JPH07177755A - Inverter device and controlling method thereof - Google Patents

Abstract

PURPOSE:To feed stably the gate power supplies for the switching elements of an inverter device, by performing the ON-OFF control of a DC circuit power supply which is related to the feeds of the gate power supplies of the positive and negative side switching elements of the inverter section of the inverter device wherein a DC power is converted into an AC power. CONSTITUTION:To the input of a photo-coupler PCX, a controlling signal gxa for a switching element SX is inputted, and the driving of the switching element SX is controlled by the output of the photo-coupler PCX via a gate resistor Rgx. In the controlling section of the switching elements, a starting signal ST for the control of an inverter device is inputted to a monostable circuit 14, and the starting signal ST is outputted from the monostable circuit 14 during a fixed term determined by the setting of the monostable circuit 14. Then, to an OR circuit 15, the output signal of the monostable circuit 14 and a controlling signal gx for the switching element SX are inputted, and the output signal gxa of the OR circuit 15 is used as the new controlling signal for the switching element SX. In case of the starting of the inverter device, the switching element SX is forced to be in ON-state during the fixed term, and a switching element SU is forced to be in OFF-state during the fixed term. Thereby, the gate power supply for the switching element SU is established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device in which gate power is directly supplied from a DC main circuit power supply.

[0002]

2. Description of the Related Art In recent years, an inverter has been reduced in size, weight and cost by integrating a main circuit, a control circuit, a protection circuit and the like. In this flow, the gate power supplied to the gate drive circuit is also the conventional DC-D.
A method of directly obtaining from a DC main circuit power source is being studied from the C converter method.

Since the gate drive circuit is directly connected to the switching element to be driven, it is electrically placed at the same potential as the switching element to be driven. When the switching elements are connected in series, the gate drive circuits of the respective switching elements are placed at different potentials, so that the power supplies of the respective gate drive circuits must also have different potentials. That is, the power supplies of the gate driving circuit must be insulated from each other for each switching element.

An example of a main circuit configuration diagram of a conventional inverter device is shown in FIG. In FIG. 4, the AC power supply 1 is a rectifier 2
The smoothing capacitor 3 and the inverter 4 are connected in parallel to the rectifier 2. The inverter 4 has six switching elements S with built-in wheeling diodes.
U to SZ, the output u of the inverter 4
v and w are connected to the motor 5. P is the positive side of the DC main circuit power supply, and N is the negative side of the DC main circuit power supply. Since the operation of the inverter is already known, detailed description will be omitted.

FIG. 5 shows in detail only the U-phase portion of the gate circuit of the gate power supply self-contained inverter device in which the power supply of the gate drive circuit is obtained directly from the main circuit DC power supply in the above inverter device.

As shown in FIG. 5, a resistor 6 and a constant voltage diode D _zx connected in series are connected to the positive side P and the negative side N of the DC main circuit power source, and the resistor 6 and the constant voltage diode D _zx are connected.
Is connected to the gate G of the switching element 8,
The drain D of the switching element 8 is connected to the positive side P of the DC main circuit power supply via the resistor 7. Switching element 8
The source S is connected to the anode of the diode D _gx, the cathode of the diode D _gx is connected to the gate power supply capacitor 9, the other terminal of the gate power supply capacitor 9 is connected to the negative side N of the DC main circuit power supply. A photocoupler PCX is connected in parallel to the gate power supply capacitor 9. The control signal gx of the switching element SX is input from the control circuit (not shown) to the input of the photocoupler PCX, and the output drives and controls the switching element SX via the gate resistance R _gx .

Here, the voltage V of the gate power supply capacitor 9
_c is given by the following equation as is well known. _{V c = V z -D v -V} sh However, V _z: the control voltage D _v of the constant voltage diode D _zx: diode D _gx forward voltage drop V _sh: threshold voltage of the switching element 8 also DC main circuit power supply The power supply of the gate drive circuit of the switching element SU on the positive side of the above is also the same as above with the resistor 10, the constant voltage diode D _zu , the resistor 11, the switching element 12, the diode D _gu , the gate power supply capacitor 13, the photo coupler PC.
U and a gate resistance R _gu .

[0008]

However, the conventional gate power supply self-contained inverter device described above has the following problems. The gate power supply of the switching element on the DC main circuit power supply N side automatically starts up when the DC main circuit voltage is established, but the gate power supply of the switching element on the DC main circuit power supply P side is the switching element on the DC main circuit power supply N side. The gate power capacitor can only be charged when is turned on.

Therefore, there is a drawback that the gate power supply capacitor on the DC main circuit power supply P side is discharged and the gate power supply voltage is lowered at the time of start-up or when the switching element on the DC main circuit power supply N side is off for a long time. It was

Therefore, the present invention solves the above problems,
An object of the present invention is to provide a gate power supply self-contained inverter device that stably supplies the gate power supply on the DC main circuit power supply P side even when the switching element on the DC main circuit power supply N side is turned off for a long period of time at startup. .

[0011]

In order to achieve the above object, in an inverter device according to a first aspect of the present invention, a direct current is converted into an alternating current, and an inverter section composed of a plurality of switching elements and a gate of the inverter section. There is provided an inverter device having a gate power supply means for supplying power from a DC main circuit power supply and a control means for performing on / off control of a switching element of the inverter section related to the supply of the gate power.

In the control method of the inverter device according to the second aspect of the present invention, the switching element on the negative side of the DC main circuit power source is turned on for a certain period when the inverter device is started,
Turn off the switching element on the positive side of the DC main circuit power supply.

In the control method of the inverter device according to the third aspect of the present invention, when the OFF state of the switching element on the negative side of the DC main circuit power source continues for a certain period or more, the switching element on the negative side of the DC main circuit power source is turned on. Then, the switching element on the positive side of the DC main circuit power supply is turned off.

In the control method of the inverter device according to the fourth aspect of the present invention, the gate power supply voltage of the switching element on the positive side of the DC main circuit power supply is monitored, and when the gate power supply voltage becomes equal to or lower than a preset voltage, the The switching element on the negative side of the main circuit power supply is turned on, and the switching element on the positive side of the DC main circuit power supply is turned off.

[0015]

In the inverter device according to the first aspect of the present invention configured as described above, the switching elements on the positive side and the negative side of the DC circuit power source relating to the supply of the gate power source of the inverter section for converting DC to AC are provided. Stable supply of gate power by performing on / off control.

Further, in the control method of the inverter device according to the second aspect of the present invention, the switching device on the negative side of the DC main circuit power supply is turned on and the switching device on the positive side is turned off for a certain period when the inverter device is started. By setting the state, the gate power supply of the switching element on the positive side of the DC main circuit power supply is established at the time of startup.

Further, in the control method of the inverter device according to the third aspect of the present invention, when the OFF state of the switching element on the negative side of the DC main circuit power source continues for a certain time or longer, the switching element on the negative side is turned on. By turning off the switching element on the positive side, the gate power of the switching element on the positive side can be stably supplied.

Further, in the control method of the inverter device according to the fourth aspect of the present invention, the gate power supply voltage of the switching element on the positive side of the DC main circuit power supply is monitored to make the gate power supply voltage equal to or lower than a preset value. Then, the negative side switching element is turned on and the positive side switching element is turned off, so that the gate power supply of the positive side switching element is stably supplied.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention, and particularly shows only a U-phase part of a gate circuit and a control part of an inverter.

The gate power supply self-contained inverter part is
A resistor 6 and a constant voltage diode Dzx connected in series are connected to the P side and N side of the DC main circuit power source. The connection point between the resistor 6 and the constant voltage diode D _zx is connected to the gate G of the switching element 8, and the drain D of the switching element 8 is connected to the P side of the DC main circuit power source via the resistor 7. The source S of the switching element 8 is connected to the anode of the diode D _gx, the cathode of the diode D _gx is connected to the gate power supply capacitor 9, the other terminal of the gate power supply capacitor 9 is connected to the N side of the DC main circuit power supply There is. A photocoupler PCX is connected in parallel to the gate power supply capacitor 9.

The control signal g of the switching element SX is input from the switching element control section to the input of the photocoupler PCX.
xa is input, and the output drives and controls the switching element SX via the gate resistance R _gx .

The switching element control unit comprises a monostable circuit 14
A start signal ST for inverter control is input to and a signal is output for a fixed period determined by the setting of the monostable circuit 14. OR the output signal with the control signal gx of the switching element SX.
It is input to the circuit 15 and the output gxa of the OR circuit 15 is used as a new control signal for the switching element SX.

By carrying out the control of this method, it is possible to forcibly turn on the switching element SX by outputting the gate signal for a certain period at the start of the inverter regardless of the presence or absence of the conventional control signal.

The output of the monostable circuit 14 is the NOT circuit 16
Is input to the AND circuit 17, and its output is input to the AND circuit 17. A
A conventional switching element S is connected to the other input of the ND circuit 17.
Input the control signal gu of U and output gua of AND circuit 17
Is used as a new control signal for the switching element SU.

That is, at the start of the inverter, the control signal of the switching element SU is forcibly cut off and the switching element SU is turned off. As described above, in the present embodiment, the gate power supply of the switching element SU is established by forcibly turning on the switching element SX and turning off the switching element SU for a certain period when the inverter starts.

FIG. 2 is a block diagram showing a second embodiment of the present invention, and particularly shows only the U phase of a gate circuit and a control unit of a gate power supply self-contained inverter device. The gate power supply self-contained inverter is the first inverter shown in FIG.
The configuration is the same as that of the above embodiment.

The switching element control section inputs the control signal gx of the switching element SX to the time switch circuit 18 during the normal operation of the inverter circuit, and inputs the output thereof to the monostable circuit 14. In the time switch circuit 18, the timer is set when the off signal of the control signal gx is input,
When the time set by the time switch circuit 18 has elapsed, a timer signal is output to operate the monostable circuit 14. Also,
It is assumed that the time switch circuit 18 is released when the ON signal of the control signal gx is input. An OR circuit 15 outputs the output of the monostable circuit 14 by the timer signal and the conventional control signal gx.
, And the output controls the switching element SX as a new control signal gxb.

That is, when the switching element SX remains in the off state for a certain period or longer, the on signal is forcibly given. The output of the monostable circuit 14 is input to the NOT circuit 16 and the output thereof is input to the AND circuit 17. The control signal gu of the conventional switching element SU is input to the other input of the AND circuit 17, and the switching element SU is controlled by using the output gub of the AND circuit 17 as a new control signal of the switching element SU.

That is, the switching element SU is forcibly turned off. Therefore, according to the present embodiment, the switching element SX can be set so as not to remain in the off state for a certain period or more, and the gate power supply of the switching element SU can be stably supplied.

Next, a third embodiment of the present invention will be described.
FIG. 3 is a block diagram showing a third embodiment of the present invention, and particularly shows only a U-phase portion of a gate circuit and a control unit of a gate power supply self-contained inverter.

The gate power supply self-contained inverter portion has the same structure as that of the first embodiment shown in FIG. The switching element control unit inputs the voltage of the capacitor 13, which is the gate power supply voltage on the DC main circuit power supply P side, and the preset voltage E to the comparator 19 for comparison. The comparator 19 outputs a signal when the gate power supply voltage is lower than the preset voltage E. The output signal of the comparator 19 and the conventional control signal gx are input to the OR circuit 15,
Its output controls the switching element SX as a new control signal gxc.

The output signal of the comparator 19 is NOT
It is input to the circuit 16 and the output of the NOT circuit 16 is the AND circuit 17
Entered in. The conventional control signal gu is input to the other input of the AND circuit 17, and the switching element SU is controlled by using the output guc of the AND circuit 17 as a new control signal.

As described above, according to this embodiment, when the gate power source voltage on the DC main circuit power source P side is equal to or lower than the preset voltage value, the switching element SU is in the off state and the switching element SX is turned on. Because it is on,
The gate power source on the DC main circuit power source P side is charged.

The control signals of the gate power supply self-contained inverter device shown as the first to third embodiments of the present invention may be used alone or in combination of two or more. There is no particular restriction.

Further, although only the switching elements SU and SX have been described as the description of the present invention, the relationship between the other switching elements SV and SY and the switching element SW.
Since it is obvious that the relationship between SZ and SZ is exactly the same, detailed description will be omitted.

[0036]

As described above, according to the present invention, the gate power can be stably supplied from the DC main circuit power supply by adding only a few control components and control sequences without significantly changing the conventional control. Therefore, it is possible to provide an inverter device and a control method therefor capable of stable control.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a U-phase component of a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a U-phase component according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a U-phase component of a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing an example of a conventional inverter circuit.

FIG. 5 is a configuration diagram showing an example of a conventional gate power supply self-contained inverter circuit.

[Explanation of symbols]

8,12 ... switching elements 9 and 13 ... gate power supply capacitor D _zx, D _zu ... constant voltage diode D _gx, D _gu ... diode PCX, PCU ... photocouplers R _gx, R _gu ... gate resistance SU～SZ ... switching element 14 … Monostable circuit 15… OR circuit 16… NOT circuit 17… AND circuit 18… Time switch circuit 19… Comparator

Claims (4)

[Claims] 1. An inverter section comprising a plurality of switching elements, which converts direct current into alternating current, gate power supply means for supplying a gate power source of the inverter section from a direct current main circuit power source, and the above-mentioned relating to the supply of the gate power source. An inverter device comprising: a switching device on the positive side of the DC main circuit power supply and a switching device on the negative side of the DC main circuit power supply of the inverter section, the control device performing on / off control by a predetermined method. 2. A method of controlling an inverter device having a plurality of switching elements, wherein a gate power source is supplied from a DC main circuit power source to a gate of the switching element, wherein a negative side of the DC main circuit power source is present for a certain period when the inverter device is started. And a switching element on the positive side of the direct-current main circuit power supply in an off state. 3. A method for controlling an inverter device having a plurality of switching elements, wherein a gate main power source supplies a gate power source to a gate of the switching element, wherein an OFF state of the switching element on the negative side of the DC main circuit power source is A control method for an inverter device, characterized in that the switching element on the negative side of the DC main circuit power supply is turned on and the switching element on the positive side of the DC main circuit power supply is turned off when the operation is continued for a certain period or longer. 4. A method of controlling an inverter device having a plurality of switching elements, wherein the gate power supply is supplied from a direct current main circuit power supply to the gate of the switching element, wherein a gate power supply voltage of the switching element on the positive side of the direct current main circuit power supply is used. When the gate power supply voltage falls below a preset voltage, the switching element on the negative side of the DC main circuit power supply is turned on and the switching element on the positive side of the DC main circuit power supply is turned off. A method for controlling an inverter device, comprising: