JP2010220449A - Power conversion apparatus and elevator device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a comparatively simple structured power conversion apparatus capable of accurately detecting deterioration of a semiconductor module, and to provide an elevator device using the same. <P>SOLUTION: The power conversion apparatus has semiconductor modules (11-16 and 21-26) including semiconductor switching elements, a drive circuit that switches on or off the semiconductor switching elements, and a control device 5 that gives an on- or off-command signal to the drive circuit and further includes a temperature detection unit that detects the temperature of the semiconductor module, and a deterioration decision unit that decides deterioration of the semiconductor module based on the detection result of the temperature detection unit. Furthermore, the temperature detection unit detects the temperature when the switching frequencies of the semiconductor switching elements are changed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power converter including a semiconductor switching element and an elevator apparatus using the power converter.

  In general, inside a semiconductor module, a semiconductor switching element such as an insulated gate bipolar transistor (IGBT) is fixed on an insulating substrate by soldering. Repeated energization and interruption of the semiconductor switching element causes the temperature of the semiconductor switching element to rise and fall, stress concentrates on the solder due to the difference in linear expansion coefficient between the semiconductor switching element and the insulating substrate, and cracks occur due to fatigue. appear. As the crack progresses, heat dissipation of the semiconductor switching element is hindered, the thermal resistance increases, and the semiconductor switching element is destroyed. As means for detecting this before destruction, a method of detecting an increase in thermal resistance using a temperature detecting element as in Patent Document 1 or a solder and resistance laminate as in Patent Document 2 is attached. There is a method for detecting the state of a crack.

  Further, as disclosed in Patent Document 3, there is also a method of detecting an increase in thermal resistance due to deterioration by determining normality and abnormality from a relationship between an estimated value obtained by calculating a loss from an operation command and a temperature change rate in a control device.

  In these examples, Patent Document 1 requires a temperature detection element, and Patent Document 2 requires a laminate of solder and a resistor, which is not suitable for miniaturization of a semiconductor module. In Patent Document 3, an expensive control circuit for calculating the loss is required.

  On the other hand, as a method for detecting the temperature, there is a method using a change in resistance value due to the temperature of the gate resistance as in Patent Document 4. An example in which a gate resistor is mounted on a semiconductor chip is described in Patent Document 5, and the temperature of the semiconductor chip can be estimated from a change in the resistance value of the gate resistor mounted on the semiconductor chip. However, since the thermal resistance between the chip and the case cannot be detected even if the temperature of the semiconductor chip is known, it cannot be applied to detection of crack progress.

  Moreover, as what detects the thermal resistance change of the semiconductor module used for the power converter device which drives an elevator, like patent document 6, the difference between the case temperature of a semiconductor module and a radiator temperature is detected, and specific operation is performed. An example of determining an abnormality from a temperature difference when operating in a mode, or in Patent Document 7, how much the temperature difference when operating in a predetermined operation mode by providing a temperature sensor inside the semiconductor module from the initial value is increased. There is a method of detecting deterioration depending on whether In the former example, a solder crack inside the semiconductor module cannot be detected, and in both examples, temperature detection in a specific operation mode is necessary, which may lead to a decrease in elevator service.

  Further, Patent Document 8 discloses an example of detecting a change in thermal resistance of a semiconductor module used in a power conversion device that drives an electric vehicle or a hybrid vehicle. In this example, utilizing the temperature characteristics of the voltage drop of the semiconductor element, the remaining life is evaluated by checking when the vehicle is stopped. However, the voltage drop of the semiconductor element is about several volts in the on state, but is applied several hundred volts or more in the off state, so that accurate measurement is difficult. In this example, for example, when measuring the temperature rise on the upper arm side, the lower arm is turned on / off. However, since the on-voltage of the IGBT is low, it is sufficient that the measured IGBT itself is not turned on / off. Since the temperature cannot be raised, accurate evaluation is difficult.

  On the other hand, as a method of suppressing the temperature rise of the IGBT during normal operation, the switching of each phase is stopped every certain period in the three-phase inverter (for example, the upper arm side remains on and the lower arm side remains off). ) There is a two-phase modulation mode for reducing switching loss, and Patent Document 9 describes a method of switching to a two-phase modulation mode when a temperature detection element is attached to an inverter and it is determined that the temperature is equal to or higher than a predetermined temperature. However, this is useful for protecting the temperature from exceeding the allowable temperature, but the deterioration cannot be determined.

JP-A-9-148523 JP 2008-34707 A JP 2003-134895 A JP 2000-124781 A JP 2002-83964 A JP 2007-269413 A JP 2007-230728 A JP 2002-119043 A JP 2003-199381 A

  The present invention has been made in view of the above problems, and provides a power conversion device capable of detecting deterioration of a semiconductor module with high accuracy with a relatively simple configuration and an elevator device using the power conversion device.

  A power conversion device according to the present invention includes a semiconductor module including a semiconductor switching element, a drive circuit that performs on / off switching of the semiconductor switching element, and a control device that provides an on / off command signal to the drive circuit. The power conversion device further includes a temperature detection unit that detects the temperature of the semiconductor module, and a deterioration determination unit that determines deterioration of the semiconductor module based on a detection result of the temperature detection unit. The temperature when the switching frequency of the element is changed is detected.

  The elevator apparatus according to the present invention includes a car, a rope that suspends the car, and a motor that drives the rope to raise and lower the car, and supplies power to the motor by the power converter according to the present invention. Further, in the period of increasing the number of times of switching, the loading capacity of the car is set to 0.3 to 0.7 times that is substantially half of the rated loading mass.

  ADVANTAGE OF THE INVENTION According to this invention, the power converter device which can detect deterioration of a semiconductor module with a comparatively simple structure with sufficient precision, and an elevator apparatus using the same are realizable.

The structure of 1st embodiment of this invention is shown. The temperature curve in 1st embodiment is shown. It is explanatory drawing of the detection method in 1st embodiment. The temperature characteristic of the gate resistance regarding 1st embodiment is shown. The structure of 2nd embodiment of this invention is shown. The structure of the detection part in 3rd embodiment of this invention is shown. The temperature curve in 4th embodiment of this invention is shown. A range suitable for detection is shown as a fifth embodiment of the present invention.

  FIG. 1 shows a schematic configuration of a power conversion apparatus according to a first embodiment of the present invention and an elevator apparatus that is driven and controlled using the power conversion apparatus. AC power received from the commercial power supply 71 is converted into DC power by the PWM rectifier 2 and supplied to the inverter 1 via the smoothing capacitor 72. The inverter 1 converts DC power into AC power having a desired frequency and supplies the AC power to a motor 73 driven by the AC power. In a configuration in which a car 81 and a counterweight 84 are suspended by ropes 85 on both sides of the motor 73 and the curling wheel 83, the motor 73 is rotated to raise and lower the car 81. Control of the elevator apparatus is performed by the control apparatus 5 based on a signal from a speed detector 74 including a current sensor 6 and an encoder.

  The control device 5 controls the speed by the elevator control unit 51 from the speed detector 74, the load sensor 82 of the car and the elevator call information (not shown), and the current control unit 52 generates necessary torque. Control the current. In response to commands from the PWM carrier wave generation unit 54 and the current control unit 52, the pulse generation unit 55 generates a PWM pulse, and an ON / OFF command SG for each switching element is sent to the gate drive circuit 3 via the pulse transmission unit 56. . In the gate drive circuit 3, the on / off command signal is converted into an IGBT drive signal, and a gate voltage signal is applied via the gate resistors 31 and 32, whereby each of the semiconductor modules 11 to 16 constituting the inverter 1. A semiconductor switching element (IGBT here) is driven. Here, in the semiconductor module 12, the gate resistor 31 is mounted on the IGBT semiconductor chip, and the other gate resistor 32 is mounted on the insulating substrate 122 different from the insulating substrate 121 on which the IGBT and semiconductor diodes of the free-wheeling diode are mounted. Is arranged. Each of the gate resistors 31 and 32 has a characteristic that the resistance value changes depending on the temperature, and the temperature can be detected using these resistors.

  In addition, when the rectifier side is the PWM rectifier 2 as shown in FIG. 1, the control circuit and the gate drive circuit for driving the semiconductor switching elements of the respective semiconductor modules 21 to 26 are used as in the inverter 1. Is the same as the inverter, and is not shown for simplification of the drawing.

  The control device 5 has a modulation method switching unit 53 for switching between two-phase modulation and three-phase modulation. In response to this switching command, the pulse generation unit 55 performs both two-phase modulation switching and three-phase modulation switching. Of pulses can be generated.

  Further, there is a deterioration determination unit 4. Voltage detection units 412 and 422 detect the voltage V1 and V2 across the gate resistance from the two gate resistors 31 and 32 via the insulating units 411 and 421, and the voltage comparison unit 43 detects the voltage. The ratio V1 / V2 is detected. The voltage across the gate resistor is detected by detecting the voltage across the gate current supplied from the gate drive circuit 3 at the maximum value.

  FIG. 3 shows a timing chart of detection. The on / off command SG from the pulse transmitter 56 to the gate drive circuit 3 is initially in an off state, but an on command is input at t10. Due to the delay of the photocoupler in the gate drive circuit 3, for example, the gate current starts to flow at time t11. As the gate current flows, the gate voltage rises. The gate current reaches its peak value at t12, and at this time, the voltage command between the two ends of the gate resistance is detected by giving a detection command SD to the voltage detectors 412 and 422. Since the time from the on-command timing t10 to t12 when the gate current becomes maximum is substantially determined from the gate power supply voltage and the gate resistance, the detection command SD can be given by the delay circuit 401 that is delayed by this time.

  Since the voltage across the gate resistance is also maximized when the gate current is maximized, the maximum value is obtained by comparing the sequentially detected data with the previous data without using the signal from the pulse transmitter 56. However, since the change of the gate current is fast at that time, it is preferable to perform the comparison operation at high speed.

  Thereafter, since the gate voltage Vge further rises and reaches the gate threshold voltage at the time t13, the collector current Ic starts to flow. As the collector current Ic increases, the collector-emitter voltage Vce decreases by the voltage of the wiring inductance. Thereafter, Vce further decreases to reach an ON steady state. In this way, at the time t12 when the voltage across the gate resistance is detected, the collector current Ic and the collector-emitter voltage Vce have not changed yet, so that there is no potential fluctuation and noise is unlikely to occur, so that it can be accurately detected. Further, when an OFF command is input at t14, the gate current Ig starts to flow in a negative direction at t15, which is slightly delayed, and the voltage Vce starts to increase at t16 and the OFF operation is performed. It is also possible to detect the voltage across the gate resistance at this time.

  Next, a method for detecting an increase in thermal resistance due to deterioration will be described with reference to FIG. FIG. 2 shows, as part of an example of elevator operation, speed v, motor current i, semiconductor switching element of semiconductor module 12 when accelerating at time t1 and ending at time t2 and running at a constant speed. Loss P and changes in the switching element chip-case temperature difference ΔTj-c. The motor current is actually a sinusoidal current with a variable frequency, but here, a short-term effective current value is shown to indicate the magnitude of the current.

  The period from time t1 to t2 is an acceleration period, and the speed v increases. During acceleration, the current is larger than the constant speed period after t2 due to the influence of inertia, so the loss is also large. In actual elevators, the speed does not always increase linearly, for example, because the acceleration is changed to improve the ride comfort during the acceleration period, but here the acceleration is assumed to be constant for the sake of simplicity. did.

  From time t3 to t4, the switching loss is reduced by the two-phase modulation switching method, that is, the switching of one phase of the three phases is stopped one by one in order from the magnitude relationship. The system has been switched to a three-phase modulation switching system that switches all three phases. This increases the loss even if the current is the same. In FIG. 2, ΔTj−c indicates the initial state of the semiconductor module with a dotted line, and indicates the state of deterioration due to solder cracks with a solid line. Since the thermal resistance is increased in the deteriorated state, the temperature is higher than that in the initial state. In addition, the temperature difference between time t5, which is the two-phase modulation switching method, and time t6, after switching to the three-phase modulation switching method, also increases in the degraded state (ie, ΔT> ΔT0). Usually, in order to directly compare the initial state and the deteriorated state, it is preferable to compare under conditions where the other environments match, and it is preferable to store the initial state. A temperature difference between time t5 and time t6 can be detected by a simple circuit or method.

  In general semiconductor modules, the thermal resistance between the semiconductor chip and the case and the thermal resistance between the case and the radiator reach a steady value in about 1 second, whereas the thermal time constant of the radiator is from one minute to several minutes. Minutes. Therefore, if the time between t3 and t4 is set to several seconds, ΔTj-c can be sufficiently changed and detected, and the temperature of the radiator hardly increases. That is, the period t3 to t4 in which the number of times of switching is increased by switching from the two-phase modulation method to the three-phase modulation method is longer than the time until the thermal resistance between the semiconductor chip and the case reaches a steady value, and the heat sink of the semiconductor module By setting the time shorter than the thermal time constant, the temperatures Tc and Tj can be detected with high accuracy without impairing the heat dissipation performance. Moreover, in an elevator that is a relatively high-rise building and goes straight from the entrance floor (for example, the first floor) to the observation floor, the speed is constant for several tens of seconds, so t3 to t4 are detected during that period. Enough time can be secured.

  Next, a method for detecting an increase in thermal resistance due to deterioration will be described.

  The temperature characteristics of the gate resistors 31 and 32 are shown in FIG. In the gate resistance used in the present embodiment, the resistance value at 125 ° C. is twice that of the resistance value at 25 ° C.

  Here, the gate resistors 31 and 32 have the same resistance value, and the resistance value R (T) at the temperature T is expressed by the equation (1).

R (T) = R0. {1+ (2R0-R0) / (125-25). (T-25)}
= R0 · {1 + R0 · (T−25) / 100} (1)

  The resistance value of the gate resistor 31 mounted on the semiconductor chip is R1, the voltage at both ends is V1, the resistance value of the gate resistor 32 mounted on an insulating substrate different from the insulating substrate on which the semiconductor chip is disposed is R2, and the voltage at both ends Is V2. Here, the temperature of the gate resistor 31 is the temperature Tj of the semiconductor chip, and the temperature of the gate resistor 32 is the case temperature Tc. In this embodiment, the resistance value R0 of both resistors at 25 ° C. is 1Ω.

  At t5 in FIG. 2, the case temperature Tc (t5) = 70 ° C., the loss P (t5) = P0 = 1000 W, and the standard value Rth (j−c) of the thermal resistance between the chip and the case = 0.02 [K / W], Tj (t5) is expressed by equation (2).

Tj (t5) = Tc (t5) + Rth (j−c) · P (t5) (2)
= 70 + 0.02 × 1000 = 90 ° C.

Therefore, the resistance value is
R1 (t5) = R1 (T = 90 ° C.) = 1 × {1 + 1 × (90−25) / 100} = 1.65Ω
R2 (t5) = R2 (T = 70 ° C.) = 1 × {1 + 1 × (70−25) / 100} = 1.45Ω
Assuming that the maximum value of the gate current is Ig (t5), the voltages V1 and V2 across the gate resistors are as follows.

V1 (t5) = Ig (t5) · R1 (t5) = 1.65 · Ig (t5)
V2 (t5) = Ig (t5) · R2 (t5) = 1.45 · Ig (t5)

  The voltages V1 (t5) and V2 (t5) are detected by the voltage detection units 412 and 422 in FIG. 1, and the output of the voltage comparison unit 43 is expressed by equation (3).

(V1 / V2) | t5 = V1 (t5) / V2 (t5) = 1.65 / 1.45
= 1.138 (3)

  When receiving the signal transmitted from the modulation system switching unit 53 at the time point t5, the detection adjustment unit 44 temporarily stores the value of V1 / V2 at the time point t5 in the detection value storage unit 45.

  Next, the case where the thermal resistance Rth (jc) between the chip and the case has not increased at t6 in FIG. 2 will be described. Assume that the loss is k times the loss P0 at the time t5. Tc at t6 is expressed by equation (4), where Rth (c−f) = 0.01 [K / W] is the thermal resistance between the case of the semiconductor module and the radiator. Here, the temperature of the radiator is Tfin.

Tc (t6) = Tc (t5) + Rth (cf). (K-1) .P0 + (Tfin (t6)
-Tfin (t5)) (4)

  Here, since the time from t5 to t6 is about several seconds, the temperature change of the radiator can be ignored.

  When the switching frequency is about 10 kHz, the loss is larger than the steady loss, and when switching from two-phase modulation to three-phase modulation, the number of times of switching is 3/2 = 1.5 times, and the power factor Is relatively high (0.9 or more), switching at a large current value may have stopped during two-phase modulation, and loss including steady loss may be about 1.5 times. Therefore, the loss increase ratio is set to k = 1.5.

Tc (t6) = 70 + 0.01 × (1.5-1) × 1000 = 75 ° C.
Tj (t6) = Tc (t6) + Rth (j−c) · P (t6)
= 75 + 0.02 × 1.5 × 1000 = 105 ° C.

Therefore, each resistance value is
R1 (t6) = 1 × {1 + 1 × (105−25) / 100} = 1.8Ω
R2 (t6) = 1 × {1 + 1 × (75−25) / 100} = 1.5Ω

  Therefore, the output of the voltage comparison unit 43 is expressed by equation (5).

    (V1 / V2) | t6 = V1 (t6) / V2 (t6) = 1.8 / 1.5 = 1.2 (5)

  From the voltage ratio at t5 and t6, the voltage comparator 46 derives the difference between the equations (3) and (5) as the following equation (6).

(V1 / V2) | t6- (V1 / V2) | t5 = 1.2-1.138 = 0.062
... (6)

  On the other hand, the case where thermal resistance increases due to deterioration will be described below. Here, assuming that the thermal resistance is γ times, the post-degradation thermal resistance Rth (j−c) ′ is expressed by equation (7).

    Rth (j−c) ′ = γ · Rth (j−c) (7)

  Here, it is assumed that γ = 1.2, that is, the thermal resistance between the chip and the case becomes 1.2 times the initial value.

First, the temperature at t5 is the same as when there is no deterioration, assuming that the loss is P and Rth (c−f), and it may be considered that Tc (t5) ′ = 70 ° C. Since the chip temperature Tj has a thermal resistance of γ times,
Tj (t5) ′ = Tc (t5) ′ + Rth (j−c) · γ · P0
= 70 + 0.02 × 1.2 × 1000 = 70 + 24 = 94 ° C.
It becomes. Therefore, each resistance value is
R1 (t5) ′ = R1 (T = 94 ° C.) = 1 × {1 + 1 × (94−25) / 100}
= 1.69Ω
R2 (t5) ′ = R2 (T = 70 ° C.) = 1 × {1 + 1 × (70−25) / 100}
= 1.45Ω

  Assuming that the maximum value of the gate current is Ig (t5) ′, the voltages V1 and V2 across the gate resistors are as follows.

V1 (t5) ′ = Ig (t5) ′ · R1 (t5) ′ = 1.65 · Ig (t5) ′
V2 (t5) ′ = Ig (t5) ′ · R2 (t5) ′ = 1.45 · Ig (t5) ′

  The voltages V1 (t5) ′ and V2 (t5) ′ are detected by the voltage detectors 412 and 422 in FIG. 1, and the output of the voltage comparator 43 is expressed by equation (8).

(V1 / V2) | t5 '= V1 (t5)' / V2 (t5) '= 1.69 / 1.45
= 1.166 (8)

  When the detection adjustment unit 44 receives a signal transmitted from the modulation system switching unit 53 at time t5, the detection adjustment unit 44 temporarily stores the value of V1 / V2 at t5 in the detection value storage unit 45.

  Next, the time point t6 will be described. The loss is k times the loss P0 at time t5. Assuming that the thermal resistance between the case of the semiconductor module and the heatsink remains unchanged at Rth (cf) = 0.01 [K / W], equation (9) is obtained.

Tc (t6) '= Tc (t5)' + Rth (cf). (K-1) .P0 + (Tfin (t6) '
-Tfin (t5) ') (9)

  Again, since the time from t5 to t6 is about several seconds, the temperature change of the radiator can be ignored.

The loss increase ratio is the same as when it is not degraded, and k = 1.5.
Tc (t6) ′ = 70 + 0.01 · (1.5-1) · 1000 = 75 ° C.
Tj (t6) ′ = Tc (t6) ′ + Rth (j−c) · γ · P (t6)
= 75 + 0.02 × 1.2 × 1.5 × 1000 = 111 ° C.

Therefore, each resistance value is
R1 (t6) ′ = 1 × {1 + 1 × (111−25) / 100} = 1.86Ω
R2 (t6) ′ = 1 × {1 + 1 × (75−25) / 100} = 1.5Ω

  Therefore, the output of the voltage comparison unit 43 is expressed by equation (10).

(V1 / V2) | t6 '= V1 (t6)' / V2 (t6) '= 1.86 / 1.5 = 1.24
... (10)

  From the voltage ratio at t5 and t6, the voltage comparator 46 derives the difference between the equations (8) and (10) as in the equation (11).

(V1 / V2) | t6 '-(V1 / V2) | t5' = 1.24-1.166 = 0.074
(11)

  In the voltage ratio comparison unit 48, 0.062 calculated by the equation (6) before deterioration and 0.074 calculated by the equation (11) at the time of deterioration are compared with the determination threshold value 47. Here, by setting the determination threshold value to 0.070, it is possible to detect deterioration of the thermal resistance. When the deterioration of the thermal resistance is detected, the deterioration information is transmitted from the thermal resistance increase determination unit 49 to the elevator control unit 51 in the control device 5. The deterioration information is displayed on the diagnosis result output unit 57 and is transmitted to the management room of the building where the elevator (not shown) is installed and the remote monitoring room of the elevator maintenance company by the diagnosis result transmission unit 58.

  In this way, an increase in thermal resistance due to deterioration can be detected using the difference between the temperature changes ΔT and ΔT0 when the loss shown in FIG. 2 is increased. In the above-described embodiment, the thermal resistance increase rate γ is set to 1.2. However, by changing the determination threshold value 47, other numerical values can be set.

  Although the deterioration determination unit 4 may be provided inside the semiconductor module, it is preferable to reduce the size of the semiconductor module in order to reduce the size of the power converter. Therefore, it is preferable to provide a terminal for detecting the voltage across the gate resistors 31 and 32 in the semiconductor module.

  The above-described embodiment is suitable for downsizing the power conversion device, does not require an expensive control circuit, and can detect deterioration of the semiconductor module without degrading the service of the elevator device.

  FIG. 5 shows a power conversion apparatus and an elevator apparatus using the same according to the second embodiment of the present invention. Hereinafter, a configuration different from the embodiment of FIG. 1 will be mainly described.

  In this embodiment, the loss is changed by changing the switching frequency at t5 in FIG. The control device 5 is provided with PWM carrier wave generation units 541 and 542 corresponding to two kinds of switching frequencies, and this is used to switch which carrier wave is used by the pulse generation unit 55 according to a command from the modulation system switching unit 53. .

  The switching frequency by the carrier wave generation unit 542 is set higher than the switching frequency by the carrier wave generation unit 541. Therefore, by switching from the carrier wave generating unit 541 to the carrier wave generating unit 542 at t3 to t4 in FIG. 2, the switching loss can be increased similarly to the state at t3 to t4 in FIG.

  Further, in this embodiment, instead of using a gate resistor for temperature detection, a temperature sensor 91 provided on an insulating substrate 121 on which a switching element chip is mounted and a temperature sensor 92 for measuring a case temperature, The temperature detectors 41 and 42 detect the chip temperature Tj and the case temperature Tc, and the temperature difference ΔTj−c is detected by the temperature comparator 430. The ΔTj−c between t5 and t6 in FIG. 2 is compared, and if the difference is greater than a predetermined threshold, it is determined that the thermal resistance has increased. Here, a thermistor or the like is used as the temperature sensor.

  In the present embodiment, since the temperature is directly detected by the temperature sensor, the configuration of the temperature difference detection unit 40 can be simplified.

  FIG. 6 shows a part of a power conversion apparatus and an elevator apparatus to which the power conversion apparatus according to the third embodiment of the present invention is applied. This figure shows one phase of the inverter 1 in FIG. One semiconductor module 1U includes an upper arm (11) and a lower arm (12), and a plurality (three in FIG. 6) of semiconductor switching elements are connected in parallel in each arm. Due to the parallel connection of the semiconductor switching elements, the capacity of the semiconductor module is increased. For simplification of the drawing, the upper arm (11) is not shown, but the same number of switching elements are connected. Here, the temperature of the semiconductor switching element of the lower arm (12) is detected because the emitter of the semiconductor switching element of the upper arm (11) is connected to the load, so that the potential varies due to switching. On the other hand, since the emitter of the semiconductor switching element of the lower arm (12) is connected to the negative electrode, there is no change in potential due to switching, and noise can be detected with high accuracy.

  The gate voltage is detected with respect to the gate resistor 312 connected to the semiconductor switching element 1212 located at the center of the module. In the semiconductor module, the current sharing is equalized between the parallel elements inside, and the temperature of each element is almost the same, but the temperature rise tends to be larger if it is placed in the center of the semiconductor module, so it deteriorates In order to improve detection reliability, detection is performed at the center of the semiconductor module.

  If Tc = 70 ° C. and Tj = 90 ° C., then R1 = R (90 ° C.) = 1.65Ω and R2 = R (70 ° C.) = 1.45Ω. Here, assuming that the gate current flowing through the gate resistor 32 is Ig, the current flowing through the resistor 312 is Ig / 3, which is obtained by dividing the gate current into approximately three equal parts. Therefore, the both-ends voltage of the resistor is expressed by equations (12) and (13).

V1 = R1 · Ig / 3 = 1.65 / 3 · Ig (12)
V2 = R2 · Ig = 1.45 · Ig (13)

  In order to obtain the voltage ratio as in the embodiment of FIG. 1, the difference in the current value between the equations (12) and (13) is corrected. That is, by multiplying the detection value of the voltage detection unit 412 of the resistor 312 by the parallel number correction unit 414 by the parallel number correction value 413 (three times here), the voltage comparison unit 43 and subsequent circuits are the same as those in the first embodiment. And a calculation method can be used.

  In the present embodiment, the resistance values of the gate resistors 311 to 313 incorporated in the semiconductor chip and the resistance value of the gate resistor 32 arranged separately from these gate resistors are the same, but the resistance values are different. In this case, the numerical value of the parallel number correction value 413 may be changed according to the resistance value and the parallel number.

  FIG. 7 shows a method for detecting an increase in thermal resistance in a power conversion apparatus and an elevator apparatus using the same according to a fourth embodiment of the present invention. FIG. 7 corresponds to FIG. 2 in the first embodiment. In the case of FIG. 2, an increase in thermal resistance is detected from a change in temperature rise when the number of switching between t3 and t4 is increased to increase the loss, but in the present embodiment, conversely from t3 to t4. The increase in thermal resistance is detected from the change in temperature difference when the number of times of switching is reduced. Since the temperature difference ΔT can be expressed by the product of the loss variation ΔP and the thermal resistance, the variation increases as the thermal resistance increases due to deterioration. Therefore, an increase in thermal resistance can be detected in the same manner as when the loss in FIG. 2 is increased.

  When increasing the loss in order to detect an increase in thermal resistance, it is necessary to prevent Tj from exceeding the allowable temperature of the semiconductor switching element. However, in this embodiment, the allowable temperature need not be considered.

  FIG. 8 shows the relationship between the current when the elevator is in a power running operation and the actual loading ratio with respect to the rated loading mass of the elevator in the power converter and the elevator apparatus using the same according to the fifth embodiment of the present invention. . In general elevators, the weight of the counterweight is determined so that it is balanced when the load is about half of the rating. Therefore, the current is minimized when the loading rate is about 0.5, and the current when the loading rate is increased by 1.0 and when the loading rate is lowered without loading is increased. Even if the current value I0 when the loading ratio is 1.0 is changed from the two-phase modulation method to the three-phase modulation method as shown in FIG. 2 within a range of 2/3 or less (the number of times of switching is 3 / Since the loss does not exceed the loss when the current value is I0, the temperature Tj does not exceed the allowable temperature.

  As shown in FIG. 8, for example, if the loading ratio is 0.3 to 0.7, even if the two-phase modulation method is changed to the three-phase modulation method, the current during rated loading will not be exceeded. Even if the loss is increased for detection, the temperature of the semiconductor chip of the semiconductor switching element does not exceed the allowable temperature. Detecting whether the loading ratio is within a range of 0.3 to 0.7, which is a value that can increase the loss in the elevator control unit 51, based on a signal from the load sensor 82 in FIG. 1 or FIG. The modulation method may be switched by transmitting the information to the modulation method switching unit 53.

  Needless to say, various embodiments are possible within the scope of the technical idea of the present invention. For example, as the semiconductor switching element, other semiconductor switching elements such as a power MOSFET can be used in addition to the IGBT. The present invention is not limited to an inverter, and can be implemented in a converter using a semiconductor module, various switching power supplies, and the like. Furthermore, the power conversion device according to the present invention can be applied to a device in which a constant current state continues in addition to an elevator, and brings about the same effect.

DESCRIPTION OF SYMBOLS 1 Inverter 2 PWM rectifier 3 Gate drive circuit 4 Degradation determination part 5 Control apparatus 6 Current sensor 11-16, 21-26 Semiconductor module 31, 32 Gate resistance 43, 46 Voltage comparison part 44 Detection adjustment part 45 Detection value storage part 47 Determination Threshold 48 Voltage ratio comparison unit 49 Thermal resistance increase determination unit 51 Elevator control unit 52 Current control unit 53 Modulation method switching unit 54 PWM carrier wave generation unit 55 Pulse generation unit 56 Pulse transmission unit 57 Diagnosis result output unit 58 Diagnosis result transmission unit 71 Commercial Power supply 72 Smoothing capacitor 73 Motor 74 Speed detector 81 Car 82 Load sensor 83 Curling wheel 84 Balance weight 85 Rope 401 Delay circuit 411, 421 Insulating part 412, 422 Voltage detection part

Claims (7)

A semiconductor module including a semiconductor switching element;
A drive circuit for switching on and off the semiconductor switching element;
A control device for supplying an on / off command signal to the drive circuit;
In a power converter having
A temperature detector for detecting the temperature of the semiconductor module;
A degradation determination unit that determines degradation of the semiconductor module based on a detection result of the temperature detection unit;
With
The power detection device, wherein the temperature detection unit detects a temperature when the number of times of switching of the semiconductor switching element is changed.   The power converter according to claim 1, wherein the control device changes the number of times of switching by switching a switching modulation mode between two-phase modulation and three-phase modulation.   The power conversion device according to claim 1, wherein the control device changes the number of times of switching by changing a switching frequency.   4. The period of changing the number of times of switching according to claim 1 is longer than a time during which a thermal resistance between the semiconductor switching element and the case in the semiconductor module reaches a steady value. The power converter characterized by being small with respect to the thermal time constant of a heat radiator.   5. The power conversion device according to claim 1, wherein the temperature detection unit includes a gate resistor connected between the semiconductor switching element and the drive circuit. 6.   6. The power conversion device according to claim 5, wherein the temperature detection unit includes means for detecting a resistance value from a voltage across the gate resistance at a gate current peak during switching. In an elevator apparatus comprising: a car, a rope that hangs the car, a motor that drives the rope to raise and lower the car, and a power converter that supplies power to the motor.
The power conversion device includes a semiconductor module including a semiconductor switching element, a drive circuit that performs on / off switching of the semiconductor switching element, and a control device that provides an on / off command signal to the drive circuit, and A temperature detection unit that detects a temperature; and a deterioration determination unit that determines deterioration of the semiconductor module based on a detection result of the temperature detection unit, wherein the temperature detection unit changes a switching frequency of the semiconductor switching element. Temperature is detected,
The elevator apparatus characterized in that a loading capacity of the car is 0.3 to 0.7 times a rated loading mass in a period in which the switching frequency is increased.

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