Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Current driver
Reexamination Certificate
2002-06-19
2003-03-25
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Current driver
C327S112000, C327S427000, C327S389000
Reexamination Certificate
active
06538481
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving control device, a power converting device, a method of controlling the power converting device and a method of using the power converting device which are suitable for use as an inverter, and more particularly to an improvement in suppression of the influence of a noise pulse with a switching operation of a power switching element.
2. Description of the Background Art
FIG. 5
is a circuit diagram showing a structure of a conventional driving control device to be the background of the present invention. A driving control device
151
is constituted by a high breakdown voltage integrating circuit and comprises a pulse generator
51
, switching elements
52
and
53
, resistive elements
58
and
59
, a flip-flop circuit
54
, switching elements
55
and
56
, and an inverter element
57
. The pulse generator
51
alternately sends a pulse to two outputs A and B synchronously with an input signal sent to a terminal HIN.
A series circuit of the switching element
52
and the resistive element
58
constitutes a level shift circuit. Similarly, a series circuit of the switching element
53
and the resistive element
59
constitutes another level shift circuit. The level shift circuits invert, level-shift and transmit the pulse output from the pulse generator
51
to the flip-flop circuit
54
. The flip-flop circuit
54
is an RS flip-flop circuit, is set by a pulse sent to an input C and is reset by a pulse sent to an input D. The switching elements
55
and
56
and the inverter element
57
constitute a buffer circuit for amplifying an output signal of the flip-flop circuit
54
and outputting the amplified signal to a terminal HO.
When using the driving control device
151
, a control electrode of a power switching element
71
is connected through the terminal HO to a connecting portion of the switching elements
55
and
56
which are connected in series. Impedances
73
and
74
may be connected to the control electrodes of the power switching element
71
and a power switching element
72
. The power switching elements
71
and
72
are connected to each other in series. A load
81
is connected through a terminal OUT to a connecting portion of the power switching elements
71
and
72
. An inductive load such as a motor is usually used for the load
81
.
A power voltage of the pulse generator
51
is supplied from an external d.c. power supply connected to a terminal GND and a terminal Vcc. Power voltages of the flip-flop circuit
54
, the switching elements
55
and
56
and the inverter element
57
are supplied through terminals VS and VB. The terminal VS is connected to the terminal OUT. A set of level shift circuits having the switching elements
52
and
53
and the resistive elements
58
and
59
are connected to the terminals GND and VB. Consequently, these level shift circuits convert a level of a signal having an electric potential of the terminal GND as a reference potential into a level of a signal having an electric potential of the terminal VS as the reference potential.
FIG. 6
is a timing chart showing a signal of each portion in an operation of the driving control device
151
. In the following drawings, the designation of each portion in the device is exactly used as that of the signal in each portion. For example, the same designation “HIN” is added to a signal input to the terminal HIN.
When the signal input to the terminal HIN rises to have a high level, a pulse having the high level is sent from the output A of the pulse generator
51
so that a pulse having a low level is sent to the input C of the flip-flop circuit
54
. As a result, the flip-flop circuit
54
is set so that a signal of the terminal HO rises to have the high level. Consequently, the power switching element
71
is turned on. Correspondingly, a current I flowing in the power switching element
71
is started to be increased and a voltage V
DS
between a pair of main electrodes of the power switching element
71
is started to be dropped.
When the signal input to the terminal HIN falls to have the low level, the pulse having the high level is sent from the output B of the pulse generator
51
so that the pulse having the low level is sent to the input D of the flip-flop circuit
54
. As a result, the flip-flop circuit
54
is reset so that the signal of the terminal HO falls to have the low level. Consequently, the power switching element
71
is turned off. Correspondingly, the current I is started to be decreased and the voltage V
DS
is started to be raised. Thus, the power switching element
71
is turned on and off synchronously with the signal input through the terminal HIN.
In the conventional driving control circuit
151
, however, there has been a problem in that a noise pulse is induced to the input of the flip-flop circuit
54
with the switching operation of the power switching element
71
and the switching operation of the power switching element
71
is thereby influenced in some cases.
FIG. 7
is a timing chart showing the signal of each portion in the device which is obtained when the power switching element
71
is turned on, illustrating the influence of the noise pulse.
When a pulse is sent to the output A, the power switching element
71
is turned on so that the voltage V
DS
is dropped. The drop in the voltage V
DS
implies a rise in the electric potential of the terminal VS. If a voltage of a power supply to be connected to the power switching elements
71
and
72
is 300 V, the electric potential of the terminal VS is raised from 0 toward 300 V. If a change rate dV/dt of the voltage V
DS
is great, a current flows through the terminal VS by the action of a floating capacitance present in the driving control device
151
. As a result, the current flows through a parasitic capacitance of the switching element
53
so that a noise pulse having a low level is applied to the input D of the flip-flop circuit
54
in some cases.
When the noise pulse is applied to the input D, the flip-flop circuit
54
is reset. As a result, the signal of the terminal HO is returned to the low level so that the power switching element
71
is turned off. Consequently, the current I is started to be decreased so that the voltage V
DS
is started to be raised. More specifically, a normal turn-on operation of the power switching element
71
is blocked.
FIG. 8
is a timing chart showing a signal of each portion in the device which is obtained when the power switching element
71
is turned off, illustrating the influence of the noise pulse. When a pulse is sent to the output B, the power switching element
71
is turned off so that the voltage V
DS
is raised. The rise in the voltage V
DS
implies the drop in the electric potential of the terminal VS. If the voltage of the power supply to be connected to the power switching elements
71
and
72
is 300 V, the electric potential of the terminal VS is dropped from 300 V toward 0. If a change rate dV/dt of the voltage V
DS
is great, a current flows through the terminal VS by the action of a floating capacitance present in the driving control device
151
. As a result, the current flows through a parasitic capacitance of the switching element
52
so that a noise pulse having a low level is applied to the input C of the flip-flop circuit
54
in some cases.
When the noise pulse is applied to the input C, the flip-flop circuit
54
is set. As a result, the signal of the terminal HO is returned to the high level so that the power switching element
71
is turned on. Consequently, the current I is started to be increased so that the voltage V
DS
is started to be dropped. More specifically, a normal turn-off operation of the power switching element
71
is blocked. In the conventional driving control device
151
, thus, there has been a problem in that the influence of the noise pulse is caused with the switching operation of the power switching element
71
in some cases.
SUMMARY OF THE INVENTION
In order to eliminate the drawbacks of the con
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tran Toan
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