KR20050011030A - Aging Diagnosis Method and Apparatus for Power Conversion Systems - Google Patents

Abstract

PURPOSE: A method and an apparatus for diagnosing the degradation of a power conversion apparatus are provided to diagnose the deteriorated state of a semiconductor element for power while a power conversion apparatus operates by using a degradation diagnosing portion. CONSTITUTION: An apparatus for diagnosing the degradation of a power conversion apparatus includes a main circuit, a controller for converting single-phase and three-phase input voltages to a desired output voltage, a first resistor series circuit(10), a second resistor series circuit(20), an isolation circuit(30), an amplifying circuit(40), an A/D converter(50), and a degradation diagnosing portion(70). The first resistor series circuit is coupled between a collector node of a power semiconductor element and a ground. The second resistor series circuit is coupled between an emitter node of the power semiconductor element and the ground. The isolation circuit isolates a voltage between a predetermined node of the first resistor series circuit and the ground. The degradation diagnosing portion performs degradation diagnosis using a digitalized signal converted in the A/D converter.

Description

Aging Diagnosis Method and Apparatus for Power Conversion Systems

The present invention relates to a method and apparatus for diagnosing deterioration of a power converter. More particularly, the present invention relates to a method of operating a power converter for determining a deterioration state of a power semiconductor device, which is a main component for determining lifetime and operation characteristics among components of a power converter. The present invention relates to a method and an apparatus for diagnosing deterioration of a power converter measured during the test.

In general, the power converter can be classified into the AC-DC rectifier of FIG. 1, the DC-DC converter of FIG. 2, and the DC-AC inverter of FIG. 3. These power converters are used as key devices in industrial processes such as plating, telecommunications, electric furnaces, and train drives in the industrial sector. The market size is estimated at 300 billion won in domestic market and 15 trillion won in global market annually. In addition, the power converter is mainly related to the power control part of the industrial equipment, so a short time stoppage causes a huge loss of the entire product production, especially in a device installed in a place such as a hospital. Stop driving causes a big problem that is directly related to human life. Therefore, in order to prevent this, a separate device is used to install a separate device, but the price of the device is tens of millions of won to hundreds of millions of units due to the high economic burden.

In order to increase the operation reliability of the power conversion device, the inspection is most important, but it is difficult to secure manpower for inspection, and it is very difficult to check it efficiently due to the large number of parts. In addition, the inspection time should be avoided, so the inspection time is short and requires a lot of effort. However, the diagnosis method during the termination of the power conversion device under such a burden is not established worldwide.

This lack of diagnostic methods for power converters not only causes problems in securing the safety of the power converter, but also causes serious problems in economic inefficiency of the device. In the absence of accurate performance diagnosis after purchasing expensive devices, relying on simple data provided by the product company to estimate the life of the device and to dispose of it and replace it with a new device even if it can be fully utilized, is a great economic loss. to be.

The establishment of an efficient diagnostic method of the power converter not only means safe operation of the device, but also improves the stability of the entire system equipped with the power converter and increases the utilization of expensive equipment. It is important to increase added value.

Accordingly, the present invention has been proposed in view of the above-described conventional situation, and is an apparatus for measuring the deterioration state of a power semiconductor device, which is a main component that determines a lifetime and operation characteristics among the components of a power conversion device during operation of the power conversion device. And to provide a method.

To realize this, the change in the voltage V _{CE_ON} between the collector and the emitter at the turn-on of the power semiconductor device is measured statically and dynamically, and the charge charged in the output capacitor of the power semiconductor device to quantitatively measure the degree of deterioration of the power semiconductor device by measuring the agreement amount (Q _TOT = Q _C + Q _R) of the (Q _C) and the reverse recovery charge of the parallel diode (recovered charge, Q _R) It is characterized by supplying a method.

In the semiconductor device for power and structure, the terminal voltage (V _{CE_ON} ) between the collector and the emitter during turn-on greatly increases the saturation voltage (V _{CE, SAT} ) and the voltage drop generated by the lead wire (Vesistive Voltage Drop; V). _{It can} be divided into (V _{CE_ON} = V _{CE, SAT} + V _{CE, RDROP} ). The saturation voltage caused by the difference in the doping concentration and the movement of holes and charges in the internal structure of the power semiconductor device, and the magnitude of the voltage drop occurring in the lead wire which is essential for manufacturing, depend on the conditions and time of using the power semiconductor device. It causes a change, and deterioration of the power semiconductor element is accumulated by the continuous accumulation of such a temperature change and vibration, and eventually, the power semiconductor element is destroyed. The method of measuring the change of the voltage (V _{CE_ON} ) between the collector and the emitter at the time of turn-on of the power conversion device can be effectively measured even during operation. It is primarily proposed in the present invention.

At turn-on of the power semiconductor device, the switch current rises with a constant slope to the load current. During this time, since the power semiconductor device is continuously turned off, the product of the switch instantaneous voltage and the instantaneous current appears as a thermal loss. In particular, the overcurrent appearing after reaching the load current has a considerably larger value than the normal current, and the magnitude and duration of the overcurrent are the charge (Q _C ) and the antiparallel diode charged in the output capacitor of the power semiconductor device. a recovery charge (RecoveredCharge; Q _R) is determined by the agreed amount (Q _TOT = Q _C + Q _R) of the. As a result, switching losses during overcurrent are a large part of switching losses at turn-on. As the power semiconductor device deteriorates, the Q _TOT shows a change, and as a result, a method for diagnosing the deterioration state of the switch is proposed by measuring the amount.

1 is a view showing an AC-DC rectifier circuit of an AC single-phase circuit as a power converter;

2 shows a DC-DC booster converter circuit as a power converter;

3 shows a DC-AC inverter circuit as a power converter;

4 is a view showing resistance components that generate a voltage V _{CE_ON} between both ends of a collector and an emitter at turn-on of a power semiconductor device used in a power converter;

FIG. 5 is a diagram illustrating a change distribution according to a temperature and a conduction current of a saturation voltage V _{CE_SAT} of a power semiconductor device used in a power conversion device. FIG.

FIG. 6 illustrates the deterioration of the power converter by measuring the static change in voltage V _{CE_ON} between the collector and the emitter at turn-on of the power semiconductor device used in the power converter according to the preferred embodiment of the present invention. A diagram showing a device for diagnosing,

FIG. 7 illustrates a static change in the voltage V _{CE_ON} between the collector and the emitter at the turn-on of the power semiconductor device used in the power converter according to another exemplary embodiment of the present invention, and the collector current (of the power converter). A diagram showing an apparatus for diagnosing deterioration of a power converter by measuring conduction current)

8 is a view showing a change in conduction current according to a pulse width modulation (PWM) switching operation during an operation of a power converter;

FIG. 9 is a diagram illustrating a dynamic change in voltage V _{CE_ON} between both ends of a collector and an emitter at turn-on of a power semiconductor device during PWM switching; FIG.

FIG. 10 is a view illustrating waveforms of conduction current according to the charge Q _C charged in the output capacitor of the power semiconductor device during the turn-on / off operation and the recovery charge Q _R of the anti-parallel diode.

<Description of Symbols for Major Parts of Drawings>

10,20: resistance series circuit 30: isolation circuit

40: amplification circuit 50: analog / digital converter

60: digital signal processor 70: degradation diagnostic unit

80: current sensing unit

Hereinafter, an apparatus and a method for diagnosing deterioration of a power converter of the present invention will be described with reference to the accompanying drawings.

FIG. 4 is a diagram illustrating a distribution of resistance components that generate voltage V _{CE_ON} between the collector and the emitter at turn-on in an internal structure of a power semiconductor device, and FIG. 5 according to temperature and current values. 6 is a diagram illustrating a change in saturation voltage, and FIG. 6 is a degradation diagnosis device of a power conversion device proposed by the present invention for measuring a change in voltage V _{CE_ON} between a collector and an emitter during turn-on. Figure is a diagram.

As shown in FIG. 4, due to the movement of holes and charges inside a power semiconductor device such as an integrated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOST), an integrated gate committed (IGCT), and the like. An internal resistance is generated, thereby generating a saturation voltage (V _{CE_SAT} ) of the power semiconductor device, which is determined according to the junction temperature and the conduction current of the power semiconductor device as shown in FIG. 5. The trend is increasing. In addition, since a conductor is attached and a lead wire is connected to make a collector terminal, an emitter terminal, and a gate terminal in a semiconductor layer, a resistance component is generated here, and a voltage drop occurs due to the conduction of current. ; V _{CE, RDROP} ).

When a power conversion device is configured with a power semiconductor device having such characteristics and operated in an actual field, it undergoes numerous transient states such as overvoltage and overcurrent in addition to the normal voltage and current. In addition, since the operation is performed under adverse conditions such as external mechanical vibration, the contact resistance of the mechanically attached lead wires increases with time. Therefore, the voltage drop V _{CE_RDROP} component increases in proportion to the conduction of current as the power semiconductor device deteriorates.

The _sum of the saturation voltage (V _{CE_SAT} ) of the power semiconductor device and the voltage drop (V _{CE_RDROP} ) component that occurs in the lead wire is between the collector and the emitter at the terminal between the collector and the emitter of the power semiconductor device at turn-on. Since the voltage between the two ends of (V _{CE_ON} ) is shown to the outside, the present invention can measure it and use it as the deterioration index of the power semiconductor device in the power converter.

The circuit configuration for measuring this is shown in FIG. That is, the degradation diagnostic apparatus of the power converter according to the present embodiment includes the first and second resistor series circuits 10 and 20, an isolation circuit 30, an amplifier circuit 40, and an analog / And a digital conversion unit 50, a digital signal processing unit 60 and a deterioration diagnosis unit 70.

The first resistor series circuit 10 includes a plurality of resistors R1 to R_n having a high resistance value connected between the collector terminal and the ground of the power semiconductor device constituting the power converter, and the second resistor The series circuit 20 is composed of a plurality of resistors R1 'to Rn' having a high precision resistance value connected between the emitter terminal of the power semiconductor element and the ground.

The isolation circuit 30 is connected between a predetermined node between the resistors of the first resistor series circuit 10 and the ground of the second resistor series circuit 20 to change a voltage between the predetermined node and the ground. Isolate to prevent variation by ingredients.

The amplification circuit 40 amplifies using a high precision resistor even if the change in voltage V _{CE_ON} between the collector and the emitter is only a few _mmV . The analog / digital conversion unit 50 converts the measurable amplified analog signal passed through the amplification circuit 40 into a digital signal.

The digital signal processing unit 60 performs digital signal processing for degradation diagnosis by using the digital signal passed through the analog / digital conversion unit 50 as degradation diagnostic data.

The degradation diagnosis unit 70 accumulates and stores data processed by the digital signal processor 60 to perform degradation diagnosis.

On the other hand, in the present invention and the collector according to the switching operation of the power semiconductor device by the PWM (Pulse Width Modulation) signal (S1) (S2) input to the gate terminal (G) of the power semiconductor device constituting the power conversion device and The change in dynamic slope is measured using the relationship between the voltage V _{CE_ON} between the emitters and the conduction current I, and used as a diagnostic index for degradation of power semiconductor devices.

This may be implemented by the degradation diagnosis device of the power converter as shown in FIG. 7, and the degradation diagnosis device of the power converter of FIG. 7 may be formed in the collector terminal of the power semiconductor device as compared with the device of FIG. 6. And a current sensing unit 80 connected to sense a collector current (I _C , ie, a conduction current) of the power conversion element, and transmit the sensed current to the amplifying circuit 40. The amplifying circuit 40 amplifies the collector current (that is, the conduction current) input from the current sensing unit together with the voltage V _{CE_ON} between the collector and the emitter input from the isolation circuit, and converts the analog / digital converter. The unit 50 converts the amplified voltage and the collector current (ie, the conduction current) between both ends of the collector and the emitter that have passed through the amplifier circuit 40 into a digital signal. In addition, the digital signal processor 60 deteriorates the digital signal for the amplification voltage between the collector and the emitter passing through the analog / digital converter 50 and the digital signal for the collector current (that is, the conduction current). Digital signal processing for degradation diagnosis is performed using the diagnostic data, and the degradation diagnosis unit 70 performs a digital signal and a collector current (for the amplification voltage between both ends of the collector and the emitter in the digital signal processor 60). That is, deterioration diagnosis is performed by accumulating and storing the digital signal processed data for the conduction current.

As shown in FIG. 8, since the pulse conduction time of PWM switching is a short time such as 10us to 20us, the power semiconductor device may be considered to be in a thermal equilibrium state during t ₀ and t ₇ . While starting operation at t ₀ and reaching the steady state conduction current of t _7, the voltage between the collector and emitter (V _{CE_ON} ) follows the trajectory of the initial T _start graph as shown in FIG. 9. The slope at this time is determined as follows.

If the power semiconductor device is degraded by various surroundings during long time operation of the power semiconductor device, the saturation voltage and lead wire voltage drop increase, and the V _{CE_ON} characteristic curve is _shifted from T _start to T _max . The slope at this time is determined as follows.

Comparing the slope_ {1} (t) and the slope_ {2} (t) values shows that the slope_ {2} (t) ~~> ~~ slope_ {1} (t) phenomenon is exhibited as the degradation progresses. have.

Therefore, the slope_ {1} (t) and slope_ {2} (t) change trends based on the data obtained by the voltage measuring circuit _{VCE_ON} between the collector and the emitter shown in FIG. By continuously calculating and monitoring, it is possible to dynamically estimate the degree of degradation of the power semiconductor device.

10 shows voltage and current waveforms of a power semiconductor device according to a switching state. Even when the turn-on signal is applied to the switch at time t ₁ , the power semiconductor element remains turned off while the conduction current I _C (t) increases to the load current I _F (t), and even after reaching the load current. An additional current flows due to the charge Q _C charged in the output capacitor of the power semiconductor device and the recovery charge Q _R of the anti-parallel diode, causing an overshoot phenomenon of the current. At this time, the magnitude of the overcurrent generated is several times larger than the normal current, and the switching semiconductor is large because the power semiconductor device handles the DC-Link voltage (V _d ). Compared to the switching losses between t ₁ and t ₂ , the switching losses from t ₂ to t _3, where overcurrent occurs, are several times greater. In addition, the maximum occurrence time of the overcurrent (t_ {3} -t_ {2}) is determined by the magnitude of the output capacitance and the reverse recovery charge caused by the physical properties inside the power semiconductor device. As the device changes as it deteriorates, it can be used as a degradation diagnostic index by measuring and tracking the size of the region in which the overcurrent appears.

As described in detail above, according to the present invention, by developing a method for diagnosing the degradation state of the power semiconductor device constituting the power conversion device during the operation of the power conversion device to ensure the safe operation of the power conversion device and Innovative ways to maximize utilization are in place. Therefore, the present invention continuously escapes from the method of diagnosis based on experience and passive historical data without accurate judgment evidence, and continuously monitors the state of the power semiconductor device during operation of the power conversion device while the device is in operation. This protects individual devices as small as possible and further ensures safe operation of the entire system.

In particular, various industrial driving devices such as subways, train drives, rolling mills, large agricultural pump drives, power generation equipment cooling inverters, etc., which have suffered many difficulties in the industrial field due to technical difficulties in maintenance and economic efficiency in securing maintenance personnel. It will be widely applied.

Claims (16)

A power conversion device including a power semiconductor device comprising a controller configured to perform a control function for converting a single-phase and three-phase input power of a main circuit into a desired output power form including a semiconductor element for power, And deteriorating the power converter by measuring a voltage between the collector and the emitter at turn-on, which are electrical parameters of the power semiconductor device. The method of claim 1, And diagnosing deterioration of the power converter by additionally measuring a conduction current of the power semiconductor device. The method of claim 2, It is characterized by measuring the dynamic gradient change of the conduction current of the power semiconductor device with respect to the voltage between the both ends of the collector and the emitter according to the switching operation of the power semiconductor device to use the power semiconductor device degradation diagnostic index Degradation diagnosis method of power converter. The method of claim 2, Degradation of the power semiconductor device by measuring the size of the region where the overcurrent of the power semiconductor device appears by using the voltage between both ends of the collector and the emitter according to the switching operation of the power semiconductor device and the conduction current of the power semiconductor device. Deterioration diagnostic method of a power converter, characterized in that used as a diagnostic index. The method of claim 4, wherein The size of the region in which the overcurrent appears, is obtained by measuring the sum of the sum of the charge charged in the output capacitor of the power semiconductor element and the recovery charge of the anti-parallel diode. The method according to any one of claims 1 to 5, The power semiconductor device is a degradation diagnostic method of the power converter, characterized in that any one selected from IGBT, MOSFET and IGCT. The method according to any one of claims 1 to 5, And the power converter is any one selected from an AC-DC rectifier, a DC-DC converter, and a DC-AC inverter. The method according to any one of claims 1 to 5, And the degradation diagnosis method of the power conversion device, wherein the power conversion device performs a degradation diagnosis at rest and during operation. The method according to any one of claims 1 to 5, And measuring the voltage between both ends of the collector and the emitter during turn-on of the power semiconductor device in the thermal equilibrium state of the power semiconductor device and using the same as a static deterioration diagnostic index. A power conversion device including a power semiconductor device comprising a controller configured to perform a control function for converting a single-phase and three-phase input power of a main circuit into a desired output power form including a semiconductor element for power, A first resistor series circuit comprising a plurality of resistors having a high precision resistance value connected between the collector terminal of the power semiconductor element and ground; A second resistor series circuit comprising a plurality of resistors having a high precision resistance value connected between the emitter terminal and the ground of the power semiconductor element; An isolation circuit connected between a predetermined node between the resistors of the first resistor series circuit and the ground of the second resistor series circuit, and isolating the voltage between the node and the ground so as not to be changed by other components; An amplifying circuit for amplifying the signal passing through the isolation circuit; An analog / digital converting unit converting the analog signal amplifiable in the amplifying circuit into a digital signal; And thermal conversion diagnostic processing means for performing digital signal processing for degradation diagnosis by using the digitally converted signal as degradation diagnostic data. The method of claim 10, And a current sensing unit which senses a conduction current of the power semiconductor element and transfers it to the amplification circuit. And the amplifying circuit amplifies the conduction current together with the signal passing through the isolation circuit. The method of claim 11, The heat exchange diagnostic processing means measures the dynamic gradient change of the conduction current of the power semiconductor device with respect to the voltage between the both ends between the collector and the emitter according to the switching operation of the power semiconductor device. Deterioration diagnostic apparatus of the power converter, characterized in that used as. The method of claim 11, The heat exchange diagnosis processing means may be configured to determine the size of the region in which the overcurrent of the power semiconductor device appears by using the voltage between both ends of the collector and the emitter according to the switching operation of the power semiconductor device and the conduction current of the power semiconductor device. Deterioration diagnostic apparatus of a power converter, characterized in that for measuring the power semiconductor device degradation diagnostic index. The method of claim 13, The size of the region in which the overcurrent appears, is obtained by measuring the sum of the sum of the charge charged in the output capacitor of the power semiconductor element and the recovery charge of the anti-parallel diode. The method according to any one of claims 10 to 14, And the power semiconductor device is any one selected from IGBTs, MOSFETs, and IGCTs. The method according to any one of claims 10 to 14, And the power converter is any one selected from an AC-DC rectifier, a DC-DC converter, and a DC-AC inverter.