JP2001309670A - Driving circuit for inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a spike current which generates when a capacitor is charged making a current decreasing element needless. SOLUTION: An anode of a diode 9 is connected to an output terminal 13 which is directly connected to an output winding of a transformer 100, instead to an output terminal 12 for outputting an output voltage Vcc. When an electric charge is made to a capacitor 10 through the transformer 100, a diode 9, a capacitor 10 and a lower arm IGBT 3, the transformer 100 is operated as a constant current supply source. Therefore a peak value of a charging current IH to the capacitor 10 is limited by the primary current value flown in the input winding of the transformer 100 and there is no spike current generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device, and more particularly to a drive circuit of an inverter device using a charge pump type gate drive circuit as a gate drive circuit of a switching element for generating an inverter output.

[0002]

2. Description of the Related Art FIG. 6 shows a driving circuit of a first conventional inverter device, which shows a simplest half bridge as an example of an n-phase driving circuit. The drive circuit of this conventional inverter device includes a DC power supply 1 and an upper arm IGBT (Insulated Gate Bipol) connected to the positive electrode of the DC power supply 1.
ar Transistor) 2, a lower arm IGBT 3 connected in series with the upper arm IGBT 2, and an upper arm drive circuit 4.
A lower arm drive circuit 5; a lower arm drive circuit power supply 8 connected to the lower arm drive circuit 5;
And an output terminal 12 on the positive electrode side of the power supply 8 for the lower arm drive circuit.
And a diode 9 whose cathode is connected to a capacitor 10. The upper arm drive circuit 4 drives the upper arm IGBT 2 based on the upper arm on / off signal 6. Lower arm drive circuit 5
Is the lower arm IG based on the lower arm on / off signal 7.
BT3 is being driven. Specifically, when the lower arm on / off signal 7 is an ON command, the output voltage of the power supply 8 for the lower arm drive circuit is applied to the gate G of the lower arm IGBT 3 via the lower arm drive circuit 5, The lower arm IGBT3 is turned on. On the other hand, when the lower arm on / off signal 7 is an off command, the lower arm drive circuit 5 short-circuits the gate G and the emitter E of the lower arm IGBT 3 to turn off the lower arm IGBT 3.

The upper arm IGBT 2 is turned on / off in the same manner. However, unlike the lower arm IGBT 3, the power supplied to the upper arm drive circuit 4 is prepared as follows.

That is, when the lower arm IGBT 3 is turned on, the output voltage from the lower arm driving power supply 8 is charged to the capacitor 10 via the diode 9 along the path shown by the dotted line in FIG. Be prepared for on. That is, the electric charge stored in the capacitor 10 at this time is used as the power supply of the upper arm drive circuit 4.

[0005] Upper arm IGBT2 and lower arm IGBT3
Are complementarily turned on / off so as not to be turned on at the same time, so that when the lower arm IGBT3 is turned on, the upper arm IGBT2 is turned off. Accordingly, at this time, the capacitor 10 is charged by the lower arm drive circuit power supply 8 as described above. At this time, the upper arm on /
The off signal 6 outputs an off command, and the upper arm drive circuit 4 short-circuits the gate G and the emitter E of the upper arm IGBT 2.

Next, when the upper arm on / off signal 6 outputs an ON command, the upper arm drive circuit 4
0 is applied to the gate G and the emitter E of the upper arm IGBT2.
To turn on the upper arm IGBT2.

As described above, since the lower arm IGBT 3 is turned on, the output voltage of the lower arm drive power supply 8 is pumped to the capacitor 10 via the diode 9 and is used as the power supply for the drive circuit of the upper arm IGBT 2. . This method is called a charge pump method.

As shown in FIG. 6, a lower arm driving power supply 8 includes a transformer 100, a diode 104,
It is composed of a capacitor 105, a power MOSFET 101, a current detection resistor 103, and a control IC 102.

The transformer 100 includes an input winding and an output winding, and the input winding is connected to the DC power supply 1 via a power MOSFET 101 and a current detection resistor 103. The diode 104 has an anode connected to one end of the output winding of the transformer 100. Capacitor 105
Is connected between the cathode of the diode 104 and the negative of the output winding of the transformer 100. The control IC 102
Connected to the capacitor 105 and the current detection resistor 103,
The switching of the power MOSFET 101 is controlled.

In FIGS. 1, 2, 5 and 7, the configuration of the lower arm drive circuit power supply 8 is simplified and the transformer 100
, Only the diode 104 and the capacitor 105 are shown.

In the power supply 8 for the lower arm drive circuit, the DC power supply 1 is subjected to high frequency PWM switching by the power MOSFET 101 and DC / DC converted by the transformer 100 to generate a DC voltage Vcc at the output. Here, the diode 104 is a rectifying diode, and the capacitor 10
Reference numeral 5 denotes a smoothing capacitor, and the voltage across the capacitor 105 becomes the output voltage Vcc output from the output terminal 12. Further, the control IC 102 monitors the voltage of the output voltage Vcc, and controls the power MO so that the output voltage Vcc becomes a predetermined constant voltage regardless of the voltage fluctuation of the DC power supply 1 or the output current.
The switching of the SFET 101 is controlled. Further, the control IC 102 detects a current flowing through the power MOSFET 101 by measuring a voltage across the detection resistor 103, and detects a power MOSFE from an overcurrent flowing when the power is turned on.
T101 is prevented from being damaged, the power supply circuit is damaged due to an increase in the load current by indirectly detecting the load current,
The life is prevented from being shortened.

The drive circuit of this conventional inverter device is as follows:
A DC power supply 1 is provided based on an upper arm on / off signal 6 and a lower arm on / off signal 7 from a controller (not shown).
Are alternately turned on / off by the upper arm IGBT2 and the lower arm IGBT3 to obtain a positive potential and a negative potential of the DC power supply 1 as an output. Or get a three-phase AC output as a three-phase,
It is used in motor devices that control the rotation of motors and the like.

However, in the drive circuit of the first conventional inverter device described above, the charging current when charging the capacitor 10 is not limited, and a spike current is generated, and the diode 9 is destroyed. There was a problem.

A drive circuit of an inverter device for solving such a problem is described in Japanese Patent Application Laid-Open No. 4-138068. FIG. 8 shows a drive circuit of a second conventional inverter device described in Japanese Patent Application Laid-Open No. 4-138068. The configuration of the drive circuit of the second conventional inverter device is substantially the same as the drive circuit of the first conventional inverter device, except that the resistor is connected in series with the positive output of the power supply 8 for the lower arm drive circuit. A flow element 11 is added. The current-reducing element 11 does not need to be a resistor in particular, and the same effect can be obtained with other elements having a current-reducing action, such as a reactor and a semiconductor.

In the drive circuit of the second conventional inverter device, the spike current when the electric charge is charged in the capacitor 10 can be suppressed.
1 is required, so that there are problems such as an increase in the number of parts and deterioration in reliability.

[0016]

In the drive circuit of the above-mentioned conventional inverter device, a current reducing element for suppressing a spike current generated when a capacitor is charged with electric charge is required, and the number of components increases. There were problems such as deterioration of reliability.

An object of the present invention is to provide a drive circuit of an inverter device which can suppress a spike current generated when a capacitor is charged with a charge without requiring a current reducing element.

[0018]

In order to achieve the above object, a drive circuit for an inverter device according to the present invention comprises first and second switching elements connected in series and driven ON / OFF complementarily, A positive electrode and a negative electrode are provided at one end of the first switching element not connected to the second switching element and at one end of the second switching element not connected to the first switching element, respectively. One end of the input winding, comprising a connected DC power supply, first and second drive circuits for respectively turning on / off the first and second switching elements, and an input winding and an output winding. A transformer connected to the DC power supply, a third switching element provided between the other end of the input winding of the transformer and ground, and an anode at one end of the output winding. A connected first rectifier element and a first capacitor connected between the cathode of the first rectifier element and the other end of the output winding and supplying drive power to the first drive circuit. A driving circuit power source configured, one end of which is connected to the second driving circuit, and the other end of which is connected to a connection point between the first switching element and the second switching element. And a second capacitor for supplying drive power to the inverter device, wherein an anode is connected to one end of an output winding of the transformer, and a second capacitor is connected to a cathode. A rectifying element is provided.

According to the present invention, when the second switching element is turned on and electric charge is supplied to the second capacitor, the electric charge passes through the transformer, the second diode, the second capacitor, and the second switching element. Then, the second capacitor is charged. At this time, since the transformer acts as a constant current source, the peak value of the charging current to the second capacitor is limited by the magnitude of the primary current flowing through the input winding of the transformer, and no spike current is generated. .

[0020]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a drive circuit of an inverter device according to an embodiment of the present invention. In FIG. 1, the same components as those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted.

In the drive circuit of the inverter device of the present embodiment, the anode of the diode 9 is connected not to the output terminal 12 for outputting the output voltage Vcc but to one end of the output winding of the transformer 100. 13 is directly connected.

In the drive circuit of the inverter device according to the present embodiment, the charging path of the capacitor 10 when the lower arm IGBT 3 is turned on is shown by a broken line in FIG. As shown in FIG. 2, in the present embodiment, via the transformer 100, the diode 9, the capacitor 10, and the lower arm IGBT 3,
The capacitor 10 is charged. At this time, the transformer 100 acts as a constant current source. For this reason, the peak value of the charging current IH to the capacitor 10 is limited by the magnitude of the primary current flowing through the input winding of the transformer 100. The charging current IH is supplied to the diode 104 and the capacitor 10 for supplying a voltage to the lower arm driving circuit 5.
5, the output voltage Vcc of the lower arm drive circuit power supply 8 does not change.

FIG. 3 shows a drive signal Vin of the power MOSFET 101, an input current Iin to the transformer 100, and a diode 10 in the drive circuit of the inverter device according to the present embodiment.
4, the output voltage Vcc of the lower arm drive circuit power supply 8, the voltage VGEL applied to the gate G and the emitter E of the lower arm IGBT 3, the charging current IH output from the diode 9, and the voltage VH across the capacitor 10. It is a figure showing a voltage and current waveform. FIG. 4 is a diagram showing voltage / current waveforms of the same signals as those shown in FIG. 3 in the drive circuit of the conventional first inverter device shown in FIG.

3 and 4, a spike current is not generated in the charging current IH flowing through the diode 9 in FIG. 3, whereas a spike current is generated in the charging current IH in FIG. I understand.

As described above, according to the drive circuit of the inverter device of the present embodiment, it is possible to prevent the generation of a spike current when the charge to the capacitor 10 is charged without the necessity of the current reducing element. Can be. That is, according to the present embodiment, since the number of parts is not increased,
An inexpensive, compact, and highly reliable drive circuit for an inverter device that performs stable operation can be realized.

[0027]

As described above, the present invention has an effect that a spike current generated when a capacitor is charged with electric charge can be suppressed without requiring a current reducing element.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a drive circuit of an inverter device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an operation of a drive circuit of the inverter device of FIG. 1;

FIG. 3 is a diagram showing voltage / current waveforms in a drive circuit of the inverter device according to the embodiment.

FIG. 4 is a diagram showing voltage / current waveforms in the drive circuit of the conventional first inverter device shown in FIG.

FIG. 5 is a circuit diagram showing a configuration of a drive circuit of a conventional first inverter device.

FIG. 6 is a circuit diagram showing a configuration of a lower arm drive circuit power supply 8 in FIG. 5;

FIG. 7 is a circuit diagram showing a configuration of a drive circuit of a second conventional inverter device.

[Explanation of symbols]

 Reference Signs List 1 DC power supply 2 Upper arm IGBT 3 Lower arm IGBT 4 Upper arm drive circuit 5 Upper arm drive circuit 6 Upper arm on / off signal 7 Lower arm on / off signal 8 Power supply for lower arm drive circuit 9 Diode 10 Capacitor 11 Resistance 12, 13 Output Terminal 100 Transformer 101 Power MOSFET 102 Control IC 103 Detection resistor 104 Diode 105 Capacitor

Claims (2)

[Claims] 1. A first and a second switching element which are connected in series and driven ON / OFF complementarily, and one end of the first switching element which is not connected to the second switching element. A DC power supply in which a positive electrode and a negative electrode are respectively connected to one end of the second switching element that is not connected to the first switching element; and ON / OFF driving of the first and second switching elements, respectively. A first and second drive circuit, an input winding and an output winding, a transformer having one end of the input winding connected to the DC power supply, and the other end of the input winding of the transformer. A third switching element provided between the output winding and a ground, a first rectifying element having an anode connected to one end of the output winding, a cathode of the first rectifying element and the output winding. end And a first capacitor connected between the first drive circuit and a first capacitor for supplying drive power to the first drive circuit. One end is connected to the second drive circuit, and the other end is connected to the second drive circuit. First
And a second capacitor connected to a connection point between the switching element and the second switching element and supplying a driving power to the second driving circuit, wherein the output winding of the transformer is provided. And a second rectifier element having an anode connected to one end of the first rectifier and a cathode connected to the second capacitor. 2. The drive circuit according to claim 1, wherein said first and second switching elements are IGBTs.