Power converter and power conversion method

Abstract

To provide a power converter and a power conversion method that effectively utilize a power semiconductor with an appropriate life by suppressing damage to the power semiconductor when an operation condition at the time of facility operation is set.SOLUTION: A power converter 100 includes a rectifier unit 200 that inputs an AC voltage from an AC power supply 1000 and outputs a DC voltage, an inverter unit 4 that converts the DC voltage output from the rectifier unit into the AC voltage, a control unit 7 that controls trial operation of the inverter unit 4 based on a predetermined operation condition, and a damage amount processing unit 9 that calculates and accumulates a damage amount of the inverter unit 4 during a trial operation period of the inverter unit 4 by the control unit 7, and acquires an operation result of the inverter unit 4 based on the accumulated damage amount.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device, and more particularly to a power conversion device and a power conversion method for supplying AC power to a motor, for example. [Background technology]

[0002] Power conversion devices, such as general-purpose inverters, are widely used in the industrial world as motor drive devices in manufacturing equipment, lifting equipment, transport equipment, etc. In these various applications, general-purpose inverters are required to operate stably, and if a general-purpose inverter should stop operating, it could have a significant impact on production, as it could cause the production of factories or the operation of facilities to stop.

[0003] General-purpose inverters use semiconductor elements (hereafter referred to as power semiconductors) such as IGBTs (Insulated Gate Bipolar Transistors) and diodes to control the flow and interruption of current and perform the desired power conversion. Power semiconductors are bonded by wire bonding or soldering to a copper foil pattern formed on an insulating substrate, which electrically connects them to an external circuit.

[0004] The insulating substrate is mounted on a metal base, and the power semiconductors are cooled through the metal base. A component that incorporates power semiconductors in a housing that has a cooling structure and an electrical connection structure with an external circuit is called a power module.

[0005] When current flows through and is cut off in a power semiconductor, the power semiconductor generates heat, and a temperature difference (hereafter referred to as △T) occurs between the junction and the fin (metal base with a cooling structure). When the inverter is stopped, heat generation stops and △T becomes small.

[0006] The joints of the power semiconductors mentioned above (wire bonding, joints with copper foil patterns) generally use materials with different thermal expansion coefficients, so fluctuations in ΔT cause thermal stress to be applied to the joints. Repeated fluctuations in ΔT can cause peeling or cracks in the joints, leading to failure.

[0007] The time it takes for such a breakdown to occur varies depending on the magnitude and frequency of ΔT. The magnitude and frequency of ΔT vary depending on how the power conversion device is used and the device driven by the power conversion device.

[0008] In addition, the load on the IGBT and the diode also varies depending on the usage of the device. Therefore, in order to prevent such failures, it is necessary to take measures to understand the degree of load on the IGBT and the diode according to the usage of the power conversion device.

[0009] A conventional technique in this technical field is Patent Document 1. Patent Document 1 discloses a technique for calculating the temperature change amplitude of a power semiconductor from the current flowing through the power semiconductor, the operating frequency, and the carrier frequency in a power conversion device that drives a motor, calculating thermal stress from power cycle curve data and the temperature change amplitude, estimating the remaining life of the power semiconductor based on this thermal stress signal, and outputting the result on a display unit.

[0010] Furthermore, Patent Document 1 discloses a method for extending the life of a power semiconductor when the accumulated thermal stress reaches a predetermined threshold value, or when the remaining life time per set time is calculated and compared with the expected life time, and when the remaining life time is shorter than the expected life time due to load fluctuations or the like, an alarm signal is output to a display unit, the current limit level is lowered, or the upper limit value of the carrier frequency is lowered. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2004 / 082114 Summary of the Invention [Problem to be solved by the invention]

[0012] In the configuration shown in Patent Document 1, the remaining life of the power semiconductors and alarm signals are displayed on the operation panel, making it possible to take life-extending measures by automatically adjusting the operating conditions or for an operator to replace the power conversion device before the system abnormally stops.

[0013] However, in the configuration shown in Patent Document 1, there is a risk that the life diagnosis will only output an alarm signal when the damage to the power semiconductor reaches a predetermined threshold, and there is a concern that the alarm signal will be output just before the power semiconductor is destroyed.

[0014] In addition, the configuration shown in Patent Document 1 shows the operation of automatically adjusting the current value and carrier frequency based on an alarm signal, but does not take into consideration the impact on the entire system due to changes in operating conditions after the equipment is put into operation, and there is a concern that it is unclear what impact the automatic adjustment of parameters will have on the entire system.

[0015] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a power conversion device and a power conversion method that can realize a short-term life diagnosis of power semiconductors in order to effectively utilize the power semiconductors with an appropriate life span. [Means for solving the problem]

[0016] One aspect of the present invention that solves the above problem is a power conversion device that includes an inverter unit that converts a DC voltage into an AC voltage, a control unit that controls operation of the inverter unit based on predetermined operating conditions, and a damage amount processing unit that calculates an amount of damage to the inverter unit during an operation period of the inverter unit by the control unit, and generates data indicative of an operating result based on the calculated damage amount and the operating conditions.

[0017] Another aspect of the present invention is a power conversion method for a power conversion device in which an inverter unit converts a DC voltage into an AC voltage, a control unit controls the operation of the inverter unit based on specified operating conditions, and a damage amount processing unit calculates the amount of damage to the inverter unit while the inverter unit is being operated by the control unit, wherein a planned operation period during which the inverter unit will operate normally is set in advance, and the damage amount calculation unit measures the amount of damage to the inverter unit during the operation period of the inverter unit by the control unit, calculates an estimated time of damage to the inverter unit based on the measured amount of damage and the operating conditions, and generates data indicative of an operation result based on the calculated estimated time of damage, the planned operation period, and the operating conditions. Effect of the Invention

[0018] According to the present invention, it is possible to provide a power conversion device and a power conversion method capable of performing a life diagnosis on a power semiconductor in a short period of time in order to effectively utilize the power semiconductor within an appropriate life span. [Brief description of the drawings]

[0019] [Figure 1] 1 is a circuit diagram showing a configuration example of a power conversion device according to a first embodiment of the present invention. [Diagram 2] 4 is a flowchart illustrating an example of processing in a damage amount processing unit according to the first embodiment of the present invention. [Diagram 3] FIG. 2 is an explanatory diagram showing an example of a waveform under an operating condition in the first embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory diagram showing a display example of a test run result in the first embodiment of the present invention. [Diagram 5] FIG. 4 is a circuit diagram showing a modified example of the power conversion device according to the first embodiment of the present invention. [Figure 6] FIG. 4 is a circuit diagram showing a configuration example of a power conversion device according to second and third embodiments of the present invention. [Figure 7] FIG. 11 is an explanatory diagram showing an example of a display of a test run result in the second embodiment of the present invention. [Figure 8]11 is a flowchart illustrating an example of processing in a damage amount processing unit and a damage amount estimation unit according to the second embodiment of the present invention. [Figure 9] FIG. 11 is an explanatory diagram showing an example of a display of an operation result in the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. <Embodiment 1> First, a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a circuit diagram showing a configuration example of a power conversion device in the first embodiment. For example, as shown in Fig. 1, a power conversion device 100 is connected to an AC power source 1000 and a motor 2000, and is also connected to an external device 5 via an input / output unit 6.

[0021] As shown in FIG. 1, for example, the power conversion device 100 is composed of a rectifier unit 200 that inputs an AC voltage from an AC power source 1000 and outputs a DC voltage, a smoothing capacitor 3 that smoothes the DC voltage, an inverter unit 4 that converts the DC voltage into AC power, an input / output unit 6 that inputs and outputs signals with an external device 5, a control unit 7 that outputs a drive signal to the inverter unit 4, a voltage detection unit 81 that detects the DC voltage, current detection units 82, 83 that detect the output current of the inverter unit 4, a damage amount processing unit 9 that calculates the amount of damage (an index of the degree of deterioration or damage) of the power semiconductors of the inverter unit 4 using the DC voltage and the output current, a display unit 10 that displays, for example, an LCD display, and an operation unit 11 that has, for example, operation buttons and inputs operations by an operator.

[0022] Rectification unit 200 is composed of a plurality of diodes, and converts the AC voltage input from AC power supply 1000 into a DC voltage, and outputs it to both electrodes of smoothing capacitor 3. The rectification action of the diodes in rectification unit 200 generates a DC voltage such that a positive voltage is generated in the DC voltage wiring on the node P side, and a negative voltage is generated in the DC voltage wiring on the node N side.

[0023] The smoothing capacitor 3 is connected to the DC voltage wiring at the nodes P and N, and smoothes the DC voltage. Note that, although a method of full-wave rectifying three-phase AC is shown as a representative example in Fig. 1, a method of full-wave rectifying single-phase AC or a method of voltage-doubler rectifying single-phase AC may also be used.

[0024] The inverter unit 4 is composed of, for example, six power semiconductors 41 to 46. When the motor 2000 is in power running mode, the power semiconductors 41 to 46 convert the DC voltage of the smoothing capacitor 3 into AC power and output it to the motor 2000, and when the motor 2000 is in regenerative running mode, the power semiconductors 41 to 46 operate to charge the smoothing capacitor 3 with regenerative energy from the motor 2000.

[0025] Here, when the DC voltage is below the reference voltage, it is determined that the motor is in power running, and when the DC voltage is above the reference voltage, it is determined that the motor is in regeneration. Alternatively, a method may be used in which the motor power factor is estimated from control information held by the control unit 7 to determine whether the motor is in power running or regeneration.

[0026] The power semiconductor shown in FIG. 1 uses the circuit symbol for an IGBT as a representative example, but it is also possible to use other power semiconductors such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0027] The external device 5 includes an output unit 51 that outputs a signal to the power conversion device 100, and an input unit 52 that inputs a signal from the power conversion device 100. Here, in the first embodiment, the input unit 52 may be a liquid crystal panel that obtains input information by touching a display screen, but is not limited thereto, and may be an input / output device consisting of a display panel and a keyboard. Note that the liquid crystal panel and the input / output device are not shown in the figure.

[0028] Here, a case will be taken as an example in which the external device 5 is a device (such as a computer, a smartphone, or an operator) that has a function of operating the power conversion device 100 using a liquid crystal panel or various buttons.

[0029] When predetermined operating conditions (setting parameters required for inverter operation) of the power conversion device 100 are input by an operator to the external device 5, the power conversion device 100 receives a signal (operating conditions, etc.) from the output unit 51 and operates under these operating conditions. Various parameters such as current values ​​and voltage values ​​resulting from this are output from the power conversion device 100 to the input unit 52 of the external device 5. The predetermined operating conditions include carrier frequency (Hz), boost amount (%), current limit, acceleration / deceleration time (seconds), etc.

[0030] As another example, a case will be taken where a device such as a PLC (Programmable Logic Controller) connected to the external device 5 via a field bus is applied. In this case, the operating conditions of the power conversion device 100 are input based on a command from an upper layer of the field bus, and the power conversion device 100 receives a signal from the output unit 51 and operates under the operating conditions. Various parameters such as a current value and a voltage value generated as a result are output from the power conversion device 100 to the input unit 52 of the external device 5 as analog signals.

[0031] The display unit 10 is composed of a 7-segment LED that displays internal data such as various parameters and frequency settings, an operation lamp that lights up when the inverter is operating, etc., and the operation unit 11 is composed of a RUN key that is pressed to operate the inverter, a STOP key that is pressed to decelerate and stop the inverter, a JOG dial, etc.

[0032] With regard to the transmission and reception of basic signals, the external device 5 and the display unit 10 described above correspond to each other, and the external device 5 and the operation unit 11 described above correspond to each other, but the display unit 10 and the operation unit 11 differ from the output unit 51 and the input unit 52 of the external device 5 in that they are located within the power conversion device 100.

[0033] Voltage detection unit 81 detects the DC voltage of smoothing capacitor 3. Since the system voltage can be as high as several hundred volts, voltage detection unit 81 generally uses a signal obtained by dividing the DC voltage using resistors and converting it to about several volts. Current detection units 82 and 83 each detect the current of at least two phases of the three-phase output of inverter unit 4 using a current sensor such as a shunt resistor or a current transformer.

[0034] This is because if leakage current to ground is ignored, the total three-phase AC current is 0 A; therefore, by calculating the current for the remaining phase from the measurement results of any two of the three-phase AC, it is possible to detect the current values ​​of essentially all of the three-phase AC.

[0035] The control unit 7 outputs a drive signal to the inverter unit 4 based on predetermined operating conditions received from the external device 5 via the operation unit 11 or the input / output unit 6 in response to a command from an operator or a command from a higher layer of the field bus. The control unit 7 controls the motor 2000 to operate as desired (trial operation state) by performing feedback control using the predetermined operating conditions input from the external device 5 as command values ​​and detection values ​​of various detection units such as the voltage detection unit 81 and the current detection units 82 and 83 as control amounts.

[0036] Specifically, the control unit 7 calculates a gate signal based on the current value detected by the current detection units 82 and 83, the speed command, and the set carrier frequency. The calculated gate signal is amplified by a gate driver (not shown) and input to an IGBT (not shown) as a gate voltage. The ratio of the gate on period to the carrier period is called the on-duty.

[0037] This outputs a voltage so that the motor 2000 operates at the command speed. The junction temperature rises due to Joule loss when the inverter unit 4 is on, switching loss when switching between current interruption, and recovery loss, and the junction temperature drops when the inverter unit 4 is off.

[0038] In the inverter section 4, the power semiconductors 41 to 46 are joined with materials having different thermal expansion coefficients, and therefore stress is applied to the joints when the temperature of the power semiconductors 41 to 46 rises and falls. The resistance to this stress is called the power cycle resistance, and is indicated by the number of usable repetitions at a given temperature amplitude, called the life cycle.

[0039] Therefore, if the temperature history of the power semiconductors 41 to 46 is known, it is possible to estimate the lifespan. Here, the lifespan refers to the estimated time that elapses from the start of use of the power semiconductors 41 to 46 after installation of the equipment until they are damaged (hereinafter, referred to as the estimated damage time).

[0040] The damage amount processing unit 9 is composed of circuits such as a DSP, memory, microcontroller, etc., and calculates the amount of damage to the power semiconductors 41 to 46 in the inverter unit 4 based on information such as the values ​​detected by the voltage detection unit 81, the current detection units 82, 83, the carrier frequency set as a specified operating condition, and the duty value calculated when controlling the motor 2000.

[0041] The rainflow method is an example of a damage calculation method. The rainflow method measures the amplitude and frequency of irregular repeated stress loads to predict fatigue life. By using this method, it is possible to calculate the amount of damage to power semiconductors caused by junction temperature ripple.

[0042] In addition, the damage amount processing unit 9 is configured to store the damage amount generated at the calculation period in a memory unit, thereby being able to calculate both the damage amount calculated at the calculation period and the damage amount accumulated during the operating time of the power conversion device 100.

[0043] In calculating the amount of damage, it is necessary to store the temperature history of the power semiconductors 41-46 and detect the peak temperature at which the damage, which is important for highly accurate life prediction, is maximum. This temperature history is stored in a memory in the damage amount processing unit 9. The output information such as the amount of damage calculated by the damage amount processing unit 9 may be output to the input unit 52 via the input / output unit 6 or may be displayed on the display unit 10.

[0044] Next, an example of a flow for setting operating conditions during a test run before installation of the equipment will be described with reference to Fig. 1. Here, the test run in this embodiment refers to driving the inverter unit 4 to operate the motor 2000 before installation of the equipment based on predetermined operating conditions, i.e., operating conditions set by an operator.

[0045] First, the operating conditions set in advance by the operator for the test run and the test run signals that manage the start and end of the test run are input from the operation unit 11 and the output unit 51 to the control unit 7. As described above, these signals are based on commands from the LCD operator, field bus, and operation unit 11, and are input to the power conversion device 100 via connectors such as a control terminal block and operation buttons.

[0046] The control unit 7 outputs a drive signal to the inverter unit 4 based on the input operating conditions to perform a test run of the motor 2000. The voltage detection unit 81 and the current detection units 82 and 83 perform feedback control by outputting the voltage detection value and the current detection value during the test run to the control unit 7, respectively.

[0047] During the trial run, the damage amount processing unit 9 calculates the amount of damage based on the voltage detection value of the voltage detection unit 81, the current detection values ​​of the current detection units 82 and 83, as well as information such as the carrier frequency and duty value received from the control unit 7, and stores the calculated amount in a memory (not shown). The damage amount processing unit 9 outputs part or all of the trial run results, including the amount of damage, to the external device 5 and the display unit 10. The details of the trial run results will be described later.

[0048] Here, the operation of the damage amount processing unit 9 during a trial run will be described with reference to Fig. 2. Fig. 2 is a flowchart illustrating an example of processing in the damage amount processing unit of the first embodiment of the present invention. In Fig. 2, the RUN signal is set as a trigger for a trial run, and when, for example, the RUN key of the operation unit 11 is pressed and the inverter unit 4 starts switching, the RUN signal turns ON (YES route of step S21).

[0049] In step S21, when the stop key of the operation unit 11 is pressed to stop switching of the inverter unit 4, the RUN signal is turned OFF (NO route of step S21).

[0050] When the RUN signal is turned ON at the start of the trial run (START) (step S21), as described above, the damage amount processing unit 9 obtains information required for calculating the damage amount from the voltage detection unit 81, the current detection units 82 and 83, and the control unit 7 (step S22). The items to be detected here include the U-, V-, and W-phase currents, the duty ratio, the carrier frequency, and the DC voltage.

[0051] Thereafter, the damage amount processing unit 9 calculates the damage amount D[i] of the power semiconductors (a total of 12 elements including IGBTs and diodes) described in the inverter unit 4, and the accumulated damage amount d (=ΣD[i]) accumulated in each element. At this time, the process for the 12 elements (inverter unit 4, rectifier unit 200) is repeatedly executed in the following manner (step S23).

[0052] The damage amount processing unit 9 first calculates the loss (step S24), the junction temperature (step S25), the damage amount D[i] (step S26), and then calculates the accumulated damage amount d (=ΣD[i]) accumulated in each element (step S27).

[0053] When the processing for 12 elements has been completed (YES route in step S28), the damage amount processing unit 9 outputs the damage amount D[i] and the accumulated damage amount d to the external device 5 and the display unit 10 (step S29). The damage amount processing unit 9 repeats the above processing while the RUN signal is ON, and when the RUN signal is turned OFF, the damage amount processing unit 9 ends the processing (NO route in step S21).

[0054] In this way, the operator of the power conversion device 100 can obtain the instantaneous amount of damage D[i] and the accumulated amount of damage d during the test run period (the period during which the RUN signal is ON).

[0055] In Fig. 2, a signal synchronized with the switching of the inverter unit 4 is set as the trigger for the trial run, but a different signal can be used as the trigger to obtain the same effect. For example, an ON signal can be input from the external device 5 during the period for which the amount of damage is to be calculated, and this signal can be replaced with the RUN signal described in Fig. 2 etc.

[0056] The external device 5 displays information output from the input / output unit 6 to the input unit 52 on the liquid crystal panel, and outputs information directly inputted through an operation onto the display screen of the liquid crystal panel from the output unit 51 to the input / output unit 6.

[0057] As explained in Figure 2, the operator performs multiple test runs according to multiple different operating conditions that he or she has set up in advance, and then determines the final operating conditions that are suitable for operation after the equipment is installed based on the results of each test run (test run results) displayed on the LCD panel. These are called the appropriate operating conditions.

[0058] Examples of the predetermined operating conditions, i.e., parameters, that the operator adjusts through the LCD panel include carrier frequency (Hz), boost amount at startup (%), current limit in the 0 Hz range, acceleration / deceleration time, etc. Each parameter will be described below.

[0059] The carrier frequency is a frequency that switches the power semiconductors of the inverter section 4. In the case of IGBTs, it is generally set to about several hundred Hz to several tens of kHz, and while raising the carrier frequency can avoid the audible range and reduce noise, it also increases switching loss, leading to increased damage.

[0060] The 0 Hz range current limit is a parameter that adjusts the value of the current that flows when sensorless vector control is started up until magnetic flux is established inside motor 2000. Increasing the 0 Hz range current limit value, in other words, increasing the current value in a low-speed range where the rotation frequency of motor 2000 is, for example, called the 0 Hz range (approximately 3 Hz or less), increases the magnetic flux inside motor 2000 before motor 2000 starts to rotate or immediately after it starts to rotate, which can suppress steady slippage after the brake is released in an elevator, for example.

[0061] However, continuous switching of the main current in the low-frequency region increases the junction temperature ripple, and therefore increasing the 0Hz current limit value accelerates the increase in damage, resulting in a shortened lifespan of the power semiconductor.

[0062] The startup boost amount refers to the amount by which the current flowing through motor 2000 is temporarily added to the 0 Hz range current limit value when motor 2000 starts rotating during startup of sensorless vector control. Unlike the 0 Hz range current limit value, the startup boost amount increases the current only at startup, so it decays with a time constant within the 0 Hz range.

[0063] For example, in the brake release operation of an elevator, slippage occurs if the brake is released before the magnetic flux is established inside the motor 2000. By adjusting the startup boost amount, it is possible to suppress the transient slippage that occurs immediately after the brake is released. However, like the 0 Hz current limit, this increases the current value of the motor 2000 in the low frequency region, which shortens the life of the power semiconductor.

[0064] The acceleration / deceleration time represents the time (acceleration time) required for the motor 2000 connected to the power conversion device 100 to increase its rotational speed from a stopped or slow-rotating state to a desired rotational speed, and the time (deceleration time) required for the motor 2000 to decrease its rotational speed from a high-rotating state to a desired rotational speed.

[0065] As the acceleration / deceleration time becomes shorter, the acceleration torque and deceleration torque increase, so the output current value of the inverter increases, while the time in the low frequency region where the junction temperature ripple increases becomes shorter.

[0066] In this way, the amount of damage changes by adjusting the acceleration / deceleration time depending on the operating specifications of motor 2000. When changing the acceleration / deceleration time for the purpose of reducing the amount of damage, whether it is better to make it longer or shorter depends on the specifications of the load side of motor 2000.

[0067] Next, each waveform of the operating conditions will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing an example of waveforms of the operating conditions in the first embodiment of the present invention. Fig. 3 shows an example of the current waveforms of the current detection units 82 and 83 when one phase of the three-phase bridge is extracted, the instantaneous loss of the upper arm IGBT calculated by the damage amount processing unit 9, and the junction temperature.

[0068] In the current waveform of motor 2000 shown in FIG. 3 (motor current graph), the positive direction indicates the direction in which current flows out from inverter unit 4 to motor 2000, and the negative direction indicates the direction in which current flows in from motor 2000 to inverter unit 4.

[0069] Generally, IGBTs are elements that do not conduct reverse, so as shown in Figure 3, loss occurs in the upper arm IGBT only when the current of motor 2000 is positive (graph of upper arm IGBT instantaneous loss), and almost no loss occurs when the current of motor 2000 is negative. The junction temperature (graph of junction temperature) repeatedly rises and falls according to the thermal impedance-time characteristics inside the IGBT.

[0070] This junction temperature ripple applies thermal stress to the junction, causing additional damage. The lower the rotation speed of motor 2000 and the greater the loss, the greater the junction temperature ripple ΔT becomes, so the operator must set appropriate operating conditions that take into account the operation of motor 2000 and the amount of damage.

[0071] Next, an operation example in the present embodiment 1 will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing one display example of the test run result in the present embodiment 1 of the present invention. In Fig. 4, one example of the test run result is a display example shown on a display screen DSP1. This display screen DSP1 is, for example, the input unit 52 of the external device 5 using a liquid crystal panel, or the display unit 10 when a liquid crystal panel is used.

[0072] The information on the display screen DSP1 shows history information 4001 indicating damage estimates etc. obtained from multiple test runs, and operating condition information 4002, 4003, 4004, 4005 indicating, for example, partial parameter settings corresponding to test runs 1, 2, 3, 4, respectively. Hereinafter, the history information 4001 and the operating condition information 4002 to 4005 are collectively referred to as the test run results.

[0073] The operator can visually check the results of this trial run through the display screen DSP1, enabling a life diagnosis to be performed to obtain operating conditions that will result in an appropriate life span while avoiding a situation in which the inverter unit 4, i.e., the power semiconductors 41 to 46, needs to be replaced before the scheduled operation period.

[0074] Here, the planned operation period refers to a period during which the power semiconductors 41 to 46 can actually operate without failure after the equipment is installed. In the present embodiment 1, the operating conditions that are estimated to cause damage before the planned operation period are visually presented to the operator by the history information 4001 so that the operator can exclude them from the candidates. From this, it is clear that the realization of a life diagnosis that makes it easy to select an operating condition that results in an appropriate life is important for the operator's judgment.

[0075] The historical information 4001 shows a graph of the estimated damage times 1, 2, 3, and 4 for each test run 1, 2, 3, and 4 that reached the damage level (vertical axis) previously set by the operator, with the amount of damage indicated as a numerical value on the vertical axis and the time indicating the time of damage on the horizontal axis.

[0076] In the example of Figure 4, the operating conditions of test runs 1 and 2, which reach the estimated time of damage before the planned operation period preset by the operator, place an excessive load on the power semiconductors and hasten their damage. Therefore, in the case of Figure 4, it is clear that the operating conditions of test runs 3 and 4 reach the damage level after the planned operation period on the time axis, and are therefore suitable as operating conditions after the installation of the equipment.

[0077] When the operator wishes to see the motor current, instantaneous loss, and junction temperature under each operating condition, the operator only needs to tap the waveform display portion (assuming it is a touch panel) of the operating condition to be operated on the display of the external device 5 or the liquid crystal panel of the display unit 10. One example is shown in FIG.

[0078] In this way, the operator can quantitatively grasp, for example, the relationship between the carrier frequency and loss, junction temperature ripple, and the amount of damage based on the trial run results displayed on the LCD panel of the external device 5, and then compare the load side specifications of the power conversion device 100 with the planned operation period and select one of the conditions at the time of each trial run.

[0079] In the above-described power conversion device 100, it is possible to quantitatively grasp the relationship between the operating conditions set during the trial run and the loss, junction temperature, damage amount, and planned operation period of the power semiconductors arranged in the inverter unit 4. As described above, each of the three parameters, the carrier frequency, the 0 Hz range current limit, and the startup boost amount, has a trade-off between the load side specifications of the power conversion device 100 and the damage amount of the inverter unit 4.

[0080] As described above, according to the first embodiment, it is possible to estimate the estimated time of damage beyond the planned operation period using a plurality of different operating conditions at the trial operation stage before the installation of the equipment, so that after the installation of the equipment, it is possible to realize operation under operating conditions that take into account the lifespan of the power semiconductors.

[0081] In particular, since the power semiconductor is actually operated and the lifespan is estimated from the accumulated damage during the operation, it is not necessary to wait until the power semiconductor is actually damaged in order to obtain the appropriate operating conditions, and it is possible to obtain the appropriate operating conditions in a short time while suppressing damage to the power semiconductor. As a result, it is possible to realize a lifespan diagnosis for effectively using the power semiconductor with the appropriate lifespan.

[0082] Furthermore, when the test run is repeated several times as in the first embodiment, the lifespan is judged based on the amount of damage accumulated over the number of times the test run is repeated, thereby improving the accuracy of the lifespan judgment.

[0083] Furthermore, since the lifespan indicating the amount of damage to the power semiconductors and the estimated time of breakage can be used as an index at the trial operation stage, it becomes possible to set operating conditions during trial operation that take into account the amount of damage to the inverter unit 4 in addition to the characteristics of the load side of the power conversion device 100. This eliminates the need to set operating conditions based only on the specifications of the load side, improving usability for operators of the equipment.

[0084] Next, a modified example of the first embodiment will be described with reference to Fig. 5. Fig. 5 is a circuit diagram showing a modified example of the power conversion device in the first embodiment of the present invention. The method described in the first embodiment above is not limited to the inverter unit 4 shown in Fig. 1, but can also be applied to other circuit configurations. Note that a description of units with the same reference numerals as those in Fig. 1 will be omitted.

[0085] A power conversion device 101 shown in Fig. 5 as this modification includes a rectification unit 201 including, for example, six power semiconductors 21 to 26 that configure a power regeneration converter, instead of the rectification unit 200 shown in Fig. 1. The voltage detection unit 81 and the current detection unit 82 are arranged on the AC power supply 1000 side of the rectification unit 201.

[0086] 1, when the motor 2000 is in power running mode, power is transmitted from the AC power supply 1000 to the motor 2000 via the rectifier unit 201, the smoothing capacitor 3, and the inverter unit 4, and when the motor 2000 is in regenerative running mode, regenerative power is transmitted to the AC power supply 1000 via the inverter unit 4, the smoothing capacitor 3, and the rectifier unit 201. This provides the effects of improving the power factor during power running and utilizing regenerative energy.

[0087] The rectifier unit 201 in the power conversion device 101, like the inverter unit 4, performs power running and regenerative operations by switching the power semiconductors 21 to 26, and the lifespan of the power semiconductors 21 to 26 is determined by losses that occur when current flows and is cut off, junction temperature ripple, and the amount of damage.

[0088] Although there are differences such as the fact that the carrier frequency of AC power supply 1000 is generally fixed and therefore does not have a 0 Hz range, the effect of reducing loss by lowering the carrier frequency can be obtained in the same way as in inverter unit 4. In this modification, rectifier unit 201 is a power regeneration converter, so that the power regeneration converter itself operates in the same way as inverter unit 4.

[0089] As a result, the techniques for the inverter unit 4 and the display contents on the liquid crystal panel and display unit 10 described in the general section of the present embodiment 1 can be similarly applied to the rectifier unit 201. In other words, the amount of loss and lifespan of the rectifier unit 201 can be estimated in the same manner as in the above-mentioned embodiment 1, and similar effects can be obtained. <Embodiment 2> Next, a second embodiment of the present invention will be described with reference to Fig. 6, Fig. 7, and Fig. 8. Fig. 6 is a circuit diagram showing a configuration example of a power conversion device in the second embodiment, Fig. 7 is an explanatory diagram showing a display example of a test run result in the second embodiment, and Fig. 8 is a flowchart explaining an example of processing in a damage amount processing unit and a damage amount estimation unit in the second embodiment.

[0090] As shown in Fig. 6, a power conversion device 102 of the second embodiment has a configuration in which a damage amount estimation unit 12 is added to the power conversion device 100 shown in Fig. 1, and a description of units with the same reference numerals will be omitted. The damage amount estimation unit 12 is connected to the damage amount processing unit 9 and the input / output unit 6.

[0091] The damage amount estimation unit 12 is composed of circuits such as a DSP, memory, microcontroller, etc., and has the function of inputting the amount of damage during the trial run output by the damage amount processing unit 9, the operating conditions set during the trial run, and the planned operation period, and calculating the estimated time of each damage by changing, for example, the carrier frequency parameters by a pre-set number from the parameters set during the trial run.

[0092] In this way, the damage amount estimation unit 12 generates multiple operating conditions different from the trial run as candidates, and no actual trial run is conducted for these generated candidate operating conditions. Instead, information such as the amount of damage and estimated time of breakage is all estimated by calculation based on information such as the amount of damage actually obtained during the trial run.

[0093] In the second embodiment, the operating condition is changed to the carrier frequency, but the present invention is not limited to this and may be changed to another parameter. As an example, when the carrier frequency is reduced, the switching loss is reduced in proportion to the reduction in the carrier frequency, since the switching loss is roughly proportional to the carrier frequency.

[0094] Therefore, the damage amount estimation unit 12 reduces only the switching loss component of the loss calculation result in the damage amount processing unit 9 by the ratio of the carrier frequency without changing the conduction loss component, calculates the reduced damage amount accordingly, and outputs the test run result including the damage amount to the input unit 52 of the external device 5. By configuring the power conversion device 102 in this way, it is possible to reduce the number of test runs that have conventionally been performed multiple times.

[0095] In Fig. 7, an example of the test run result is the display screen DSP2. The display screen DSP1 in Fig. 4 described in the above-mentioned embodiment 1 shows the relationship between the amount of damage and time during each test run performed multiple times. In the case of the display screen DSP2 shown in Fig. 7, history information 7001 showing the operating conditions of the test run and damage estimates under different operating conditions, operating condition information 7002 during the test run, and multiple different operating condition information 7003, 7004, and 7005 (candidate operating conditions) obtained by changing the parameters of the operating condition information 7002 are displayed.

[0096] The relationship between the amount of damage and time during trial operation and the relationship between the amount of damage and time under each operating condition calculated by the damage amount estimation unit 12 when the parameters set during trial operation are updated are shown together with the parameters set during trial operation and for each operating condition.

[0097] Display screen DSP2 displays history information 7001 obtained from one test run, as well as operating condition information 7003, 7004, and 7005 corresponding to each operating condition 1, 2, and 3 when the parameters set during the test run are updated. Furthermore, operating condition information 7002 for the test run and damage estimation results when the plant was operated under operating condition information 7003, 7004, and 7005 set by changing the parameters are displayed in history information 7001. Here, operating condition information 7003, 7004, and 7005 indicate operating conditions 1, 2, and 3, respectively.

[0098] Based on the information displayed in Fig. 7, the operator checks the planned operation period against the estimated time of damage and judges whether the parameters set during the trial run satisfy the planned operation period. If, as a result, the parameters for each operating condition set during the trial run do not result in an estimated time of damage that exceeds the planned operation period, the operator selects the operating conditions with the optimal parameters from those displayed in Fig. 7 and starts the trial run again.

[0099] Next, the operation of the second embodiment will be described with reference to Fig. 8. Fig. 8 is a flowchart for explaining an example of processing in the damage amount processing unit and the damage amount estimating unit of the second embodiment. In the processing flow shown in Fig. 8, a processing flow including the damage amount estimating unit 12 after the RUN signal is turned OFF is added to the processing flow in the first embodiment shown in Fig. 2. That is, the YES route of step S21 becomes the processing flow of the damage amount processing unit 9, and the NO route becomes the processing flow of the damage amount estimating unit 12.

[0100] 8, after the RUN signal is turned OFF (NO route in step S21), the damage amount estimation unit 12 acquires the planned operation period from the external device 5 or the operation unit 11 (step S81). The damage amount estimation unit 12 then calculates the damage amount estimate de when the parameters are changed based on the information used in the damage amount processing unit 9 and the calculation result (step S82), and further calculates the estimated time of breakage under each condition (step S83). Finally, the damage amount estimation unit 12 outputs the operating conditions under which operation is possible for a period longer than the planned operation period to the external device 5 or the display unit 10, and ends the process (step S84).

[0101] In this way, by adding a new damage amount estimation unit 12, like the power conversion device 102, the relationship between the amount of damage and time under conditions in which parameters related to the amount of damage to the power semiconductors are changed during each trial run can be displayed on the liquid crystal panel or display unit 10 of the external device 5 so that the operator can check it.

[0102] As described above, according to the present embodiment 2, damage estimation, i.e., life estimation, can be performed using a plurality of different operating conditions in one test run, and therefore optimal operating conditions can be derived efficiently even with fewer test runs compared to the above-described embodiment 1. As a result, not only is the life diagnosis performed in a shorter period of time than the above-described embodiment 1, and damage to the power semiconductors is kept to a minimum, but the frequency of operation by the operator and the workload of checking conditions are reduced, improving usability.

[0103] In the second embodiment, since the planned operation period is known, the operation conditions that will reach the estimated damage time before the planned operation period are reached may be automatically removed from the options by calculation of the damage amount estimation unit 12. This applies to both the case where the parameters of the operation conditions are automatically changed and the case where the operator manually sets them. In such a case where the options are automatically removed, it is desirable that the interval between the planned operation period and the estimated damage time can be arbitrarily set in units of days, weeks, months, or years. <Embodiment 3> Next, a third embodiment of the present invention will be described with reference to Fig. 6 and Fig. 9 described in the second embodiment. Fig. 9 is an explanatory diagram showing an example of a display of an operation result in the third embodiment of the present invention. In the third embodiment, the configuration itself is similar to that of the second embodiment, so the configuration in Fig. 6 will be used for the description.

[0104] The power conversion device 103 in the present embodiment 3 has the same configuration as the power conversion device 102 shown in the above-described embodiment 2, but differs in the contents displayed on the external device 5 and the display unit 10. Note that a description of units with the same reference numerals as those in FIG. 1 will be omitted.

[0105] In the above-mentioned second embodiment, a parameter setting method utilizing the trial operation before the installation of the equipment was described, but the present invention is not limited to this, and a similar parameter setting method can be applied even after the installation of the equipment.

[0106] When the operating pattern obtained after the installation of equipment with determined operating conditions differs from the operating pattern assumed before the installation of the equipment, there may be a discrepancy in the damage amount estimation results (estimated time of damage) before and after the installation of the equipment. If the operating pattern differs from the previous assumption, it is desirable to verify the validity of the currently set operating condition parameters by inspection, etc., before the power semiconductor reaches the end of its life.

[0107] The third embodiment differs from the second embodiment in the method of updating the parameters taking into account the amount of damage that gradually accumulates during actual operation after the equipment is installed using parameters set during trial operation.

[0108] In the above-mentioned embodiment 2, the lifespan was estimated during trial operation and operating conditions that exceed the planned operation period were derived. However, in the embodiment 3 described below, the lifespan is estimated at the stage of actual operation after installation of the equipment, when the damage to the power semiconductors is small, as in the trial operation, and operating conditions that exceed the planned operation period are derived.

[0109] 6, the power conversion device 103 has an overall configuration similar to that of the power conversion device 102 shown in FIG 5, but differs in that information after installation of the equipment is added to signals exchanged between the external device 5 and the input / output unit 6. Also, the power conversion device 103 of the present embodiment 3 is different in that the operations of the control unit 7, damage amount processing unit 9, damage amount estimation unit 12, etc. of the above-mentioned embodiments are performed after installation of the equipment, since the operation control of the power conversion device 103 of the present embodiment 3 is performed after installation of the equipment.

[0110] The control unit 7 controls the operation of the power conversion device 103 during actual operation after the installation of the equipment, and also controls the startup of the inverter unit 4. The damage amount processing unit 9 differs from the above-mentioned embodiment 2 only in that it operates after the installation of the equipment, and the damage amount estimation unit 12 differs from the above-mentioned embodiment 2 in that it generates an operation result based on parameters that are changed during actual operation based on the outputs of the control unit 7 and the damage amount processing unit 9.

[0111] An example of the test run result is shown on the display screen DSP3 in Fig. 9. In Fig. 9, the timing when an attempt was made to update the parameters after the equipment was installed is indicated as the present, and the relationship between the amount of damage and time indicated by the solid line shows how the amount of damage accumulates due to actual operation from the start of equipment operation.

[0112] 9, the relationship between the amount of damage and time indicated by the dashed line represents the state in which the damage level is reached with the parameters set during equipment operation calculated by the damage amount processing unit 9. In the history information 9001, the relationship between the amount of damage and time indicated by the dashed line represents the state in which the damage level is reached under conditions in which major parameters related to the lifespan of the power semiconductors are changed among the parameters set during equipment operation estimated by the damage amount estimation unit 12.

[0113] The operator compares the planned operation period with the estimated time of damage, and judges whether the parameters set during operation of the equipment satisfy the planned operation period. If the parameters set during operation of the equipment do not satisfy the planned operation period, the operator selects optimal parameters from the operating conditions displayed in FIG. 8 and operates the equipment again (operator taps on manual setting 9008).

[0114] 9, the power conversion device 103 calculates a plurality of operating conditions under which the device can operate longer than the scheduled operation period based on a plurality of operating policies, and also describes the impact of updating the set parameters. This is because there is a risk that the load side specifications of the power conversion device 103 may deteriorate as the life of the power semiconductor is extended by updating the parameters.

[0115] Since a user of the power conversion device 103 needs to consider the impact on the entire system due to a change in specifications after the facility is already in operation, it is preferable to display and confirm in advance what kind of impact a parameter update will have.

[0116] 9 shows, as an example, four operation policies 9002, 9003, 9004, and 9005, and operation condition 1 and operation condition 2 are displayed as operation condition information 9006 and 9007, respectively. Here, an operation policy indicates a setting guideline for each parameter constituting the operation condition. It is assumed that a necessary number of operation policies are set according to the types of parameters constituting the operation conditions.

[0117] Operation policy 9002 is a screen setting that allows the reduction of the carrier frequency on display screen DSP3. The setting to reduce the carrier frequency can be made by tapping this operation policy 9002. Operation policy 9003 is a screen setting that allows the reduction of the 0 Hz range current limit value and the boost amount at startup on display screen DSP3. The setting to reduce the 0 Hz range current limit value and the boost amount at startup can be made by tapping this operation policy 9003.

[0118] The operation policy 9004 is a screen setting that allows adjustment of the acceleration / deceleration time on the display screen DSP3. The acceleration / deceleration time can be adjusted by tapping on this operation policy 9004. The operation policy 9005 is a screen setting that allows operation of, for example, starting and stopping the elevator operation in a phase with little damage on the display screen DSP3. The operation policy 9005 can be set to start and stop the elevator operation.

[0119] Regarding the operation policy 9005, the junction temperature ripple increases in the power semiconductors mainly in the region where the motor 2000 is rotating at low speed, and the amount of damage increases. For this reason, by starting from a phase with less damage or stopping from a phase with less damage, the phase through which a large current flows during low speed rotation is not fixed, and the degree of accumulation of the amount of damage in each phase is leveled out, and the life span of the inverter unit 4 as a whole can be extended.

[0120] On the other hand, since the phase through which the current flows at starting and stopping is not fixed, it is difficult to achieve accurate position control of the motor 2000, and there is a risk that changing the parameters will change the behavior of the speed, position, etc. at starting and stopping.

[0121] As described above, the power conversion device 103 in the present embodiment 3 is different from the power conversion device 102 described in the above-mentioned embodiment 2 in that it uses a method for updating parameters during the operation period after the equipment is put into operation. In other words, since the operation conditions are optimized after the equipment is installed, it is possible to find operation conditions that will exceed the planned operation period before damage to the power semiconductor progresses by performing a lifespan estimation in a short period of time during actual operation, similar to the test run in the other embodiments 1 and 2.

[0122] In this manner, in the third embodiment, parameters that satisfy the planned operation period are calculated based on a plurality of operation policies, and the estimated time of damage when the parameters are updated and the effects of the parameter update are displayed together, and the parameters can be changed in real time with interactivity through the operation of the operator. This not only enables the ideal parameters to be found early on, but also improves the ease of use for the operator in deriving appropriate operating conditions.

[0123] As described above, according to the third embodiment, even if the operation pattern after the installation of the equipment differs from the operation pattern assumed before the installation of the equipment, it is possible to suppress deviation from the estimated result of the damage amount in a short period of time. In particular, in the above-mentioned third embodiment, since the power conversion device 103 has been installed and actual operation has started, the operation policy is changed minutely during actual operation and the life diagnosis is repeated, so that it is possible to suppress damage to semiconductors and derive optimal operation conditions early even after the installation of the equipment.

[0124] Here, in the above-mentioned embodiments 1 to 3, the examples have been shown in which the embodiments 1 and 2 are applied before the installation of the equipment, and the embodiment 3 is applied after the installation of the equipment, but the present invention is not limited to this, and any of the embodiments 1, 2, and 3 may be applied during trial operation or during actual operation after the installation of the equipment. For example, when the embodiments 1 and 2 are applied after the installation of the equipment, the use is a test operation after the installation of the equipment (for example, a test mode), and when the embodiment 3 is applied before the installation of the equipment, the use is a trial operation as it is.

[0125] In each of the above-described embodiments, a partial area of ​​DSPs 1, 2, and 3 may be displayed on the external device 5 and the other area may be displayed on the display unit 10, or the entire area may always be displayed on the external device 5 and a partial area may be displayed on the display unit 10. Of course, the entire area may always be displayed on the display unit 10 and a partial area may be displayed on the external device 5.

[0126] Furthermore, in the above-described first embodiment, an example in which the power conversion device 100 and the external device 5 are connected by a bus has been shown, but the present invention is not limited to this, and the power conversion device 100 and the external device 5 may be connected by a network such as the Internet to enable remote control. This also applies to the modified examples and other embodiments.

[0127] As in the above-mentioned embodiments and modifications, power conversion devices widely used as motor drive devices in the industrial world, such as manufacturing equipment, lifting equipment, and transport equipment, contribute to realizing long-term stable operation with reduced damage to inverters (power semiconductors) in various applications from the viewpoint of diagnosing life spans by setting operating conditions before and after installation in the equipment. In particular, the present invention is suitable for applications of power conversion devices where start-stop control is frequently performed due to power cycles.

[0128] Furthermore, the present invention is not limited to the above-described embodiments and modifications, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. Furthermore, each of the above configurations and functions may be realized in part or in whole by software in which a processor interprets and executes a program that realizes each function, or may be realized by hardware, for example, by designing an integrated circuit. [Explanation of symbols]

[0129] 3. Smoothing capacitor 4 Inverter section 5 External device 6 Input / output section 7 Control section 9 Damage amount processing section 10 Display section 11 Control section 12 Damage amount estimation section 21 Power Semiconductors 22 Power Semiconductors 23 Power Semiconductors 24 Power Semiconductors 25 Power Semiconductors 26 Power Semiconductors 41 Power Semiconductors 42 Power Semiconductors 43 Power Semiconductors 44 Power Semiconductors 45 Power Semiconductors 46 Power Semiconductors 81 Voltage detection section 82 Current detection section 83 Current detection section 100 Power conversion device 101 Power conversion device 102 Power conversion device 103 Power conversion device 200 Rectifier 201 Rectifier

Claims

1. A power conversion device, An inverter unit that converts DC voltage into AC voltage; A control unit that controls the operation of the inverter unit based on predetermined operating conditions; a damage amount processing unit that calculates a damage amount of the inverter unit during an operation period of the inverter unit by the control unit, and generates data indicating an operation result based on the calculated damage amount and the operation conditions; A power conversion device comprising:

2. 2. The power conversion device according to claim 1, further comprising a voltage detection unit that detects a DC voltage and a current detection unit that detects an output current of the inverter unit, and the damage amount processing unit calculates an amount of damage based on the detected DC voltage and output current during an operation period of the inverter unit.

3. 2. The power conversion device according to claim 1, wherein different predetermined operating conditions are set for each of a plurality of operations that have been set in advance, the control unit controls the operations for the plurality of operations, and the damage amount processing unit acquires an operating result including an estimated time of damage for each operation based on the amount of damage accumulated for each operation.

4. 2. The power conversion device according to claim 1, further comprising a display unit, the display unit displaying at least a part of an operation result based on data generated by the damage amount processing unit.

5. 2. The power conversion device according to claim 1, wherein the power conversion device is connected to a display device, and the damage amount processing unit outputs at least a part of the operation results based on the generated data to the display device.

6. 2. The power conversion device according to claim 1, wherein the power conversion device is connected to an external device that accepts an operation input from an operator, and the control unit inputs the predetermined operating conditions from the external device.

7. 2. The power conversion device according to claim 1, wherein the inverter section is a power regeneration converter.

8. 2. The power conversion device according to claim 1, wherein a motor is connected to the output side of the inverter unit, and the predetermined operating conditions include a parameter for adjusting a current value when the rotational frequency of the motor is in a low-speed range.

9. 2. The power conversion device according to claim 1, wherein a test run signal for managing the start and end of a test run of the inverter unit is input to the control unit.

10. 2. The power conversion device according to claim 1, a damage amount estimation unit that estimates an operation result by calculating an estimated time of damage when the operating conditions are changed based on a planned operation period during which the inverter unit operates normally, the planned operation period, the operating conditions, and the amount of damage measured by the damage amount processing unit.

11. 11. The power conversion device according to claim 10, wherein the power conversion device is connected to an external device that accepts operational input from an operator, the operation period is an operation period after installation of equipment, and when a change in the operation conditions is accepted from the external device during the operation period, the control unit changes the operation conditions and continuously controls the operation of the inverter unit.

12. 12. The power conversion device according to claim 11, wherein the damage amount estimation unit estimates an estimated time of damage based on an amount of damage accumulated during the operating period, and creates a plurality of operating conditions with parameter settings that lengthen the non-damage period indicated by the estimated estimated time of damage relative to the specified planned operating period.

13. A power conversion method for a power conversion device, comprising: an inverter unit converting a DC voltage into an AC voltage; a control unit controlling an operation of the inverter unit based on a predetermined operating condition; and a damage amount processing unit calculating an amount of damage to the inverter unit during operation of the inverter unit by the control unit, a planned operation period during which the inverter unit operates normally is set in advance, and the damage amount processing unit measures the amount of damage to the inverter unit during the operation period of the inverter unit by the control unit, calculates an estimated time of damage to the inverter unit based on the measured amount of damage and the operating conditions, and generates data indicating an operating result based on the calculated estimated time of damage, the planned operation period, and the operating conditions.

14. 14. The power conversion method according to claim 13, wherein the power conversion device further comprises a damage amount estimation unit that estimates an amount of damage, and the damage amount estimation unit calculates an estimated time of damage when the operating conditions are changed based on the planned operation period, the operating conditions, and the amount of damage measured by the damage amount processing unit, to estimate an operating result.

15. 15. The power conversion method according to claim 14, wherein the power conversion device is connected to an external device that accepts operational input from an operator, the operation period is an operation period after installation of equipment, and when a change in the operation conditions is accepted from the external device during the operation period, the control unit changes the operation conditions to continuously control the operation of the inverter unit.

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