JP2001217699A - Drive device for current control type element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To limit the current which flows to the base terminal of a drive transistor(TR), when the TR is turned on reversely. SOLUTION: When the output of a drive circuit 33 decreases to low level, while a drive TR T1 is off, a drive TR T2 turns off and an inductive load L1 generates a counterelectromotive force. With the generated counterelectromotive force, the potential at a point P in the figure rises. When the voltage at the point P exceeds the value obtained by adding the forward drop voltages of diodes 11 and 12 to the potential at the base terminal of the drive TR T1, the diodes 11 and 12 are biased forward to turn on the drive TR T1 reversely. When the output of a drive circuit 33 rises to high level, the drive TR T2 is turned on and the drive TR T1 enters reverse recovering operation. Current, flowing to the base terminal of the drive TR T1, is limited by the impedance of the diodes 11 and 12, and then electric charges accumulated in the drive TR T1 are small, so that it is turned off in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a current control element for supplying a driving current to an inductive load.

[0002]

2. Description of the Related Art A drive device for a current control type element for driving an inductive load is used, for example, in a chopper circuit and an H-bridge circuit for controlling an induction motor. In these circuits, a protection circuit is provided to protect the current control type element from a back electromotive force generated by an inductive load. FIG. 9 is a diagram showing a part of an H-bridge circuit provided with a protection circuit, which is described in, for example, Japanese Patent Application Laid-Open No. 8-84060. In FIG. 9, T101 and T102 are current control type switching transistors (hereinafter simply abbreviated as drive transistors) for supplying a drive current to an inductive load L1 such as a motor, and drive circuits connected to base terminals, respectively. It is driven by 103 and 133. The power supply voltage Vcc is connected to the collector terminal of the driving transistor T101, and the emitter terminal of the driving transistor T102 is grounded. An inductive load L1 is connected between the emitter terminal of the driving transistor T101 and the collector terminal of the driving transistor T102.

The diodes 102, 1 are connected between the emitter terminals and the base terminals of the driving transistors T101, T102, respectively.
22 is connected. By flowing a current due to the back electromotive force generated from the inductive load L1 to these diodes 102 and 122, the destruction of the driving transistors T101 and T102 is prevented. For example, when the driving transistor T102 is turned on by the driving circuit 133, a current flows in a direction indicated by A in the figure. Thereafter, when the driving transistor T102 is turned off by the driving circuit 133, a back electromotive force is generated from the inductive load L1, and the potential at point P in the figure rises due to the back electromotive force. The potential at point P is the driving transistor T101
When the potential becomes higher than the potential of the base terminal, the diode 102 is forward-biased, and a current flows in a direction indicated by C in FIG. Then, the driving transistor T101 is turned on in the reverse direction, and the circulating current due to the back electromotive force flows in the direction indicated by B in the drawing.

[0004]

SUMMARY OF THE INVENTION A driving transistor T
The current in the direction C in the figure to turn on 101 in the reverse direction is
The current flows into the base terminal of the driving transistor T101 in a low impedance state via the diode 102. Therefore, the inside of the driving transistor T101 is in an excessively charged state. When the driving transistor T102 is turned on again while the driving transistor T101 is turned on in the reverse direction, the driving transistor T101 enters a reverse recovery operation, and a current flows in the P direction again in the A direction. At this time, the electric charge accumulated in the driving transistor T101 stays as it is. Therefore, the reverse recovery operation of the driving transistor T101 takes a long time, and a current flows in a direction from the collector to the emitter, that is, in the forward direction, while being in the off state. As a result, there is a problem that a large through current flows through the driving transistor T101 and the driving transistor T102.

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive device for a current control element which limits the current flowing to the control terminal of the current control transistor when the current control transistor is turned on in the reverse direction. .

[0006]

The present invention will be described with reference to FIGS. 1, 6, and 7 showing one embodiment. (1) The invention according to claim 1 is a current control type transistor T1 for supplying a drive current to an inductive load L1 connected to a drive terminal (emitter terminal), and the current control type transistor T1 is connected to the inductive load L1. And a protection means 12 for supplying a current due to a back electromotive force generated from the inductive load L1 to the control terminal (base terminal) of the current control type transistor T1 so as to turn on in a direction opposite to the driving direction of the current control type transistor T1 It is applied to the driving device for Then, the protection means 12 (1
6) current limiting means 1 for limiting the current supplied to the control terminal (base terminal) of the current control transistor T1
By providing 1 (17), the above object is achieved. (2) According to a second aspect of the present invention, in the current control type element driving device according to the first aspect, the current limiting means includes a control terminal (base terminal) of the current control type transistor T1 via the protection means 12. And at least one diode 11 having a forward direction of a current supplied to the diode. (3) According to a third aspect of the present invention, in the current control type element driving device according to the first aspect, the current limiting means includes a control terminal (base terminal) of the current control type transistor T1 via the protection means 16. And a zener diode 17 that reverses the direction of the current supplied to the power supply. (4) According to a fourth aspect of the present invention, in the current controlling element driving device according to the first aspect, the current limiting means includes a resistor connected in series with the protection means 16. . (5) The current controlling element driving device according to the fifth aspect of the present invention includes a current controlling transistor T1 for supplying a driving current to an inductive load L1 connected to a driving terminal (emitter terminal); The driving means 105 for driving the current control transistor T1 by the inverter using the MOS transistor 52, and the direction in which the current control transistor T1 drives the inductive load L1 using the diode 52a parasitic on the MOS transistor 52. The current generated by the back electromotive force generated from the inductive load L1 so as to turn on in the reverse direction is supplied to the control terminal (base terminal) of the current control transistor T1
52a, which is provided separately to the protection means 52a, and a current limiting means having a higher impedance than the protection means 52a which supplies the current generated by the back electromotive force to the control terminal (base terminal) of the current control type transistor T1 by limiting the current. 11,
12, the switching means 15 interposed between the driving means 105 and the control terminal (base terminal), and the protection means 52 when the current control transistor T1 is turned on in the reverse direction.
a, the current is supplied to the control terminal (base terminal) of the current control transistor T1 via the current control transistor T1.
The above-mentioned object is achieved by providing a control means 106 for switching and controlling the switching means 15 so as to supply a current to a control terminal (base terminal) via the terminals 1 and 12.

In the section of the means for solving the above-mentioned problems, the present invention is associated with the drawings of the embodiments for easy understanding of the present invention, but the present invention is not limited to the embodiments. is not.

[0008]

As described in detail above, claims 1 to 5
According to the invention described in (1), the current control transistor is turned on in the reverse direction, thereby protecting the current control transistor from the back electromotive force generated by the inductive load connected to the driving terminal. In the device, the current supplied to the control terminal of the current control transistor is limited. Therefore, when electric charges are accumulated in the current control type transistor in accordance with the current flowing through the control terminal, the electric charge accumulated in the current control type transistor is reduced by the limited amount of the current. As a result, since the current-controlled transistor is turned off earlier, a large current that passes through the current-controlled transistor is less likely to flow, so that the loss due to such a through-current can be suppressed and the current can be reduced by the through-current. The control type transistor is prevented from being damaged.

In particular, according to the present invention, the impedance of the current supplied to the control terminal of the current control type transistor when the current control type transistor is turned on in the reverse direction is lower than when the current control type transistor is turned on in the reverse direction. Increased the limit. Therefore, the current control type transistor is turned on in the reverse direction faster than in the case where the current supplied to the control terminal of the current control type transistor is always limited. As a result, the current supplied to the control terminal of the current control transistor decreases, so that the charge stored in the current control transistor decreases as described above, and a large current flows through the current control transistor. The loss due to such a through current can be suppressed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a circuit diagram of a current control type semiconductor device according to a first embodiment of the present invention, which is a part of an H-bridge circuit for controlling an induction motor, for example. In FIG. 1, current-controlled switching transistors (hereinafter simply referred to as driving transistors) T1 and T2 are switching devices that supply a driving current to an inductive load L1 such as a motor, and are each connected to a base terminal. Drive circuit 1
Driven by 3, 33. The power supply voltage V1 is connected to the collector terminal of the driving transistor T1, and the emitter terminal of the driving transistor T2 is grounded. An inductive load L1 is connected between the emitter terminal of the driving transistor T1 and the collector terminal of the driving transistor T2.

The emitter terminal of the driving transistor T1
Between the base terminals, a circulating diode 11 and a diode 12 are connected in series. The diodes 11 and 12 each have an anode connected to the emitter terminal of the driving transistor T1 and a cathode connected to the base terminal of the driving transistor T1.

The emitter terminal of the driving transistor T2
Similarly to the driving transistor T1, a circulating diode 31 and a diode 32 are connected in series between the base terminals. The diodes 31 and 32 have an anode connected to the emitter terminal side of the driving transistor T2 and a cathode connected to the base terminal side of the driving transistor T2, respectively.

FIG. 2 shows an example of a circuit constituting the driving circuits 13 and 33. In FIG. 2, drive circuits 13 and 33 include a switching transistor 21 and a resistor 2
2 and a impedance adjustment circuit IA including a transistor 24, a capacitor 23, a resistor 25, and a diode 26. The switching circuit SC outputs an output terminal 27 according to the level of the voltage signal input from the input terminal 20 of the drive circuits 13 and 33.
Outputs a driving current for driving the driving transistors T1 and T2. The impedance adjustment circuit IA changes the impedance between the output terminals of the drive circuits 13 and 33 and the ground based on the level of the voltage signal input from the input terminal 20.

The operation of the drive circuit 13 will be described. When a high-level voltage signal is input to the input terminal 20, the switching transistor 21 of the switching circuit SC is turned on, so that a driving current flows through the resistor 22 and the diode 26. This drive current is supplied from the output terminal 27 to the base terminal of the drive transistor T1 (FIG. 1) to drive the drive transistor T1 (FIG. 1). At this time, by charging the capacitor 23 of the impedance adjustment circuit IA, the transistor 24 is turned on after a lapse of a predetermined time. When the transistor 24 is turned on, the impedance between the output terminal 27 and the ground, that is, the impedance between the base terminal of the driving transistor T1 (FIG. 1) and the ground decreases.

Next, when a low-level voltage signal is input to the input terminal 20 of the drive circuit 13, the switching transistor 21 is turned off, so that the output terminal 27 is connected to the base terminal of the drive transistor T1 (FIG. 1). The drive current stops flowing. At this time, the electric charge accumulated in the capacitor 23 is discharged through the transistor 24 and the resistor 25, and the on state of the transistor 24 is maintained for a while after the switching transistor 21 is turned off. That is, for a while after the driving transistor T1 (FIG. 1) is turned off, the driving transistor T1 is turned off.
1 (FIG. 1) maintains a low impedance between the base terminal and the ground. Therefore, by utilizing this period, it is possible to quickly extract the charge accumulated in the collector region of the driving transistor T1 (FIG. 1) to the base region. As a result, the turn-off time of the driving transistor T1 (FIG. 1) is reduced.

When the discharge of the capacitor 23 is completed, no current flows to the base terminal of the transistor 24, and the transistor 24 is turned off. As a result, the impedance between the base terminal and the ground of the driving transistor T1 (FIG. 1) increases.

The driving circuit 33 operates similarly to the driving circuit 13. That is, a driving current for driving the driving transistor T2 (FIG. 1) is output from the output terminal 27 in accordance with the level of the voltage signal input to the input terminal 20 of the driving circuit 33, and the driving current is input to the input terminal 20 of the driving circuit 33. The impedance between the base terminal and the ground of the driving transistor T2 (FIG. 1) is changed based on the level of the input voltage signal.

The operation of the above-described current control type semiconductor device will be described in detail. -Upper Arm-FIG. 3 shows an upper arm portion of FIG.
3 and the signal Sig33 output from the output terminal 27 of the driving circuit 33.
It is a time chart. Output signal Sig of drive circuit 13
When 13 goes high (t1 in FIG. 3), a drive current flows through the base terminal of the drive transistor T1, the drive transistor T1 turns on in the forward direction, and a current flows in the direction indicated by Z in FIG. At this time, the impedance between the base terminal and the ground of the driving transistor T1 is reduced by the operation of the impedance adjusting circuit IA in the driving circuit 13 described above.

When the output signal Sig13 of the drive circuit 13 goes low (t2 in FIG. 3), no drive current flows through the base terminal of the drive transistor T1, and the drive transistor T1 turns off. Output signal Si of control circuit 13
g13 changes to low level for a while, that is,
For a while after the driving transistor T1 is turned off, the impedance adjustment circuit in the driving circuit 13 described above is used.
By the action of IA, the state where the impedance between the base terminal and the ground of the driving transistor T1 is low is maintained. During this period, the electric charge accumulated in the collector region of the driving transistor T1 is drawn out in the direction shown in FIG. 1D via the base terminal of the driving transistor T1. When the discharge of the capacitor 23 (FIG. 2) of the impedance adjustment circuit IA ends, the impedance between the base terminal and the ground of the driving transistor T1 increases.

On the other hand, in FIG. 1, considering the operation of the lower arm portion, the electric charge stored in the collector region of the driving transistor T1 is extracted to turn off the driving transistor T1. When the driving transistor T2 is turned on from the off state by the driving circuit 33 (t11 in FIG. 3), a current flows in the direction indicated by A in FIG. Thereafter, when the driving transistor T2 is turned off by the driving circuit 33 (t3 in FIG. 3),
Back electromotive force is generated from the inductive load L1, and the potential at point P in FIG. 1 rises due to the back electromotive force. The potential at point P is
｛(Potential of base terminal of driving transistor T1) + (forward drop voltage of diode 11) + (diode 1
2, the diodes 11 and 12 are forward-biased, and a current flows in the direction indicated by C → E in FIG.

At this time, as described above, as the impedance between the base terminal and the ground of the driving transistor T1 is increased, the driving transistor T1 is turned on in the reverse direction, and the driving transistor T1 is turned on in the reverse direction from the emitter terminal to the collector terminal. In other words, the current flows in the direction shown in FIG. In the steady state, current flows mainly in the direction indicated by B, and a small amount of current flows from the emitter terminal to the base terminal, that is, the direction indicated by C → E.

Further, the diode 11 and the diode 12
Are connected in series, the impedance is higher than in the case of one diode, so that the current flowing from the emitter terminal to the base terminal is less likely to flow. As a result, the amount of charge flowing from the base terminal into the driving transistor T1 is reduced.

When the drive circuit 33 outputs a signal to turn on the drive transistor T2 again while the current flowing in the directions indicated by B and C, that is, the circulating current is flowing (t4 in FIG. 3). , The driving transistor T2 is turned on. When the driving transistor T2 is turned on, the driving transistor T1 shifts to the reverse recovery operation. At this point, although the impedance between the base terminal and the ground of the driving transistor T1 is in a high state, the electric charge accumulated in the driving transistor T1 is suppressed as described above. As a result,
The driving transistor T1 is immediately turned off,
A large through current flowing from the collector terminal of the driving transistor T1 to the emitter terminal can be reduced.

Thereafter, when the driving transistor T2 is turned off again by the driving circuit 33 (t5 in FIG. 3), the driving transistor T1 is turned on in the reverse direction, similarly to the case of the above-described timing t3, and the emitter terminal is turned on. Circulating current flows from the collector terminal to the collector terminal. After that, when the output signal Sig13 of the drive circuit 13 goes high (t6 in FIG. 3), a drive current flows through the base terminal of the drive transistor T1. As a result, when the driving transistor T1 is turned on in the forward direction, the same operation as at the timing t1 described above is repeated.

FIG. 4 is a time chart of the signal Sig 33 output from the output terminal 27 of the drive circuit 33 and the signal Sig 13 output from the output terminal 27 of the drive circuit 13. FIG.
FIG. 2 is a diagram illustrating an operation of a lower arm portion of the circuit diagram of FIG. 1. In FIG. 4, when the output signal Sig33 of the drive circuit 33 becomes high level (t1 ′ in FIG. 4), a drive current flows through the base terminal of the drive transistor T2, and the drive transistor T2 turns on in the forward direction. Current flows in the direction indicated by G in FIG. At this time, the impedance between the base terminal and the ground of the driving transistor T2 is reduced by the action of the impedance adjusting circuit IA in the driving circuit 33 described above.

When the output signal Sig33 of the driving circuit 33 goes low (t2 'in FIG. 4), the driving transistor T2
No drive current flows through the base terminal of the drive transistor T2, and the drive transistor T2 is turned off. Output signal of control circuit 33
For a while after the Sig 33 changes to the low level, that is, for a while after the driving transistor T2 is turned off, the operation of the impedance adjustment circuit IA in the driving circuit 33 described above causes the base terminal of the driving transistor T2 to have a negative polarity. The state where the impedance between the grounds is low is maintained.
During this period, the electric charge accumulated in the collector region of the driving transistor T2 is drawn out to the ground through the base terminal of the driving transistor T2. When the discharge of the capacitor 23 (FIG. 2) of the impedance adjustment circuit IA is completed,
The impedance between the base terminal and the ground of the driving transistor T2 increases.

On the other hand, in FIG. 5, considering the operation of the upper arm portion, the electric charge accumulated in the collector region of the driving transistor T2 is drawn out to turn off the driving transistor T2. When the drive transistor T1 is turned on from the off state by the drive circuit 13 (t11 'in FIG. 4), a current flows in the direction indicated by D in FIG. Thereafter, when the driving transistor T1 is turned off by the driving circuit 13 (t in FIG. 4).
3 '), a back electromotive force is generated from the inductive load L1, and the back electromotive force lowers the potential at point P in FIG. When the potential at the point P becomes lower than the potential of the emitter terminal of the driving transistor T2, that is, the ground potential, the potential of the base terminal of the driving transistor T2 becomes lower than the potential of the emitter terminal. When the potential of the base terminal of the driving transistor T2 is
When it is lower than {(ground potential)-(forward drop voltage of diode 32)-(forward drop voltage of diode 31)}, diodes 31 and 32 are forward-biased, and the direction shown by I → J in FIG. Current flows through

At this time, as described above, as the impedance between the base terminal and the ground of the driving transistor T2 is increased, the driving transistor T2 is turned on in the reverse direction, and the driving transistor T2 is turned on in the reverse direction from the emitter terminal to the collector terminal. , That is, the current flows in the direction indicated by H in FIG. In the steady state, current flows mainly in the direction indicated by H, and a small amount of current flows from the emitter terminal to the base terminal, that is, in the direction indicated by I → J.

Further, a diode 31 and a diode 32
Are connected in series, the impedance is higher than in the case of one diode, so that the current flowing from the emitter terminal to the base terminal is less likely to flow. As a result, the charge flowing from the base terminal into the driving transistor T2 is reduced.

When the drive circuit 13 outputs a signal to turn on the drive transistor T1 again while the current flowing in the directions indicated by H and I, that is, the circulating current is flowing (t4 'in FIG. 5). ), The driving transistor T1 is turned on. Driving transistor T1
Is turned on, the driving transistor T2 shifts to a reverse recovery operation. At this point, although the impedance between the base terminal and the ground of the driving transistor T2 is in a high state, the electric charge accumulated in the driving transistor T2 is reduced as described above. As a result, the driving transistor T2 is immediately turned off, and a large through current flowing from the collector terminal to the emitter terminal of the driving transistor T2 can be reduced.

Thereafter, when the driving transistor T1 is turned off again by the driving circuit 13 (t5 'in FIG. 5),
As in the case of the timing t3 'described above, the driving transistor T2 is turned on in the reverse direction, and a circulating current flows from the emitter terminal to the collector terminal. After that, when the output signal Sig33 of the drive circuit 33 becomes high level (t6 'in FIG. 5), a drive current flows through the base terminal of the drive transistor T2. As a result, when the driving transistor T2 is turned on in the forward direction, the same operation as the above-described timing t1 'is repeated.

According to the first embodiment described above,
The following operational effects can be obtained. (1) The diode 11 and the diode 12 are connected in series between the base terminal and the emitter terminal of the driving transistor T1, and the diode 31 and the diode 32 are connected in series between the base terminal and the emitter terminal of the driving transistor T2. . Therefore, the impedance can be increased as compared with the case where one diode is connected.
When the driving transistors T1 and T2 are turned on in the reverse direction, the current flowing from the respective base terminals is reduced, and the electric charge stored in the driving transistors T1 and T2 can be reduced. For this reason, the reverse recovery time of the driving transistors T1 and T2 is shortened and the transistor is immediately turned off, so that a large through current flowing from the collector terminal to the emitter terminal of the driving transistors T1 and T2 can be reduced. . As a result, it is possible to obtain an effect of reducing useless loss and protecting the driving transistor that is not performing the reverse recovery operation.

(2) Since the upper and lower arms are formed into symmetrical circuits, the driving transistors T1 and T2
1 is different from the operation of the inductive load L1 in FIGS. 1 and 5,
The effect of the above (1) is obtained. (3) Because the on state of the transistor 24 is maintained for a while after the switching transistor 21 is turned off by the impedance adjustment circuit IA,
The impedance between the base terminals and the ground of the driving transistors T1 and T2 is kept low. As a result,
Since the charges accumulated in the collector regions of the driving transistors T1 and T2 can escape to the base region, the turn-off time of the driving transistors T1 and T2 is reduced.

In the above description, both the upper and lower arms of the current control type semiconductor device, that is, the driving transistor T1
For both T2 and T2, a plurality of diodes were respectively connected in series between the emitter terminal and the base terminal. However, the driving transistor T1
And at least one of T2 and T2, a plurality of diodes may be connected in series between the emitter terminal and the base terminal. In this case, since the through current of the driving transistor having the diode connected in series decreases, it is possible to prevent the other driving transistor from being destroyed by the through current.

In the above description, the diodes 11 and 12 and the diodes 31 and 32 in FIGS.
Are connected in series two by two, but three or more diodes may be connected in series.

Second Embodiment In the second embodiment, a Zener diode and a diode are connected in series between the base terminal and the emitter terminal of the driving transistor as compared with the first embodiment. Is different. FIG. 6 is a circuit diagram of a current control type semiconductor device according to the second embodiment. The same components as those in the first embodiment are represented by the same symbols. In FIG. 6, a circulating diode 16 and a Zener diode 17 for increasing impedance are connected in series between an emitter terminal and a base terminal of the driving transistor T1. The anode of the diode 16 is connected to the emitter terminal of the driving transistor T1, and the anode of the Zener diode 17 is connected to the base terminal of the driving transistor T1.

The emitter terminal of the driving transistor T2
Similarly to the driving transistor T1, a circulating diode 36 and a zener diode 37 for increasing impedance are connected in series between the base terminals. The anode of the diode 36 is connected to the emitter terminal of the driving transistor T2, and the anode of the Zener diode 37 is connected to the base terminal of the driving transistor T2. The diodes 16 and 36 are provided so that a sufficient drive current flows through the base terminals of the drive transistors T1 and T2 when the drive transistors T1 and T2 are turned on in the forward direction, respectively.

The operation of the above-described current control type semiconductor device will be described in detail with reference to the time chart of FIG. Note that, similarly to the first embodiment, the upper arm for driving the driving transistor T1 and the lower arm for driving the driving transistor T2 are symmetrical. Therefore, in this description, only the upper arm will be described.

When the output signal Sig13 of the drive circuit 13 goes high (t1 in FIG. 3), a drive current flows through the base terminal of the drive transistor T1 and the drive transistor T1
Turn on in the forward direction, and a current flows in the direction indicated by Z in FIG. At this time, the impedance between the base terminal and the ground of the driving transistor T1 is reduced by the operation of the impedance adjusting circuit IA in the driving circuit 13 described above.

When the output signal Sig13 of the drive circuit 13 goes low (t2 in FIG. 3), no drive current flows through the base terminal of the drive transistor T1, and the drive transistor T1 is turned off. Output signal Si of control circuit 13
g13 changes to low level for a while, that is,
For a while after the driving transistor T1 is turned off, the impedance adjustment circuit in the driving circuit 13 described above is used.
By the action of IA, the state where the impedance between the base terminal and the ground of the driving transistor T1 is low is maintained. During this period, the electric charge accumulated in the collector region of the driving transistor T1 is drawn out in the direction shown in FIG. 6D via the base terminal of the driving transistor T1. When the discharge of the capacitor 23 (FIG. 2) of the impedance adjustment circuit IA ends, the impedance between the base terminal and the ground of the driving transistor T1 increases.

On the other hand, in FIG. 6, considering the operation of the lower arm portion, the electric charge accumulated in the collector region of the driving transistor T1 is extracted to turn off the driving transistor T1. When the driving transistor T2 is turned on from the off state by the driving circuit 33 (t11 in FIG. 3), a current flows in the direction indicated by A in FIG. Thereafter, when the driving transistor T2 is turned off by the driving circuit 33 (t3 in FIG. 3),
A counter electromotive force is generated from the inductive load L1, and the potential at the point P in FIG. 6 increases due to the counter electromotive force. The potential at point P is
When the voltage is higher than {(potential of the base terminal of the driving transistor T1) + (zener voltage of the zener diode 17) + (forward drop voltage of the diode 16)}, the diode 16 is forward-biased and C → E in FIG. A current flows in the direction shown by.

At this time, as described above, as the impedance between the base terminal and the ground of the driving transistor T1 is increased, the driving transistor T1 is turned on in the reverse direction, and the driving transistor T1 is turned on in the reverse direction from the emitter terminal to the collector terminal. In other words, the current flows in the direction shown in FIG. In the steady state, current flows mainly in the direction indicated by B, and a small amount of current flows from the emitter terminal to the base terminal, that is, the direction indicated by C → E.

Further, by connecting the Zener diode 17 and the diode 16 in series, the diode becomes 1
Since the impedance is higher than in the two cases, the current flowing from the emitter terminal to the base terminal is less likely to flow. As a result, the driving transistor T1 is connected from the base terminal.
The charge flowing into the inside is reduced.

When the drive circuit 33 outputs a signal to turn on the drive transistor T2 again while the current flowing in the directions indicated by B and C, that is, the circulating current is flowing (t4 in FIG. 3). , The driving transistor T2 is turned on. When the driving transistor T2 is turned on, the driving transistor T1 shifts to the reverse recovery operation. At this point, although the impedance between the base terminal and the ground of the driving transistor T1 is in a high state, the electric charge accumulated in the driving transistor T1 is suppressed as described above. As a result,
The driving transistor T1 is immediately turned off,
A large through current flowing from the collector terminal of the driving transistor T1 to the emitter terminal can be reduced.

Thereafter, when the driving transistor T2 is turned off again by the driving circuit 33 (t5 in FIG. 3), the driving transistor T1 is turned on in the opposite direction as in the case of the above-mentioned timing t3, and the emitter terminal is turned on. Circulating current flows from the collector terminal to the collector terminal. After that, when the output signal Sig13 of the drive circuit 13 goes high (t6 in FIG. 3), a drive current flows through the base terminal of the drive transistor T1. As a result, when the driving transistor T1 is turned on in the forward direction, the same operation as at the timing t1 described above is repeated.

According to the second embodiment described above,
A zener diode 17 and a diode 16 are connected in series between the base terminal and the emitter terminal of the driving transistor T1, and a zener diode 37 and a diode 3 are connected between the base terminal and the emitter terminal of the driving transistor T2.
6 were connected in series. Therefore, similarly to the first embodiment, the impedance can be increased as compared with the case where one diode is connected, so that the electric charge accumulated in the driving transistors T1 and T2 can be reduced. Therefore, the driving transistors T1 and T1
Since the reverse recovery time of the transistor 2 is shortened and the transistor is immediately turned off, a large through current flowing from the collector terminal to the emitter terminal of the driving transistors T1 and T2 can be reduced. As a result, it is possible to obtain an effect of reducing useless loss and protecting the driving transistor that is not performing the reverse recovery operation.

In the above-described current control type semiconductor device,
A resistor can be used instead of the Zener diodes 17 and 37. In this case, the impedance between the base terminal and the emitter terminal of the driving transistors T1 and T2 increases due to the resistance of the resistor. And FIG.
When the potential at point P rises, the potential at point P is higher than {(potential of the base terminal of the driving transistor T1) + (voltage drop by resistor) + (forward drop voltage of diode 16)}. Then, the diode 16 is forward-biased and a current flows in the direction indicated by C → E in FIG.

Third Embodiment A third embodiment is different from the first and second embodiments in that the driving circuit of the driving transistor is different, and that the driving circuit and the base of the driving transistor are different. The difference is that a switch is provided between the terminal. Note that, similarly to the first and second embodiments, the driving transistor T1
Since the upper arm for driving the driving transistor T2 and the lower arm for driving the driving transistor T2 are symmetrical, only the upper arm will be described in this description.

FIG. 7 is a circuit diagram of a current control type semiconductor device according to the third embodiment, in which the lower arm portion is omitted. 7, the current control type semiconductor device includes a driving transistor T1 and a driving circuit 105 for driving the driving transistor T1, and drives an inductive load L1. The power supply voltage V1 is connected to the collector terminal of the driving transistor T1, and the inductive load L1 and the collector terminal of a driving transistor (not shown) forming the lower arm are connected to the emitter terminal of the driving transistor T1.

The P-type MOS switch 15 is provided between the output terminal 53 of the driving circuit 105 and the base terminal of the driving transistor T 1, and the P-type MOS switch 15 is controlled to open and close by the control circuit 106. Control circuit 106
Uses the timing of the drive signal of the drive transistor T1 input to the input terminal 50 of the drive circuit 105 to open and close the P-type MOS switch 15 in accordance with the on / off state of the drive transistor T1 as described later. I do. As in the first embodiment, a circulating diode 11 and a diode 12 are connected in series between the base terminal and the emitter terminal of the driving transistor T1. The diodes 11 and 12 have an anode connected to the emitter terminal of the driving transistor T1 and a cathode connected to the base terminal of the driving transistor T1, respectively.

The drive circuit 105 is a circuit replacing the drive circuit 13 in the first and second embodiments, and drives the drive transistor T1 to turn on / off. The drive circuit 105 is floating with respect to the ground potential,
It includes a positive voltage source V3 based on the potential of the emitter terminal of the driving transistor T1, a switching P-type MOS switch 51, and an N-type MOS switch 52. The P-type MOS switch 51 and the N-type MOS switch 52 have parasitic diodes 51a and 52a, respectively, in parallel with the switches due to the structure of the device. Drive circuit 10
5 is connected to the base terminal of the driving transistor T1, and the lower output terminal 54 of the driving circuit 105 is connected to the emitter terminal of the driving transistor T1.

In the drive circuit 105, when the input terminal 50 goes low, the P-type MOS switch 51 is turned on,
The N-type MOS switch 52 is turned off, and the driving transistor T1 is turned on. On the other hand, when the input terminal 50 goes high, the P-type MOS switch 51 is turned off and the N-type
The switch 52 is turned on and the driving transistor T1 is turned off. The control circuit 106 includes a driving transistor T1
Is in the reverse ON state due to the back electromotive force generated in the inductive load L1 described above, a high level signal is output to turn off the P-type MOS switch 15, and the driving transistor T1 is turned ON in the reverse direction. Otherwise, open / close control is performed so that a low-level signal is output to turn on the P-type MOS switch 15.

The operation of the above-described current control type semiconductor device will be described in detail with reference to the time chart of FIG. In the third embodiment, the output signal Sig13 of the drive circuit 13 in FIG.
3 and the output signal Sig33 of the drive circuit 33 may be replaced with the output signal of the drive circuit for driving the drive transistor T2 (not shown). When the output signal Sig53 of the drive circuit 105 becomes high level (t1 in FIG. 3), at this time, the P-type MOS switch 1
5 is on, the drive current flows to the base terminal of the drive transistor T1, the drive transistor T1 turns on in the forward direction, and the current flows in the direction indicated by Z in FIG.

When the output signal Sig53 of the drive circuit 105 goes low (t2 in FIG. 3), the drive transistor T1
No drive current flows through the base terminal of the drive transistor T1, and the drive transistor T1 is turned off. On the other hand, considering the operation of the lower arm portion (not shown), the drive transistor (not shown) is turned on from the off state by the drive circuit (not shown) while the drive transistor T1 is being turned off. Then (t11 in FIG. 3), a current flows in the direction indicated by A in FIG. Thereafter, when a drive transistor (not shown) is turned off by a drive circuit (not shown) (FIG. 3).
At t3), a back electromotive force is generated from the inductive load L1, and the back electromotive force causes the potential at point P in FIG. 7 to rise. At this point, since the P-type MOS switch 15 is turned on, the potential at the point P becomes ｛(the potential of the base terminal of the driving transistor T1) + (the forward drop of the diode 52a existing in the N-type MOS switch 52). Voltage)｝, the diode 52a is forward-biased and D
→ A current flows in the direction indicated by E.

As a result, the driving transistor T1 is turned on in the reverse direction, and a current flows in the reverse direction from the emitter terminal to the collector terminal, that is, in the direction shown in FIG. 7B. As described above, the driving transistor T1
Are turned on in the reverse direction, the P-type MOS switch 15 is controlled to be turned off. Therefore, the path of the current flowing into the base terminal of the driving transistor T1 is only the path having a high impedance in which the diode 11 and the diode 12 are connected in series, that is, the path indicated by C → E in FIG. The current flowing from the terminal to the base terminal is less likely to flow. As a result, the amount of charge flowing from the base terminal into the driving transistor T1 is reduced.

When the driving transistor T2 is turned on again by a driving circuit (not shown) in the state where the current flowing in the directions indicated by B and C, that is, the circulating current is flowing (t4 in FIG. 3), The transistor T1 shifts to the reverse recovery operation. As described above, the electric charge stored in the driving transistor T1 is suppressed to a small level. As a result, the driving transistor T1 is immediately turned off, and penetrates from the collector terminal of the driving transistor T1 to the emitter terminal. Large through current can be reduced.

Thereafter, when the drive transistor (not shown) is turned off again by the drive circuit (not shown) (t5 in FIG. 3), the drive transistor T1 is turned on in the reverse direction, as in the case of the above-described timing t3. Thus, a circulating current flows from the emitter terminal to the collector terminal. Further thereafter, the output signal Sig53 of the drive circuit 105
Becomes high level (t6 in FIG. 3), a drive current flows through the base terminal of the drive transistor T1. As a result, when the driving transistor T1 is turned on in the forward direction,
The same operation as at the timing t1 described above is repeated.

According to the third embodiment described above,
The following operational effects can be obtained. A voltage source V3 between the base terminal and the emitter terminal of the driving transistor T1 with reference to the potential of the floating emitter terminal;
A driving circuit 105 having a P-type MOS switch 51 and an N-type MOS switch 52;
Diodes 11 and 12 were provided. Until the driving transistor T1 turns on in the reverse direction, the P-type MO
By turning on the S switch 15, the current path flowing to the base terminal of the driving transistor T1 is changed to a path having a low impedance (D in FIG. 7), and is quickly turned on in the reverse direction. While the driving transistor T1 is turned on in the reverse direction, the P-type
Turn off the OS switch 15 and turn on the driving transistor T1.
The current path flowing through the base terminal is only a path having a high impedance by the diodes 11 and 12 (C in FIG. 7). For this reason, the reverse recovery time of the driving transistor T1 is shortened and the transistor is immediately turned off, so that a large through current flowing from the collector terminal to the emitter terminal of the driving transistor T1 can be reduced. As a result, it is possible to obtain an effect of reducing useless loss and protecting the driving transistor that is not performing the reverse recovery operation.

In the above description, the drive circuit 105 is configured by a simple inverter. However, even when a drive circuit having another configuration is used, the terminal having the lower voltage is connected to the terminal having the higher voltage. The present invention can be applied when a current path as shown by D in FIG.

Further, the two diodes 11 and 12 are connected in series in order to increase the impedance between the base terminal and the emitter terminal of the driving transistor T1, but will be described in the first and second embodiments. As described above, even if one of the diodes is replaced with a Zener diode or a resistor, the same effect as in the present embodiment can be obtained.

Fourth Embodiment A fourth embodiment is different from the third embodiment in that a plurality of N-type MOS switches are used in a driving circuit for driving a driving transistor. The switch between the drive transistor and the base terminal of the drive transistor is omitted,
And that the diode between the base terminal and the emitter terminal of the driving transistor is omitted. Note that, similarly to the first to third embodiments, the driving transistor T
1 is symmetrical with the lower arm that drives the driving transistor T2, and therefore, only the upper arm will be described in this description.

FIG. 8 is a circuit diagram of the current control type semiconductor device according to the fourth embodiment, in which the lower arm portion is omitted. 8, the current control type semiconductor device includes a driving transistor T1, a driving circuit 107 for driving the driving transistor T1, and drives an inductive load L1. The power supply voltage V1 is connected to the collector terminal of the driving transistor T1, and the inductive load L1 and the collector terminal of a driving transistor (not shown) forming the lower arm are connected to the emitter terminal of the driving transistor T1.

The drive circuit 107 is a circuit replacing the drive circuit 105 in the third embodiment, and drives the drive transistor T1 to turn on / off. Drive circuit 10
Reference numeral 7 denotes a positive voltage source V3 floating with respect to the ground potential and based on the potential of the emitter terminal of the driving transistor T1, and a P-type MOS switch 7 for switching.
1 and two N-type MOS switches 72 connected in series.
And 73. P-type MOS switch 71, N-type M
The OS switches 72 and 73 include parasitic diodes 71a, 72a and 7
3a are present. The output terminal 74 of the drive circuit 107 on the higher voltage side is connected to the base terminal of the drive transistor T1, and the output terminal 75 of the drive circuit 107 on the lower voltage side is connected to the emitter terminal of the drive transistor T1.

In the drive circuit 107, when the input terminal 70 goes low, the P-type MOS switch 71 is turned on,
The N-type MOS switches 72 and 73 are turned off, and the driving transistor T1 is turned on. On the other hand, when the input terminal 70 goes high, the P-type MOS switch 71 is turned off,
The N-type MOS switches 72 and 73 are turned on, and the driving transistor T1 is turned off.

The operation of the above-described current control type semiconductor device will be described with reference to the time chart of FIG. 3 focusing on parts different from the third embodiment. At time t3 in FIG. 3, when the driving transistor (not shown) is turned off by the driving circuit (not shown), the back electromotive force is generated from the inductive load L1. The potential at point P in FIG. 8 increases due to the back electromotive force. The potential at the point P is ｛(potential of the base terminal of the driving transistor T1) + (N-type MOS switch 72
(The forward drop voltage of the diode 72a existing at
+ (Diode 73 existing in N-type MOS switch 73
a), the diodes 72a and 73a are forward-biased and C → in FIG.
A current flows in the direction indicated by E.

As a result, the driving transistor T1 is turned on in the reverse direction, and a current flows in the reverse direction from the emitter terminal to the collector terminal, that is, in the direction shown in FIG. 8B. The path of the current flowing into the base terminal of the driving transistor T1 is a diode 72a and a diode 7a.
3a is connected in series and has a high impedance, so that the current flowing from the emitter terminal to the base terminal hardly flows. As a result, the amount of charge flowing from the base terminal into the driving transistor T1 is reduced, and the reverse recovery time of the driving transistor T1 is reduced.

According to the fourth embodiment described above,
N-type MOS switches 72 and 73 in drive circuit 107
Were connected in a two-tiered manner. Therefore, N-type M
Diode 72 parasitic to OS switches 72 and 73
Since a and 73a increase the impedance between the base terminal and the emitter terminal of the driving transistor T1, the charge accumulated in the driving transistor T1 when the driving transistor T1 is turned on in the reverse direction can be reduced. Therefore, the driving transistor T
Since the reverse recovery time of the transistor 1 is shortened and the transistor is immediately turned off, a large through current flowing from the collector terminal to the emitter terminal of the driving transistor T1 can be reduced. As a result, it is possible to obtain an effect of reducing useless loss and protecting the driving transistor that is not performing the reverse recovery operation. Furthermore, parasitic diodes 72a and 73a
Is used, so the mounting space can be reduced as compared with the case where a diode is separately provided, so that the size can be reduced.
Cost can also be reduced.

In the above description, the N-type MOS switch 72
And 73 are stacked in two stages, but the present invention is not limited to two stages, and may be formed by stacking three or more stages.

In the above description of the first to fourth embodiments, it is necessary to flow a large circulating current in the reverse direction from the emitter terminals of the driving transistors T1 and T2 to the collector terminals. And T2
Is desired to be sufficiently large. In this regard, the driving transistors T1 and T
2 is, for example, a general power bipolar transistor.
The semiconductor device disclosed in Japanese Patent Application Laid-Open Publication No. H10 (1995) is a current-controlled transistor, which is called a so-called GTBT, the reverse current amplification factor h′FE is substantially equal to the forward current amplification factor hFE. It is particularly effective as a driving transistor.

The correspondence between each component in the claims and each component in the embodiment of the invention will be described. The emitter terminal is a drive terminal, the drive transistor T1 is a current control transistor, the base terminal Is a control terminal, diodes 12, 16, 32, and 36 are protection means, diode 11, zener diode 17 and a resistor are current limiting means, P-type MOS switch 51 and N-type MOS switch 52 are MOS-type transistors,
The driving circuit 105 includes a P-type MOS switch 15
Is the switching means, the control circuit 106 is the control means,
Each corresponds.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a current control type semiconductor device according to a first embodiment.

FIG. 2 is a diagram illustrating an example of a circuit constituting drive circuits 13 and 33.

FIG. 3 is a time chart of signals of an upper arm portion of FIG. 1;

FIG. 4 is a time chart of signals of a lower arm portion of FIG. 1;

FIG. 5 is a diagram illustrating a lower arm portion of FIG. 1;

FIG. 6 is a circuit diagram of a current control type semiconductor device according to a second embodiment.

FIG. 7 is a circuit diagram of a current control type semiconductor device according to a third embodiment.

FIG. 8 is a circuit diagram of a current control type semiconductor device according to a fourth embodiment.

FIG. 9 is a circuit diagram showing a part of an H-bridge circuit provided with a protection circuit according to a conventional technique.

[Explanation of symbols]

11,12,16,31,32,36 ... Diode, 13,3
3, 105, 107: driving circuit of driving transistor, 1
5, 51, 71 ... P-type MOS switch, 17, 37 ... Zener diode, 52, 72, 73 ... N-type MOS switch,
15a, 51a, 52a, 71a, 72a, 73a: parasitic diode, 106: control circuit, L1
... Inductive load, T1, T2 ... Drive transistor,
V1, V3 ... voltage source

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshio Shimoda 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 5J055 AX27 AX32 AX55 AX64 BX16 CX13 CX20 DX04 DX53 DX60 DX84 EX04 EX07 EX11 EY01 EY10 EY12 EY13 EY17 EY21 EY29 EZ07 EZ21 EZ63 GX01 GX04

Claims (5)

[Claims] A current control transistor for supplying a drive current to an inductive load connected to a drive terminal; and a current control type transistor that is turned on in a direction opposite to a direction in which the current control type transistor drives the inductive load. A current control type element driving device comprising: protection means for supplying a current generated by a back electromotive force generated from an inductive load to a control terminal of the current control type transistor, wherein the current control type transistor is controlled via the protection means. A current control type element driving device, comprising: current limiting means for limiting a current supplied to a terminal. 2. The current controlling element driving device according to claim 1, wherein said current limiting means sets a forward direction of a current supplied to a control terminal of said current controlling transistor via said protection means. A current-control-type element driving device comprising at least one diode. 3. The current controlling element driving device according to claim 1, wherein said current limiting means reverses a direction of a current supplied to a control terminal of said current controlling transistor via said protection means. A driving device for a current control type device, comprising: a Zener diode described below. 4. The current controlling element driving device according to claim 1, wherein said current limiting means includes a resistor connected in series with said protection means. apparatus. 5. A current controlling transistor for supplying a driving current to an inductive load connected to a driving terminal; a driving means for driving the current controlling transistor by an inverter using a MOS transistor; A current generated by the back electromotive force generated from the inductive load is applied to the current control type transistor so that the current control type transistor is turned on in a direction opposite to a direction in which the inductive load is driven by using a diode parasitic on a MOS type transistor. Protection means for supplying the control terminal of the current control transistor, and a current limiting means having a higher impedance than the protection means, which is provided separately from the protection means and supplies the current by the back electromotive force to the control terminal of the current control transistor. A switching unit interposed between the driving unit and the control terminal; When the transistor is turned on in the reverse direction, a current is supplied to the control terminal of the current control type transistor through the protection means, and when the current control type transistor is turned on in the reverse direction, the current limiting means is supplied. And a control means for switching and controlling the switching means so as to supply a current to the control terminal via the control terminal.