Abstract:
The process according to the invention for controlling an electronic power component contains a process for piloting the opening and/or closure of this component. The piloting process comprises a plurality of steps for controlling the application of a succession of different commutation voltages on a control electrode of said component between the instant when the piloting process begins and the instant when the opening and/or closure of the electronic power component is to stop. The process comprises the step consisting in interrupting said piloting process and in immediately triggering off a process for safeguarding the integrity of the electronic power component if the component does not react in a predetermined imparted time.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a process and a system for controlling an electronic power component.  
           [0002]    More precisely, this invention relates to a control process comprising a process for piloting the opening and/or closure of the electronic power component, the piloting process comprising a plurality of steps for controlling the application of a succession of different commutation voltages on a control electrode of said component between the instant when the piloting process begins and the instant when the opening and/or closure of the electronic power component must stop, the passage from one step to the following step in this piloting process being effected automatically as soon as a corresponding condition of passage is satisfied.  
         BACKGROUND OF THE INVENTION  
         [0003]    Such control processes are known under the terms of  CATS control and disclosed for power transistors in “CATS Control: Assessment of the Robustness and Application to the Servo - Control of Closure ”, N. IDIR, H. SAWEZYN, J. J. FRANCHAUD, R. BAUSIERE, University of Lille 1, Laboratoire L2EP.  
           [0004]    These CATS control processes have been developed to control the derivative di/dt of the intensity of the current circulating between the collector and the emitter of the power transistor as well as the variations of the derivative dv/dt of the voltage at the terminals of the power transistor.  
           [0005]    This object is attained by applying a plurality of different successive voltages between the beginning and the end of the commutation process of the transistor. Among this succession of voltages, at least one, so-called braking voltage has an intermediate value different from those adapted to maintain the power transistor in the conducting and non-conducting states. The value of this braking voltage is chosen so as to brake commutation of the power transistor and consequently to limit and control the variations of the derivatives di/dt and dv/dt respectively upon closure and upon opening of the power transistor. The period during which this braking voltage is applied on the control electrode of the power transistor must be controlled with precision in order to limit the losses of commutation, i.e. the power consumed during each commutation. To that end, the end of the application of this braking voltage is automatically controlled when one or more conditions of passage are satisfied. For example, in the afore-cited document, the end of the application of the braking voltage is automatically controlled if the voltage at the terminals of a diode mounted in anti-parallel position with respect to the power transistor is less than a predetermined threshold and if the derivative of this same voltage is less than another threshold.  
           [0006]    However, in the event of dysfunction of the power transistor, the condition of passage for controlling the end of the application of the braking voltage can never be satisfied. Under these conditions, the control process remains blocked, this being translated by the maintaining of the braking voltage on the control electrode of the power transistor for an undetermined duration. At best, this situation leads to consuming energy unnecessarily and, at worst, to deteriorating the power transistor.  
           [0007]    It is an object of the present invention to overcome this drawback by proposing a control process of the CATS control type of an electronic power component, in which the unnecessary consumption of energy or the deterioration of the component is avoided.  
         SUMMARY OF THE INVENTION  
         [0008]    The invention therefore relates to a control process as described hereinabove, characterized in that it comprises the following steps of:  
           [0009]    reading the value of at least one operational parameter characteristic of the reaction of the electronic power component in response to the successive application of said commutation voltages,  
           [0010]    verifying, thanks to the values read, whether this reaction of the electronic power component is produced in a predetermined imparted time,  
           [0011]    if so, allowing said piloting process to continue normally, and  
           [0012]    if not, interrupting said piloting process and immediately triggering off a process for safeguarding the integrity of the electronic power component.  
           [0013]    In the above process, the reaction time of the electronic-power component, in response to the application of the successive commutation voltages, is supervised permanently. As soon as this reaction time exceeds a predetermined imparted time, which is the case for example in the event of dysfunction of the electronic power component, the process interrupts the opening and/or closure piloting process and automatically activates a process of safeguard. Consequently, in such a control process, it is impossible that the process piloting each opening and/or closure remains blocked. The unnecessary consumption of energy or the deterioration of the electronic power component is therefore avoided.  
           [0014]    In accordance with other characteristics of a process according to the invention:  
           [0015]    at least one condition of passage from one step to the following in said piloting process is a function of the values read for said at least one operational parameter and, in order to verify whether the reaction of the electronic power component is produced in the predetermined imparted time, the process comprises the step consisting in verifying that at least this condition of passage is satisfied before the predetermined imparted time has elapsed.  
           [0016]    the process comprises the step consisting in verifying that all the conditions of passage between said plurality of steps of said piloting process are satisfied before a predetermined imparted time common to all these conditions of passage has elapsed.  
           [0017]    the common time is counted from the instant when the execution of said piloting process begins, and this common time is representative of a maximum time to effect commutation of the electronic power component.  
           [0018]    one of the operational parameters read is the voltage V CE  between the collector and emitter electrodes of the electronic power component.  
           [0019]    one of the operational parameters read is the voltage on the control electrode.  
           [0020]    one of the steps of said piloting process consists in controlling the application on said control electrode of a braking voltage adapted to brake commutation of the electronic power component.  
           [0021]    the value of the braking voltage is strictly included between the values of the voltages for maintaining the electronic power component respectively in the closed state and in the open state.  
           [0022]    said piloting process is a process for piloting the closure of the electronic power component and the condition of passage between the step of controlling the application of a braking voltage and the following step is satisfied if the voltage between the collector and emitter electrodes is less than a first predetermined threshold.  
           [0023]    the process for piloting the closure of the electronic power component begins by the step of controlling the application of the braking voltage.  
           [0024]    said piloting process is a process for piloting the opening of the electronic power component and the condition of passage between a preceding step and the step controlling the application of the braking voltage is satisfied if the voltage between the collector and emitter electrodes is greater than a second predetermined threshold.  
           [0025]    the value of the second threshold corresponds to half the voltage to be commuted.  
           [0026]    said preceding step is a step for controlling the application of a voltage of value strictly lower than that of the braking voltage.  
           [0027]    in the process for piloting the opening of the electronic power component, the condition of passage between the step controlling the application of the braking voltage and a following step is satisfied if the voltage between the collector and emitter electrodes attains a maximum.  
           [0028]    The invention also relates to a system for controlling an electronic power component adapted to execute a process for piloting the opening and/or closure of this component, said piloting process containing a plurality of steps for controlling the application of a succession of different commutation voltages on a control electrode of the electronic power component between the instant when said piloting process starts and the instant when the opening and/or closure of the electronic power component must finish, the passage from one step to the following step in this piloting process being automatically effected as soon as a corresponding condition of passage is satisfied,  
           [0029]    characterized in that the system comprises a computer adapted to:  
           [0030]    read the value of at least one operational parameter characteristic of the reaction of the electronic power component in response to the successive application of said commutation voltages,  
           [0031]    verify, thanks to the values read, whether this reaction of the electronic power component is produced in a predetermined imparted time,  
           [0032]    if so, allow said piloting process to continue normally, and  
           [0033]    if not, interrupt said piloting process and immediately trigger off a process for safeguarding the integrity of the electronic power component.  
           [0034]    In accordance with other characteristics of a control system according to the invention:  
           [0035]    at least one condition of passage from one step of said piloting process to the following is a function of the values read for said at least one operational parameter and, in order to verify whether the reaction of the electronic power component is produced in the predetermined imparted time, the computer is adapted to verify that at least one condition of passage is satisfied before a predetermined time imparted for this condition of passage has elapsed.  
           [0036]    the computer is adapted to verify that all the conditions of passage between said plurality of steps of said piloting process are satisfied before a predetermined imparted time common to all these conditions of passage has elapsed.  
           [0037]    The invention also relates to a data recording support comprising instructions for the execution of the steps of a process for controlling an electronic power component according to the invention, when said instructions are executed by a computer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0038]    The invention will be more readily understood on reading the following description given by way of non-limiting example with reference to the accompanying drawings, in which:  
         [0039]    [0039]FIG. 1 is a schematic illustration of the architecture of a system according to the invention.  
         [0040]    [0040]FIG. 2 is a flowchart of a process for controlling the opening of an electronic power component according to the invention.  
         [0041]    [0041]FIGS. 3A and 3B are graphs, each illustrating the evolution in the course of time of an operational parameter of the electronic power component during the application of the process of FIG. 2.  
         [0042]    [0042]FIG. 4 is a flowchart of a process for controlling the closure of an electronic power component according to the invention; and  
         [0043]    [0043]FIGS. 5A and 5B are graphs, each illustrating the evolution in the course of time of an operational parameter of the electronic power component during the application of the process of FIG. 4. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0044]    Referring now to the drawings, FIG. 1 shows an electronic igniter  4  adapted to control the power transistors of an electronic commutation device  6  as a function of orders transmitted by a computer  8 .  
         [0045]    The commutation device  6  is for example a conventional three-phase inverter made from IGBT (Insulated Gate&gt;Bipolar Transistor)power transistors  10  and diodes  12  connected in anti-parallel position between the collector and the emitter of each of the transistors  10 .  
         [0046]    The transistor  10  is typically capable of commuting currents going up to 1000 A and of withstanding a voltage V CE  between the collector and the emitter in the non-conducting state, i.e. in the open state, included between 250 and 4000 V. In the conducting state, i.e. in the closed state, the voltage V CE  is generally less than 5 V.  
         [0047]    In order to simplify the illustration, only one of these transistors  10  and one of these diodes  12  are shown here.  
         [0048]    This three-phase inverter  6  is for example intended to supply a rotating electric machine  14 . Under these conditions, the function of the computer  8  is to deliver to the igniter  4  orders for controlling the power developed by the machine  14 , and the function of the igniter is to convert these orders into instructions for controlling each of the power transistors  10 . The process of conversion of the orders delivered by the computer into instructions for controlling each of the power transistors is conventional and will not be described here.  
         [0049]    Only those elements of the igniter  4  necessary for understanding the novel control system described here are shown in FIG. 1. Moreover, as the control system employed in the igniter  4  is the same for each of the power transistors  10 , only the control system of one of these power transistors will be described here in detail.  
         [0050]    The igniter  4  comprises a unit  20  for piloting the voltage V GE  applied to the gate of the transistor  10 , a circuit  22  for acquisition of data relative to the voltage V CE  between the collector and the emitter of the transistor  10 , and a logic processing unit  24  adapted, from the information delivered by the circuit  22 , to control the piloting unit  20 .  
         [0051]    The piloting unit  20  is adapted to apply, on the gate of the transistor  10 , four different voltages V 15 , V 10 , V 0  and V −10  corresponding respectively to a voltage for maintaining the transistor in the conducting state, for braking the commutation of the transistor, for blocking the transistor and for maintaining the transistor in the non-conducting state. Conventionally, voltages V 5  and V 0  are respectively equal to +15 V and 0 V. The value of the braking voltage is preferably strictly included between those of the voltages V 0  and V 15  and for example chosen here to be equal to 10 V.  
         [0052]    The voltage V −10  is adapted to maintain the power transistor  10  in the non-conducting state, even if said voltage is disturbed, for example because of electromagnetic disturbances caused by the commutation of other power transistors located nearby. To that end, its value is chosen to be clearly lower than that of the blocking voltage so that a disturbance cannot modify this value to render it higher than the blocking voltage, which would risk bringing about a non-controlled commutation of the power transistor  10 . Here, this value is chosen to be equal to −10 V.  
         [0053]    The data acquisition circuit  22  comprises three circuits  30 ,  32  and  34  for analyzing data relative to the voltage V CE  and a step-down transformer circuit  36  connected to the input of each of these three analysis circuits.  
         [0054]    The circuit  36  is intended to transform the voltage V CE  taken at the collector of the transistor  10  into a voltage which is proportional but included between 0 and 5 V delivered at the input of the three analysis circuits  30  to  34 .  
         [0055]    The circuit  30  is a conventional analog comparator intended to compare the voltage delivered by the circuit  36  with a threshold S 1  and to deliver the result of this comparison to the logic processing unit  24 . The value of the threshold S 1  corresponds here to a value of the voltage V CE  below which it is admitted that the transistor  10  is in the conducting state. The value of threshold S 1  is constant and preferably chosen to be less than 50 V and here equal to 10 V.  
         [0056]    The circuit  32  is also a conventional analog comparator adapted to compare the voltage delivered by the step-down transformer circuit  36  with a threshold S 2  and to deliver the result of this comparison to the logic processing unit  24 . The value of the threshold S 2  is, here, constant and chosen to correspond substantially to half the voltage V CE  to be commuted. Here, the value of S 2  is chosen to be equal to 500 V.  
         [0057]    The circuit  34  is adapted to detect the voltage peak V CE  which is produced just before the transistor  10  has finished its commutation towards the non-conducting state and to deliver this information to the logic processing unit  24 . The circuit  34  is also made in conventional manner with the aid, for example, of analog components.  
         [0058]    The logic processing unit  24  is a computer forming machine with finite states, capable of passing automatically from a state of controlling the piloting unit  20  to another when a condition of passage to the following state is satisfied. The logic processing unit  24  is, here, adapted to execute instructions recorded on a data recording support  40 . This recording support  40  contains, here, instructions for executing the steps of the processes described hereinbelow with reference to FIGS. 3 and 4.  
         [0059]    Moreover, on this data recording support  40  there are also recorded the parameters necessary for the development of the process of FIGS. 2 and 4 and in particular two constants T MAX OPENING  and T MAX CLOSURE  corresponding to the maximum times for respectively passing from the non-conducting state to the conducting state, and vice versa.  
         [0060]    So as to present a good insensitivity to the disturbances of the ambient medium, the logic processing unit  24  is advantageously a CPLD (Complex Programmable Logic Device) component programmed in a VHDL (Very High Descriptive Language).  
         [0061]    Moreover, the logic processing unit  24  controls a timer  42  adapted to be triggered off at the beginning of each commutation of the transistor  10  and an input  44  for reading the voltage V GE  on the gate of the transistor  10 .  
         [0062]    Functioning of the igniter  4  will now be described, firstly in the case of the control of the opening of the transistor  10  with reference to FIGS. 2, 3A and  3 B, and then in the case of the control of the closure of the transistor  10  with reference to FIGS. 4, 5A and  5 B.  
         [0063]    The logic processing unit  24  triggers off a process  50  for piloting the opening of the transistor  10  at a determined instant, for example, as a function of the orders transmitted by the computer  8 .  
         [0064]    Simultaneously, the logic processing unit  24  activates, at step  54 , the timer  42  and permanently reads, during step  58 , the data transmitted by the acquisition circuit  22  and the voltage V GE .  
         [0065]    The process  50  aims at braking the opening of the transistor  10  in order to control the variations of the derivative dV CE /dt.  
         [0066]    The evolution of the voltage V CE  and of the voltage V GE  during the normal development of the process  50  is respectively represented in FIGS. 3A and 3B. On these graphs, the time scale has been divided into three periods, each corresponding to the steps of the process  50  and therefore bearing the same numbers.  
         [0067]    The process  50  begins by a step  52  during which the logic processing unit  24  controls the piloting unit  20  so that the latter applies the blocking voltage V 0  on the gate of the transistor  10 .  
         [0068]    During this step, the voltage V GE  is therefore normally zero and the voltage V CE  must begin to increase. This step automatically stops when one of the two conditions of passage  58  or  60  is satisfied.  
         [0069]    The condition of passage  58  is satisfied when the comparator  32  indicates to the logic processing unit  24  that the voltage V CE  is higher than the threshold S 2  If this condition  58  is satisfied before the condition of passage  60 , the logic processing unit automatically proceeds to step  64 .  
         [0070]    The condition of passage  60  is satisfied as soon as the timer  42  indicates that the duration T MAX OPENING  has elapsed. If this condition of passage  60  is satisfied before the condition of passage  58 , then the piloting process  50  is interrupted and a process of safeguard  66  is activated.  
         [0071]    At step  64 , the logic processing unit controls the piloting unit  20  so that the latter applies on the gate of the transistor  10  the braking voltage V −10 . In this way, during this step  64 , the voltage V GE  must normally be equal to 10 V and the voltage V CE  must continue to increase.  
         [0072]    Step  64  stops as soon as one of the conditions of passage  70  or  72  is satisfied.  
         [0073]    The condition of passage  70  is satisfied when the circuit  34  delivers to the logic processing unit  24  a datum according to which the voltage V CE  has attained its maximum, i.e. the point where the derivative is cancelled. If this condition  70  is satisfied before condition  72 , the logic processing unit automatically proceeds to step  74  of the process  50 .  
         [0074]    The condition of passage  72  is satisfied as soon as the timer indicates that the time elapsed since the beginning of the process  50  is greater than the duration T MAX OPENING . If this condition of passage  72  is satisfied before condition  70 , the logic processing unit  24  automatically and immediately proceeds with the interruption of the process  50  and with the execution of the process  66  of safeguard.  
         [0075]    At step  74 , the logic processing unit controls the piloting unit  20  so that the latter applies the voltage V −10  on the gate of the transistor  10  in order to maintain the transistor  10  in the non-conducting state.  
         [0076]    After step  74 , the process  50  ends, since the commutation of the transistor  10  is finished. The logic processing unit then controls the maintenance of the voltage V 10  as long as no new order of commutation has been received.  
         [0077]    During the safeguarding process  66 , the logic processing unit  24  controls the piloting unit  20  so that it immediately applies the voltage V 10  for maintaining the transistor  10  in the non-conducting state. Moreover, a failure of commutation for opening is indicated, for example, to the computer  8  in order that this information be possibly subjected to particular processing.  
         [0078]    [0078]FIG. 4 represents the process for controlling closure of the transistor  10 .  
         [0079]    The logic processing unit  24  triggers off a process  80  for piloting the closure of the transistor  10  at a determined instant, for example, as a function of the orders transmitted by the computer  8 .  
         [0080]    Simultaneously, the logic processing unit  24  activates, in step  82 , the timer  42  and permanently reads, in step  84 , the data relative to the voltage V CE  transmitted by the acquisition circuit  22  and the voltage V GE .  
         [0081]    The process  80  aims at braking closure of the transistor  10  in order to control the variations of the derivative di E /dt of the current circulating in the transistor  10 . The evolution of the voltage V CE  and of the voltage V GE  during normal development of the process  80  are respectively represented in FIGS. 5A and 5B.  
         [0082]    In these graphs, the time scale has been divided into three periods each corresponding to the steps of the process  80  and therefore bearing the same numbers.  
         [0083]    The process  80  begins by a step  86  for controlling the application of the braking voltage V 10 .  
         [0084]    Step  86  ends as soon as one of the conditions of passage  88  or  90  is satisfied. This step normally being very short with respect to the others, it has been represented by a dot in FIGS. 5A, 5B.  
         [0085]    The condition of passage  88  is satisfied as soon as the voltage V GE  read by the logic processing unit  24  is greater than or equal to 10 V. If the condition of passage  88  is satisfied before condition of passage  90 , the logic processing unit  24  automatically proceeds to step  92  for maintaining a voltage V GE  equal to 10 V.  
         [0086]    During step  92 , the voltage V GE  is therefore normally equal to 10 V and the voltage V CE  begins to decrease.  
         [0087]    The step  92  ends as soon as a condition of passage  94  or  96  is satisfied. The condition of passage  94  is satisfied here as soon as the analog comparator  32  indicates to the logic processing unit  24  that the voltage V CE  is lower than the threshold S 2 . If the condition of passage  94  is satisfied before condition  96 , the logic processing unit  24  automatically proceeds to a step  98  for controlling the piloting unit  20  so that the latter applies on the gate  10  the voltage V 15  for maintaining the transistor  10  in the conducting state.  
         [0088]    Step  98  terminates as soon as a condition of passage  100  or  102  is satisfied. The condition of passage  100  is satisfied here as soon as the voltage V CE  is lower than the threshold S 1 . If the condition of passage  100  is satisfied before condition  102 , the logic processing unit  24  then proceeds automatically to step  104  for controlling maintenance of the voltage V 15  on the gate of the transistor  10 . The piloting process  80  is finished.  
         [0089]    The conditions  90 ,  96  and  102  are automatically satisfied as soon as the timer  42  indicates that the time elapsed since the beginning of the process  80  is greater than the duration T MAX CLOSURE . If one of these conditions is satisfied, while one of the steps  86 ,  92  or  98  has not yet ended, the logic processing unit  24  interrupts the process  80  and immediately begins execution of the safeguarding process  66  described with reference to FIG. 2.  
         [0090]    It is important to note that, in the form of embodiment described here, the logic processing unit  24 , in addition to executing piloting processes for braking the opening and closure of the transistor  10 , permanently supervises the correct development of these processes in time. In particular, the logic processing unit  24  here supervises whether the conditions of passage from one step to the following in the piloting processes are satisfied in a predetermined period of time corresponding to a maximum duration for the piloting process to be ended. As soon as the logic processing unit  24  ascertains that not all the steps of the piloting process have been carried out within the time imparted, it interrupts this piloting process and immediately executes a safeguarding process  66 . In this way, the process described hereinabove avoids any blocking of the piloting process.  
         [0091]    The values of the thresholds for the processes for piloting the opening and closure of the transistor  10  have been chosen to be identical. In a variant, the values of the thresholds for the process for piloting opening of the transistor  10  are different from those for piloting closure thereof.