JP2000224861A - Protective method for inverter apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce regenerative current in the self-protected operation of an intelligent power module(IPM) and to protect the inside device of the IPM in an inverter apparatus on which the IPM is mounted. SOLUTION: A commercial power supply 1 is converted into a direct current by an AC/DC conversion part 2. Its converted DC power supply is smoothed by a capacitor 3 to be supplied to an IPM 4. In this inverter apparatus, which generates a voltage to be applied to a motor (a three-phase four-pole motor) 5 by the IPM 4, overheating or overcurrent of internal insulated-gate bipolar transistors(IGBTs) is detected. Then, all the IGBTs in the upper arm or the lower arm the turned off to be protected; while a 'false-out'(FO) signal is output to a microcomputer 10 to promote the cutoff operation of the inverter apparatus. The microcomputer 10 turns on the IGBTs, which are turned on immediately prior to the detection of the FO signal out of at least the upper arm of the IPM 4, when the IGBTs 4b in the lower arm are turned off by the protective operation of the IPM 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IPM (Inte
The present invention relates to a protection technology for an inverter device equipped with an integrated power module.
The present invention relates to a method for protecting an inverter device for appropriately protecting internal devices.

[0002]

2. Description of the Related Art An inverter device is equipped with an IPM incorporating a power device (IGBT), a driving circuit (including a logic circuit), and a protection circuit. The inverter device has, for example, the configuration shown in FIG.
The DC / DC converter 2 converts the DC power into DC power, smoothes the converted DC power with a capacitor 3 and supplies it to an IPM 4.
4 generates a voltage applied to a motor (for example, a three-phase four-pole motor) 5.

[0003] IPM4 is an IGBT constituting an upper arm.
4a and an IGBT 4b forming a lower arm, and drive circuits 4c and 4 for driving these IGBTs 4a and 4b.
d, and an overheat detection circuit 4e and an overcurrent detection circuit 4f for a self-protection function. The control signals (PWM signals) from the microcomputer 6 turn on and off the IGBTs 4a and 4b in a predetermined manner.

When the overheat detecting circuit 4e or the overcurrent detecting circuit 4f detects overheating or overcurrent of the IGBT, the IPM 4 turns off the IGBTs 4a and 4b of the lower arm or the upper arm for a predetermined time by the self-protection function of the IPM 4. While shutting off the gate) and protecting the internal device, the FO (False Out) signal of the abnormal signal is output in order to prompt the operation of the inverter device to be shut off.

When the microcomputer 6 receives the FO signal, it stops outputting the PWM signal and stops the rotation control of the motor 5, that is, turns off all the IGBTs 4a and 4b. In this way, by interrupting the operation of the inverter device, it is possible to prevent the internal devices (the IGBTs 4a, 4b, etc.) from being damaged by overheating or overcurrent.

[0006]

However, in the above-described inverter device, even if the operation of the inverter device is cut off due to the self-protection operation of the IPM 4, the energy stored in the motor coil during the rotation of the motor 5 is reduced. Is regenerated to the capacitor 3 through the DC line, and the voltage across the capacitor 3 increases due to the reverse current and the regenerated current, which may cause malfunction and destruction of the internal device of the IPM 4.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce a regenerative current at the time of self-protection operation of an IPM so as to prevent malfunction and destruction of an internal device of the IPM. And a protection method for the inverter device.

[0008]

In order to achieve the above object, the present invention includes a power device for controlling the rotation of a motor, is equipped with an IPM having a self-protection function, and is provided with a FO signal from the IPM. A method of protecting an inverter device for turning off a power device, comprising:
When a protection operation is performed on the lower arm of the PM and the power device of the lower arm is turned off, at least the IP
A power device that is turned on immediately before the detection of the FO signal in the upper arm of M is turned on, and all power devices of the lower arm are turned off.

The present invention is a method for protecting an inverter device which includes a power device for controlling the rotation of a motor, has an IPM having a self-protection function, and turns off the power device by a FO signal from the IPM. , A protection operation is performed on the lower arm of the IPM,
When the power device of the upper arm of M is turned off, at least the power device of the lower arm of the IPM that is turned on immediately before the detection of the FO signal is turned on, and all the power devices of the upper arm are turned off. It is characterized by having made it.

In this case, it is preferable that the time during which the power device is in the on state is a predetermined time which is determined in advance or until the motor is restarted.

It is preferable that the apparatus further comprises current detecting means for detecting a current flowing through each winding of the motor, and that the power device be turned on until the detected current becomes a predetermined value or less.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described in detail with reference to FIG. In the figure, the same parts as those in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

Referring to FIG. 1, this inverter device has the functions of a microcomputer 6 shown in FIG.
When the self-protection function of the IGBT 4 is activated and the FO signal is output, the IGBT 4 of the upper arm or the lower arm of the IPM 4
a, 4b, a microcomputer 10 for turning on at least one phase of the IGBT; energy stored in the motor 5 is returned between the IPM 4 and the motor 5 to be consumed by the winding resistance of the motor 5; To reduce the regenerative current.

A protection method applied to the inverter device having the above configuration will be described with reference to FIG. In FIG. 2, FIG.
The same parts as those described above are denoted by the same reference numerals, and redundant description will be omitted.

First, when the rotation of the motor 5 is controlled by the microcomputer 10, the IPM 4 performs a protection function due to overheating or overcurrent of the IGBT. For example, all the IGBTs 4b of the lower arm are turned off for a certain time. , FO signals are output.

For example, current is applied between the U phase and the V phase,
When a current flows between the winding U and the winding V, the IPM
When the lower arm IGBT 4b is turned off by the protection operation of No. 4, the winding current becomes Tu → Ru → Lu → Lv → Rv
Reflux in the order of → Dv → Tu (see FIG. 2). Note that Lu, L
v and Lw are the inductances of the motor 5, Ru, Rv and R
w is a winding resistance of the motor 5, and Du, Dv and Dw are freewheel diodes.

At this time, if the FO signal is detected and the IGBTs 4a and 4b of the upper and lower arms are all turned off and the operation of the inverter device is interrupted, the path of the return current is cut off. Since current is regenerated to the capacitor 3 via the DC line, the voltage across the capacitor 3 increases, and the device of the IPM 4 may malfunction or break down.

Accordingly, the microcomputer 1 of the present invention
0, when the FO signal from the IPM 4 is detected, Tu which is turned on immediately before the protection function of the upper arm is activated.
(IGBT 4a) to the ON state, and all I
The GBT 4b is turned off. Then, the return current is Tu
→ Ru → Lu → Lv → Rv → Dv → Tu, and the energy stored in the coil is consumed. When the return current is reduced, all phases of the IGBTs 4a and 4
Even if b is turned off and the operation of the inverter device is cut off, since the regenerative current is small, malfunction or destruction of the device inside the IPM 4 can be prevented.

It should be noted that the time for keeping the Tu (IGBT 4a) in the ON state may be until the motor 5 is restarted.

The time for consuming the energy stored in the coil, that is, the time for keeping only the Tu (IGBT 4a) of the upper arm that is on immediately before the protection function is activated, in the on state is determined empirically. It may be a value obtained from

Further, a time period during which the energy stored in the coil is completely consumed is determined empirically, and this time is set in a timer (an internal timer of the microcomputer 10). Phase IG
When the BTs 4a and 4b are turned off, regenerative current can be prevented from occurring.

In particular, in the case of a compressor of an air conditioner,
Since it is necessary to wait at least 2 minutes before restarting after stopping the compressor, when the protection function of the IPM 4 is activated, only the Tu (IGBT 4a) which is turned on immediately before the protection function is activated in the upper arm is reduced by 2 minutes. By setting the ON state for more than one minute, the regenerative current can be sufficiently reduced. In this case, all the IGs of the lower arm are protected by the protection function of IPM4.
Since the time to turn off the BT 4b is predetermined, this time elapses at least by the Tu (IGB
While only T4a) is in the ON state, all the IGBTs 4b in the lower arm may be turned off.

In the above-described embodiment, a case has been described where all the IGBTs 4b of the lower arm are turned off for a certain time by the operation of the protection function of the IPM 4, but all the IGBTs 4a of the upper arm are turned off for a certain time by the operation of the protection function. It can also be applied to cases where In this case, when the FO signal from the IPM 4 is detected, the IGBT 4b of the lower arm that is turned on immediately before the protection function is activated.
May be turned on, and all the IGBTs 4a of the upper arm may be turned off.

FIG. 3 is a schematic block diagram for explaining another embodiment of the present invention. In the figure, the same parts as those in FIG.

In FIG. 3, the inverter device includes current sensors (eg, CTs) 11a, 11b, 11c for detecting currents flowing through windings U, V, W, and a current detection circuit 1
In addition to the functions of the microcomputer 10 shown in FIG. 1 and the FO signal from the IPM 4,
One or more of the IGBTs 4a and 4b of the upper arm or the lower arm are turned on, the current detector 11 detects the winding current, and the reduction of the winding current is determined to determine all of the IPMs 4. And a microcomputer 13 for turning off the IGBTs 4a and 4b.

The microcomputer 13 of this embodiment
For example, in the upper arm, only the Tu (IGBT 4a), which is turned on immediately before the protection function is activated, is turned on, and the IGBT 4b of the lower arm is turned off, thereby reducing the return current. The current (reflux current) is detected by the current sensor 11a and the current detection circuit 12, and when the return current decreases to a predetermined value, all the IGBTs 4a and 4b of the IPM 4 are turned off and the operation of the inverter device is cut off.

As described above, since all the IGBTs 4a and 4b of the IPM 4 are turned off after confirming that the reflux current has been reduced, the regenerative current is small, and malfunction or destruction of the internal device of the IPM 4 can be reliably prevented. it can.

[0028]

According to the present invention described above, the following effects can be obtained. According to the present invention, an IPM is mounted on an inverter device for controlling the rotation of a motor, and a lower arm (or an upper arm) is turned off by the protection operation of the IPM so that the IPM is turned off.
While the GBT is protected, when the FO signal for urging the inverter device to shut down is output, the IGBT that is turned on immediately before the protection operation of the upper arm (or the lower arm) is kept in the ON state. Since the energy stored in the coil of the motor is consumed, the regenerative current can be reduced, and the malfunction and destruction of the internal device of the IPM can be prevented.

Further, the present invention has a current detecting means for detecting a current flowing through the winding of the motor, and keeps the IGBT on until the detected current becomes a predetermined value or less. Therefore, there is an effect that the malfunction and destruction of the IPM device can be reliably prevented.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a schematic block diagram of a device to which a method for protecting an inverter device is applied.

FIG. 2 is a schematic circuit diagram for explaining the operation of the inverter device shown in FIG.

FIG. 3 shows another embodiment of the present invention, and is a schematic block diagram of a device to which a method for protecting an inverter device is applied.

FIG. 4 is a schematic block diagram of a conventional inverter device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 AC / DC conversion part 3 Capacitor 4 IPM 4a IGBT (power device of upper arm) 4b IGBT (power device of lower arm) 4c, 4d Drive circuit 4e Overheat detection circuit 4f Overcurrent detection circuit 5 Motor (three-phase) 4 pole motor) 6,10,13 Microcomputer 11a, 11b, 11c Current sensor (CT) 12 Current detection circuit

Claims (4)

[Claims] 1. A method of protecting an inverter device including a power device for controlling rotation of a motor, including an IPM having a self-protection function, and turning off the power device by a FO signal from the IPM. I
When a protection operation is performed on the lower arm of the PM and the power device of the lower arm is turned off, at least the IP
A power device that is turned on immediately before the detection of the FO signal in the upper arm of M is turned on, and all power devices of the lower arm are turned off. . 2. A method of protecting an inverter device including a power device for controlling rotation of a motor, including an IPM having a self-protection function, and turning off the power device by a FO signal from the IPM. I
When a protection operation is performed on the lower arm of the PM and the power device of the upper arm of the IPM is turned off, at least the power device of the lower arm of the IPM that is turned on immediately before the detection of the FO signal is turned on,
A method of protecting an inverter device, wherein all power devices of the upper arm are turned off. 3. The method of protecting an inverter device according to claim 1, wherein the time during which the power device is turned on is a predetermined time or a time until the motor is restarted. 4. The inverter according to claim 1, further comprising current detection means for detecting a current flowing through each winding of the motor, and turning on the power device until the detected current becomes a predetermined value or less. How to protect the device.