WO2024232029A1 - 電力変換装置及びモータ駆動システム - Google Patents

電力変換装置及びモータ駆動システム Download PDF

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Publication number
WO2024232029A1
WO2024232029A1 PCT/JP2023/017511 JP2023017511W WO2024232029A1 WO 2024232029 A1 WO2024232029 A1 WO 2024232029A1 JP 2023017511 W JP2023017511 W JP 2023017511W WO 2024232029 A1 WO2024232029 A1 WO 2024232029A1
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Prior art keywords
value
current
capacitor
voltage
rectifier
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PCT/JP2023/017511
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English (en)
French (fr)
Japanese (ja)
Inventor
樹 松永
航平 恩田
静里 田村
昂司 岡川
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Priority to CN202380097923.0A priority Critical patent/CN121079890A/zh
Priority to JP2025519240A priority patent/JPWO2024232029A1/ja
Priority to PCT/JP2023/017511 priority patent/WO2024232029A1/ja
Publication of WO2024232029A1 publication Critical patent/WO2024232029A1/ja
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/42—Conversion of DC power input into AC power output without possibility of reversal
    • H02M7/44—Conversion of DC power input into AC power output without possibility of reversal by static converters
    • H02M7/48—Conversion of DC power input into AC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode

Definitions

  • This application relates to a power conversion device and a motor drive system.
  • Some power conversion devices for driving motors convert AC power supplied from an AC power source into DC power, and then convert the converted DC power back into AC power.
  • These power conversion devices generally include a converter circuit made up of a rectifier circuit and a smoothing capacitor, and an inverter circuit.
  • the converter circuit converts AC power into DC power, and the smoothing capacitor smoothes the converted DC voltage.
  • the inverter circuit drives the motor by converting the DC power converted by the converter circuit back into AC power.
  • Power conversion devices are required to have the ability to detect abnormal conditions and protect the circuit in order to prevent damage to the circuit when an abnormality occurs. For example, there is technology that detects an overloaded state of a motor and protects the inverter circuit from damage caused by an overcurrent.
  • Patent Document 1 As a technology to meet such demands, a technology has been disclosed for protecting a converter circuit from overcurrent when the AC power supply becomes unbalanced (see, for example, Patent Document 1).
  • the current flowing through the diodes that make up the rectifier circuit is estimated based on the current detected by a current detector provided at the output of the rectifier circuit and the phase of the AC power supply, thereby protecting the rectifier circuit and, by extension, the converter circuit from destruction due to overcurrent.
  • Patent Document 1 is configured to detect the current on the output side of the rectifier circuit, so the large DC input current output from the rectifier circuit is detected, which creates the problem that the current detector becomes large, i.e., the power conversion device becomes large.
  • This application discloses technology to solve the above problems, and aims to provide a power conversion device that can protect the converter circuit without providing a current detector that detects the current output from the rectifier circuit.
  • the power conversion device disclosed in the present application is A power conversion device including a converter circuit including a rectifier circuit having a plurality of rectifier elements and a smoothing capacitor, and converting AC power into DC power, an inverter circuit that converts the DC power converted by the converter circuit into AC power, and a control device that controls the inverter circuit, the control device includes a capacitor current estimator that estimates a current flowing through the smoothing capacitor, and a DC input current estimator that estimates a DC input current output from the rectifier circuit, the capacitor current estimating unit estimates a capacitor current value flowing through the smoothing capacitor based on a capacitance of the smoothing capacitor and a DC bus voltage value applied to the smoothing capacitor; The DC input current estimating unit estimates a DC input current value output by the rectifier circuit based on the estimated capacitor current estimate value and a DC output current value input to the inverter circuit.
  • the DC input current output by the rectifier circuit can be estimated without using a current detector, making it possible to protect the converter circuit from overcurrent and providing a compact power conversion device by not having a current detector.
  • FIG. 1 is a schematic diagram showing a configuration of a power conversion device and a motor drive system according to a first embodiment
  • FIG. 11 is a schematic diagram showing a configuration of a power conversion device and a motor drive system according to a modification of the first embodiment.
  • FIG. 11 is a schematic diagram showing a configuration of a power conversion device and a motor drive system according to a second embodiment.
  • FIG. 11 is a schematic diagram showing a configuration of a power conversion device and a motor drive system according to a third embodiment.
  • 13 is a flowchart showing an operation of a DC bus voltage estimator of the power conversion device according to the third embodiment.
  • FIG. 13 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to a fourth embodiment.
  • FIG. 13 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to a fifth embodiment.
  • FIG. 13 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to a sixth embodiment.
  • FIG. 2 is a diagram illustrating an example of a hardware configuration of a control device according to the first to sixth embodiments.
  • Embodiment 1 A power conversion device according to a first embodiment and a motor drive system including the same will be described below with reference to the drawings.
  • Fig. 1 is a schematic diagram showing the configuration of the power conversion device and the motor drive system according to the first embodiment.
  • the motor drive system 10 is configured to convert AC power obtained from an AC power source 1 in a power conversion device 2 into DC power, and then convert the converted DC power back into AC power to drive a motor 3. That is, the motor drive system 10 drives the motor 3 using the AC power converted in the power conversion device 2 as a drive source.
  • the power conversion device 2 includes a converter circuit 21, an inverter circuit 22, a DC bus voltage sensor 23, a DC output current sensor 24, and a control device 25.
  • the converter circuit 21 converts AC power from the AC power source 1 into DC power, and outputs the DC power to the inverter circuit 22.
  • the converter circuit 21 includes a rectifier circuit 210 and a smoothing capacitor 211 .
  • the rectifier circuit 210 is composed of a plurality of rectifier elements. As shown in Fig. 1, the rectifier circuit 210 includes diodes as rectifier elements.
  • the anode of the diode D1 and the cathode of the diode D2 are connected to form an AC input terminal, which is connected to the R phase of the AC power supply 1.
  • the anode of the diode D3 and the cathode of the diode D4 are connected to form an AC input terminal, which is connected to the S phase of the AC power supply 1.
  • the anode of the diode D5 and the cathode of the diode D6 are connected to form an AC input terminal, which is connected to the T phase of the AC power supply 1.
  • the cathodes of diodes D1, D3, and D5 are connected together to form a positive potential terminal of the DC voltage, and are connected to the positive potential terminal P of the smoothing capacitor 211 and the positive potential terminal of the inverter circuit 22.
  • the anodes of diodes D2, D4, and D6 are connected together to form a negative potential terminal of the DC voltage, and are connected to the negative potential terminal N of the smoothing capacitor 211 and the negative potential terminal of the inverter circuit 22.
  • the rectifier circuit 210 has six rectifier elements each composed of a diode, but this is not limited to the configuration.
  • two or more diodes may be connected in series to form one rectifier element, or two or more diodes may be connected in parallel to form one rectifier element.
  • the smoothing capacitor 211 smoothes the DC voltage output from the rectifier circuit 210, and outputs the smoothed DC voltage to the inverter circuit 22.
  • the smoothing capacitor 211 has a positive potential terminal P and a negative potential terminal N.
  • the smoothing capacitor 211 is defined by a capacitance value Cm and a parasitic resistance value Rs. 1, the smoothing capacitor 211 is configured with one capacitor, but the configuration is not limited to this.
  • the smoothing capacitor 211 may be configured with two or more capacitors connected in series, in parallel, or in series-parallel.
  • the inverter circuit 22 converts the DC power output from the converter circuit 21 into AC power, and outputs the AC power to the motor 3 .
  • the inverter circuit 22 includes six switching elements Q1 to Q6.
  • the switching elements are IGBTs (Insulated Gate Bipolar Transistors).
  • the emitter of switching element Q1 and the collector of switching element Q2 are connected and connected to the U-phase of motor 3.
  • the emitter of switching element Q3 and the collector of switching element Q4 are connected and connected to the V-phase of motor 3.
  • the emitter of switching element Q5 and the collector of switching element Q6 are connected and connected to the W-phase of motor 3.
  • the collectors of the switching elements Q1, Q3, and Q5 are connected to each other and form a positive potential terminal for the DC voltage, and are connected to the positive potential terminal P of the smoothing capacitor 211 and the positive potential terminal of the converter circuit 21.
  • the emitters of the switching elements Q2, Q4, and Q6 are connected to each other and form a negative potential terminal for the DC voltage, and are connected to the negative potential terminal N of the smoothing capacitor 211 and the negative potential terminal of the converter circuit 21.
  • the inverter circuit 22 has six switching elements each composed of an IGBT, but this is not limited to this.
  • one switching element may be composed of two or more IGBTs connected in series, or one switching element may be composed of two or more IGBTs connected in parallel.
  • FIG. 1 shows an example in which the switching elements of the inverter circuit 22 are configured with IGBTs, this is not limited to this configuration.
  • they may be configured with MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).
  • the switching elements are not limited to those configured with Si (silicon) semiconductors, and may be semiconductors such as SiC (silicon carbide) and GaN (gallium nitride), which are wide band gap semiconductors. They may also be configured with switching elements such as GaN-HEMTs (Gallium Nitride - High Mobility Transistors).
  • the converter circuit 21 and the inverter circuit 22 are connected by a positive potential terminal and a negative potential terminal, which may be called a DC bus.
  • the DC bus voltage sensor 23 detects a DC bus voltage value Vdc applied between the positive potential terminal P and the negative potential terminal N of the smoothing capacitor 211 , and outputs the DC bus voltage value Vdc to the control device 25 .
  • the DC output current sensor 24 is connected between the smoothing capacitor 211 and the inverter circuit 22 , detects the DC output current value Iout input to the inverter circuit 22 , and outputs the DC output current value Iout to the control device 25 .
  • the DC output current sensor 24 is connected between the inverter circuit 22 and the smoothing capacitor 211 on the negative potential terminal side of the inverter circuit 22, but it may also be connected between the inverter circuit 22 and the smoothing capacitor 211 on the positive potential terminal side of the inverter circuit 22.
  • the control device 25 includes a capacitor current estimating unit 250 , a DC input current estimating unit 251 , and an inverter circuit control unit 252 .
  • the capacitor current estimation unit 250 estimates the capacitor current value Ic flowing through the smoothing capacitor 211 based on the DC bus voltage value Vdc output from the DC bus voltage sensor 23, the capacitance value Cm of the smoothing capacitor 211, and the parasitic resistance value Rs.
  • the estimated capacitor current value Ic is output to the DC input current estimation unit 251.
  • the capacitor current value Ic is estimated based on the following equation (1).
  • s is the Laplace operator.
  • the capacitor current value Ic may be estimated using equation (2) in which Rs is omitted.
  • the DC input current estimation unit 251 estimates the DC output current value Iin output from the rectifier circuit 210 based on the capacitor current value Ic output from the capacitor current estimation unit 250 and the DC output current value Iout output from the DC output current sensor 24.
  • the estimated DC input current value Iin is output to the inverter circuit control unit 252.
  • the DC output current value Iin is estimated based on the following equation (3).
  • the inverter circuit control unit 252 is a controller for the inverter circuit 22.
  • the inverter circuit control unit 252 outputs a control signal for driving the motor 3 to the inverter circuit 22. More specifically, the inverter circuit control unit 252 generates a control signal for the inverter circuit 22 based on a voltage command value for the voltage to be output from the inverter circuit 22.
  • the inverter circuit control unit 252 determines that the DC input current is an overcurrent when the DC input current value Iin output from the DC input current estimating unit 251 exceeds a predetermined current threshold value. When the inverter circuit control unit 252 determines that the DC input current value is an overcurrent, it outputs a control signal to stop the inverter circuit 22 or to reduce the AC power output to the motor 3, thereby reducing the DC input current to protect the converter circuit 21. By performing the above operations, it becomes possible to protect the converter circuit 21 from an overcurrent without providing a current detector for detecting the DC input current output from the rectifier circuit 210.
  • Fig. 2 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to a modification of the first embodiment.
  • a rectifier circuit 210 and an inverter circuit 22 are shown in a simplified manner because they have the same configuration as in Fig. 1.
  • the difference from Fig. 1 is that a differential circuit 26 is provided in a smoothing capacitor 211.
  • the differentiation circuit 26 is connected between the positive potential terminal P and the negative potential terminal N of the smoothing capacitor 211.
  • the differentiation circuit 26 is configured by connecting one terminal of a capacitor 261 and one terminal of a resistor 262 in series.
  • the capacitor 261 has a capacitance value Cf
  • the resistor 262 of the differentiation circuit 26 has a resistance value Rde.
  • the other terminal of the capacitor 261 of the differentiation circuit 26 is connected to the positive potential terminal P of the smoothing capacitor 211, and the other terminal of the resistor 262 of the differentiation circuit 26 is connected to the negative potential terminal N of the smoothing capacitor 211.
  • the voltage sensor 23a detects the voltage at the connection point between the capacitor 261 of the differentiation circuit 26 and the resistor of the differentiation circuit 26, and outputs the detected differentiation circuit voltage value Vde to the capacitor current estimation unit 250 of the control device 25.
  • the capacitor current estimating unit 250 included in the control device 25 estimates the capacitor current value Ic based on the following equation (4).
  • the differentiation circuit 26 is configured with a capacitor 261 and a resistor 262, but a differentiation circuit using an operational amplifier or the like can also achieve the same effect.
  • the control device 25 that controls the inverter circuit 22 includes a capacitor current estimation unit 250 that estimates the current Ic flowing through the smoothing capacitor 211, and a DC input current estimation unit 251 that estimates the DC input current Iin output from the rectifier circuit 210.
  • the capacitor current estimation unit 250 estimates the capacitor current value Ic flowing through the smoothing capacitor 211 based on the capacitor capacitance Cm of the smoothing capacitor 211 and the DC bus voltage value Vdc applied to the smoothing capacitor 211
  • the DC input current estimation unit 251 is configured to estimate the DC input current value Iin output by the rectifier circuit 210 based on the estimated capacitor current estimate value Ic and the DC output current value Iout input to the inverter circuit 22.
  • This configuration allows the DC input current Iin output by the rectifier circuit 210 to be estimated without using a current detector, so it becomes possible to determine whether or not there is an overcurrent based on the estimated DC input current Iin, making it possible to protect the converter circuit 21 from an overcurrent. Furthermore, since no current detector is provided, it is possible to reduce the size of the power conversion device.
  • the motor drive system 10 includes the above-mentioned power conversion device 2 and a motor 3 driven by AC power converted by the power conversion device 2.
  • the power conversion device 2 can be protected from an overcurrent of the DC input current value Iin output by the rectifier circuit 210, so damage to the power conversion device 2 is suppressed, stable operation is achieved, and stable motor drive is possible.
  • Embodiment 2 A power conversion device and a motor drive system including the same according to the second embodiment will be described below with reference to the drawings.
  • Fig. 3 is a schematic diagram showing the configuration of the power conversion device and the motor drive system according to the second embodiment.
  • the difference from Fig. 1 of the first embodiment is that the power conversion device 2 according to the second embodiment does not have a DC output current sensor 24 but has an AC output current sensor 27.
  • the other configurations are the same as those of the first embodiment, and description thereof will be omitted.
  • the AC output current sensor 27 is connected between the inverter circuit 22 and the motor 3, detects the AC output current flowing in the U phase, V phase, and W phase of the motor 3, and outputs the AC output current values Iu, Iv, Iw flowing in each of the U phase, V phase, and W phase of the motor 3 to the control device 25.
  • AC output current sensor 27 is provided to detect AC output currents of all three phases, namely, U phase, V phase, and W phase of motor 3.
  • AC output current sensor 27 may be provided to detect AC output currents flowing through any two of U phase, V phase, and W phase of motor 3, and the current flowing through one phase for which AC output current is not detected may be estimated from the detection values of the AC output currents flowing through the two phases.
  • the control device 25 differs from the first embodiment in that it further includes a DC output current estimating unit 253 .
  • the DC output current estimation unit 253 estimates the DC output current value Iout input to the inverter circuit 22 based on the DC bus voltage value Vdc output from the DC bus voltage sensor 23, the AC output current values Iu, Iv, Iw detected by the AC output current sensor 27, and the control signal output by the inverter circuit control unit 252, and outputs the estimated DC output current value Iout to the DC input current estimation unit 251.
  • the DC output current estimating unit 253 estimates the DC output current value Iout based on the following equation (6).
  • Pout is the AC power output by the inverter circuit 22 and is the driving power of the motor 3
  • PLoss is the circuit loss generated in the inverter circuit 22.
  • the circuit loss PLoss generated in the inverter circuit 22 can be determined in advance by design, but is not limited to this.
  • the circuit loss PLoss generated in the inverter circuit 22 may be calculated based on the AC output current values Iu, Iv, and Iw detected by the AC output current sensor 27 and the control signal output from the inverter circuit control unit 252.
  • the AC power Pout output by the inverter circuit 22 can be calculated, for example, by the following equation (7).
  • Vq* is the q-axis output voltage command value output from the inverter circuit control unit 252
  • Vd* is the d-axis output voltage command value output from the inverter circuit control unit 252.
  • Iq is the q-axis current converted based on the AC output current values Iu, Iv, Iw detected by the AC output current sensor 27 and the rotation angle of the motor 3 or the voltage frequency output by the inverter circuit 22.
  • Id is the d-axis current converted based on the AC output current values Iu, Iv, Iw detected by the AC output current sensor 27 and the rotation angle of the motor 3 or the voltage frequency output by the inverter circuit 22.
  • the q-axis output voltage command value Vq* and the d-axis output voltage command value Vd* output from the inverter circuit control unit 252 are used, but a voltage sensor may be provided between the inverter circuit 22 and the motor 3, and the q-axis output voltage and the d-axis output voltage converted based on the detection value of the voltage sensor and the rotation angle of the motor 3 or the voltage frequency output by the inverter circuit 22 may be used.
  • the DC output current value Iout can be estimated from equations (6) and (7), and the DC output current estimating unit 253 outputs the estimated DC output current value Iout to the DC input current estimating unit 251.
  • the DC input current estimation unit 251 estimates the DC input current value Iin by using equation (3) based on the capacitor current value Ic estimated by the capacitor current estimation unit 250 and the DC output current value Iout estimated by the DC output current estimation unit 253, as in the first embodiment.
  • the capacitor current estimation unit 250 estimates the capacitor current value Ic based on the DC bus voltage value Vdc output from the DC bus voltage sensor 23, but the same effect can be achieved by estimating it using the differentiation circuit 26 described in the modified example of embodiment 1.
  • the same effect as that of the first embodiment can be achieved. That is, the DC input current Iin output by the rectifier circuit can be estimated without using a current detector. Furthermore, even if the DC output current sensor 24 of the first embodiment is not provided, and an AC output current sensor 27 is provided as in the second embodiment, the DC output current value Iout can be estimated, and the DC input current Iin can be estimated using this, so that the same effect as that of the first embodiment can be achieved.
  • FIG. 4 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to the third embodiment. What differs from Fig. 1 of the first embodiment is that the power conversion device 2 according to the third embodiment does not have a DC bus voltage sensor 23 but has an AC input voltage sensor 28. The other configurations are the same as those of the first embodiment, and description thereof will be omitted.
  • the AC input voltage sensor 28 is provided between the AC power supply 1 and the converter circuit 21, detects the AC input line voltages applied between the R phase, S phase, and T phase lines input to the converter circuit 21, and outputs the AC input line voltage values Vrs, Vst, Vtr applied between the R phase, S phase, and T phase lines of the converter circuit 21 to the control device 25.
  • AC input voltage sensor 28 is provided to detect the AC input line voltages of all three phases, the R phase, the S phase, and the T phase, of converter circuit 21.
  • AC input voltage sensor 28 may be provided to detect the AC input line voltage between any two of the R phase, the S phase, and the T phase of converter circuit 21, and the line voltage of one phase for which an AC input line voltage is not detected may be estimated from the detected values of the AC input line voltages of two phases.
  • the AC input voltage sensor 28 is configured to detect the AC input line voltages of the R, S, and T phases, but it may also be configured to detect the AC input phase voltages of the R, S, and T phases, and estimate the AC input line voltages applied between the R, S, and T phases from the AC input phase voltages applied to the R, S, and T phases of the converter circuit 21.
  • the control device 25 differs from the first embodiment in that it further includes a DC bus voltage estimating unit 254 .
  • the DC bus voltage estimation unit 254 estimates the DC bus voltage applied to the capacitor, which is the voltage applied between the positive potential terminal P and the negative potential terminal N of the smoothing capacitor 211, based on the AC input line voltage values Vrs, Vst, Vtr output from the AC input voltage sensor 28, the capacitance value Cm of the smoothing capacitor 211, and the DC output current value Iout output by the DC output current sensor 24, and outputs the DC bus voltage estimate value Vdc_est to the capacitor current estimation unit 250.
  • the DC bus voltage estimating unit 254 extracts the maximum one from the AC input line voltage values Vrs, Vst, Vtr input from the AC input voltage sensor 28, and sets it as a maximum value Vmax (step S101).
  • the maximum value Vmax of the extracted AC input line voltage is compared with the previous DC bus voltage estimate Vdc_est_old (step S102).
  • the previously estimated DC bus voltage is represented as the DC bus voltage estimate Vdc_est_old, with respect to the DC bus voltage estimate Vdc_est. If there is no previous DC bus voltage estimate Vdc_est_old, proceed to step S103.
  • step S102 if the maximum value Vmax of the AC input line voltage is equal to or greater than the previous DC bus voltage estimate Vdc_est_old (Yes in step S102), proceed to step S103.
  • step S103 it is estimated that the DC bus voltage value Vdc_est is the maximum value Vmax of the AC input line voltage, and this is output to the capacitor current estimation unit 250 (step S105).
  • step S102 if the maximum value Vmax of the AC input line voltage is smaller than the previous DC bus voltage estimate value Vdc_est_old (No in step S102), the process proceeds to step S104.
  • step S104 the DC bus voltage Vdc_est is estimated based on equation (8) and output to the capacitor current estimator 250. That is, the value obtained by subtracting the value obtained by dividing the DC output current value Iout by the capacitance value Cm of the smoothing capacitor from the previous DC bus voltage estimate value Vdc_est_old is set as the DC bus voltage estimate value Vdc_est (step S105).
  • the DC bus voltage estimation unit 254 stores the estimated DC bus voltage estimate Vdc_est as the previous estimate Vdc_est_old of the DC bus voltage estimate (step S106).
  • the capacitor current estimator 250 estimates the capacitor current value Ic using the DC bus voltage value Vdc detected by the DC bus voltage sensor 23.
  • the capacitor current estimator 250 in the third embodiment estimates the capacitor current value Ic based on the DC bus voltage estimated value Vdc_est estimated by the DC bus voltage estimator 254.
  • the operation of the capacitor current estimator 250 is the same as in the first embodiment, so a description thereof will be omitted.
  • the DC input current estimation unit 251 estimates the DC output current value Iin using equation (3) based on the capacitor current Ic estimated by the capacitor current estimation unit 250 and the DC output current value Iout detected by the DC output current sensor 24.
  • the same effect as that of the first embodiment can be achieved. That is, the DC input current Iin output by the rectifier circuit can be estimated without using a current detector. Furthermore, even if the DC bus voltage sensor 23 of the first embodiment is not provided, and an AC input voltage sensor 28 is provided as in the third embodiment, the same effect as that of the first embodiment can be achieved.
  • FIG. 6 is a schematic diagram showing the configuration of the power conversion device and the motor drive system according to the fourth embodiment.
  • the power conversion device 2 according to the fourth embodiment further includes an AC input voltage sensor 28.
  • the other configurations are the same as those of the first embodiment.
  • the operation of the AC input voltage sensor 28 to detect the AC input line voltage values Vrs, Vst, and Vtr is the same as that of the third embodiment, and the detected AC input line voltage values Vrs, Vst, and Vtr are output to the control device 25. Therefore, the description of the configurations of the fourth embodiment that are the same as those of the first to third embodiments will be omitted.
  • the control device 25 differs from the first embodiment in that it includes a rectifier current estimating unit 255 .
  • the rectifier current estimation unit 255 receives the DC input current value Iin estimated by the DC input current estimation unit 251 and the AC input line voltage values Vrs, Vst, Vtr detected by the AC input voltage sensor 28.
  • the rectifier current estimation unit 255 estimates a rectifier current value flowing through each rectifier element of the rectifier circuit 210 based on these, and outputs the estimated rectifier current value to the inverter circuit control unit 252.
  • the rectifier current estimator 255 estimates AC input phase voltage values based on the AC input line voltage values Vrs, Vst, and Vtr detected by the AC input voltage sensor 28 .
  • the AC input voltage sensor 28 may be provided so as to detect the AC input phase voltage values instead of the AC input line voltage values Vrs, Vst, Vtr.
  • the AC input phase voltage values are the R-phase AC input phase voltage value Vr, the S-phase AC input phase voltage value Vs, and the T-phase AC input phase voltage value Vt.
  • the rectifier current estimator 255 determines which of the rectifier elements of the rectifier circuit 210 is conductive, based on the magnitude relationship of the AC input phase voltage values. Regarding the magnitude relationship of the AC input phase voltage values, when formula (9) is satisfied, it is determined that the diodes D1 and D6 are conductive. Vr>Vs>Vt...(9) If the formula (10) is satisfied, it is determined that the diodes D1 and D4 are conductive. Vr>Vt>Vs...(10)
  • the rectifier current estimation unit 255 determines which rectifier elements are conductive based on equations (9) to (14), and estimates the rectifier current flowing through the rectifier elements by estimating that the DC input current value Iin estimated by the DC input current estimation unit 251 flows through the conductive rectifier elements.
  • the inverter circuit control unit 252 determines that the rectifier current is an overcurrent when the rectifier current estimated value output from the rectifier current estimating unit 255 exceeds a predetermined current threshold value. When the inverter circuit control unit 252 determines that the rectifying element current is an overcurrent, it outputs a control signal to stop the inverter circuit 22 or to reduce the AC power output to the motor 3, thereby reducing the DC input current and protecting the converter circuit 21.
  • the DC input current estimation unit 251 estimates the DC input current based on the DC output current value output from the DC output current sensor 24, but by providing the AC output current sensor 27 described in embodiment 2 and providing the control device 25 with a DC output current estimation unit 253, and using the DC output current estimation value Iout, the DC input current Iin can be estimated, thereby achieving the same effects as in embodiment 1 or 2.
  • the same effects as those of the first embodiment can be obtained. That is, the DC input current Iin outputted by the rectifier circuit can be estimated without using a current detector. Also, as in the fourth embodiment, the rectifier element current estimation unit 255 determines through which rectifier element of the rectifier circuit 210 constituting the converter circuit 21 a current is flowing and further determines whether or not an overcurrent is occurring, which has the effect of reducing the DC input current and protecting the converter circuit 21. Furthermore, since it is possible to protect the rectifier elements from an overcurrent and to identify the rectifier element through which an overcurrent is flowing, it becomes easier to take measures during inspection, such as checking the operation of the rectifier circuit 210.
  • Embodiment 5 A power conversion device and a motor drive system including the same according to embodiment 5 will be described below with reference to the drawings.
  • Fig. 7 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to embodiment 5.
  • a temperature sensor 29 is further provided in addition to the configuration of Fig. 6 of embodiment 4. The temperature sensor 29 detects the temperature of the converter circuit 21, and outputs the detected temperature detection value of the converter circuit 21 to the control device 25.
  • the other configurations are the same as those of the embodiment 4. Therefore, in the embodiment 5, the description of the configurations that are the same as those of the embodiments 1 to 4 will be omitted.
  • the control device 25 according to the fifth embodiment differs from that of the fourth embodiment in that it includes a rectifying element temperature estimating unit 256 .
  • the rectifier temperature estimating unit 256 estimates the temperature of the diode, which is the rectifier element of the rectifier circuit 210, as the rectifier temperature.
  • the rectifier temperature estimation unit 256 estimates the rectifier loss P_Di based on the rectifier current value output from the rectifier current estimation unit 255 and the rectifier voltage generated in the rectifier, estimates the temperature T_Di of each rectifier element of the rectifier circuit 210 based on the rectifier loss P_Di, the rectifier thermal resistance Rth_Di, and the temperature detection value Tc detected by the temperature sensor 29, and outputs the rectifier temperature estimation value T_Di to the inverter circuit control unit 252.
  • i is the number of the diode Di, and in FIG. 7, i is a natural number from 1 to 6.
  • the rectifier element voltage value V_Di the relationship between the rectifier element current value I_Di and the rectifier element voltage value V_Di is prepared in advance as a data set, so that the rectifier element voltage value V_Di can be estimated.
  • the rectifier voltage V_Di is not limited to the example in which a data set of the rectifier voltage value V_Di corresponding to the rectifier current value I_Di is prepared in advance.
  • an approximation formula of the rectifier voltage value V_Di for the rectifier current value I_Di may be prepared, and the rectifier voltage value V_Di may be estimated from the rectifier current value I_Di using the approximation formula. Either estimation method does not limit the effect of the present embodiment.
  • the rectifier loss P_Di can be estimated by the product of the rectifier voltage value V_Di and the rectifier current value I_Di.
  • the rectifying element thermal resistance Rth_Di is the thermal resistance between the temperature sensor 29 and the rectifying element.
  • the rectifying element temperature estimating unit 256 estimates the rectifying element temperature T_Di based on the equation (15).
  • the inverter circuit control unit 252 determines that the rectifier temperature is an overtemperature when the rectifier temperature estimation value T_Di output from the rectifier temperature estimation unit 256 exceeds a predetermined rectifier temperature threshold value.
  • the inverter circuit control unit 252 determines that the rectifier element temperature T_Di is an overtemperature, it stops the inverter circuit 22 or outputs a control signal to reduce the AC power output to the motor 3, thereby reducing the DC input current Iin output by the rectifier circuit 210 and protecting the converter circuit 21.
  • the DC input current estimation unit 251 estimates the DC input current value based on the DC output current value output from the DC output current sensor 24, but as described in the fourth embodiment, the same effect can be achieved by providing the AC output current sensor 27 described in the second embodiment, providing the control device 25 with a DC output current estimation unit 253, and using the DC output current estimate value.
  • the same effects as those of the first embodiment can be obtained. That is, the DC input current Iin outputted by the rectifier circuit can be estimated without using a current detector. Also, as in the fifth embodiment, the rectifier current estimation unit 255 determines which rectifier element of the rectifier circuit 210 constituting the converter circuit 21 is overtemperature, which has the effect of reducing the DC input current to protect the converter circuit 21. Furthermore, since it is possible to protect the rectifier elements from overtemperature and to identify the rectifier element with an overtemperature, it becomes easier to take measures during inspection, such as checking the operation of the rectifier circuit 210.
  • Embodiment 6 A power conversion device and a motor drive system including the same according to the sixth embodiment will be described below with reference to the drawings.
  • Fig. 8 is a schematic diagram showing the configuration of a power conversion device and a motor drive system according to the sixth embodiment.
  • a temperature sensor 29 is further provided to the configuration of the power conversion device 2 of Fig. 1 of the first embodiment. The other configurations are the same as those of the first embodiment.
  • the temperature sensor 29 of the sixth embodiment also detects the temperature of the converter circuit 21 in the same way as in the fifth embodiment. Therefore, the description of the configuration of the sixth embodiment that is the same as that of the first to fifth embodiments will be omitted.
  • the control device 25 differs from the first embodiment in that it further includes a capacitor temperature estimation unit 257 and a capacitor constant estimation unit 258 . It is to be noted that, similarly to the first embodiment, a DC input current Iin estimated by a DC input current estimating unit 251 is output to an inverter circuit control unit 252 using the capacitor current Ic estimated by the capacitor current estimating unit 250 and the DC output current value Iout detected by the DC output current sensor 24.
  • the capacitor temperature estimation unit 257 estimates the capacitor loss P_Cap of the smoothing capacitor 211 based on the capacitor current estimate Ic output from the capacitor current estimation unit 250 and the parasitic resistance value Rs of the smoothing capacitor 211. Furthermore, it estimates the temperature T_Cap of the smoothing capacitor 211 based on the estimated capacitor loss P_Cap, the capacitor thermal resistance Rth_Cap, and the temperature detection value Tc detected by the temperature sensor 29, and outputs the capacitor temperature estimate value T_Cap to the inverter circuit control unit 252.
  • the capacitor loss P_Cap can be estimated by the product of the square of the capacitor current value Ic and the parasitic resistance value Rs, that is, it can be calculated by the formula (16).
  • P_Cap Ic2 ⁇ Rs...(16)
  • the capacitor thermal resistance Rth_Cap is the thermal resistance between the temperature sensor 29 and the smoothing capacitor 211 .
  • the capacitor temperature estimation unit 257 estimates the capacitor temperature T_Cap based on the equation (17).
  • the inverter circuit control unit 252 determines that the capacitor temperature is overtemperature when the capacitor temperature estimation value T_Cap output from the capacitor temperature estimation unit 257 exceeds a predetermined capacitor temperature threshold value.
  • the inverter circuit control unit 252 determines that the capacitor temperature T_Cap is an overtemperature, it stops the inverter circuit 22 or outputs a control signal to reduce the AC power output to the motor 3, thereby reducing the DC input current Iin and protecting the converter circuit 21.
  • the capacitor constant estimation unit 258 has a data set of the temperature dependency of the capacitance value Cm and the parasitic resistance value Rs of the smoothing capacitor 211 with respect to the capacitor temperature T_Cap. Then, using the data set, it estimates the change in the constants of the capacitance value Cm and the parasitic resistance value Rs of the smoothing capacitor 211 in association with a temperature rise or fall from the transition of the temperature T_Cap of the smoothing capacitor 211 estimated by the capacitor temperature estimation unit 257.
  • the estimated capacitor constants, the capacitance value Cm and the parasitic resistance value Rs are output to the capacitor current estimation unit 250 and the capacitor temperature estimation unit 257.
  • the capacitor current estimation unit 250 updates the capacitance value Cm and the parasitic resistance value Rs used to estimate the capacitor current value based on the capacitor constant estimate value output from the capacitor constant estimation unit 258 in response to the estimated temperature change of the capacitor.
  • the capacitor temperature estimation unit 257 updates the parasitic resistance value Rs in the equation used to estimate the capacitor temperature based on the capacitor constant estimate value output from the capacitor constant estimation unit 258.
  • the same effects as those of the first embodiment can be obtained. That is, the DC input current Iin outputted by the rectifier circuit can be estimated without using a current detector. Furthermore, as in the sixth embodiment, the capacitor temperature estimation unit 257 estimates the temperature of the smoothing capacitor 211 and determines whether or not the smoothing capacitor 211 is overheating. If it is determined that the smoothing capacitor 211 is overheating, the DC input current is reduced, thereby making it possible to protect the smoothing capacitor 211 from overheating.
  • a capacitor constant estimation unit 258 estimates the capacitance value Cm and the parasitic resistance value Rs, which are capacitor constants corresponding to temperature, based on the temperature T_Cap of the smoothing capacitor 211 estimated by the capacitor temperature estimation unit 257. This makes it possible to use updated values for the capacitance value Cm and the parasitic resistance value Rs of the smoothing capacitor 211 used in the above-mentioned formulas (1), (2), (4), and (5), and therefore it is possible to improve the estimation accuracy of the capacitor current estimation unit 250 by taking temperature dependency into consideration.
  • the derivation of the capacitor loss P_Cap in the above-mentioned equation (17) includes the parasitic resistance value Rs of the smoothing capacitor 211 as shown in equation (16), it is possible to improve the estimation accuracy of the capacitor temperature estimation unit 257 by updating the value of the parasitic resistance value Rs taking into account the temperature dependency of the parasitic resistance value Rs.
  • the control device 25 includes, for example, a processor 1000 and a storage device 1100 as a processing circuit.
  • the processor 1000 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), an integrated circuit (IC), a field programmable gate array (FPGA), various logic circuits, various signal processing circuits, and the like.
  • the processor 1000 may include a plurality of processors of the same type or different types, and each process may be shared and executed.
  • the storage device 1100 may include a random access memory (RAM) configured to be able to read and write data from the processor 1000, and a read only memory (ROM) configured to be able to read data from the processor 1000.
  • RAM random access memory
  • ROM read only memory
  • the processor 1000 executes a program input from the storage device 1100 such as a ROM.

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PCT/JP2023/017511 2023-05-10 2023-05-10 電力変換装置及びモータ駆動システム Ceased WO2024232029A1 (ja)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05199739A (ja) * 1992-01-17 1993-08-06 Mitsubishi Electric Corp インバータ装置
JP2000295839A (ja) * 1999-04-06 2000-10-20 Mitsubishi Electric Corp 電源装置
JP2001095294A (ja) * 1999-09-20 2001-04-06 Mitsubishi Electric Corp 空気調和機のインバータ制御装置
JP2020089056A (ja) * 2018-11-26 2020-06-04 トヨタ自動車株式会社 コンバータ
JP2020088975A (ja) * 2018-11-20 2020-06-04 トヨタ自動車株式会社 電気自動車
WO2022149210A1 (ja) * 2021-01-06 2022-07-14 三菱電機株式会社 電力変換装置、モータ駆動装置および冷凍サイクル適用機器

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05199739A (ja) * 1992-01-17 1993-08-06 Mitsubishi Electric Corp インバータ装置
JP2000295839A (ja) * 1999-04-06 2000-10-20 Mitsubishi Electric Corp 電源装置
JP2001095294A (ja) * 1999-09-20 2001-04-06 Mitsubishi Electric Corp 空気調和機のインバータ制御装置
JP2020088975A (ja) * 2018-11-20 2020-06-04 トヨタ自動車株式会社 電気自動車
JP2020089056A (ja) * 2018-11-26 2020-06-04 トヨタ自動車株式会社 コンバータ
WO2022149210A1 (ja) * 2021-01-06 2022-07-14 三菱電機株式会社 電力変換装置、モータ駆動装置および冷凍サイクル適用機器

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