuring component capable of holding the voltage V of the voltage source. By way of example, the capacitive element 12, 22 may consist of a capacitance sized according to the voltage V of the voltage source (from a few tens of volts to a few hundred volts). According to another advantageous example, the capacitive element 12,22 may consist of two coplanar metal lines arranged on a printed circuit incorporating the device 100, also dimensioned according to the voltage V of the voltage source.

According to a first approach (not shown), the transient current i can be measured directly by an ammeter, connected in series with the capacitive element 12,22.

According to a second, more advantageous approach, each detection circuit 11,21 comprises, in series with the capacitive element 12,22, a shunt resistor 13,23 (FIGS. 4a, 4b). It makes it possible to measure at its terminals, a voltage Ui, U2 proportional to the transient current i. Each detection circuit 11,21 can thus produce a measurement of the voltage Ui, U ₂ , which is representative of the variations of the voltage Vm at the midpoint 3. Advantageously, each detection circuit 11,21 also includes a diode 14, 24 in series with the shunt resistor 13, 23, the latter being connected to ground or a reference voltage V _refi, V _ref 2.

The diode 14, 24 allows the passage of the transient current i in the shunt resistor 13,23 only for a defined polarity. Depending on whether the voltage Vm at the mid-point 3 varies according to a falling or rising edge, the transient current i generated at the output of the capacitive element 12, 22 will be positive or negative. Thus, the diode 14 is configured to allow only the passage of the transient current ii connected to a falling edge of the voltage Vm at the midpoint 3, while the diode 24 is configured to allow only the passage of the transient current i ₂ (sign opposite to ii) connected to a rising edge of the voltage Vm at the midpoint 3.

According to a second embodiment (FIG. 2b), the first synchronization system 10 and the second synchronization system 20 are both formed of identical detection circuits 11, 21.

For it :

The first detection circuit 11 is configured to detect the falling edges of the voltage Vm at the midpoint 3, as in the first embodiment;

And the second detection circuit 21 is configured to interpret a variation, along a falling edge, of the voltage (V - Vm) resulting from the difference between the input voltage V of the high level switch 2 and the voltage Vm at the middle point 3.

The first detection circuit 11 comprises a capacitive element 12,22 connected to the midpoint 3, and the reference voltage V _refi is the ground, as illustrated in FIG. 5a. The second detection circuit 21 comprises a capacitive element connected to the input voltage V, and the reference voltage V _ref 2 is the voltage Vm at the midpoint 3, as shown in Figure 5b.

The first detection circuit 11 and the second detection circuit 21 are both intended to interpret a variation along a falling edge, respectively of the voltage Vm at the midpoint 3 and the voltage (V-Vm) above. The components previously described in the first embodiment (the diode 14,24 and the shunt resistor 13,23) forming the first and the second detection circuit 11,21 can thus be the same for the two synchronization systems 10,20. , which simplifies the industrial implementation of the invention.

In the remainder of the description, we will place ourselves in the first embodiment of the detection circuits 11, 21 for the sake of simplification; of course, the second embodiment described above is also applicable.

The first detection circuit 11 is thus configured to interpret a falling edge of the voltage Vm at the midpoint 3: it makes it possible to make a direct or indirect measurement of the transient current ii due to a decreasing time variation (falling edge) of the voltage Vm at the middle point 3.

From this measurement, the first synchronization system 10 must generate a first ATON-LS synchronization signal to enable the activation of the low level switch 1.

For this purpose, the first synchronization system 10 advantageously comprises a first processing circuit 15 (FIGS. 2a, 2b). This processing circuit 15 comprises a voltage comparator 16, which will compare the value of the measured voltage Ui (proportional to the transient current ii) with a set voltage V _ci (FIGS. 4a, 5a). As soon as the measured voltage Ui is greater than the reference voltage V _ci , the comparator 16 will send a pulse to a memory point 17. Said pulse passes the first synchronization signal ATON-LS, at the output of the memory point 17, in an activated state 1 (Figure 3). For example, the memory point 17 can be realized by an asynchronous latch (latch or "latch" according to the English terminology). The memory point 17 (ATON-LS) is reset as soon as the PWM-LS control signal goes to state 0 (FIG. 3).

The first ATON-LS synchronization signal, generated by the first synchronization system 10, and the first PWM-LS control signal are then combined in an AND type logic gate 18, to form, directly at the output of said logic gate 18 , the first SLS on / off signal (FIG. 3). The first SLS on / off signal is transmitted to the first control circuit 19 and will activate / deactivate the low level switch 1.

In the first synchronization system 10, the difference between the reference voltage and the reference voltage (V _ci -V _refi ) makes it possible to adjust the switching level (Ui> V _ci ) of the voltage comparator 16, to create the ATON-LS signal. The adjustment of this level makes it possible to compensate for the propagation time of the system: it is possible, for example, to define this voltage difference so that the signal ATON-LS is activated in state 1 substantially before Vm reaches its minimum value.

The second detection circuit 21, for its part, is configured to interpret a rising edge of the voltage Vm at the middle point 3. It makes it possible to make a direct or indirect measurement of the transient current i ₂ due to an increasing temporal variation in the voltage Vm at middle point 3. From this measurement, the second synchronization system 20 must generate an ATON-HS synchronization signal to enable the activation of the high level switch 2.

For this purpose, the second synchronization system 20 advantageously comprises a second processing circuit 25 (FIGS. 2a, 2b). This processing circuit 25 comprises a voltage comparator 26, which compares the value of the measured voltage U2 (proportional to the transient current 12) with a set voltage V _C 2 (FIGS. 4b, 5b). As soon as the measured voltage U2 is greater than the reference voltage V _C 2, the comparator 26 will send a pulse to a memory point 27. Said pulse passes the second synchronization signal ATON-HS, at the output of the memory point 27, in an activated state 1. As an example, the memory point 27 can be realized by an asynchronous flip-flop. The memory point 27 (ATON-HS) is reset as soon as the PWM-HS control signal goes to state 0 (FIG. 3).

The second synchronization signal ATON-HS, generated by the second synchronization system 20, and the second control signal PWM-HS are then combined in an AND type logic gate 28, to form, directly at the output of said logic gate 28. a second SHS on / off signal (FIG. 3). The second activation / deactivation signal SHS is transmitted to the second control circuit 29 and will activate / deactivate the high level switch 2.

In the second synchronization system 20, the difference between the reference voltage and the reference voltage (V _C2 -V _ref2 ) makes it possible to adjust the switching level (U ₂ > V _{c 2)} of the voltage comparator 26, to create ATON-HS signal. Adjusting this level makes it possible to compensate for the propagation time of the system: for example, it will be possible to define this voltage difference for the ATON-HS signal to be activated at state 1 substantially before Vm reaches its maximum value.

As illustrated in the timing diagram of FIG. 3, the first and second activation / deactivation signals S _LS , S _HS make it possible to optimize the dead times t _m , by activating the low level switch 1 and the low-level switch respectively as soon as possible. switch high 2, after the other switch has been disabled. Indeed, starting from a fixed minimum delay T _M defined (for example 0 to 20ns) between the control signals PWM-LS and PWM-HS, the synchronization signals ATON-LS and ATON-HS combined with said PWM control signals -LS, PWM-HS in an AND gate 18,28, are able to switch to state 1, respectively the first S _LS and the second S _HS activation / deactivation signal controlling the switches low level 1 and high level 2: which makes it possible to secure the alternative switching of the switches 1, 2 while having effective dead times t _m optimized (for example between 4 to 30ns).

The optimization of the dead times t _m makes it possible to minimize the losses and thus to maximize the efficiency (or the energy efficiency) of the converter provided with the device 100.

The synchronization signals ATON-LS and ATON-HS are generated for each switching cycle of the low level 1 and high 2 level switches; the device 100 according to the invention thus allows automatic activation (setting to state 1) of a switch 1.2 at each switching cycle, and at the earliest after the deactivation of the other switch 2.1, by the interpretation of the variation of the voltage Vm at the midpoint 3.

The fact that each synchronization system 10, 20 is dedicated to activating a switch 1, 2 also makes it possible to efficient interpretation of the voltage variation Vm and a direct and rapid transmission of the instruction to the associated switch.

DC-DC converters with switches

I, 2 fast allow switching from 5 to 20 ns Vm signal: synchronization system 10,20 must, in this case, have a response time less than these values to minimize the dead time.

To overcome a failure of detection circuits

II, 21 or comparators 16, 26 of the processing circuits 15, 25, a failure which would not result in the non-generation of the first synchronization signal ATON-LS and the second synchronization signal ATON-HS respectively, each processing circuit 15 , 25 may comprise an OR type logic gate 30 combining the output signal of the comparator 16, 26 and a control signal PWM-LS (t _T o) or PWM-HS (t _T o) (respectively for the level switch bottom 1 and the high level switch 2) delayed by a defined delay t _T o (FIG. 6). In other words, the delayed control signal PWM-LS (t _T o) or PWM-HS (t _T o) goes to a state 1 with a delay of t _T o relative to the control signal PWM-LS or PWM-HS.

Thus, the first ATON-LS and second ATON-HS synchronization signals are always generated at the output of the processing circuits 15, 25, to form the first SLS on / off signal and the second SHS on / off signal for the first time. activation respectively of the low level switch 1 and the high level switch 2. A failure of the detection circuits 11,21 or the comparators 16,26 of the processing circuits 15,25 can not interrupt the operation of the electronic device in half-bridge 100. Finally, for questions of flexibility, the half-bridge electronic device 100 may comprise a system for neutralizing the automatic detection function of rising and / or falling edges of the voltage Vm at the midpoint 3 of the synchronization systems 10,20. . For example, the OR logic gate 30 illustrated in FIG. 6 may comprise a third input (not shown) fed by a digital signal set to the state 1 for the neutralization: the activation / deactivation signals SHS, SLS in output of the AND-type logic gates (28, 29) then depend only on the PWM-HS, PWM-LS control signals.

The operation of the half-bridge electronic device 100 according to the invention will now be described with reference to the timing diagram of FIG.

Take the example of a digital pulse PWM input signal corresponding to an alternation of states 1 and 0. Via a delay generation device 40, a first PWM-LS control signal, of which the pulses are shifted by a fixed time T _M , and a second PWM-HS control signal, whose pulses are inverted and offset with respect to the PWM input signal of a time T _M , are generated. The dead time T _M is defined according to the invention to a minimum, or even a zero value.

As illustrated in FIG. 3, the starting point of the timing diagram corresponds to state 1 for the PWM input signal, which generates a first PWM-LS control signal at state 1 controlling the closing (activation) of the signal. low level switch 1. The voltage Vm at the midpoint 3 has a minimum value, typically 0.

When the PWM input signal goes to the 0 state, the PWM-LS control signal also goes to the 0 state and the first control circuit 19 controls the deactivation (opening) of the low level switch 1. The voltage Vm at the midpoint 3 increases to a maximum value, typically the voltage V.

The second synchronization system 20 interprets this rising edge of the voltage Vm at the midpoint 3 through its detection circuit 21. At the moment when the voltage Vm reaches its maximum value, or substantially before, according to the parameterized value of the voltage difference (V _C 2 ^_ V _re f2), the second synchronization system 20, via the processing circuit 25, generates the second timing signal ATON-HS, which combines with the PWM control signal -HS in the AND type logic gate 28, to form, at the output of the logic gate 28, the second activation / deactivation signal SHS: the second synchronization signal ATON-HS makes it possible to switch to activation mode (state 1) the SHS signal for controlling the closing (activation) of the high level switch 2, in an optimized time t _m .

As soon as the input signal goes to state 1, the control signal PWM-HS goes to state 0 and the second control circuit 29 controls the deactivation (opening) of the high level switch 2. The passage in state 0 of the control signal PWM-HS resets the memory point 27 of the processing circuit 25 of the second synchronization system 20. The voltage Vm at the midpoint 3 decreases to a minimum value, typically 0.

The first synchronization system 10 interprets this falling edge of the voltage Vm at the midpoint 3 through its detection circuit 11. At the moment when the voltage Vm reaches its minimum value (or substantially before, according to the parameterized value of the voltage difference (V _c i- Vrefi)), the first synchronization system 10, via the processing circuit 15, generates the first synchronization signal ATON-LS, which combines with the PWM-LS control signal in the AND type logic gate 18, to form, at the output of said logic gate 18, the SLS activation / deactivation signal: the first ATON-LS synchronization signal will enable the SLS signal to be switched into activation mode (state 1) to control the closing (activation) of the low level switch 1, within an optimized delay t _m .

Note that, even if the optimized delay of activation of the low level switch 1 and the high level switch 2 are both named t _m , their value may be different during the switching cycles.

When the PWM input signal returns to the 0 state, the control signal PWM-LS also goes to state 0, resetting the memory point 17 of the processing circuit 15 of the first synchronization system 10 (reset) , and the first control circuit 19 controls the deactivation (opening) of the low level switch 1, and so on. For each new alternating switching cycle of the switches 1,2, the synchronization systems 10, 20 will alternatively generate the synchronization signals ATON-LS and ATON-HS to activate a switch 1,2 in a secure manner at the earliest after the other switch 2.1 has been disabled.

According to a particular mode of implementation, at least one of the switches 1,2 of the half-bridge electronic device 100 comprises a high voltage transistor, making it possible to switch voltages from several tens to a few hundred volts (for example 400V). .

The high voltage transistor may for example be formed based on III-N materials such as gallium nitride (GaN). The transistor may be a HEMT ("high electron" transistor mobility "). Alternatively, the high voltage transistor may be formed based on silicon.

According to another particular mode of implementation, at least one of the switches 1.2 of the device half-bridge comprises a high-voltage transistor in depletion mode in series with a low-voltage transistor in enrichment mode. The high voltage transistor and the low voltage transistor may form a cascode circuit, the gate of the high voltage transistor being in this case connected to the source of the low voltage transistor. They may alternatively form a cascade circuit, the gate of the high voltage transistor being in this case controlled by a control circuit 19,29.

The invention also relates to a method for synchronizing the alternating activation of a low level switch 1 and a high level switch 2 in a half bridge electronic device 100. The low level switch 1 and the level switch 2 are respectively controlled by a first activation / deactivation signal S _LS and a second activation / deactivation signal S _HS · The method comprises the following steps:

a) disabling the low level switch 1 when a first PWM-LS control signal goes to the 0 state; said first PWM-LS control signal goes to the 0 state as soon as the PWM input signal goes to the 0 state;

b) interpreting a variation along a rising edge of the voltage Vm at the midpoint 3 to generate a second synchronization signal ATON-HS;

c) the activation (on mode) of the high level switch 2, by the second activation / deactivation signal S _HS resulting directly from the combination, in an AND type logic gate 28, of the second synchronization signal ATON- HS and a second PWM-HS control signal; d) disabling the high level switch 2 when the second PWM-HS control signal changes to the 0 state; said second PWM-HS control signal goes to state 0 as soon as the PWM input signal goes to state 1;

e) interpreting a variation along a falling edge of the voltage Vm at the midpoint 3 to generate a first ATON-LS synchronization signal, distinct from the second ATON-HS timing signal;

f) activation of the low level switch 1, by the first SLS on / off signal resulting directly from the combination, in an AND type logic gate 18, of the first ATON-LS synchronization signal and the first signal PWM-LS.

Steps a) to f) are repeated for each new cycle of alternating switching of the low level switch 1 and the high level switch 2.

Advantageously, the method comprises in step d), a reset (reset) of the second synchronization signal ATON-HS; the reset takes place when the second control signal PWM-HS goes to state 0.

Advantageously, the method also comprises, in step a), a reset of the first synchronization signal ATON-LS; reset occurs when the first control signal PWM-LS changes to state 0.

The interpretation of the variation according to a rising edge of the voltage Vm at the midpoint 3 (step b) comprises the detection of a determined high level of said voltage Vm. The determined level may be the maximum value of the voltage Vm or alternatively a value substantially less than the maximum value. The choice of the determined high level makes it possible to generate, more or less soon after deactivation of the low level switch 1, the second synchronization signal ATON-HS to activate the high level switch 2.

The interpretation of the falling edge variation of the voltage Vm at the midpoint 3 (step e)) includes detecting a determined low level of said voltage Vm. The low level determined may be the minimum value of the voltage Vm or alternatively a value substantially greater than the minimum value. The choice of the determined low level makes it possible to generate, more or less soon after the deactivation of the high level switch 2, the first synchronization signal ATON-LS to activate the low level switch 1.

Preferably, step b) is effected by interpreting a variation, along a falling edge, of the voltage (V-Vm) resulting from the difference between the input voltage V of the high-level switch 2 and the voltage Vm at the midpoint 3. The first and the second synchronization system 10,20 can thus be formed by the same detection circuits 11,21 and treatment 15,25.

To compensate for a failure of the detection circuits 11, 21 or comparators 16, 26 of the synchronization systems 10, 20, the steps c) and f) of activating respectively the high level switch 2 and the low level switch. 1 may occur after a time t _t defined ("Time Out").

For this, the method comprises a step b '), operated in case of failure in step b), for generating the second synchronization signal ATON-HS after a defined delay t _T o; it also comprises a step e '), operated in case of failure in step e), for generating the first synchronization signal ATON-LS after a defined delay t _T o. The half-bridge electronic device 100 and the method according to the invention can find applications in the field of power converters DC-DC, AC-DC, etc.

Naturally, the invention is not limited to the embodiments described, and alternative embodiments can be made without departing from the scope of the invention as defined by the claims.

Claims

A half-bridge electronic device (100), comprising in series a high-level switch (2) and a low-level switch (1), connected at a mid-point (3), the low-level switch (1) and the high level switch (2) being respectively controlled by a first (SLS) and a second (SHS) activation / deactivation signal, the device (100) being characterized in that it comprises:

A first synchronization system (10) configured to interpret a variation, along a falling edge, of the voltage (Vm) at the midpoint (3), and to generate a first synchronization signal (ATON-LS);

A second synchronization system (20) configured to interpret a variation, along a rising edge, of the voltage (Vm) at the midpoint (3), and to generate a second synchronization signal (ATON-HS), distinct from the first synchronization signal (ATON-LS);

A first AND-type logic gate (18) combining the first synchronization signal (ATON-LS) with a first control signal (PWM-LS), to form, at the output of said first logic gate (18), the first activation / deactivation signal (SLS);

A second AND-type logic gate (28) combining the second synchronization signal (ATON-HS) with a second control signal (PWM-HS), to form, at the output of said second logic gate (28), the second activation / deactivation signal (SHS) ·

2. Electronic half-bridge device (100) according to the preceding claim, wherein each synchronization system (10,20) comprises a detection circuit (11,21) and a processing circuit (15,25).

3. A half-bridge electronic device (100) according to the preceding claim, wherein each detection circuit comprises a capacitive element (12,22) for generating a transient current (1,11,12) depending on the voltage variations. (Vm) at the midpoint (3).

4. A half-bridge electronic device (100) according to the preceding claim, wherein each detection circuit (11,21) comprises, in series with the capacitive element (12,22), a diode (14,24) and a shunt resistor (13,23), for measuring a voltage (U, Ui, U ₂ ) proportional to the transient current (1,11,12).

The half-bridge electronic device (100) according to one of claims 2 to 4, wherein each processing circuit (15, 25) is configured to generate from measurements of the detection circuit (11, 21). , the synchronization signal (ATON-LS, ATON-HS).

6. A half-bridge electronic device (100) according to the preceding claim, wherein each processing circuit (15,25) comprises a voltage comparator (16,26) and a memory point (17,27).

Electronic half-bridge device (100) according to the preceding claim, in which each processing circuit (15, 25) comprises a logic gate (30) of the OR type, between the voltage comparator (16, 26) and the memory point (17,27), combining an output signal of the comparator (16,26) and a delayed control signal (PWM-HS (t _T o)) of a defined delay (tTO).

Electronic half-bridge device (100) according to one of claims 2 to 7, wherein the second detection circuit (21) is configured to interpret a variation, along a falling edge, of the voltage (V-Vm). ) resulting from the difference between the input voltage (V) of the high level switch (2) and the voltage (Vm) at the midpoint (3).

9. Electronic half-bridge device (100) according to the preceding claim, wherein the first synchronization system (10) and the second synchronization system (20) are formed of identical detection and processing circuits.

10. Electronic half bridge device (100) according to one of the preceding claims, wherein at least one of the switches (1,2) comprises a high voltage transistor.

11. Electronic half bridge device (100) according to the preceding claim, wherein the high voltage transistor is formed based on GaN.

12. A half-bridge electronic device (100) according to one of the two preceding claims, wherein at least one of the switches (1,2) comprises a high voltage transistor in depletion mode in series with a low-voltage transistor. Enrichment mode.

13. A method of synchronizing the alternating activation of a low level switch (1) and a high level switch (2) in a half-bridge electronic device (100), characterized in that it comprises the steps following: a) deactivation of the low level switch (1) when a first control signal (PWM-LS) changes to state 0,

b) the interpretation of a variation along a rising edge of the voltage (Vm) at the midpoint (3), to generate a second synchronization signal (ATON-HS), c) the activation of the high level switch (2), by a second enable / disable signal (SHS) resulting directly from the combination of the second synchronization signal (ATON-HS) with a second control signal (PWM-HS) in a logic gate (28). ET type,

d) disabling the high level switch (2) when the second control signal (PWM-HS) changes to state 0,

e) interpreting a variation along a falling edge of the voltage (Vm) at the midpoint (3) to generate a first synchronization signal (ATON-LS), distinct from the second synchronization signal (ATON-HS),

f) activating the low level switch (1) by a first enable / disable signal (SLS) resulting directly from the combination of the first synchronization signal (ATON-LS) with the first control signal (PWM); -LS) in a logic gate (18) of the AND type.

14. Synchronization method according to the preceding claim, wherein the steps a) to f) are repeated for each new cycle of alternate switching of the low level switch (1) and the high level switch (2).

15. synchronization method according to one of the two preceding claims, wherein step b) is performed by interpreting a variation, along a falling edge, the voltage (V - Vm) resulting from the difference between the voltage input (V) of the high level switch (2) and the voltage (Vm) at the midpoint (3).

16. A synchronization method according to one of the three preceding claims, comprising a step b '), operated in case of failure in step b) in the interpretation of a variation along a rising edge of the voltage (Vm). at the midpoint (3), for generating the second synchronization signal (ATON-HS) after a defined delay (t _T o).

17. Synchronization method according to one of the four preceding claims, comprising a step e '), operated in case of failure in step e) in the interpretation of a variation along a falling edge of the voltage (Vm) at the midpoint (3), for generating the first synchronization signal (ATON-LS) after a defined delay (t _T o).