JP2000333467A - Inverter apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter apparatus which comprises an abnormality detection circuit, with circuit constitution of which is simple and whose power consumption is low. SOLUTION: On the basis of AC voltages Vu, Vv, Vw at respective phases of this inverter apparatus, the continuity fault of high-side switching elements 11 to 13 can be detected. Thereby, an abnormality detection part (a controller 30), which detects abnormalities in the high-side switching elements 11 to 13, can form a signal voltage which indicates the abnormalities is the high-side switching elements 11 to 13, while the low-side power-supply voltage of the inverter apparatus is used as a reference. The circuit configuration of the inverter apparatus can be sharply simplified, and a reduction in the control electric power of the inverter apparatus can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter for converting DC power into AC power, and more particularly to an inverter for converting DC power into AC power for driving a single-phase or three-phase AC motor.

[0002]

2. Description of the Related Art In a conventional three-phase inverter, an abnormality of a switching element is detected, the switching element having the abnormality is shut off by itself, and a diagnostic signal indicating the abnormal state is reported to an external control circuit. One having a detection circuit is known. The abnormality detection circuit built in the inverter device operates with a control power supply voltage based on the DC power supply potential on the lower side of the inverter device. Therefore, the diagnostic signal output from the abnormality detection circuit is a DC signal on the lower side of the inverter device. It is common to form the signal voltage with reference to the power supply potential because the circuit configuration is simplified.

However, in this abnormality detection circuit, the low-side element abnormality detection section for detecting an abnormality of the power element on the LO-SIDE side of the inverter apparatus naturally has a LO-SIDE based on the DC power supply potential on the lower side of the inverter apparatus. Although it is preferable in terms of circuit configuration to employ a circuit configuration for detecting an abnormality in the side power element, the HI-SID of the inverter device is used.
The high-side element abnormality detection unit for detecting an abnormality of the E-side power element is configured such that the high-side element abnormality detection unit uses the HI-SI
It is preferable in terms of the circuit configuration to employ a circuit configuration for detecting the abnormality of the DE-side power element. For this reason, the output signal voltage of the high-side element abnormality detection unit is adjusted from the above-described reference potential to the low-side DC of the inverter device. The level has been converted to a reference potential based on the power supply potential using a potential insulating element such as a photocoupler or a transformer.

[0004]

However, this photocoupler has a high component cost, and the power consumption of the photocoupler is more than tens of mA for driving the light emitting diode, which is a large proportion of the control power of the inverter device. Therefore, the power supply circuit for supplying the control power has been increased in size and cost.

The present invention has been made in view of the above problems, and has as its object to provide an inverter apparatus having a simple circuit configuration and a low power consumption abnormality detection circuit.

[0006]

SUMMARY OF THE INVENTION An abnormality detecting section of an inverter device according to the present invention detects a conduction abnormality of a high-side switching element based on an inter-phase voltage pattern of an AC output terminal of each phase of the inverter device. The conduction abnormality may occur, for example, due to a failure of the high-side switching element itself, or to a failure of a control circuit that drives and controls the high-side switching element.

With this configuration, the potential (AC output voltage) of the AC output terminal of each phase of each inverter device is set with reference to the lower DC power supply potential of the inverter device (hereinafter, also simply referred to as the lower power supply potential). Because of this, the circuit part of the abnormality detection unit that detects the abnormality of the high-side switching element (hereinafter also referred to as the high-side element abnormality detection unit or simply the abnormality detection circuit) has the low-side power supply potential. A circuit configuration applied to the lower power supply terminal can be employed.

As a result, the high side element abnormality detecting section can form a signal voltage indicating the high side element abnormality with reference to the lower power supply potential.
The potential insulation element for converting the output signal of the high-side element abnormality detection unit, which is conventionally required, to the low-side power supply potential reference can be omitted, and the circuit configuration is greatly simplified and control power is saved. be able to.

According to a second aspect of the present invention, in the inverter device according to the first aspect, the abnormality detecting unit further outputs an abnormality occurrence notification signal related to the detected conduction abnormality of the high-side switching element of the inverter device. Since the signal voltage is formed as a signal voltage based on the lower DC power supply potential and transmitted to the outside, the circuit configuration is simplified. According to a third aspect of the present invention, in the inverter device according to the first or second aspect, the abnormality detection unit further includes an AC output of the predetermined high-side switching element in a section where the predetermined high-side switching element is expected to conduct. When the phase voltage of the terminal is smaller than the predetermined threshold value, it is determined that the predetermined high-side switching element has a conduction failure. Therefore, the abnormality detection unit based on the lower power supply potential ensures that the high-side switching element has a conduction failure. Can be determined.

More specifically, when the high-side switching element of the inverter device has a conduction failure due to its own abnormality, or when a self-abnormality detection circuit built in each high-side switching element has its own abnormality, In the case of the cutoff state, the inter-phase voltage between the AC output terminal of the abnormal high-side switching element and another AC output terminal of the inverter device turns on the abnormal high-side switching element. In this section, the voltage becomes much lower than the voltage equivalent to the power supply voltage.
Therefore, by detecting the potential of each AC output terminal of the inverter device with reference to the lower power supply potential and monitoring the difference therebetween, it is possible to easily detect a conduction failure of the high-side switching element.

When the DC power supply voltage input to the inverter device is a high voltage, the voltage of each AC output terminal (AC voltage of each phase) may be much higher than the input voltage range of the abnormality detecting unit. In this case, the AC voltage of each phase can be divided by a resistance voltage dividing circuit or the like and easily processed, so that no problem occurs.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Overall Configuration) FIG.
This will be described with reference to FIGS. This inverter device has 1
An in-vehicle three-phase inverter that performs 20-degree conduction control.
FIG. 1 shows the overall configuration, FIG. 2 shows a high-side element abnormality detection circuit incorporated in the controller 30 for detecting a high-side abnormal state, FIG. 3 shows switching patterns of each part of the inverter device at each time, and FIG. FIG. 6 to FIG. 6 show the current paths of each part of the inverter device at each time. (Overall Configuration) In FIG. 1, reference numeral 1 denotes a high-voltage on-vehicle battery (DC power supply) for supplying power required for traveling, 2 denotes a smoothing capacitor for stabilizing a DC power supply voltage applied to an inverter device, and 3 denotes an inverter. Motors 11 to 16 serving as loads on the apparatus are power switching elements, and in this embodiment, IGBTs are used. 21 to 26 include a flywheel diode (FWD), 30 includes a circuit for forming a control signal for connecting and disconnecting the power switching element, a circuit for forming a control power supply for controlling the driving of the power switching element, and a protection circuit for the power switching element. Controller (control circuit),
As shown in the figure, 31 to 36 are signal lines connecting the control circuit 30 and an element controller described later, and 41 to 46 are IGBTs.
If any of the devices 11 to 16 cannot operate normally due to insufficient driving voltage, overcurrent, or overheating, the abnormality is individually detected, and the driving of the IGBT in which the abnormality has occurred is forcibly stopped for a certain period thereafter. With controller 3
0 to amplify the gate control signal received from
Element controllers 41 to 46 applied to the gate electrodes T11 to T16. This type of element controllers 41 to 4
Since the circuit configuration and operation of 6 itself are already known, description thereof will be omitted. (Basic Operation of Inverter Device) In the 120-degree energization control of the present embodiment, the IGBTs 11 to 1 have the energization patterns shown in FIG.
6 by intermittently controlling the low-side IGBT 14
16 are turned on with a shift of 120 degrees different from each other, and DUTY-control the high-side IGBTs 11 to 13 to generate pseudo three-phase AC voltages Vu, Vv, Vw and apply the same to the motor 3. (Explanation of pseudo three-phase AC voltages Vu, Vv, Vw) At the start of operation (t0), all of IGBTs 11 to 16 are in the OFF state, and no current flows, so that all of Vu, Vv, Vw are substantially VP /. 2 voltage.

Next, at time t1, the IGBTs 11, 15
Is turned on, and current flows through the path shown in FIG.
The U-phase AC voltage Vu at the AC output terminal, which is a connection point between T11 and T11, is based on the lower power supply potential VN of the DC power supply 1 (assumed to be 0 V in the following description) as a reference potential: Vu = VP-Vce (sat) 11} VP. Here, Vce (sat) 11 is a saturation voltage of the IGBT11, and the value differs depending on the energizing current. However, in the case where the higher power supply potential VP of the DC power supply 1 reaches several hundred V with respect to the lower power supply potential VN, Is a very small value, so that it can be considered that Vu = VP. In addition, IGBT1
V-phase AC voltage V at the AC output terminal, which is the connection point between 2, 15
v, the W-phase AC voltage Vw of the AC output terminal which is a connection point of the IGBTs 13 and 16 is Vv ≒ Vce (sat), respectively.
11 ≒ 0, Vw ≒ VP / 2.

FIG. 4 shows a current path at this time. Next, at time t2, the IGBT 11 is turned off, and the current flowing through the IGBT 11 is commutated to the diode FWD14. At this time, Vu is the voltage drop of the diode FWD (= −V
FN) is lower than VN, so that Vu = −VF24 ≒ VN ≒ 0, and Vv and Vw are respectively VvＶVce (sa
t) 15, Vw ≒ 0.

FIG. 5 shows a current path at this time. Next, at time t3, the IGBT 15 is turned off, and
The BT 16 turns on. In this case, a current flows through the diode FWD22 only for a short period after the IGBT 15 is turned off, and Vu, Vv, and Vw are respectively Vu = VP−Vce (sat) 11 ≒ VP, Vv = VP + VF22 ≒ VP, Vw ≒ VP. / 2,

FIG. 6 shows a current path at this time. Since the relationship between the AC voltages Vu, Vv, and Vw of each phase sequentially changes in one cycle of the electrical angle of 360 degrees, the above relationship is repeated every electrical angle of 120 degrees. Thus, at normal times, the IGBT
, The voltages Vu, Vv, and Vw alternate between approximately VP and approximately VN. (At the time of conduction failure of the IGBT 11) Next, at the time t4, the IGB
A description will be given of the potential of each part when T11 cannot be normally switched due to insufficient driving voltage or the like, and is held in the OFF state by a well-known shutoff circuit built in the element controller 41.

In this case, even if an ON drive signal is supplied from the controller 30 to the element controller 41, a high-level gate control voltage (ON voltage) is applied to the gate electrode of the IGBT 11 by a shut-off circuit built in the element controller 41. For this reason, the IGBT 11 is kept off, the current path continues to flow as shown in the current path diagram when the IGBT 11 is off, and the U-phase AC voltage Vu becomes substantially VN. (High-side element abnormality detection circuit) An example of a high-side element abnormality detection circuit which is built in the controller 30 and detects conduction abnormality of the high-side IGBTs 11 to 13 will be described with reference to FIG. The circuit configuration of the high side element abnormality detection circuit will be described together with the operation description.

In FIG. 2, reference numerals 100 to 102 denote AC voltage detection circuits (Vu, Vv, Vw detection units) for individually detecting the divided voltages of the AC voltages Vu, Vv, Vw of each phase. A pair of a resistor R01 and a resistor R02, a resistor R03 and a resistor R0 individually incorporated in 100 to 102, respectively.
4 and a pair of the resistor R05 and the resistor R06 form a resistor voltage dividing circuit. R01, R03, R05,
The resistance values of R08 are equal, and R02, R04, R06, R
09 are equal.

The emitter-follower transistors Qu and Q for amplifying currents of the respective divided voltages output from the resistor voltage dividing circuits.
v, Qw, and Q02 all have the same characteristics. Since the emitters of the emitter follower transistors Qu, Qv, and Qw are cross-connected, only the highest one of the three divided voltages is input to the negative input terminal of the differential amplifier 200 through the resistor R11. R07 is a load resistance of the emitter follower transistors Qu, Qv, Qw.

Similarly, reference numeral 103 denotes a voltage detection circuit (VP detection unit) for detecting the divided voltage of the DC power supply voltage VP. A pair of the resistors R08 and R09 built in the voltage detection circuit 103 is connected to the DC power supply voltage VP. Is configured as a resistance voltage dividing circuit. The voltage obtained by dividing the DC power supply voltage VP by the resistors R08 and R09 is current-amplified by the emitter follower transistor Q02, whereby the AC voltage detection circuits 100 to 102 are amplified.
A voltage obtained by dividing the DC power supply voltage at the same voltage division ratio as the output voltage of the differential amplifier 200 is input to the + input terminal of the differential amplifier 200 through the resistor R12.

The differential amplifying section 200 is a known differential amplifying circuit using an operational amplifier, and the AC voltages Vu, Vv,
The difference voltage between the divided signal V− of Vw and the divided signal V + of the DC power supply voltage VP is amplified. Output voltage Vout of differential amplifier
Is Becomes

That is, when any one of the IGBTs 11 to 13 is normally turned on, V− and V + are substantially equal, and Vout is substantially zero. R21, R22, Q0
1 is a clamp circuit, which turns on Q01 by a chopper signal S indicating a period (pulse interval period of PWM control) in which all of the high-side IGBTs 11 to 13 receive a normal off signal (Q02). Is turned off to reset V + to 0V.
The state where all of the high-side IGBTs 11 to 13 are turned off occurs in a so-called pulse interval period of each pulse cycle in the PWM control of the IGBTs 11 to 13.
The GBTs 11 to 13 are turned on during a so-called pulse width period of each pulse period in the PWM control, and the duty ratio becomes (pulse width period / pulse period) · 100%.

When the high-side IGBTs 11 to 13 are turned off, the AC voltages Vu, Vv, Vw of each phase are approximately 0 V to VP / 2 (the back electromotive voltage becomes positive or negative depending on the rotation state of the motor). Since the above equation is taken, the output voltage Vout of the differential amplifier becomes a negative value according to the above equation. The peak hold circuit 300 at the next stage of the differential amplifier 200 has a circuit configuration that holds the maximum value of the positive voltage, although the circuit configuration and the description of the operation are omitted, and it is continuously substantially 0 V during normal operation.

Next, at the aforementioned time t4, the IGBT
Assuming that any of 11 to 13 holds the OFF state in spite of the ON command, V− is approximately 0 V to VP / 2 despite V + being a divided value of DC power supply voltage VP. In order to take a value between them, the difference is output from the differential amplifier as a positive value according to the above equation and peak-held. The held signal is applied to a predetermined threshold voltage V
ref is compared with the reference signal IGBT, and the diagnosis signal which is pulled down by the load resistor R20 and is at the low level potential is the IGBT.
It is output as a signal indicating the conduction failure of 11 to 13.

Note that even when the chopper signal S is in a high level state (a period in which a signal for turning on the IGBTs 11 to 13 on the high side is given (corresponding to a pulse width period of PWM control)). Until the high-side IGBTs 11 to 13 are completely turned on, delays in the element controllers 41 to 46 and IGBTs
A delay is caused by the ON delay of the BT itself.

Therefore, a delay equal to the ON delay of the IGBTs 11 to 13 is given to the chopper signal S by the ON delay section 500. By using the abnormality detection circuit, it is possible to determine the conduction failure of the high-side IGBTs 11 to 13 without using a potential insulating element such as a photocoupler, and to provide a low-cost and low-power-consumption inverter device. can do. (Modification) In order to improve the detection accuracy, the gain of V− with respect to the AC voltages Vu, Vv, Vw of each phase and V + with respect to the DC power supply voltage VP
QU, Qv, Qw, Q02
Use a transistor pair made on the same wafer,
It is preferable to use the same lot product.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing an abnormality detection circuit built in the controller of FIG. 1;

FIG. 3 is a timing chart showing a switching pattern of each part of the inverter device at each time.

FIG. 4 is a current path diagram showing a current path of each part of the inverter device at time t1.

FIG. 5 is a current path diagram showing a current path of each part of the inverter device at time t2.

FIG. 6 is a current path diagram showing a current path of each part of the inverter device at time t3.

[Explanation of symbols]

11 to 13 are IGBTs (high-side switching elements), 14 to 16 are IGBTs (low-side switching elements), Vu, Vv, and Vw are AC voltages of each phase, and 30 is a controller (control unit and abnormality detection unit).

Claims (3)

[Claims] The other main terminal of the high-side switching element having one main terminal connected to the high-order terminal of the DC power supply and the other main terminal of the low-side switching element having one main terminal connected to the low-side end of the DC power supply. An inverter circuit having a plurality of phase inverter circuits each having a terminal connected to an AC output terminal, generating an AC voltage between the AC output terminals by intermittent switching of the switching element, and the high-side switching element Or an abnormality detection unit that detects conduction abnormality of the high-side switching element due to abnormality of a control circuit that drives and controls the high-side switching element. Detecting a conduction abnormality of the high-side switching element based on an inter-phase voltage pattern of a terminal. Converter equipment. 2. The inverter device according to claim 1, wherein the abnormality detection unit outputs an abnormality occurrence notification signal related to the detected conduction abnormality of the high-side switching element.
An inverter device for transmitting a signal voltage based on a DC power supply potential on a lower side of the inverter device to the outside. 3. The inverter device according to claim 1, wherein the abnormality detecting unit is configured to detect an AC output terminal of the predetermined high-side switching element in a predetermined section where the high-side switching element is expected to conduct. An inverter device, wherein when the phase voltage is smaller than a predetermined threshold value, it is determined that the predetermined high-side switching element has conduction failure.