JP5742649B2 - Driving device for switching element - Google Patents

Description

  The present invention is applied to a switching element that is connected to an inductor and in which a diode is connected in reverse parallel, and when it is determined that the current is flowing in the diode, the switching element that prohibits the ON operation of the switching element is provided. The present invention relates to a driving device.

  2. Description of the Related Art A power conversion circuit (inverter) including a series connection body of a high-potential side switching element and a low-potential side switching element that connects each terminal of a DC voltage source and a terminal of a rotating machine is well known. The inverter includes a freewheel diode connected in antiparallel to the switching element. Here, when operating the high-potential side switching element and the low-potential side switching element to flow a sinusoidal current to the rotating machine, the high-potential side switching element and the low-potential side switching element are alternately switched. Generally, a method of driving the pair of switching elements in a complementary manner by turning them on and off is generally used.

  On the other hand, an insulated gate bipolar transistor (IGBT) may be used as the switching element of the inverter. In recent years, a so-called diode built-in IGBT in which a free wheel diode is provided on the same substrate as the IGBT has been proposed as a semiconductor element constituting such an inverter.

  Since the IGBT has a forward direction from the collector to the emitter, no current flows on the reverse side. For this reason, when a pair of switching elements of the inverter are driven in a complementary manner, depending on the flow direction of the sine wave current, the current may not flow to the switching element that is in the on state. And in this case, it becomes a recirculation mode in which an electric current flows into the freewheel diode connected to this in antiparallel.

  By the way, in the diode built-in IGBT, it is known that the amount of voltage drop when a forward current flows through the freewheeling diode increases when a voltage is applied to the gate of the IGBT. For this reason, when the switching elements are operated in a complementary manner, the power loss due to the freewheeling diode when the forward current flows through the freewheeling diode increases, and as a result, the amount of heat generated by the diode built-in IGBT may increase. .

  Therefore, conventionally, as seen in, for example, Patent Document 1 below, it is determined whether or not it is a reflux mode in which a current flows through a freewheeling diode. It has also been proposed to force the switching element to turn off regardless of the command. Here, the determination as to whether the current mode is the reflux mode is made by comparing the current flowing through each terminal of the rotating machine with a threshold value. Then, the absolute value of the threshold is zero based on the delay time until the switching element is forcibly turned off in accordance with the transition from the state determined to be the reflux mode to the state where it is not. (Paragraph “0040”).

JP 2011-130599 A

  By the way, when the current used for determining whether or not it is in the reflux mode is discretely updated, the value used for determining whether or not it is in the reflux mode and when the forced off process is performed The value can be different. For this reason, it is necessary to make the threshold value larger than the maximum value of the current change amount in the update cycle. In this case, when the actual amount of change in the current is smaller than the maximum value, the IGBT cannot be turned off in spite of the reflux mode, so that the power loss of the free wheel diode increases. Therefore, in the above technique, there is a concern that the effect of reducing the amount of heat generated by the free wheel diode cannot be sufficiently exhibited.

  The present invention has been made in the process of solving the above-mentioned problems, and its object is a reflux mode in which a current is applied to a diode, which is applied to a switching element connected to an inductor and having a diode connected in antiparallel. If it is determined, the present invention is to provide a new switching element driving device that prohibits the switching element from being turned on.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

A first invention is applied to a switching element connected to an inductor and having a diode connected in anti-parallel, an acquisition unit for acquiring a value of a current flowing through the inductor, and a current and a threshold acquired by the acquisition unit Based on the size comparison, the reflux mode determining means for determining whether or not the current is flowing in the diode, and the switching element is turned on when the reflux mode is determined by the reflux mode determining means. A prohibiting unit that prohibits the operation, and a reducing unit that reduces the absolute value of the threshold when the amount of change in the current flowing through the inductor in the current update period used for the determination by the reflux mode determining unit is small. It is characterized by that.

  When the current used for the determination by the reflux mode determination means is discretely updated, the current may change during the update period. For this reason, in order to avoid a situation in which a period in which the reflux mode is determined by the reflux mode determination means despite the fact that it is not in the reflux mode, it is necessary to set a threshold value in consideration of the change in current in the update cycle. There is. And this means that it may be necessary to set a threshold value so that the region that is determined not to be in the reflux mode is enlarged even if the current mode is in the reflux mode because the amount of change in the current over the update cycle varies. means. In this regard, in the above invention, by reducing the absolute value of the threshold value as the change amount is smaller, it is determined that the mode is not the reflux mode when it is not the reflux mode. be able to.

In a second aspect based on the first aspect , the current used for the determination by the reflux mode determination means is updated at a predetermined time period, and the inductor is a coil of a rotating machine, The reduction means reduces the absolute value of the threshold value by assuming that the amount of change is small when the rotation speed of the rotating machine is small.

  The current flowing through the rotating machine tends to have a smaller rate of change of its value due to a smaller phase change rate as the rotation rate is smaller. For this reason, when the current used for the determination of the reflux mode determination means is updated in the time period, the amount of change in the current in the update period becomes smaller as the rotational speed becomes smaller. The above-described invention is configured with a reduction means paying attention to this point.

According to a third aspect of the present invention, in the first or second aspect , the inductor is a coil of a rotating machine, and includes a variable unit that makes the update cycle variable, and the reduction unit has a short update cycle, The absolute value of the threshold value is reduced assuming that the amount of change is small.

  The longer the update period, the larger the amount of change in the current phase in the update period, and the greater the amount of change in current. The above-described invention is configured with a reduction means paying attention to this point.

A fourth invention is any crab Oite the first to the third invention, the inductor is a coil of the rotating machine, wherein the reduction means, when the amplitude of the current flowing through the rotating machine is small, the amount of change Is smaller, the absolute value of the threshold is reduced.

  When the amount of change in current phase is the same, the amount of change in current value tends to decrease as the current amplitude decreases. The above-described invention is configured with a reduction means paying attention to this point.

A fifth invention is any crab Oite the first to fourth invention, the inductor is a coil of the rotating machine, the switching element connected to the inductor, and said to constitute a DC-AC converter Opening and closing between the terminal of the rotating machine and each of the positive electrode and the negative electrode of the DC voltage source, the acquisition means is a connection point between the switching element connected to the positive electrode and the switching element connected to the negative electrode More than the inductor side current or the detection value of the DC voltage source side current from the end of the switching element that is not the connection point side, the reflux mode determination means, The prohibiting means and the reducing means are provided for each of the switching elements constituting the DC-AC conversion circuit.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, in order to control the control amount of the rotating machine, the generation of the respective operation signals of the switching element connected to the positive electrode and the switching element connected to the negative electrode And the generation means is software processing means, and the reflux mode determination means, the prohibition means, and the reduction means are constituted by the software processing means.

  In the above invention, since the reflux mode determination means and the like are configured by the software processing means, the determination cycle of the reflux mode determination means tends to be discrete. For this reason, the utility value of the said reduction means is especially large.

A seventh invention is any crab Oite the first to sixth invention, a switching element the diode is connected in anti-parallel, and the diode is characterized in that it is parallel in the same semiconductor substrate.

  The freewheeling diode has a higher conduction loss when the switching element is in the on state than when the switching element is in the off state. For this reason, the utility value of the prohibition means is particularly great.

1 is a system configuration diagram according to a first embodiment. FIG. Sectional drawing which shows the cross-sectional structure of the semiconductor device concerning the embodiment. 6 is a flowchart showing a procedure of an on-operation prohibition process according to the embodiment. The figure which shows the preparation procedure of the threshold value map concerning the embodiment. The flowchart which shows the procedure of the prohibition process of ON operation concerning 2nd Embodiment. 9 is a flowchart showing a procedure of an on-operation prohibition process according to the third embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which a switching element driving device according to the present invention is applied to a switching element constituting an inverter connected to an in-vehicle main machine will be described with reference to the drawings.

  FIG. 1 shows the system configuration of this embodiment. As shown in the figure, a motor generator 10 as an in-vehicle main machine is connected to a high voltage battery 12 via an inverter INV and a converter CNV. The high voltage battery 12 is a DC voltage source whose terminal voltage is, for example, 100 V or higher. The high voltage battery 12 has a negative electrode potential different from the vehicle body potential. Specifically, in the present embodiment, the median value of the positive electrode potential and the negative electrode potential of the high-voltage battery 12 is set to be the vehicle body potential. This can be realized by connecting a pair of resistors or a pair of capacitors to the high voltage battery 12 in parallel, and connecting a connection point of the pair of resistors or the pair of capacitors to the vehicle body.

  The inverter INV is configured by connecting in parallel three series-connected bodies of a high-potential side power switching element S ¥ p (¥ = u, v, w) and a low-potential side power switching element S ¥ n. . Connection points of these power switching elements S ¥ p and power switching elements S ¥ n are connected to the respective phases of motor generator 10. In addition, between the input / output terminals (between the collector and the emitter) of the power switching element S ¥ p on the high potential side and the power switching element S ¥ n on the low potential side, the free wheel diode D ¥ p on the high potential side and The cathode and anode of the free potential diode D ¥ n on the low potential side are connected.

  On the other hand, converter CNV includes a reactor L connected between capacitor C, a series connection body of switching elements Scp and Scn connected in parallel thereto, a connection point of switching elements Scp and Scn, and a positive electrode of high-voltage battery 12. And. A high-potential-side freewheel diode Dcp and a low-potential-side freewheel are provided between the input / output terminals (between the collector and the emitter) of the high-potential-side power switching element Scp and the low-potential-side power switching element Scn. The cathode and anode of the diode Dcn are connected.

  On the other hand, the control device 20 uses the vehicle body as a reference potential, and operates the inverter INV and the converter CNV in order to control the control amount of the motor generator 10 as a control target. At this time, the control device 20 detects the rotation angle sensor 14 that detects the rotation angle of the motor generator 10, the current sensor 16 that detects the current flowing through the motor generator 10, the voltage sensor 18 that detects the input voltage of the inverter INV, and the like. Get the value. Then, an operation signal g ¥ # for operating the power switching element S ¥ # (¥ = u, v, w; # = p, n) for each of the U phase, V phase, and W phase of the inverter INV is generated. Output. Thereby, the power switching element S ¥ # is operated by the control device 20 via the drive unit DU connected to the open / close control terminals (gates). Similarly, the converter CNV is operated by generating and outputting the operation signals gcp and gcn of the power switching elements Scp and Scn of the converter CNV.

  The current sensor 16 is a means capable of detecting not only the size but also the direction of current flow. Specifically, in the present embodiment, a means for detecting a current without contacting an electric path between the motor generator 10 and the inverter INV is employed.

  The power switching elements S ¥ #, Scp, Scn are switching elements that have an input terminal and an output terminal that are uniquely defined and prevent current from flowing from the output terminal to the input terminal. Specifically, these are constituted by insulated gate bipolar transistors (IGBT). In particular, in the present embodiment, the power switching elements S ¥ #, Scp, Scn and diodes D ¥ #, Dcp, Dcn connected in reverse parallel thereto are formed adjacent to the same semiconductor substrate. doing.

  FIG. 2 shows a cross-sectional configuration of the power switching elements S ¥ #, Scp, Scn according to this embodiment and diodes D ¥ #, Dcp, Dcn connected in reverse parallel thereto.

  As illustrated, the semiconductor substrate 40 is formed with an IGBT region and a diode region. A region extending from the main surface side to the back surface side of the semiconductor substrate 40 is an N-type region 42 whose conductivity type is N-type. A P-type region 44 having a P-type conductivity is formed in the surface layer portion on the main surface side of the semiconductor substrate 40, and the N-type having a concentration higher than that of the N-type region 42 in the P-type region 44. An N type region 46 having the following conductivity type is formed. The P-type region 44 and the N-type region 46 are connected to an IGBT emitter terminal E and a diode anode terminal. A gate electrode 50 is formed on the P-type region 44 and the N-type region 46 via a gate oxide film 48.

  On the other hand, an N-type region 56 and a P-type region 54 having a higher concentration than the N-type region 42 are provided on the surface layer portion on the back side of the semiconductor substrate 40. Here, the P-type region 54 constitutes a collector region of the IGBT, and the N-type region 56 constitutes a cathode region of the diode. An N-type region 52 having a concentration lower than that of the N-type region 42 is formed between the P-type region 54 and the N-type region 56 and the N-type region 42.

  The control device 20 shown in FIG. 1 includes a central processing unit (CPU 22), a memory 24, and the like, and generates operation signals g ¥ #, gcp, gcn by executing a program stored in the memory 24. Software processing means. Next, the generation process of the operation signal g ¥ # will be described based on FIG.

  The three-phase / dq converter 26 converts the three-phase actual currents iu, iv, iw detected by the current sensor 16 into actual currents id, iq on the dq axis. The command current setting unit 28 sets command currents id * and iq * based on the required torque T *. The current feedback control unit 30 sets the d-axis command voltage vd * as an operation amount for performing feedback control of the d-axis actual current id to the command current id *, and converts the q-axis actual current iq to the command current iq *. The q-axis command voltage vq * is set as an operation amount for feedback control. The dq / 3-phase converter 32 converts the command voltages vd *, vq * on the dq axis into three-phase command voltages vu *, vv *, vw *.

  The PWM processing unit 34 generates the PWM signal g ¥ based on the magnitude comparison between the command voltage v ¥ * (¥ = u, v, w) and the carrier. Specifically, the PWM signal g ¥ in which logic “H” and “L” are determined according to which of the command voltage v ¥ * normalized by the input voltage VDC of the inverter INV and the carrier is larger is generated.

  Here, carrier frequency fc is variably set according to electric angular velocity ω of motor generator 10 and temperature T of switching element S ¥ # of inverter INV. Incidentally, the reason why the variable setting is performed according to the temperature T is to reduce the switching frequency in order to reduce the switching loss when the temperature T is high. Further, in this embodiment, the update cycle of the command voltages vd * and vq * and the sampling cycle of the actual currents iu, iv and iw are set to the carrier cycle “1 / fc”.

  The dead time generator 36 generates operation signals g ¥ p and g ¥ n as complementary signals based on the PWM signal g ¥. That is, basically, when the PWM signal g ¥ is logic “H”, the operation signal g ¥ p is set to logic “H”, the operation signal g ¥ n is set to logic “L”, and the PWM signal g ¥ is When the logic is “L”, the operation signal g ¥ p is set to the logic “L” and the operation signal g ¥ n is set to the logic “H”. However, at this time, the rising edge is delayed by the dead time with respect to the corresponding edge of the PWM signal g ¥.

  The shut-off unit 38 prohibits the switching element S ¥ # from being turned on in the reflux mode in which a current flows through the diode D ¥ # connected in reverse parallel to the corresponding switching element S ¥ # in the operation signal g ¥ #. Therefore, the on operation command is forcibly changed to the off operation command.

  In FIG. 3, the procedure of the process which the interruption | blocking part 38 performs is shown. This process is executed at the carrier cycle “1 / fc”.

  In this series of processes, first, in step S10, the carrier frequency fc and the rotational speed Nm of the motor generator 10 are acquired. In the subsequent step S12, a map calculation is performed on a threshold value Ith (> 0) for determining whether or not the recirculation mode is set. In the subsequent step S14, it is determined whether or not the actual current i ¥ is equal to or greater than the threshold value Ith. This process is for determining whether or not the lower arm of the serial connection body of the switching elements S ¥ p, S ¥ n is in the reflux mode. If an affirmative determination is made in step S14, it is determined that the lower arm is in the reflux mode. In step S16, the operation signal g \ n of the switching element S \ n of the lower arm is forcibly set as an off operation command. To do.

  On the other hand, when a negative determination is made in step S14, it is determined in step S18 whether or not the actual current i ¥ is equal to or less than “−Ith”. This process is for determining whether or not the upper arm of the serial connection body of the switching elements S ¥ p, S ¥ n is in the reflux mode. If an affirmative determination is made in step S18, it is determined that the upper arm is in the reflux mode, and in step S20, the operation signal g \ p for the switching element S \ p of the upper arm is forcibly set as an off operation command.

  In addition, when the process of said step S16, S20 is completed, or when negative determination is made in step S18, this series of processes is once complete | finished.

  In the map used in step S12, the threshold Ith is set to a smaller value as the rotational speed Nm is lower and the carrier frequency fc is higher. This is a setting for decreasing the threshold value Ith as the change amount of the actual current i ¥ is smaller in the processing cycle shown in FIG. 3 (update cycle of the actual current i ¥ used for determining the return mode).

  FIG. 4 illustrates a method for creating the map.

  FIG. 4A shows the transition of the actual current i ¥. As shown in the figure, the actual current i ¥ has a sinusoidal transition waveform. For this reason, in one electrical angle cycle, the amount of change X until the carrier cycle “1 / fc” elapses from the phase at the center of amplitude is maximized. Therefore, as shown in FIG. 4B, the ratio “X / A” between the amplitude A and the change amount X of the actual current i ¥ is calculated according to the rotational speed Nm of the motor generator 10 and the carrier frequency fc. . Further, as shown in FIG. 4C, the maximum value Arms of the effective value of the actual current i ¥ is acquired according to the rotation speed Nm and the carrier frequency fc. This is determined by the control of the control device 20, the specifications of the motor generator 10, and the like. Then, as shown in FIG. 4 (d), based on the values calculated and acquired in FIGS. 4 (b) and 4 (c), the rotational speed Nm and the carrier frequency fc are input, and the change amount X is calculated. Create a map for output. Here, the change amount X corresponding to each rotation speed Nm and the carrier frequency fc can be calculated by “(X / A) · Arms · (√2)”.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The threshold value Ith is variably set according to the carrier frequency fc and the rotation speed Nm. As a result, the threshold value Ith (> 0) can be set to a smaller value as the current change amount X in the update period of the actual current i ¥ used to determine whether or not the current mode is the reflux mode. For this reason, it is possible to enlarge the region determined to be the reflux mode while avoiding the determination to be the reflux mode despite not being the reflux mode.

  (2) The software processing means (CPU 22) determines whether or not it is in the reflux mode at discrete time intervals (every carrier cycle “1 / fc”). For this reason, the variation amount of the variation amount X in the judgment update cycle tends to be large. For this reason, the merit of variably setting the threshold value Ith is great.

(3) The power switching element S ¥ # and the free wheel diode D ¥ # are formed side by side on the same semiconductor substrate. Accordingly, since the conduction loss is increased by turning on the power switching element S ¥ # in the reflux mode, the utility value of the processing for canceling the ON operation command of the power switching element S ¥ # in the reflux mode is useful. Especially big.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 5 shows a procedure of processing performed by the blocking unit 38 according to the present embodiment. This process is executed at the carrier cycle “1 / fc”. Note that, in FIG. 5, the same step numbers are assigned for convenience to those corresponding to the processing shown in FIG.

  In this series of processing, first, in step S10a, the required torque T * is acquired in addition to the carrier frequency fc and the electrical angular velocity ω. In the subsequent step S12a, a map operation is performed on the threshold value Ith (> 0) for determining whether or not the return mode is based on the carrier frequency fc, the electrical angular velocity ω, and the required torque T *. Here, the required torque T * is a parameter having a correlation with the amplitude A of the actual current i \. That is, as shown in FIG. 1, the command currents id * and iq * are set according to the required torque T *. The amplitude A is a predetermined number times the vector norm of the command currents id * and iq *.

As the amplitude A increases, the amount of change X in the carrier period “1 / fc” increases. On the other hand, the amplitude A increases as the required torque T * increases. For this reason, the threshold value Ith is set to a smaller value as the required torque T * is smaller.
<Third Embodiment>
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 6 shows a procedure of processing performed by the blocking unit 38 according to the present embodiment. This process is executed at the carrier cycle “1 / fc”. Note that, in FIG. 6, the same step numbers are assigned for convenience to those corresponding to the processing shown in FIG.

  In this series of processing, first, in step S30, the latest actual current i ¥ (n) is sampled. In subsequent step S32, a change amount Δi ¥ (n) of the latest actual current i ¥ (n) with respect to the previous actual current i ¥ (n−1) is calculated. In step S34, a threshold value Ith is set according to the change amount Δi ¥ (n). Here, the threshold value Ith can be most appropriately set by using the amount of change in the next actual current i ¥ (n + 1) with respect to the latest actual current i ¥ (n). However, since the next actual current i ¥ (n + 1) cannot be acquired in advance, the amount of change of the next actual current i ¥ (n + 1) with respect to the latest actual current i ¥ (n) is the amount of change Δi ¥ (n ) And the threshold value Ith is set according to the change amount Δi ¥ (n). Here, the threshold value Ith is set to a smaller value as the change amount Δi ¥ (n) is smaller.

In addition, when the process of step S34 is completed, the process of step S14-S20 is performed. When the processes of steps S16 and S20 are completed, or when a negative determination is made in step S18, the sampling variable n is updated in step S36. In addition, when the process of step S36 is completed, this series of processes is once complete | finished.
<Other embodiments>
Each of the above embodiments may be modified as follows.

"About reduction measures"
In the first and second embodiments, instead of using a map, the threshold value Ith may be calculated from the carrier frequency fc, the rotational speed Nm, and the like in the manner shown in FIG. At this time, in the case of the first embodiment, it is desirable to use a map that defines the relationship between the carrier frequency fc, the rotational speed Nm, and the maximum current (effective value). Incidentally, in the modification of the second embodiment, the vector norm of the command currents id * and iq * determined from the required torque T * is used instead of this map. However, instead of this, the vector norm of the actual currents id and iq on the dq axis output from the dq converter 26 may be used.

  Further, as input parameters for grasping the amount of change in current in the current update period used for determining the return mode, the carrier frequency fc and the rotational speed Nm, or the carrier frequency fc, the rotational speed Nm and the required torque are used. Not only T *, but any one of carrier frequency fc, rotation speed Nm, and required torque T * may be used, or only current amplitude may be used.

"Generation means"
What is not limited to the current feedback control means is as described in the section “About the acquisition means”. Further, for example, rectangular wave control means or the like may be used. Even in this case, if the threshold value is variably set according to the amount of change in current in the current update cycle used for the determination of the reflux mode determination means, the period for determining the reflux mode can be shortened. it can.

  Incidentally, in such a case, since there is no carrier for PWM processing, there is no means for variably setting the sampling period in accordance with the variable setting of the carrier period. However, when the current is discretely sampled, it is effective to set the threshold value variably because the variation in the amount of change in the current in the sampling period can be significant.

"Variable means"
The fact that this is not essential is described in “Regarding the generation means”. Note that the variable setting of the sampling period does not necessarily assume that the carrier period of the PWM processing is variably set. That is, for example, also in rectangular wave control or the like, variable means for making the sampling cycle variable can be provided from the viewpoint of achieving a suitable balance between calculation load and control error.

"Operating potential of reflux mode judgment means and prohibition means"
These means may be mounted in the drive unit DU and used as the operating potential of the drive unit DU. In this case, as a means for detecting the current, it is desirable to use the output current of the sense terminal St (described in FIG. 1) that outputs a minute current having a correlation with the current flowing through the switching element S ¥ #. In this case, during a period in which the current flowing through the corresponding terminal of the motor generator 10 can be detected in the specific drive unit DU, the corresponding signal among the operation signals g ¥ # generated in the dead time generation unit 36 is the ON operation command. Period (and dead time period). Therefore, it is necessary to use a past current value as to whether or not to interrupt the next on-operation command, and this current value is different from the current value at the time when the next on-operation command is input. Moreover, the difference between these current values can vary. Therefore, even in this case, it is effective to variably set the threshold value.

"Acquisition means"
The current value as an input parameter of the reflux mode determination means is not limited to the detected current value. For example, as described in Japanese Patent Application Laid-Open No. 2008-228419, the current in each switching mode when temporarily setting various switching modes according to the on / off operation of the switching element of the inverter is predicted, and the predicted current The predicted current when performing so-called model predictive control for selecting the optimum switching mode based on the above may be used. Even in this case, if the amount of change in current in the predicted current update period is large, the merit of providing the reduction means increases.

  Further, the means for detecting the current flowing through the coil of the rotating machine is not limited to the current sensor 16 for detecting the current flowing between the inverter INV and the motor generator 10. It is illustrated in the column “About”. Further, for example, it may be a current sensor that detects a current of a DC bus connecting the low-potential side switching elements S ¥ n or a DC bus connecting the high-potential side switching elements S ¥ p. Incidentally, all current information flowing through the motor generator 10 cannot be acquired only by the current detected by the current sensor. However, if the missing current information is compensated by estimation or the like, it is possible to obtain all current information using only the DC bus current.

"Software processing means"
The reflux mode determination means, the prohibition means, and the reduction means may be hardware processing means as described in Patent Document 1. However, in this case, if the update period of the current used for determining the reflux mode is short, the threshold value for determining that the mode is not changed from the reflux mode to the reflux mode and the mode is switched from the reflux mode to the non-reflux mode. It is desirable to make the threshold value for judging different.

"Relationship between judgment cycle of reflux mode judgment means and current update cycle"
These are not necessarily equal. For example, the current update period may be longer than the determination period of the reflux mode determination means. In this case, setting the threshold value according to the determination cycle of the reflux mode determination means causes a decrease in determination accuracy. However, even in this case, the effect according to the first embodiment can be obtained if the threshold is set based on the current update period used for the determination by the reflux mode determination means. For example, if the determination cycle is Tc and the current sampling cycle is TI (Tc <TI <2 · Tc), the current update cycle used for the determination by the reflux mode determination means varies. Therefore, in this case, it is convenient to regard the update cycle as the longest cycle “2Tc”. However, the update cycle may be treated as a variable.

About inductors
For example, the reactor L of the converter CNV may be used. In other words, the switching element that is the target for determining the return mode is not limited to one that constitutes the DC / AC converter circuit (inverter INV), but may be one that constitutes the converter CNV or the like.

"others"
The rotating machine is not limited to the in-vehicle main machine.

  The switching element to be driven is not limited to that shown in FIG. In order to suppress the gate charging power consumption due to the switching element being turned on unnecessarily by the complementary driving, the on resistance of the diode is not increased by the turning on of the switching element. However, it is effective to provide prohibition means.

  DESCRIPTION OF SYMBOLS 10 ... Motor generator, 20 ... Control apparatus, 22 ... CPU, 38 ... Shut-off part.

Claims (7)

Applied to a switching element connected to an inductor and a diode connected in anti-parallel , generates an operation signal for each switching element, and outputs the operation signal for each switching element,
Obtaining means for obtaining a value of a current flowing through the inductor;
Recirculation mode determination means for determining whether or not it is a recirculation mode in which a current flows through the diode based on a magnitude comparison between the current acquired by the acquisition means and a threshold;
When it is determined that the reflux mode is determined by the reflux mode determination means, a prohibiting means for prohibiting an ON operation of the switching element;
When the amount of change in the current flowing through the inductor in the current update period used for the determination by the reflux mode determination unit is small, a reduction unit that reduces the absolute value of the threshold;
A drive device for a switching element, comprising: The current used for the determination by the reflux mode determination means is updated at a predetermined time period,
The inductor is a coil of a rotating machine,
2. The driving device of a switching element according to claim 1, wherein when the rotation speed of the rotating machine is low, the reduction unit reduces the absolute value of the threshold value by assuming that the amount of change is small. The inductor is a coil of a rotating machine,
Comprising variable means for making the update cycle variable;
3. The driving device of a switching element according to claim 1, wherein when the update period is short, the reduction unit reduces the absolute value of the threshold value by assuming that the amount of change is small. The inductor is a coil of a rotating machine,
4. The switching according to claim 1, wherein when the amplitude of the current flowing through the rotating machine is small, the reduction unit reduces the absolute value of the threshold value by assuming that the amount of change is small. Device drive device. The inductor is a coil of a rotating machine,
The switching element connected to the inductor constitutes a DC / AC conversion circuit and opens and closes between the terminal of the rotating machine and each of the positive electrode and the negative electrode of the DC voltage source,
The acquisition means includes the current on the inductor side of a connection point between the switching element connected to the positive electrode and the switching element connected to the negative electrode, or the end of the switching element that is not on the connection point side. It acquires one of the detected values of the current on the DC voltage source side,
The reflux mode determination means, the prohibition means, and the reduction means are provided for each of the switching elements constituting the DC / AC conversion circuit, respectively. The switching element drive device according to claim 1. In order to control the control amount of the rotating machine, comprising a generating means for generating respective operation signals of the switching element connected to the positive electrode and the switching element connected to the negative electrode,
The generating means is software processing means,
6. The switching element drive device according to claim 5, wherein the reflux mode determination means, the prohibition means, and the reduction means are configured by the software processing means.   The switching element drive device according to claim 1, wherein the switching element in which the diodes are connected in antiparallel and the diode are provided on the same semiconductor substrate.

Images