WO2023032150A1 - 電力変換装置及び電力変換装置を搭載した航空機 - Google Patents
電力変換装置及び電力変換装置を搭載した航空機 Download PDFInfo
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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
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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
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/49—Combination of the output voltage waveforms of a plurality of converters
Definitions
- This application relates to a power conversion device and an aircraft equipped with the power conversion device.
- the applicant has proposed that in a power conversion device comprising a three-phase inverter and three single-phase inverters connected to the three-phase inverter, the common-mode voltage is suppressed within a predetermined allowable range, and the combined output voltage is It is disclosed that both common mode noise and normal mode noise are suppressed by controlling each line voltage change width in each line voltage to satisfy a specified condition based on the DC voltage of a single-phase inverter (for example, Patent Document 1 reference).
- a short circuit prevention period (dead time) is applied to control the operation of the inverter.
- the dead time is applied, the operation path changes, the common mode voltage and the voltage fluctuation range increase, and there is a risk of noise generation.
- the present application discloses a technique for solving the above problems, and provides a power conversion device capable of reducing noise even when dead time is applied, and a power conversion device equipped with the power conversion device.
- the purpose is to provide an aircraft that
- a power conversion device disclosed in the present application is a power conversion device disposed between a power supply and a load for converting power from the power supply and supplying the power to the load, comprising a first capacitor and a plurality of switching elements and a second capacitor connected in series with the first inverter, to which a voltage lower than the voltage applied to the first capacitor is applied, and a plurality of switching elements.
- the control device for generating drive signals for driving the plurality of switching elements of the first inverter and the plurality of switching elements of the second inverter, wherein the control device A plurality of switching elements of the inverter and a plurality of switching elements of the second inverter are controlled by applying a dead time, and the output voltage of the first inverter and the output voltage of the second inverter during the dead time period.
- the fluctuation timing of the output voltage of the first inverter and the fluctuation timing of the output voltage of the second inverter are controlled so as to suppress the voltage fluctuation width of the combined voltage.
- the voltage fluctuation range of the combined voltage of the output voltage of the first inverter and the output voltage of the second inverter during the dead time period is suppressed. Since the fluctuation timing of the output voltage of the inverter and the fluctuation timing of the output voltage of the second inverter are controlled, large voltage changes and voltage distortion in the line voltage and common mode voltage can be reduced during the dead time period. In other words, short-circuit prevention and noise suppression are possible, so it is possible to reduce the size and weight of the filter connected to the subsequent stage of the inverter.
- FIG. 1 is a schematic configuration diagram showing the configuration of a power conversion system according to Embodiment 1;
- FIG. 1 is a diagram showing an example of a circuit configuration of a power conversion device according to Embodiment 1;
- FIG. 2 is a diagram showing an example of a switching element used in the power converter according to Embodiment 1;
- FIG. 4 is a diagram showing output command values of the power converter according to Embodiment 1.
- FIG. 4 is a diagram showing output command values of a three-phase, three-level inverter in the power converter according to Embodiment 1;
- FIG. 4 is a diagram showing output command values of a single-phase inverter device among the power conversion devices according to Embodiment 1.
- FIG. 4 is a diagram showing gate drive signals for driving switching elements forming a three-phase, three-level inverter in the power converter according to Embodiment 1;
- FIG. 4 is a diagram showing gate drive signals for driving switching elements that constitute a single-phase inverter device in the power conversion device according to Embodiment 1.
- FIG. FIG. 5C is a diagram showing output voltages when a three-phase, three-level inverter is driven with the waveforms of FIG. 5A and a single-phase inverter is driven with the waveforms of FIG. 5B;
- FIG. 5B is a diagram showing a gate drive signal obtained by subjecting the gate drive signal of FIG. 5A to dead time correction;
- FIG. 6B is a diagram showing a gate drive signal obtained by subjecting the gate drive signal of FIG. 5B to dead time correction
- FIG. 7B is a diagram showing output voltages when a three-phase, three-level inverter is driven with the waveforms of FIG. 7A and a single-phase inverter is driven with the waveforms of FIG. 7B
- FIG. 7B is a diagram showing output voltages when a three-phase, three-level inverter is driven by the waveforms in FIG. 7A, a single-phase inverter device is driven by the waveforms in FIG. 7B, and correction control is performed
- FIG. 8B is a diagram for explaining the generation mechanism of voltage pulses in the waveform of FIG.
- FIG. 8A; 8B is a diagram for explaining correction control for removing a voltage pulse from the waveform of FIG. 8A;
- FIG. FIG. 10 is a diagram for explaining the influence of applying dead time when the load power factor is 1 and a method for improving the influence in the power converter according to Embodiment 2;
- FIG. 10 is a diagram for explaining the influence of dead time application when the load power factor is 0 and a method for improving the influence in the power converter according to Embodiment 2;
- FIG. 10 is a diagram showing the relationship between turn-off waveforms, turn-on waveforms, and output voltage waveforms of a semiconductor element that constitutes a power converter according to Embodiment 3;
- FIG. 10 is a diagram showing the relationship between turn-off waveforms, turn-on waveforms, and output voltage waveforms of a semiconductor element that constitutes a power converter according to Embodiment 3;
- FIG. 13 is a diagram showing an example of a circuit configuration of a power conversion device according to Embodiment 4;
- FIG. 13 is a diagram showing another example of the circuit configuration of the power conversion device according to Embodiment 4;
- FIG. 10 is a diagram showing an example of a switching element used in a power conversion device according to Embodiment 4;
- FIG. 10 is a diagram showing another example of a switching element used in the power conversion device according to Embodiment 4;
- FIG. 12 is a schematic configuration diagram showing an aircraft according to Embodiment 5;
- FIG. 12 is a schematic configuration diagram showing an aircraft according to Embodiment 6;
- 2 is a hardware configuration diagram of a control device according to Embodiments 1 to 6;
- FIG. 1 is a schematic configuration diagram showing an example of a power conversion system using a power conversion device 3 according to Embodiment 1.
- a power conversion device 3 and a filter 4 are connected in series between a DC power source 1 and a load 5 (for example, a motor in FIG. 2), and a DC link capacitor is connected between the DC power source 1 and the power conversion device 3. 2 are connected in parallel.
- the power conversion device 3 includes an inverter 10 that is a power conversion section that converts the power from the DC power supply 1 into a predetermined power and outputs the power to the load 5 via the filter 4, and a control device 20 that is a control section thereof.
- the inverter 10 demonstrates a DC/AC inverter as an example.
- FIG. 2 is a diagram showing an example of the circuit configuration of the inverter 10.
- the DC/AC inverter includes a three-phase three-level inverter 30, which is a first inverter that converts DC into AC, and a second inverter 30, which converts into predetermined power.
- a single-phase inverter device 40 which is an inverter, is provided.
- the single-phase inverter device 40 has three single-phase inverters corresponding to three phases.
- the switching elements Q1 to Q12 constituting the three-phase three-level inverter 30 have a structure in which diodes are connected in anti-parallel to MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), which are semiconductor elements.
- MOSFETs Metal-Oxide-Semiconductor Field-Effect Transistors
- the switching elements Q1 to Q12 forming the three-phase three-level inverter 30 and the switching elements Q13 to Q24 forming the single-phase inverter device 40 are all preferably formed using wide bandgap semiconductors. Although the details will be described later, the switching elements Q13 to Q24 forming the single-phase inverter device 40 perform high-speed switching, so switching elements formed using a wide bandgap semiconductor are more suitable.
- FIG. 3 shows an example of the configuration of semiconductor elements applied to the switching elements Q1 to Q12 constituting the three-phase three-level inverter 30 and the switching elements Q13 to Q24 constituting the single-phase inverter device 40.
- the drain terminal D, the gate It is composed of a MOSFET 15 having a terminal G and a source terminal S and a diode 16 connected in antiparallel thereto.
- the MOSFET 15 may be a Si-MOSFET or, for example, a SiC-MOSFET using a wide bandgap semiconductor.
- the diode 16 may be a Si-diode or, for example, a SiC-diode using a wide bandgap semiconductor. However, it is preferable to use a semiconductor element using a wide bandgap semiconductor.
- the three-phase three-level inverter 30 includes series-connected P-side capacitor 31 and N-side capacitor 32, series-connected switching elements Q1 to Q4, series-connected switching elements Q5 to Q8, A series-connected switching element Q9 to a switching element Q12 are connected in parallel to the DC link capacitor 2.
- FIG. 2 the three-phase three-level inverter 30 includes series-connected P-side capacitor 31 and N-side capacitor 32, series-connected switching elements Q1 to Q4, series-connected switching elements Q5 to Q8, A series-connected switching element Q9 to a switching element Q12 are connected in parallel to the DC link capacitor 2.
- a connection point E between the P-side capacitor 31 and the N-side capacitor 32 includes a connection point Eu between the anode terminal of the diode D1 and the cathode terminal of the diode D2, a connection point Ev between the anode terminal of the diode D3 and the cathode terminal of the diode D4, and a connection point Ew between the anode terminal of the diode D5 and the cathode terminal of the diode D6.
- the cathode terminal of the diode D1 is connected to the connection point Ku between the switching elements Q1 and Q2
- the cathode terminal of the diode D3 is connected to the connection point Kv between the switching elements Q5 and Q6, and the cathode terminal of the diode D5 is It is connected to the connection point Kw between the switching element Q9 and the switching element Q10.
- the anode terminal of the diode D2 is connected to the connection point Au between the switching elements Q3 and Q4, the anode terminal of the diode D4 is connected to the connection point Av between the switching elements Q7 and Q8, and the anode terminal of the diode D6 is It is connected to a connection point Aw between the switching element Q11 and the switching element Q12.
- connection point u between the switching element Q2 and the switching element Q3, a connection point v between the switching element Q6 and the switching element Q7, and a connection point w between the switching element Q10 and the switching element Q11 are connected to the single-phase inverter device 40.
- the series-connected switching elements Q1 to Q4 form the U-phase leg
- the series-connected switching elements Q5 to Q8 form the V-phase leg
- the series-connected switching elements Q9 to Q12. constitute the legs of the W phase, respectively.
- the single-phase inverter device 40 is composed of a bridge circuit of four switching elements corresponding to each phase. That is, switching element Q13 and switching element Q14 connected in series, switching element Q15 and switching element Q16 connected in series, U-phase inverter in which capacitor 41 is connected in parallel, and switching element Q17 connected in series. Switching element Q18, switching element Q19 and switching element Q20 connected in series, V-phase inverter in which capacitor 41 is connected in parallel, switching element Q21 and switching element Q22 connected in series, switching element connected in series A W-phase inverter is provided in which Q23, switching element Q24, and capacitor 41 are connected in parallel.
- a connection point U between the switching element Q13 and the switching element Q14 is connected to a connection point u of the three-phase three-level inverter 30, and a connection point V between the switching element Q17 and the switching element Q18 is a connection point v of the three-phase three-level inverter 30.
- a connection point W between the switching elements Q21 and Q22 is connected to a connection point w of the three-phase three-level inverter 30, respectively.
- connection point Uo between the switching elements Q15 and Q16, a connection point Vo between the switching elements Q19 and Q20, and a connection point Wo between the switching elements Q23 and Q24 are connected to the filter 4, respectively.
- the control device 20 includes current sensors 101U, 101V, and 101W for each phase provided on the output side of the single-phase inverter device 40, P-side capacitor 31 and N-side capacitor 32, which are input capacitors of the three-phase three-level inverter 30.
- a voltage center (not shown) provided and a voltage sensor (not shown) provided in each capacitor 41 of the single-phase inverter device 40 receive sensor signals from the three-phase three-level inverter 30 and the single-phase inverter
- a gate drive signal is output to the switching elements Q1 to Q24 provided in the device 40, and control is performed so that the power is converted into a predetermined power.
- a current sensor may also be provided in the three-phase three-level inverter 30 .
- FIG. 4A is a diagram showing a target output voltage command value from inverter 10, and shows an example of the U phase here.
- the output waveform is a sine wave as shown.
- FIG. 4B is a diagram showing the output voltage command value (U phase) of the three-phase, three-level inverter 30, and the output waveform is a one-pulse square wave.
- FIG. 4C shows the output voltage command value (U-phase) of the single-phase inverter device 40, which is the waveform of the difference between the target output waveform of FIG. 4A and the output voltage command value of the three-phase three-level inverter 30 of FIG. 4B.
- the 3-phase 3-level inverter 30 and the single-phase inverter device 40 output voltages according to respective predetermined waveform output voltage command values according to gate drive signals from the control device 20 .
- the three-phase three-level inverter 30 generates a one-pulse waveform by low-frequency switching operation, and the single-phase inverter device 40 has a waveform in which the output voltage command value is generated by PWM (Pulse Width Modulation). Therefore, a large number of pulse-like voltage waveforms are generated. Therefore, the voltage of each capacitor 41 of the single-phase inverter device 40 is set to be smaller than the voltage of the P-side capacitor 31 and N-side capacitor 32 which are the input capacitors of the three-phase three-level inverter 30 . For example, if it is set to 1/2, it is possible to output a stable waveform with less harmonic components in the PWM operation of the single-phase inverter device 40 .
- the control device 20 drives gates using current sensors 101U, 101V, and 101W provided downstream of the single-phase inverter device 40 and sensor signals from the above-described voltage sensors (not shown) so as to maintain the voltage ratio relationship of the capacitors.
- a signal is calculated and output to each of the switching elements Q1 to Q24.
- the three-phase three-level inverter 30 generates a one-pulse waveform by low-frequency switching operation with high DC voltage, and the single-phase inverter device 40 performs high-speed switching operation with low DC voltage.
- FIG. 5A is a diagram showing ideal gate drive signals output to switching elements to output a voltage waveform corresponding to the output voltage command value (U phase) of the three-phase, three-level inverter 30.
- FIG. In the figure, from the top, the output voltage command value (U phase) of the three-phase three-level inverter 30, the gates for driving the switching elements Q1 to Q4 constituting the U-phase leg of the three-phase three-level inverter 30 It is a waveform of a drive signal.
- the switching elements Q1 to Q4 are switched on and off once per cycle.
- the voltage applied between the drain and source of the semiconductor element becomes the voltage value (Vdc/2) of the P-side capacitor 31 or the N-side capacitor 32, which is the input capacitor, while the gate drive signal is off (that is, 0). While the signal is on (that is, 1), the voltage value is 0 (actually, the internal voltage drop is applied).
- FIG. 5B is a diagram showing gate drive signals output to switching elements for outputting voltage waveforms corresponding to the output voltage command value (U-phase) of the single-phase inverter device 40.
- FIG. In the drawing, from the top, the output voltage command value and the carrier wave (U phase) of the single-phase inverter device 40, the switching element Q13 to the switching element Q16 constituting the U-phase inverter of the single-phase inverter device 40. It is a waveform of a gate drive signal.
- the switching elements Q13 to Q16 are switched on and off a plurality of times per cycle.
- the switching elements constituting the single-phase inverter device 40 that operates in PWM have a large number of switching times
- semiconductor elements suitable for high-frequency driving such as SiC-MOSFETs with small switching loss may be used.
- the voltage applied between the drain and the source of the semiconductor element is the voltage value of the capacitor 41 while the gate drive signal is off (ie 0), and the voltage value is 0 while the gate drive signal is on (ie 1). (Actually, the internal voltage drop is applied).
- each capacitor 41 of the single-phase inverter device 40 When the voltage of each capacitor 41 of the single-phase inverter device 40 is set to 1/2, for example, so that the voltage of each capacitor 41 is smaller than the voltage of the P-side capacitor 31 and the N-side capacitor 32, which are the input capacitors of the three-phase three-level inverter 30. , the voltage applied to the switching elements forming the single-phase inverter device 40 is half the voltage applied to the switching elements forming the three-phase three-level inverter 30 . These are applicable even if it is not a three-phase power converter.
- FIG. 6 shows the waveform when the switching elements Q1 to Q4 of the three-phase three-level inverter 30 are driven by the waveform of FIG. 5A, and the switching elements Q13 to Q16 of the single-phase inverter device 40 are driven by the waveform of FIG. 5B.
- FIG. 6 shows the waveform when the switching elements Q1 to Q4 of the three-phase three-level inverter 30 are driven by the waveform of FIG. 5A, and the switching elements Q13 to Q16 of the single-phase inverter device 40 are driven by the waveform of FIG. 5B.
- the U-phase output voltage of inverter 10 composite voltage obtained by superimposing the U-phase output voltage of three-phase three-level inverter 30 and the U-phase output voltage of single-phase inverter device 40
- the output voltage between the UV phases U-phase composite voltage obtained by superimposing the U-phase output voltage of the single-phase inverter device 40 on the U-phase output voltage of the three-phase three-level inverter 30 and the V-phase output voltage of the three-phase three-level inverter 30 line voltage between the V-phase composite voltage superimposed with the V-phase output voltage of the single-phase inverter device 40), the U-phase voltage and U-phase current of the three-phase three-level inverter 30, the U of the single-phase inverter device 40 4 shows waveforms of a phase voltage and a common mode voltage of the inverter 10.
- FIG. 10 composite voltage obtained by superimposing the U-phase output voltage of three-phase three-level inverter 30 and the U-phase output voltage of single-phase inverter device 40
- the amount of voltage change per step of each of the U-phase output voltage of the inverter 10 in the top two stages and the output voltage between the UV phases of the inverter 10 is defined as one level.
- One level in this case corresponds to the voltage value applied to each capacitor 41 constituting the single-phase inverter device 40 .
- the voltage applied to the capacitor 41 is 67.5 V, which is 1 level. corresponds to this.
- the common mode voltage of inverter 10 is calculated by dividing the sum of the phase voltages of the respective phases by the number of phases.
- the dead time is a period during which the upper and lower switches are turned off at the same time so that the upper and lower switches are not turned on at the same time when switching between on and off in order to prevent short-circuiting of the upper and lower arms. It is known to apply a dead time when operating a power converter as an actual machine. However, the dead time applied for short-circuit prevention may create an unintended operating path, increase voltage fluctuations in the output and common mode waveforms, distort the waveforms, and affect noise and surge voltages.
- FIGS. 7A and 7B show gate drive signals when dead time is applied to the gate drive signals of the switching elements shown in FIGS. 5A and 5B.
- FIG. 7A is a diagram in which dead time is applied to gate drive signals output to switching elements in order to output a voltage waveform corresponding to the output voltage command value (U-phase) of three-phase, three-level inverter 30.
- U-phase the output voltage command value
- the output voltage command value (U phase) of the three-phase three-level inverter 30, the switching element Q1 to the switching element Q4 constituting the U-phase leg of the three-phase three-level inverter 30 is a waveform of a gate drive signal.
- the dashed lines in the switching elements Q1 to Q4 indicate the operation before the dead time is applied (the operation in FIG. 5A).
- the dead time is introduced at the rise of the gate voltage, but it may be introduced at the fall or at both the rise and fall.
- a dead-time period applies for each switching. For example, when a dead time period of 1 ⁇ s is provided, a pattern of providing 1 ⁇ s for rising, 1 ⁇ s for falling, or 0.5 ⁇ s for rising and 0.5 ⁇ s for falling is conceivable.
- the voltage applied between the drain and the source of the semiconductor element becomes the voltage value of the P-side capacitor 31 or the N-side capacitor 32, which is the input capacitor, while the gate drive signal is off (that is, 0) as in FIG. 5A. While the signal is on (that is, 1), the voltage value is 0 (actually, the internal voltage drop is applied).
- FIG. 7B is a diagram in which the dead time is applied to the gate drive signal output to the switching element in order to output the voltage waveform corresponding to the output voltage command value (U-phase) of the single-phase inverter device 40.
- the signal before application and the solid line are the waveforms of the drive signal when the dead time is applied.
- the dead time is introduced at the rise of the gate voltage, but it may be introduced at the fall or at both the rise and fall.
- dead time is applied for each switching.
- the switching elements Q13 to Q16 are switched on and off multiple times per cycle. As in the case where the dead time is not applied, the switching elements constituting the single-phase inverter device 40 that operates in PWM have a large number of switching times. .
- the voltage applied between the drain and the source of the semiconductor element is the voltage value of the capacitor 41 while the gate drive signal is off (ie 0), and the voltage value is 0 while the gate drive signal is on (ie 1). (Actually, the internal voltage drop is applied).
- each capacitor 41 of the single-phase inverter device 40 When the voltage of each capacitor 41 of the single-phase inverter device 40 is set to 1/2, for example, so that the voltage of each capacitor 41 is smaller than the voltage of the P-side capacitor 31 and the N-side capacitor 32, which are the input capacitors of the three-phase three-level inverter 30. , the voltage applied to the switching elements forming the single-phase inverter device 40 is half the voltage applied to the switching elements forming the three-phase three-level inverter 30 . At this time, one level of the voltage output from the inverter 10 becomes the voltage applied to the elements forming the single-phase inverter device 40 . These are applicable even if it is not a three-phase power converter.
- FIG 8A and 8B show, in order from the top, the U-phase output voltage of the inverter 10 (the combined voltage obtained by superimposing the U-phase output voltage of the three-phase three-level inverter 30 and the U-phase output voltage of the single-phase inverter device 40).
- the output voltage between the UV phases of the inverter 10 (U-phase composite voltage obtained by superimposing the U-phase output voltage of the single-phase inverter device 40 on the U-phase output voltage of the three-phase three-level inverter 30 and the output voltage of the three-phase three-level inverter 30 line voltage between the V-phase output voltage and the V-phase composite voltage obtained by superimposing the V-phase output voltage of the single-phase inverter device 40), the U-phase voltage and U-phase current of the three-phase three-level inverter 30, the single-phase 4 shows waveforms of the U-phase voltage of the inverter device 40 and the common mode voltage of the inverter 10.
- FIG. 7 is a diagram showing an example of an output waveform, which corresponds to the case where dead time is applied to FIG. 6;
- Such a thin pulse-like voltage is called a voltage spike, and the occurrence of the voltage spike is due to the change in the operating path due to the application of dead time. Since such a voltage fluctuation width of two or more levels per step affects noise, a noise filter must be provided for noise suppression. Furthermore, the larger the voltage fluctuation range, the larger and heavier the noise filter becomes.
- FIG. 8B is a diagram showing the result of controlling so that the voltage spikes in FIG. 8A do not occur.
- FIG. 9A is a diagram for explaining the cause of the voltage spike in FIG. 8A.
- FIG. 8A shows a partial enlargement of the U-phase output voltage of the inverter 10 in the uppermost stage. In the output voltage waveform of , the timing of voltage fluctuation when dead time is applied does not match.
- the fall of the output voltage of the single-phase inverter is recognized with a delay of 2 ⁇ s from the rise of the output voltage of the three-phase, three-level inverter.
- the output voltage of three-phase three-level inverter 30 and , the fluctuation timing of the single-phase inverter 40 is adjusted.
- the timings of the two should be controlled so as to match each other so as not to cause a deviation.
- the variation timing of one voltage may be shifted by the dead time, or the variation timing of the other voltage may be shifted by the sum of the dead time and the circuit delay.
- FIG. 9B is an example in which the variation timing of the voltage generated by the single-phase inverter device 40 is advanced so that the variation timing of the voltage generated by the three-phase three-level inverter 30 and the variation timing of the voltage generated by the single-phase inverter device 40 are aligned.
- Timing matching is not limited to this example. Adjustment may be made by advancing or delaying the timing of the voltage generated by the three-phase, three-level inverter 30 or by advancing or delaying the timing of the voltage generated by the single-phase inverter device 40 .
- FIG. 8B shows the output voltage when controlled so that the fluctuation timing of the voltage generated by the three-phase three-level inverter 30 and the fluctuation timing of the voltage generated by the single-phase inverter device 40 are aligned so as to suppress the occurrence of voltage spikes. is shown.
- FIG. 8A by controlling the variation timing of the voltage generated by the three-phase three-level inverter 30 and the variation timing of the voltage generated by the single-phase inverter device 40 to match, the U-phase of the inverter 10 and the output voltage between the UV phases of the inverter 10 are suppressed within one level per step during the dead time period.
- the common mode voltage of the inverter 10 the amount of voltage variation per step was similarly suppressed within one level during the dead time period.
- a short-circuit prevention function can be provided, and noise caused by voltage fluctuation and voltage distortion can be reduced.
- the voltages of the capacitors 31, 32, and 41 of the inverter 10 in this manner, a short-circuit prevention function that suppresses noise generation is provided even under conditions where both common mode noise and normal mode noise can be reduced. becomes possible.
- the power conversion device 3 includes an inverter 10 having a three-phase three-level inverter 30 and a single-phase inverter device 40, and a control device 20 that controls the driving of the inverter 10.
- a high-voltage semiconductor element is used for the switching element that constitutes the three-level inverter 30, and a semiconductor element formed of a wide bandgap semiconductor is used for the switching element that constitutes the single-phase inverter device 40. Since the timing of the voltage fluctuation generated by the 3-level inverter 30 and the voltage fluctuation generated by the single-phase inverter device 40 are matched, in addition to the above effects, the loss associated with driving the switching elements is also reduced, resulting in highly efficient power conversion. Equipment can be provided.
- the noise filter can be made smaller and lighter, contributing to improved fuel efficiency.
- the influence of noise is suppressed without increasing the weight, the reliability is also improved.
- Embodiment 2 A power converter according to Embodiment 2 will be described below with reference to the drawings.
- the timing of the voltage fluctuation generated by the three-phase, three-level inverter 30 and the timing of the voltage fluctuation generated by the single-phase inverter device 40 are controlled to match each other during the dead time period.
- a control method according to the polarity of the load current that varies according to the state of the load 5 will be described.
- FIGS 10A and 10B are diagrams showing phase voltages of the three-phase, three-level inverter 30, phase voltages of the single-phase inverter device 40, and current waveforms when the states of the load 5 are different.
- FIG. 10A shows an example in which the load power factor is 1.
- the output voltage waveform of the phase voltage (same phase as the three-phase three-level inverter 30) of the single-phase inverter device 40 to which the dead time is not applied (C1)
- output voltage waveform (D1) of phase voltage of three-phase three-level inverter 30 when dead time is applied output voltage waveform (E1) of phase voltage of single-phase inverter device 40 when dead time is applied
- waveform of D1 2 is an output voltage waveform (F1) of the phase voltages of the three-phase, three-level inverter 30 that controls the timing of voltage fluctuations from FIG.
- waveforms are hereinafter simply referred to as waveforms A1, etc., and will be described.
- the current direction from the inverter to the load is assumed to be positive.
- the polarity of the output current (B) is positive when the positive voltage rises from 0 to +Vdc/2 (t1) and when it falls from +Vdc/2 to 0 (t2).
- the voltage on the negative side rises from 0 to -Vdc/2 (t3) and falls from Vdc/2 to 0 (t4)
- the polarity of the output current is negative.
- the timings t1 to t4 shown in the waveform A1 are the timings at which the output voltage of the phase voltage of the single-phase inverter device 40 also fluctuates, as can be seen from the waveform C1.
- the timing t1 at which the load current polarity is positive and the voltage changes from +Vdc/4 to -Vdc/4 does not delay, but the load current polarity is positive and the voltage is delayed by Td at timing t2 at which Vdc changes from -Vdc/4 to +Vdc/4.
- the load current polarity is negative and the voltage changes from -Vdc/4 to +Vdc/4, but the load current polarity is negative and the voltage changes from +Vdc/4 to -Vdc/4.
- the changing timing t4 is delayed by Td.
- the timings t1 and t3 also do not delay due to the polarity of the load current and the current flowing through the diodes of the switching elements for the same reason.
- Waveform F1 is an example in which control is performed so that the timing at which the output voltage of the three-phase, three-level inverter 30 fluctuates and the timing at which the output voltage of the single-phase inverter device 40 fluctuates coincide with each other from timing t1 to t4.
- the timing t1 at which the positive side voltage rises from 0 to +Vdc/2 and the timing t3 at which the negative side voltage rises from 0 to ⁇ Vdc/2 with respect to the output voltage of the three-phase three-level inverter 30 are separated by Td.
- the timing t2 at which the voltage on the positive side falls from +Vdc/2 to 0 and the timing t4 at which the voltage on the negative side falls from Vdc/2 to 0 are delayed by Td.
- the control to match the timings is not limited to this, and the timings t1 and t3 may be delayed by Td and the timings t2 and t4 may be advanced by Td with respect to the output voltage of the single-phase inverter device 40. Furthermore, the control to advance or delay the timing of the output voltage of the three-phase three-level inverter 30 and the control to advance or delay the timing of the output voltage of the single-phase inverter device 40 may be combined.
- FIG. 10B shows an example in which the load power factor is 0. From the top, output voltage waveforms (A2) of the phase voltages (for example, U phase) of the three-phase three-level inverter 30 to which dead time is not applied; A current detected by the current sensor 101U in the case of the U phase is indicated by a solid line (the dotted line is the output current when the power factor is 1).
- the output voltage waveform (D2) of the voltage, the output voltage waveform (E2) of the phase voltage of the single-phase inverter device 40 when the dead time is applied, and the phase voltage of the three-phase three-level inverter 30 whose voltage fluctuation timing is controlled from the waveform of D2. is the output voltage waveform (F2) of .
- the current direction from the inverter to the load is assumed to be positive.
- the waveform of A2 when the voltage on the positive side rises from 0 to +Vdc/2 (t11) and when the voltage on the negative side falls from Vdc/2 to 0 (t14), the polarity of the output current (B2) is negative. be.
- the positive side voltage falls from +Vdc/2 to 0 (t12) and when the negative side voltage rises from 0 to -Vdc/2 (t13), the polarity of the output current (B2) is positive.
- the timings t11 to t14 shown in the waveform A2 are the timings at which the output voltage of the phase voltage of the single-phase inverter device 40 also fluctuates, as can be seen from the waveform C2.
- waveforms D2 and E2 When the dead time is applied to the switching elements of the three-phase, three-level inverter 30 and the switching elements of the single-phase inverter device 40 under this load power factor condition of 0, waveforms D2 and E2 are obtained, respectively.
- the waveform D2 when compared with the waveform A2, the positive voltage rise timing t11, the positive voltage fall timing t12, the negative voltage rise timing t13, and the negative voltage fall timing t14 are delayed. not occurred. This is because the polarity of the load current causes the current to flow through the diode provided in the switching element during the dead time period, so no delay occurs.
- waveform E2 when compared with waveform C2, the polarity of the load current is negative and the voltage changes from +Vdc/4 to -Vdc/4 at timing t11, the polarity of the load current is positive and the voltage changes from -Vdc/4 to +Vdc. /4, the timing t13 when the polarity of the load current is positive and the voltage changes from -Vdc/4 to +Vdc/4, and the polarity of the load current is negative and the voltage changes from +Vdc/4 to -Vdc/4. Timing t14 is delayed by Td.
- the timing at which the output voltage of the three-phase, three-level inverter 30 fluctuates does not match the timing at which the output voltage of the single-phase inverter device 40 fluctuates in all of the timings t11 to t14. It will be. Therefore, in order to suppress the occurrence of voltage spikes, it is sufficient to control the fluctuation timings of both to coincide with each other.
- Waveform F2 is an example in which the output voltage fluctuation timing of the three-phase three-level inverter 30 and the output voltage fluctuation timing of the single-phase inverter device 40 are controlled to coincide from timing t11 to t14.
- timings t11, t12, t13, and t14 are delayed by Td from the output voltage of the three-phase, three-level inverter 30, as indicated by arrows.
- the control for matching the timings is not limited to this, and the timings t11, t12, t13, and t14 may be advanced by Td with respect to the output voltage of the single-phase inverter device 40. Furthermore, the control to advance or delay the timing of the output voltage of the three-phase three-level inverter 30 and the control to advance or delay the timing of the output voltage of the single-phase inverter device 40 may be combined.
- the load has a power factor of 1 and a power factor of 0; If the timing at which the voltage fluctuates and the timing at which the output voltage of the single-phase inverter device 40 fluctuates do not coincide, control may be performed so that the two coincide. By controlling the two to match each other, the output voltage fluctuation range of the inverter can be suppressed to one level per step.
- the same effects as those of the first embodiment are obtained. Furthermore, depending on the state of the load, that is, the polarity of the load current, the respective outputs after applying the dead time of the semiconductor elements constituting the three-phase three-level inverter 30 and after applying the timing and the dead time of the semiconductor elements constituting the single-phase inverter device 40 Even if there is a deviation in the voltage fluctuation timing, control is performed to match the two, so that the output voltage fluctuation width of the inverter can be suppressed to one level per step.
- the noise filter can be made smaller and lighter, contributing to improved fuel efficiency.
- Embodiment 3 A power converter 3 according to Embodiment 3 will be described below with reference to the drawings.
- the relationship between the turn-on time and turn-off time of each of the semiconductor elements and timings constituting the three-phase three-level inverter 30 and the semiconductor elements constituting the single-phase inverter device 40 and the voltage spike of the inverter 10 will be described. .
- FIG. 11A shows examples of waveforms of the inverter 10 output voltage under each condition in order from the top, turn-off waveforms (solid lines) of the semiconductor elements forming the three-phase three-level inverter 30, and turn-on of the semiconductor elements forming the single-phase inverter device 40. It is the figure which showed collectively the example of a waveform (broken line), each condition, and the variation
- the voltage on the vertical axis is The drain-source voltage means the collector-emitter voltage in the case of an IGBT (Integrated Gate Bipolar Transistor), which will be described later.
- FIG. 11B shows examples of waveforms of the output voltage of the inverter 10 under each condition in order from the top, turn-on waveforms (solid lines) of the semiconductor elements forming the three-phase three-level inverter 30, and semiconductor elements forming the single-phase inverter device 40.
- FIG. 1 is a diagram collectively showing an example of a turn-off waveform (dashed line) of , and each condition and the amount of change in the inverter output voltage.
- the turn-on time (dV/dt) of the semiconductor elements forming the single-phase inverter device 40 is -0.5 kV/ ⁇ s
- the turn-off time of the semiconductor elements forming the three-phase three-level inverter 30 is changed.
- 2 shows the output waveform of the inverter 10 when The turn-on start timing of the semiconductor elements forming the single-phase inverter device 40 and the turn-off start timing of the semiconductor elements forming the three-phase three-level inverter 30 are made to coincide with each other. That is, the start timing of the voltage fluctuation of the three-phase, three-level inverter 30 and the voltage fluctuation of the single-phase inverter device 40 are matched.
- each condition be P-1 to T-1.
- the fluctuation of the inverter output voltage under the condition Q-1 is within 67.5 V (one level) per step as indicated by the arrow in the figure.
- condition S-1 the same applies to condition S-1.
- condition R-1 the slope of the output voltage waveform changes with the arrow as a boundary, so the voltage fluctuation is less than 67.5 V (one level) per step. That is, the fluctuation of the inverter output voltage under conditions Q-1, R-1, and S-1 is within 67.5 V (one level) per step.
- the waveform of the inverter output voltage exhibits an upwardly projecting voltage spike waveform, and the inverter output voltage fluctuates by one step. exceeds 67.5V per
- the condition P-1 in which the turn-off time of the semiconductor elements constituting the three-phase three-level inverter 30 is long, the waveform of the inverter output voltage exhibits an upwardly projecting voltage spike waveform, and the inverter output voltage fluctuates by one step. exceeds 67.5V per
- the turn-off time of the semiconductor elements constituting the three-phase three-level inverter 30 is longer than the condition P-1, the voltage spike becomes large and the semiconductor elements constituting the three-phase three-level inverter 30 are turned off. It was confirmed that when the turn-off time of the device exceeded 2 kV/ ⁇ s, the fluctuation of the output voltage reached 1.5 levels per step.
- the turn-on time of the semiconductor elements constituting the three-phase three-level inverter 30 was changed while the turn-off time (dV/dt) of the semiconductor elements constituting the single-phase inverter device 40 was 0.5 kV/ ⁇ s.
- 10 shows the output waveform of the inverter 10 when The turn-off start timing of the semiconductor elements forming the single-phase inverter device 40 and the turn-on start timing of the semiconductor elements forming the three-phase three-level inverter 30 are made to coincide with each other.
- each condition be P-2 to T-2.
- the fluctuation of the inverter output voltage under the condition Q-2 is within 67.5 V (one level) per step as indicated by the arrow in the figure.
- condition S-2 the same applies to condition S-2.
- condition R-2 the slope of the output voltage waveform changes with the arrow as a boundary, so the voltage fluctuation is less than 67.5 V (one level) per step. That is, the inverter output voltage under the conditions Q-2, R-2, and S-2 is within a fluctuation of 67.5 V (one level) per step.
- the three-phase three-level inverter does not generate a voltage spike in the output voltage of the inverter 10 . It can be seen that there is a relationship between the turn-off time and the turn-on time of the semiconductor elements forming the level inverter 30 and the semiconductor elements forming the single-phase inverter device 40 .
- Y1 is the absolute value of the turn-off time of the semiconductor elements forming the three-phase three-level inverter 30
- X2 is the absolute value of the turn-on time of the semiconductor elements forming the single-phase inverter device 40
- Y2 is the three-phase three-level inverter 30
- X1 is the absolute value of the turn-off time of the semiconductor element forming the single-phase inverter device 40 .
- the power conversion device 3 includes semiconductor elements forming the single-phase inverter device 40 and semiconductor devices forming the three-phase three-level inverter 30 that satisfy the expressions (2) and (3). element is used.
- the turn-on start timing of the semiconductor elements constituting the single-phase inverter device 40 and the turn-off start timing of the semiconductor elements constituting the three-phase three-level inverter 30 are matched, and the voltage fluctuation of the three-phase three-level inverter 30 and the single
- the voltage fluctuation start timings of the phase inverter devices 40 are matched, the voltage fluctuation range of the output voltage of the inverter 10 can be suppressed to one level per step. Therefore, it is possible to reduce the size and weight of the noise filter connected to the rear stage of the power conversion device 3, and to improve the fuel efficiency. Moreover, it is possible to prevent deterioration of reliability due to the influence of noise without increasing the weight.
- Embodiment 4 The configuration of the semiconductor element that constitutes the power conversion device 3 according to the fourth embodiment will be described below. From the third embodiment, the switching time (turn-on time and turn-off time) of the semiconductor elements forming the three-phase three-level inverter 30 and the switching time of the semiconductor elements forming the single-phase inverter device 40 are expressed by the formulas (2) and (3). ), the output voltage fluctuation range can be suppressed to one level per step.
- the semiconductor elements forming the three-phase three-level inverter 30 and the semiconductor elements forming the single-phase inverter device 40 shown in FIG. 2 are MOSFETs. Other semiconductor devices that can satisfy the switching time of .
- FIG. 12A has a structure in which diodes are connected in antiparallel to IGBTs, which are semiconductor elements, as switching elements Q1 to Q12 constituting a three-phase three-level inverter 30, and switching elements Q13 to Q24 constituting a single-phase inverter device 40.
- IGBTs which are semiconductor elements
- switching elements Q1 to Q12 constituting a three-phase three-level inverter 30, and switching elements Q13 to Q24 constituting a single-phase inverter device 40.
- 1 is a circuit configuration diagram showing an example having a structure in which diodes are connected in anti-parallel to MOSFETs, which are semiconductor elements, as .
- the switching elements Q1 to Q12 constituting the three-phase three-level inverter 30 have a structure in which diodes are connected in anti-parallel to IGBTs, which are semiconductor elements, and the switching elements Q13 to Q24 constituting the single-phase inverter device 40.
- 1 is a circuit configuration diagram showing an example having a structure in which diodes are connected in anti-parallel to a HEMT (High Electron Mobility Transistor) which is a semiconductor element; FIG.
- the structures of the switching elements Q1 to Q24 constituting the three-phase three-level inverter 30 and single-phase inverter device 40 shown in FIGS. 12A and 12B will be described with reference to FIGS. 13A and 13B.
- FIG. 13A is an example showing the configuration of semiconductor elements applied to the switching elements Q1 to Q12 constituting the three-phase three-level inverter 30.
- IGBT 13 having a collector terminal C, a gate terminal G and an emitter terminal E and an IGBT 13 in antiparallel with this. and a diode 14 connected thereto.
- the IGBT 13 may be a Si-IGBT or, for example, a SiC-IGBT using a wide bandgap semiconductor.
- the diode 14 may be a Si-diode or, for example, a SiC-diode using a wide bandgap semiconductor.
- FIG. 13B is an example showing another configuration of the semiconductor elements applied to the switching elements Q13 to Q24 that constitute the single-phase inverter device 40.
- the HEMT 17 has a drain terminal D, a gate terminal G, and a source terminal S, and vice versa. and a diode 18 connected in parallel.
- HEMT 17 is, for example, a GaN-HEMT using a wide bandgap semiconductor.
- Diode 18 may be a Schottky barrier diode, Si-diode, or SiC-diode using a wide bandgap semiconductor, for example. However, it is preferable to use a semiconductor element using a wide bandgap semiconductor.
- a structure in which a diode is antiparallel-connected to an IGBT or a structure in which a diode is antiparallel-connected to a HEMT can be used as a semiconductor element.
- the structure of these semiconductor elements can set the switching time so as to satisfy the conditions of the formulas (2) and (3) shown in the third embodiment, so that the same effects as those of the third embodiment can be obtained. .
- FIG. 14 is a diagram showing an example of an aircraft 100 according to Embodiment 5, and is a block diagram showing a state in which the power converter described in Embodiments 1 to 4 is mounted.
- the aircraft 100 is an electric aircraft, and its propulsion power system 60 includes a power source 63, a power source (DC power source) 1 connected to the power source 63, and a step-down chopper circuit connected to the power source 1 and converting to a predetermined voltage.
- the load 61 is a propulsion system load for obtaining propulsive force, such as an electric motor.
- the power converters of Embodiments 1 to 4 are used as the inverter 10 for the electric aircraft of the propulsion system power system 60 mounted on the aircraft 100 . Since it is required to reduce the weight of the equipment to be mounted on something that flies in the sky like an aircraft, a propulsion system power system equipped with the power conversion device described in Embodiments 1 to 4 in order to reduce the size and weight of the noise filter 60, the inverter 10 for electric aircraft can generate a waveform with less voltage distortion, thereby reducing the weight of the noise filter and suppressing increases in weight and cost. Therefore, the fuel efficiency of the electric aircraft is also improved.
- FIG. 15 is a diagram showing an example of an aircraft 100 according to Embodiment 6, and is a block diagram showing a state in which the power converter described in Embodiments 1 to 4 is mounted.
- Aircraft 100 is an electric aircraft, and its equipment system 70 includes a power source 74, an AC/DC converter 72 connected to power source 74 for converting AC power into DC power, and a power source connected to AC/DC converter 72.
- the load 71 is an equipment load, such as an air conditioner, an engine starter, and an electric motor used to drive an auxiliary power device.
- the power converters of Embodiments 1 to 4 are used as the inverter 10 for the electric aircraft of the equipment-based power system 70 mounted on the aircraft 100 . Since it is required to reduce the weight of the equipment to be mounted on an object that flies in the sky, such as an aircraft, in order to reduce the size and weight of the noise filter, the equipment-based power system equipped with the power conversion device described in Embodiments 1 to 4 By installing it in 70, the same effects as in the fifth embodiment can be obtained.
- the control device is composed of a processor 1000 and a storage device 2000, as shown in FIG. 16 as an example of hardware.
- the storage device includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory.
- an auxiliary storage device such as a hard disk may be provided instead of the flash memory.
- Processor 1000 executes a program input from storage device 2000 .
- the program is input to the processor 1000 from the auxiliary storage device via the volatile storage device.
- the processor 1000 may output data such as calculation results to the volatile storage device of the storage device 2000, or may store the data in the auxiliary storage device via the volatile storage device.
- Embodiments 1 to 6 described above show examples in which one three-phase three-level inverter 30 as the first inverter and the single-phase inverter device 40 as the second inverter include three single-phase inverters.
- the first inverter need not be three-phase, and may be single-phase.
- the second inverter may be one single-phase inverter.
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Abstract
Description
以下、実施の形態1に係る電力変換装置について図を用いて説明する。
図1は実施の形態1に係る電力変換装置3を用いた電力変換システムの一例を示す概略構成図である。図1において、直流電源1と負荷5(例えば図2のモータ)との間に、電力変換装置3とフィルタ4が直列に接続され、直流電源1と電力変換装置3との間にDCリンクコンデンサ2が並列に接続されている。電力変換装置3は直流電源1からの電力を所定の電力に変換してフィルタ4を介して負荷5に出力する電力変換部であるインバータ10とその制御部である制御装置20とを具備する。なお、本実施の形態1において、インバータ10はDC/ACインバータを例に説明する。
図3は、三相3レベルインバータ30を構成するスイッチング素子Q1からQ12と単相インバータ装置40を構成するスイッチング素子Q13~Q24に適用される半導体素子の構成を示す一例で、ドレイン端子D、ゲート端子G、ソース端子Sを有するMOSFET15とこれに逆並列接続されたダイオード16とで構成される。MOSFET15は、Si-MOSFETであっても、ワイドバンドギャップ半導体を用いた例えばSiC-MOSFETであってもよい。また、ダイオード16はSi-ダイオードであっても、ワイドバンドギャップ半導体を用いた例えばSiC-ダイオードであってもよい。しかし、望ましくはワイドバンドギャップ半導体を用いた半導体素子である方がよい。
Vcom=(Vu+Vv+Vw)/3 ・・・(1)
また、コモンモード電圧の1ステップあたりの電圧変化量は単相インバータ装置40を構成しているコンデンサ41に印加される電圧(ここでは67.5V)を3で除した値(67.5/3=22.5(V))に相当する。
デッドタイムとは、上下アームの短絡を防止するために、オンとオフとの切り替えタイミングにおいて、上下のスイッチが同時にオンならないように同時オフの状態にする期間のことである。電力変換装置を実機で動作させる場合デッドタイムを適用することは知られている。しかし、短絡防止のために適用するデッドタイムによって、意図しない動作経路が発生し、出力波形及びコモンモード波形の電圧変動が大きくなり、波形が歪み、ノイズ及びサージ電圧に影響を与えることがある。
図8Aは、図7Aの波形で3相3レベルインバータ30のスイッチング素子Q1~スイッチング素子Q4を駆動し、図7Bの波形で単相インバータ装置40のスイッチング素子Q13~スイッチング素子Q16を駆動した時の出力波形の例を示す図であり、図6にデッドタイムを適用した場合のものに相当する。
以下、電圧スパイクが発生しないように制御する方法について説明する。
図9Aは、図8Aの電圧スパイクの発生原因を説明するための図である。図8Aの最上段のインバータ10のU相の出力電圧の一部拡大を示すが、電圧スパイクΔVが3レベル(202.5V)の箇所では、三相3レベルインバータの出力電圧波形と単相インバータの出力電圧波形において、デッドタイム適用時の電圧変動のタイミングが一致していない。図9Aでは、三相3レベルインバータの出力電圧の立ち上がりから2μs遅れて単相インバータの出力電圧の立下りが認められる。この差異は、デッドタイム及びゲート回路の遅延によってずれが生じることで発生するものと考えられる。そこで、本実施の形態では、三相3レベルインバータ30の出力電圧と単相インバータ40の出力電圧との合成電圧の電圧変動幅が抑制されるように、三相3レベルインバータ30の出力電圧と、単相インバータ40の変動タイミングが調整される。具体的には、ずれが発生しないように両者のタイミングを一致させるように制御すればよい。例えば、一方の電圧の変動タイミングをデッドタイム分だけずらしてもよく、一方の電圧の変動タイミングをデッドタイムと回路遅延との合計分ずらしてもよい。
以下、実施の形態2に係る電力変換装置について図を用いて説明する。実施の形態1では、デッドタイム期間中に三相3レベルインバータ30で生成する電圧の変動のタイミングと単相インバータ装置40で生成する電圧の変動タイミングとを合わせるように制御することを説明したが、本実施の形態2では、負荷5の状態に応じて変動する負荷電流の極性に応じた制御方法について説明する。
図10Aは、負荷力率が1の場合の例で、上から順に、デッドタイムを適用していない三相3レベルインバータ30の相電圧(例えばU相)の出力電圧波形(A1)、インバータ10の出力電流(B1)でU相の場合電流センサ101Uで検出される電流、デッドタイムを適用していない単相インバータ装置40の相電圧(三相3レベルインバータ30と同じ相)の出力電圧波形(C1)、デッドタイム適用時の三相3レベルインバータ30の相電圧の出力電圧波形(D1)、デッドタイム適用時の単相インバータ装置40の相電圧の出力電圧波形(E1)、D1の波形から電圧変動のタイミングを制御した三相3レベルインバータ30の相電圧の出力電圧波形(F1)である。これら波形に対し、以下単に波形A1、等と称して説明する。
A1の波形において、正側の電圧が0から+Vdc/2に立ち上がるとき(t1)及び+Vdc/2から0に立ち下がるとき(t2)、出力電流(B)の極性は正である。また、負側の電圧が0から―Vdc/2に立ち上がるとき(t3)及びVdc/2から0に立ち下がるとき(t4)、出力電流の極性は負である。波形A1に示したタイミングt1からt4は波形C1からわかるように単相インバータ装置40の相電圧の出力電圧も変動するタイミングである。
A2の波形において、正側の電圧が0から+Vdc/2に立ち上がるとき(t11)及び負側の電圧がVdc/2から0に立ち下がるとき(t14)、出力電流(B2)の極性は負である。また、正側の電圧が+Vdc/2から0に立ち下がるとき(t12)及び負側の電圧が0から―Vdc/2に立ち上がるとき(t13)、出力電流(B2)の極性は正である。波形A2に示したタイミングt11からt14は波形C2からわかるように単相インバータ装置40の相電圧の出力電圧も変動するタイミングである。
以下、実施の形態3に係る電力変換装置3について図を用いて説明する。本実施の形態3では、三相3レベルインバータ30を構成する半導体素子及びタイミングと単相インバータ装置40を構成する半導体素子のそれぞれターンオン時間、ターンオフ時間とインバータ10の電圧スパイクとの関係について説明する。
また、図11Bは、上から順に各条件でのインバータ10出力電圧の波形の例、三相3レベルインバータ30を構成する半導体素子のターンオン波形(実線)と単相インバータ装置40を構成する半導体素子のターンオフ波形(破線)の例、及び各条件とインバータ出力電圧の変化量をまとめて示した図である。なお、上から2段目の波形を示す図の縦軸は図11Aと同様である。
2×Y2 ≧ X1 ≧ Y2・・・(2)
2×Y1 ≧ X2 ≧ Y1・・・(3)
ここで、Y1は三相3レベルインバータ30を構成する半導体素子のターンオフ時間の絶対値、X2は単相インバータ装置40を構成する半導体素子のターンオン時間の絶対値、Y2は三相3レベルインバータ30を構成する半導体素子のターンオン時間の絶対値、X1は単相インバータ装置40を構成する半導体素子のターンオフ時間の絶対値である。
以下、実施の形態4に係る電力変換装置3を構成する半導体素子の構成について説明する。実施の形態3より、三相3レベルインバータ30を構成する半導体素子のスイッチング時間(ターンオン時間及びターンオフ時間)と単相インバータ装置40を構成する半導体素子のスイッチング時間を式(2)及び式(3)の条件範囲内で異ならせた場合でも、出力電圧変動幅を1ステップあたり1レベルに抑えることができる。実施の形態3では、図2に示した三相3レベルインバータ30を構成する半導体素子及び単相インバータ装置40を構成する半導体素子がMOSFETであったが、本実施の形態4では実施の形態3のスイッチング時間を満足できる他の半導体素子について以下説明する。
以下、実施の形態5に係る航空機について説明する。
図14は、実施の形態5に係る航空機100の一例を示す図で、実施の形態1から4で説明した電力変換装置が搭載された状態を示すブロック図である。航空機100は電動航空機であり、その推進系電力システム60として、電力源63、電力源63に接続された電源(DC電源)1、電源1に接続され所定の電圧に変換する降圧チョッパ回路を備えたDC/DCコンバータ50、DC/DCコンバータ50で降圧された直流電力を交流電力に変換するインバータ10、インバータ10から電力が供給される負荷61、及びDC/DCコンバータ50、インバータ10を制御する制御装置62を備える。ここで負荷61は推進力を得るための推進系負荷であり、例えば電動モータである。
以下、実施の形態6に係る航空機について説明する。
図15は、実施の形態6に係る航空機100の一例を示す図で、実施の形態1から4で説明した電力変換装置が搭載された状態を示すブロック図である。航空機100は電動航空機であり、その装備品系電力システム70として、電力源74、電力源74に接続され交流電力を直流電力に変換するAC/DCコンバータ72、AC/DCコンバータ72に接続された電源(DC電源)1、電源1に接続され所定の電圧に変換する降圧チョッパ回路を備えたDC/DCコンバータ50、DC/DCコンバータ50で降圧された直流電力を交流電力に変換するインバータ10、インバータ10から電力が供給される負荷71、及びDC/DCコンバータ50、インバータ10、AC/DCコンバータ72を制御する制御装置73を備える。ここで負荷71は装備品系負荷であり、例えば空気調和機、エンジンスタータ、及び補助電力装置の駆動に用いる電動モータ等を指す。
上述の実施の形態1から6では、第1のインバータとしての三相3レベルインバータ30が1つ、第2のインバータとしての単相インバータ装置40が3つの単相インバータを具備する例を示したが、構成はこれに限るものではない。第1のインバータは3相でなくてもよく、単相であってもよい。第1のインバータが単相インバータ1つの場合、第2のインバータは単相インバータ1つでよい。
従って、例示されていない無数の変形例が、本願明細書に開示される技術の範囲内において想定される。例えば、少なくとも1つの構成要素を変形する場合、追加する場合または省略する場合、さらには、少なくとも1つの構成要素を抽出し、他の実施の形態の構成要素と組み合わせる場合が含まれるものとする。
Claims (8)
- 電源と負荷との間に配置され、前記電源からの電力を変換して前記負荷に供給する電力変換装置であって、
第1のコンデンサ及び複数のスイッチング素子を備えた第1のインバータと、
前記第1のインバータと直列に接続され、前記第1のコンデンサに印加される電圧より小さい電圧が印加される第2のコンデンサ及び複数のスイッチング素子を備えた第2のインバータと、
前記第1のインバータの複数のスイッチング素子及び前記第2のインバータの複数のスイッチング素子を駆動する駆動信号を生成する制御装置と、を備え、
前記制御装置は、
前記第1のインバータの複数のスイッチング素子及び前記第2のインバータの複数のスイッチング素子に対しデッドタイムを施して制御するとともに、
デッドタイム期間中の前記第1のインバータの出力電圧と前記第2のインバータの出力電圧との合成電圧の電圧変動幅が抑制されるように、前記第1のインバータの出力電圧の変動タイミング及び前記第2のインバータの出力電圧の変動タイミングを制御する、電力変換装置。 - 前記制御装置は、
デッドタイム期間中の前記第1のインバータの出力電圧と前記第2のインバータの出力電圧との合成電圧の前記電圧変動幅を1ステップあたり1レベル内となるように制御する、請求項1に記載の電力変換装置。 - 前記制御装置は、
前記第1のインバータの出力電圧の変動タイミングと前記第2のインバータの出力電圧の変動タイミングとを一致させるように制御する、請求項1または2に記載の電力変換装置。 - 前記制御装置は、負荷電流の極性に基づいて、前記第1のインバータの出力電圧の変動タイミングと前記第2のインバータの出力電圧の変動タイミングとを一致させるように制御する、請求項3に記載の電力変換装置。
- 前記制御装置は、
前記第1のインバータを前記第2のインバータよりも低い駆動周波数で駆動する、請求項1から4のいずれか1項に記載の電力変換装置。 - 前記制御装置は、
前記第1のインバータの具備するスイッチング素子のターンオフ時間の絶対値をY1、
前記第2のインバータの具備するスイッチング素子のターンオン時間の絶対値をX2、
前記第1のインバータの具備するスイッチング素子のターンオン時間の絶対値をY2、
前記第2のインバータの具備するスイッチング素子のターンオフ時間の絶対値をX1とするとき、
2×Y2 ≧ X1 ≧ Y2 、及び
2×Y1 ≧ X2 ≧ Y1
を満たすように、前記第1のインバータの複数のスイッチング素子及び前記第2のインバータの複数のスイッチング素子を制御する、請求項5に記載の電力変換装置。 - 前記第1のインバータの複数のスイッチング素子及び前記第2のインバータの複数のスイッチング素子はそれぞれ半導体素子を含み、前記第1のインバータの複数のスイッチング素子はSi半導体で形成され、前記第2のインバータの複数のスイッチング素子はワイドバンドギャップ半導体で形成されている、請求項5または6に記載の電力変換装置。
- 請求項1から7のいずれか1項に記載の電力変換装置を搭載した航空機。
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JP2010035252A (ja) * | 2008-07-25 | 2010-02-12 | Mitsubishi Electric Corp | 電力変換装置 |
JP2012060856A (ja) * | 2010-09-13 | 2012-03-22 | Omron Corp | パワーコンディショナ |
WO2020166003A1 (ja) | 2019-02-14 | 2020-08-20 | 三菱電機株式会社 | 電力変換装置 |
WO2021166164A1 (ja) * | 2020-02-20 | 2021-08-26 | 三菱電機株式会社 | 電力変換装置および航空機の電力システム |
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WO2009116273A1 (ja) * | 2008-03-19 | 2009-09-24 | 三菱電機株式会社 | 電力変換装置 |
JP2010035252A (ja) * | 2008-07-25 | 2010-02-12 | Mitsubishi Electric Corp | 電力変換装置 |
JP2012060856A (ja) * | 2010-09-13 | 2012-03-22 | Omron Corp | パワーコンディショナ |
WO2020166003A1 (ja) | 2019-02-14 | 2020-08-20 | 三菱電機株式会社 | 電力変換装置 |
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