JP2019030042A - Electric power conversion system - Google Patents

Abstract

To increase a pressure rise rate and reduce a loss of a switching element, and suppress destabilization of an output of an inverter circuit.SOLUTION: An electric power conversion system 100 performs a pressure rise gate operation with a phase of which a two-phase modulation conversion voltage command generated by performing two-phase modulation conversion of a three-phase voltage command becomes the minimum or the maximum, and generates a gate signal using a limit short-circuit duty in which a short-circuit duty Du is limited by using a short-circuit duty limitation coefficient Lim_Du defined based on a current IL, a reactor minimum current value IL_lim_min, and a reactor maximum current value IL_lim_max, flowing in a reactor 13 of a Z source pressure rise circuit 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power conversion device including a Z source booster circuit.

  FIG. 11 is a diagram illustrating a circuit configuration example of a power conversion device including a conventional Z source booster circuit (see, for example, Patent Document 1).

  The power conversion device shown in FIG. 11 includes a DC power source 1, a Z source booster circuit 2, and an inverter circuit 3.

  The Z source booster circuit 2 includes a diode 11 having an anode connected to the positive side of the DC power source 1, a reactor 12 having one end connected to the cathode of the diode 11, and a reactor having one end connected to the negative side of the DC power source 1. 13, one end connected to one end (input side) of the reactor 12, the other end connected to the other end (output side) of the reactor 13, and one end connected to the other end (output side) of the reactor 12. And a capacitor 15 having the other end connected to one end of the reactor 13. The inverter circuit 3 is connected to the output of the Z source booster circuit 2 (the other end of the reactors 12 and 13). The Z source booster circuit 2 boosts the output DC voltage of the DC power supply 1 and outputs it to the inverter circuit 3.

  The inverter circuit 3 includes switching elements 16 to 21 and free wheel diodes 22 to 27 connected in reverse parallel to the switching elements 16 to 21, respectively. Switching elements 16 and 17 are connected in series to form a U-phase arm of inverter circuit 3. Switching elements 18 and 19 are connected in series to form a V-phase arm of inverter circuit 3. Switching elements 20 and 21 are connected in series to constitute a W-phase arm of inverter circuit 3. By controlling on / off of the switching elements 16 to 21 so that the phases of the phases (U phase, V phase, W phase) are shifted from each other by 120 degrees, the output DC voltage of the Z source booster circuit 2 is changed to AC (3 Phase AC voltage). The inverter circuit 3 is connected to the output of the inverter circuit 3 (the connection point of the switching elements 16 and 17, the connection point of the switching elements 18 and 19, and the connection point of the switching elements 20 and 21) of the generated three-phase AC voltage. Output to the motor 4.

  When the upper and lower switching elements of any one of the U phase, V phase, and W phase of the inverter circuit 3 are simultaneously turned on to cause a short circuit operation, the Z source booster circuit 2 discharges the capacitors 14, 15 and the reactor 12, 13 charging is performed. Next, when one of the switching elements turned on at the same time is turned off, the reactors 12 and 13 are discharged and the capacitors 14 and 15 are charged. As a result, the voltage output to the inverter circuit 3 increases.

  Non-Patent Document 1 discloses a technique for performing the above-described short-circuit operation when a switching element switches from on to off or from off to on.

  Patent Document 2 discloses a technique for performing a short-circuit operation during a zero voltage vector period in order to suppress a decrease in output voltage due to an arm short circuit.

US Patent Application Publication No. 2003/0231518 JP 2009-141989

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL.39, NO.2, MARCH / APRILL 2003 P504〜510

  In one carrier cycle, the absolute value of the voltage command may be larger than the absolute value of the carrier, and the switching element may be always on or off. In this case, according to the technique disclosed in Non-Patent Document 1, switching of the switching element from on to off or switching from off to on is not performed, and a short circuit operation cannot be performed. Therefore, in the technique disclosed in Non-Patent Document 1, it is necessary to limit the voltage command so that the absolute value of the voltage command does not become larger than the absolute value of the carrier.

  In the technique disclosed in Patent Document 2, depending on the length of the zero voltage vector period, the length of the period in which the switching element is short-circuited is limited by the minimum on-time limit and the minimum off-time limit of the switching element. For this reason, the short circuit operation may not be performed. Therefore, in the technique disclosed in Patent Document 2, there is a limit to the boosted voltage value by the Z source booster circuit 2.

  Further, in the techniques disclosed in Non-Patent Document 1 and Patent Document 2, the loss of the switching elements 16 to 21 increases due to the short-circuit operation for the boost operation, and the temperature rises. Capacity is reduced.

  Further, when the current flowing through the reactor 13 of the Z source booster circuit 2 becomes discontinuous, the output voltage of the inverter circuit 3 becomes unstable.

  An object of the present invention is to solve the above-described problems, to provide a power conversion device that can increase the step-up rate and reduce the loss of the switching element, and can suppress the instability of the output of the inverter circuit. is there.

  In order to solve the above problems, a power converter according to the present invention includes a first reactor having one end connected to a positive electrode side of a DC power source, and a second reactor having one end connected to a negative electrode side of the DC power source. One end connected to one end of the first reactor, the other end connected to the other end of the second reactor, one end connected to the other end of the second reactor, and the like. Other than the first reactor, which has a Z source booster circuit having a second capacitor connected to one end of the first reactor, and a plurality of switching elements and is an output of the Z source booster circuit And an input connected to the other end of the second reactor and converting the output DC voltage of the Z source booster circuit into a three-phase AC voltage by switching of the plurality of switching elements and outputting the same to an AC motor. A three-phase voltage command that calculates an output voltage of the inverter circuit, a three-phase voltage command calculation unit that calculates an active power command, and a rotation angle of the AC motor. Two-phase modulation conversion is performed on the three-phase voltage command calculated by the command calculation unit to generate a two-phase modulation conversion voltage command, and a two-phase modulation state signal indicating the state of the two-phase modulation conversion voltage command is generated 2 A phase modulation conversion unit; a basic gate signal generation unit that generates a basic gate signal based on a two-phase modulation conversion voltage command generated by the two-phase modulation conversion unit and a predetermined carrier signal; and a voltage of the first capacitor And a short-circuit duty calculation unit that calculates a short-circuit duty that is a time for short-circuiting the output of the Z-source booster circuit based on the command value of the voltage of the first capacitor, and the three-phase A reactor minimum current value which is a minimum value of a current flowing through the second reactor, based on an active power command calculated by a pressure command calculation unit, a power supply voltage of the DC power supply, and a maximum load power of the AC motor; A current limit value calculation unit that calculates a reactor maximum current value that is a maximum value of a current that flows through the second reactor; a reactor minimum current value and a reactor maximum current value that are calculated by the current limit value calculation unit; 2 based on the current flowing through the reactor 2, the short-circuit duty limit coefficient calculation unit that calculates the short-circuit duty limit coefficient, and the short-circuit duty calculated by the short-circuit duty calculation unit is calculated by the short-circuit duty limit coefficient calculation unit Generates a boost gate signal based on the limit short-circuit duty limited by the limit factor and the carrier signal. Based on the boosting gate signal generator, the two-phase modulation state signal generated by the two-phase modulation converter, and the boosting gate signal generated by the boosting gate signal generator. A boosting gate signal generating unit for each switching element that generates a boosting gate signal, and the basic gate signal generating unit so that the boosting gate operation is performed in a phase where the two-phase modulation conversion voltage command is a lower limit value or an upper limit value. The final gate signal generation for generating the gate signal for each switching element based on the basic gate signal generated by the switching element and the boosting gate signal for each switching element generated by the switching element-specific boosting gate signal generation unit A section.

  In the power conversion device according to the present invention, it is desirable that a carrier signal used by the basic gate signal generation unit and a carrier signal used by the boosting gate signal generation unit are different.

  Further, in the power conversion device according to the present invention, the switching element-specific boosting gate signal generation unit generates boosting gate signals for one or more switching elements among a plurality of switching elements constituting the same phase. It is desirable.

  According to the power conversion device of the present invention, it is possible to increase the step-up rate and reduce the loss of the switching element, and to suppress instability of the output of the inverter circuit.

It is a figure which shows the structural example of the power converter device which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the control part shown in FIG. It is a figure which shows the characteristic of the short circuit duty limiting coefficient which the short circuit duty limiting coefficient calculating part shown in FIG. 2 produces | generates. It is a figure which shows the structural example of the three-phase voltage command calculating part shown in FIG. It is a figure which shows an example of the three-phase voltage command which the three-phase voltage command calculating part shown in FIG. 2 outputs. FIG. 3 is a diagram illustrating an example of a two-phase modulation conversion voltage command and a two-phase modulation state signal output by the two-phase modulation conversion unit illustrated in FIG. 2. It is a figure which shows an example of the basic gate signal which the basic gate signal generation part shown in FIG. 2 outputs. FIG. 3 is a diagram illustrating an example of a boosting gate signal output by a boosting gate signal generation unit illustrated in FIG. 2. FIG. 3 is a diagram illustrating an example of a switching element boosting gate signal output by a switching element boosting gate signal generation unit illustrated in FIG. 2; It is a figure which shows an example of the gate signal which the last gate signal generation part shown in FIG. 2 outputs. It is a figure which shows the structural example of the conventional power converter device.

  Embodiments of the present invention will be described below.

  FIG. 1 is a diagram illustrating a configuration example of a power conversion device 100 according to an embodiment of the present invention.

  1 includes a DC power source 1, a Z-source booster circuit 2, an inverter circuit 3, voltage sensors 5, 10, current sensors 6, 7, 9, a rotation angle sensor 8, and a control. Part 31.

  The Z source booster circuit 2 includes a diode 11, reactors 12 and 13, and capacitors 14 and 15.

  The anode of the diode 11 is connected to the positive electrode side of the DC power source 1. One end of the reactor 12 (first reactor) is connected to the cathode of the diode 11. That is, the reactor 12 is connected to the positive electrode side of the DC power source 1 through the diode 11. One end of the reactor 13 (second reactor) is connected to the negative electrode side of the DC power supply 1.

  Capacitor 14 (first capacitor) has one end connected to one end (input side) of reactor 12 and the other end connected to the other end (output side) of reactor 13. Capacitor 15 (second capacitor) has one end connected to one end (input side) of reactor 13 and the other end connected to the other end (output side) of reactor 12. The inverter circuit 3 is connected to the outputs of the Z source booster circuit 2 (the other end of the reactor 12 and the other end of the reactor 13).

  The inverter circuit 3 includes switching elements 16 to 21 and free wheel diodes 22 to 27 connected in reverse parallel to the switching elements 16 to 21, respectively. Switching elements 16 and 17 are connected in series to form a U-phase arm of inverter circuit 3. Switching elements 18 and 19 are connected in series to form a V-phase arm of inverter circuit 3. Switching elements 20 and 21 are connected in series to constitute a W-phase arm of inverter circuit 3. A motor 4 (AC motor) is connected to a connection point of the switching elements 16 and 17, a connection point of the switching elements 18 and 19, and a connection point of the switching elements 20 and 21. By controlling on / off of the switching elements 16 to 21 so that the phases of the phases (U phase, V phase, W phase) are shifted from each other by 120 degrees, the output DC voltage of the Z source booster circuit 2 is changed to AC (3 Phase AC voltage) and output to the motor 4.

  When the upper and lower switching elements of any one of the U-phase, V-phase, and W-phase of the inverter circuit 3 are turned on at the same time, the capacitors 14 and 15 are discharged and the reactors 12 and 13 are charged. . Next, when one of the switching elements turned on at the same time is turned off, the reactors 12 and 13 are discharged and the capacitors 14 and 15 are charged. As a result, the voltage output to the inverter circuit 3 increases.

  The voltage sensor 5 detects the voltage Vc applied to the capacitor 14 and outputs the detection result to the control unit 31.

  The current sensors 6 and 7 detect motor currents Iu and Iw flowing through the motor 4 and output detection results to the control unit 31.

  The rotation angle sensor 8 detects the rotation angle θ of the motor 4 and outputs the detection result to the control unit 31.

  The current sensor 9 detects the current IL flowing through the reactor 13 and outputs the detection result to the control unit 31.

  The voltage sensor 10 detects the power supply voltage Ve of the DC power supply 1 and outputs the detection result to the control unit 31.

  The control unit 31 includes a voltage Vc detected by the voltage sensor 5, motor currents Iu and Iw detected by the current sensors 6 and 7, θ detected by the rotation angle sensor 8, a current IL detected by the current sensor 9, Based on the power supply voltage Ve detected by the voltage sensor 10 and the like, gate signals Gup, Gun, Gvp, Gvn, Gwp, and Gwn for controlling on / off of the switching elements 16 to 21 are generated, and the switching elements 16 to 21 are generated. Output.

  FIG. 2 is a diagram illustrating a configuration example of the control unit 31.

  2 includes a three-phase voltage command calculation unit 32, a two-phase modulation conversion unit 33, a basic gate signal generation unit 34, a subtractor 35, a short-circuit duty calculation unit 36, and a boosting gate signal. A generation unit 37, a switching element-specific boosting gate signal generation unit 38, a final gate signal generation unit 39, a current limit value calculation unit 51, a short-circuit duty limit coefficient calculation unit 52, and a multiplier 53 are provided.

The three-phase voltage command calculation unit 32 instructs the motor currents Iu and Iw detected by the current sensors 6 and 7, the rotation angle θ detected by the rotation angle sensor 8, and the output torque of the motor 4 input from the outside. Based on the motor torque command to be generated, three-phase voltage commands Vu ^* , Vv ^* , Vw ^* for instructing the output voltage of the inverter circuit 3 are generated and output to the two-phase modulation conversion unit 33. Further, the three-phase voltage command calculation unit 32 calculates an active power command P ^* and outputs a current limit value calculation unit 51. Details of the active power command P ^* will be described later.

The two-phase modulation conversion unit 33 performs two-phase modulation conversion on the three-phase voltage commands Vu ^* , Vv ^* and Vw ^* generated by the three-phase voltage command calculation unit 32 based on the rotation angle θ detected by the rotation angle sensor 8. To generate two-phase modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** . The two-phase modulation conversion unit 33 outputs the generated two-phase modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** to the basic gate signal generation unit 34. Further, the two-phase modulation conversion unit 33 is a two-phase modulation state signal Vu ^** min, Vu ^** max, Vv ^** min indicating the state of the two-phase modulation conversion voltage commands Vu ^** , Vv ^** , Vw ^**. , Vv ^** max, Vw ^** min, Vw ^** max. Specifically, the two-phase modulation conversion unit 33 receives the two-phase modulation state signals Vu ^** min when the two-phase modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** become the voltage lower limit value. Two-phase modulation status signal Vu ^** max when Vv ^** min and Vw ^** min are set to high level and the two-phase modulation conversion voltage commands Vu ^** , Vv ^** and Vw ^** reach the voltage upper limit value. , Vv ^** max, Vw ^** max are set to the high level. The two-phase modulation conversion unit 33 uses the generated two-phase modulation state signals Vu ^** min, Vu ^** max, Vv ^** min, Vv ^** max, Vw ^** min, Vw ^** max for boosting each switching element. The data is output to the gate signal generation unit 38.

The basic gate signal generation unit 34 is based on the three-phase voltage commands Vu ^* , Vv ^* , Vw ^* generated by the two-phase modulation conversion unit 33 and a predetermined carrier signal a, and the basic gate signals Gup0, Gun0, Gvp0, Gvn0, Gwp0, Gwn0 are generated and output to the final gate signal generation unit 39.

The subtractor 35 subtracts the voltage Vc detected by the voltage sensor 5 from the DC voltage command Vc ^* (command value) indicating the voltage across the capacitor 14 and outputs the deviation ΔVc to the short-circuit duty calculator 36.

  The short-circuit duty calculator 36 calculates a short-circuit duty Du that is a short-circuit time required for boosting based on the deviation ΔVc generated by the subtractor 35. The short-circuit duty calculation unit 36 outputs the calculated short-circuit duty Du to the multiplier 53.

  The boosting gate signal generation unit 37 generates a boosting gate signal Gz based on a limited short-circuit duty Du_lim output from a multiplier 53 described later and a predetermined carrier signal a. For example, the boosting gate signal generation unit 37 generates the boosting gate signal Gz by a triangular wave comparison method in which the carrier signal a is a triangular wave and the limited short-circuit duty Du_lim is compared with the carrier signal a.

The switching element boosting gate signal generation unit 38 includes a logical product calculator corresponding to each of the switching elements 16 to 21 constituting the inverter circuit 3. The switching element-specific boosting gate signal generation unit 38 includes two-phase modulation state signals Vu ^** min, Vu ^** max, Vv ^** min, Vv ^** generated by the two-phase modulation conversion unit 33 by each logical operation unit ^{. *} Max, Vw ^** min, Vw ^** max, and the boost gate signal Gz generated by the boost gate signal generator 37 are calculated. The switching element-specific boost gate signal generation unit 38 outputs the calculation result of each AND operator to the final gate signal generation unit 39 as the switching element-specific boost gate signals Gzup, Gzun, Gzvp, Gzvn, Gzwp, Gzwn. .

  The final gate signal generation unit 39 includes a logical sum calculator corresponding to each of the switching elements 16 to 21 constituting the inverter circuit 3. The final gate signal generation unit 39 is generated by the switching gate boosting gate signal Gzup, Gzun, Gzvp, Gzvn, Gzwp, Gzwn generated by the switching device boosting gate signal generation unit 38 and the basic gate signal generation unit 34. The logical sum of the basic gate signals Gup0, Gun0, Gvp0, Gvn0, Gwp0, Gwn0 is calculated. The final gate signal generation unit 39 outputs the operation result of each logical sum calculator to the switching elements 16 to 21 as the gate signals Gup, Gun, Gvp, Gvn, Gwp, Gwn.

The current limit value calculation unit 51 is based on the active power command P ^* calculated by the three-phase voltage command calculation unit 32, the power supply voltage Ve detected by the voltage sensor 10, and the load maximum power Pmax input from the outside. Then, according to the following equations (1) to (3), a reactor minimum current value IL_lim_min indicating the minimum value of the current flowing through the reactor 13 and a reactor maximum current value IL_lim_max indicating the maximum value of the current flowing through the reactor 13 are calculated. .

  In the expressions (1) to (3), K1 and K2 are constants. Current limit value calculation unit 51 outputs calculated reactor minimum current value IL_lim_min and reactor maximum current value IL_lim_max to short-circuit duty limit coefficient calculation unit 52.

  The short-circuit duty limit coefficient calculation unit 52 is based on the following equation (4) based on the reactor minimum current value IL_lim_min and the reactor maximum current value IL_lim_max calculated by the current limit value calculation unit 51 and the current IL detected by the current sensor 9. ), (5), the short-circuit duty limit coefficient Lim_Du for limiting the short-circuit duty Du is calculated.

  FIG. 3 is a diagram illustrating characteristics of the short-circuit duty limit coefficient Lim_Du.

  As shown in FIG. 3, when the current IL is smaller than the reactor minimum current value IL_lim_min, the short-circuit duty limit coefficient Lim_Du is 1. When current IL is equal to or greater than reactor minimum current value IL_lim_min and smaller than reactor maximum current value IL_lim_max, short-circuit duty limit coefficient Lim_Du becomes a smaller value between 1 and 0 as current IL is larger. When current IL is equal to or greater than reactor maximum current value IL_lim_max, short-circuit duty limit coefficient Lim_Du is zero.

  Referring back to FIG. 2, the short-circuit duty limit coefficient calculation unit 52 outputs the calculated short-circuit duty limit coefficient Lim_Du to the multiplier 53.

  The multiplier 53 multiplies the short-circuit duty Du calculated by the short-circuit duty calculator 36 by the short-circuit duty limit coefficient Lim_Du calculated by the short-circuit duty limit coefficient calculator 52, and generates a boost gate signal as the limited short-circuit duty Du_lim. To the unit 37.

  FIG. 4 is a diagram illustrating a configuration example of the three-phase voltage command calculation unit 32.

  The three-phase voltage command calculation unit 32 shown in FIG. 4 includes a three-phase-dq coordinate conversion unit 41, a current command generation unit 42, subtractors 43 and 44, PI control units 45 and 46, and a dq coordinate-3 phase. A conversion unit 47 and an active power command calculation unit 48 are provided.

  The three-phase-dq coordinate conversion unit 41 converts the motor currents Iu and Iw detected by the current sensors 6 and 7 based on the rotation angle θ of the motor 4 detected by the rotation angle sensor 8 into currents Id, Convert to Iq. The three-phase-dq coordinate conversion unit 41 outputs the current Id to the subtractor 43 and outputs the current Iq to the subtractor 44.

The current command generation unit 42 generates current commands Id ^* and Iq ^* in the dq coordinate system for instructing a current flowing through the motor 4 based on a motor torque command input from the outside. The current command generator 42 outputs the generated current command Id ^* to the subtractor 43 and the active power command calculator 48, and outputs the generated current command Iq ^* to the subtractor 44 and the active power command calculator 48.

The subtractor 43 subtracts the current Id generated by the three-phase-dq coordinate conversion unit 41 from the current command Id ^* generated by the current command generation unit 42 and outputs a deviation ΔId to the PI control unit 45. The subtracter 44 subtracts the current Iq generated by the three-phase-dq coordinate conversion unit 41 from the current command Iq ^* generated by the current command generation unit 42 and outputs a deviation ΔIq to the PI control unit 46.

The PI control unit 45 performs a PI calculation based on the deviation ΔId output from the subtracter 43 and generates a voltage command Vd ^* . The PI control unit 45 outputs the generated voltage command Vd ^* to the dq coordinate-3 phase conversion unit 47 and the active power command calculation unit 48. The PI control unit 46 performs a PI calculation based on the deviation ΔIq output from the subtractor 44 and generates a voltage command Vq ^* . The PI control unit 46 outputs the generated voltage command Vq ^* to the dq coordinate-3 phase conversion unit 47 and the active power command calculation unit 48.

The dq coordinate / three-phase conversion unit 47 generates a voltage command Vd ^* output from the PI control unit 45 and a voltage command Vq ^* output from the PI control unit 46 based on the rotation angle θ of the motor 4 in a three-phase coordinate system. Is converted to a three-phase voltage command Vu ^* , Vv ^* , Vw ^* , which is a voltage command for the two-phase modulation conversion unit 33.

Based on the current commands Id ^* and Iq ^* generated by the current command generator 42 and the voltage commands Vd ^* and Vq ^* generated by the PI controllers 45 and 46, the active power command calculator 48 is expressed by the following formula ( According to 6), the active power command P ^* is calculated and output to the current limit value calculation unit 51.

  Next, operation | movement of the power converter device 100 which concerns on this embodiment is demonstrated.

FIG. 5 is a diagram illustrating the three-phase voltage commands Vu ^* , Vv ^* , and Vw ^* output from the three-phase voltage command calculation unit 32.

As shown in FIG. 5, the three-phase voltage command calculation unit 32 outputs the three-phase voltage commands Vu ^* , Vv ^* , Vw ^{* in} which the phases of the phases are shifted to the two-phase modulation conversion unit 33.

FIG. 6 shows two-phase modulation conversion voltage commands Vu ^** , Vv ^** , Vw ^** output from the two-phase modulation conversion unit 33, and two-phase modulation state signals Vu ^** min, Vu ^** max, Vv ^*. It is a figure which shows ^* min, Vv ^** max, Vw ^** min, Vw ^** max.

As shown in FIG. 6, the two-phase modulation conversion unit 33 performs two-phase modulation conversion on the three-phase voltage commands Vu ^* , Vv ^* , and Vw ^{* so} that any one of the U phase, the V phase, and the W phase is always the lower limit. Two-phase modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** are generated so that the value or upper limit value is reached. Further, when the two-phase modulation conversion voltage command Vu ^** is a lower limit value, the two-phase modulation conversion unit 33 sets the two-phase modulation state signal Vu ^** min to a high level and sets the two-phase modulation conversion voltage command Vu ^{*. When *} is the upper limit value, the two-phase modulation state signal Vu ^** max is set to the high level, and when the two-phase modulation conversion voltage command Vv ^** is the lower limit value, the two-phase modulation state signal Vv ^** If min is high and the two-phase modulation conversion voltage command Vv ^** is the upper limit, the two-phase modulation state signal Vv ^** max is high and the two-phase modulation conversion voltage command Vw ^** is the lower limit. When the two-phase modulation state signal Vw ^** min is high level, and the two-phase modulation conversion voltage command Vw ^** is the upper limit value, the two-phase modulation state signal Vw ^** max is high level. And

  FIG. 7 is a diagram illustrating an example of a basic gate signal output from the basic gate signal generation unit 34. In FIG. 7, the basic gate signal Gup0 corresponding to the upper switching element 16 constituting the U phase and the basic gate signal Gun0 corresponding to the lower switching element 17 constituting the U phase are shown.

When the two-phase modulation conversion voltage command Vu ^** reaches the lower limit value, the basic gate signal generation unit 34 fixes the basic gate signal Gup0 and fixes the basic gate signal Gun0 on. Further, when the two-phase modulation conversion voltage command Vu ^** reaches the upper limit value, the basic gate signal generation unit 34 fixes the basic gate signal Gup0 on and fixes the basic gate signal Gun0 off.

  FIG. 8 is a diagram illustrating an example of the boosting gate signal Gz output from the boosting gate signal generation unit 37.

  The boosting gate signal generation unit 37 determines the carrier frequency of the boosting gate signal Gz based on the carrier signal a, and sets the duty ratio of the boosting gate signal Gz based on the limited short-circuit duty Du_lim output from the multiplier 53. decide.

  FIG. 9 is a diagram illustrating an example of the boosting gate signal for each switching element output from the boosting gate signal generation unit for each switching element 38. FIG. 9 shows switching element-specific boost gate signal Gzup corresponding to switching element 16 constituting the U-phase arm and switching element-specific boost gate signal Gzun corresponding to switching element 17 constituting the U-phase arm. .

As shown in FIG. 9, the switching element-specific boosting gate signal generation unit 38 has the two-phase modulation state signal Vu ^** min shown in FIG. 6 at a high level and the boosting gate signal Gz shown in FIG. When it is at a high level, the switching element-specific boosting gate signal Gzup is at a high level, and at other times, it is at a low level. Further, the switching element boosting gate signal generation unit 38 has a case where the two-phase modulation state signal Vu ^** max shown in FIG. 6 is at a high level and the boosting gate signal Gz shown in FIG. 8 is at a high level. The switching element-specific boosting gate signal Gzun is set to the high level, and in other cases, the boosting gate signal Gzun is set to the low level.

  FIG. 10 is a diagram illustrating an example of the gate signal output from the final gate signal generation unit 39. FIG. 10 shows gate signal Gup corresponding to switching element 16 constituting the U-phase arm and gate signal Gun corresponding to switching element 17 constituting the U-phase arm.

  As shown in FIG. 10, the final gate signal generation unit 39 is in the case where the basic gate signal Gup0 shown in FIG. 7 is at a high level and when the switching element-specific boost gate signal Gzup shown in FIG. 9 is at a high level. The gate signal Gup is set to the high level. Further, the final gate signal generation unit 39 generates the gate signal Gun when the basic gate signal Gun0 shown in FIG. 7 is at a high level and when the switching element-specific boost gate signal Gzun shown in FIG. 9 is at a high level. High level.

In the present embodiment, two-phase modulation conversion is performed on the three-phase voltage commands Vu ^* , Vv ^* , and Vw ^{* so} that any one of the U-phase, V-phase, and W-phase always becomes the lower limit value or the upper limit value. Modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** are generated. Then, the switching gate operation for boosting the output of the Z source booster circuit 2 is performed by short-circuiting the switching element corresponding to the phase that is the lower limit value or the upper limit value. Therefore, the boosting gate operation can always be performed using the switching element corresponding to any phase, so that the boosting rate can be increased. In addition, since one of the switching elements constituting the inverter circuit 3 is continuously turned on or off, switching loss can be reduced.

  Further, in the present embodiment, the short-circuit duty limit coefficient Lim_Du shown in FIG. 3 is generated, and the boost gate signal Gz is generated using the limited short-circuit duty Du_lim that limits the short-circuit duty Du based on the short-circuit duty limit coefficient Lim_Du. . Therefore, when the current IL flowing through the reactor 13 is smaller than the reactor minimum current value IL_lim_min, the short-circuit duty limit coefficient Lim_Du becomes 1, and the short-circuit duty Du is used as it is as the limited short-circuit duty Du_lim to generate the boost gate signal Gz. Is done. When the current IL becomes equal to or greater than the reactor minimum current value IL_lim_min, the short circuit duty limit coefficient Lim_Du decreases as the current IL increases, and the limited short circuit duty Du_lim also decreases. When current IL becomes equal to or greater than reactor maximum current value IL_lim_max, short-circuit duty limit coefficient Lim_Du becomes zero, and limit short-circuit duty Du_lim also becomes zero. In this case, the switching elements 16 to 21 of the inverter circuit 3 are controlled based on the gate signals Gup, Gun, Gvp, Gvn, Gwp, and Gwn generated according to the basic gate signals Gup0, Gun0, Gvp0, Gvn0, Gwp0, and Gwn0. Is done.

  Therefore, the power converter device 100 according to the present embodiment can operate in a continuous mode (CCM: Continuous Current Mode) in which a current of a certain level or more always flows through the reactor 13. By operating the power conversion device 100 in the continuous mode, the voltage (capacitor voltage) of the capacitor 14 of the Z source booster circuit 2 can be stabilized, and the output of the inverter circuit 3 can be prevented from becoming unstable.

As described above, according to the present embodiment, the power conversion apparatus 100 boosts the output DC voltage of the DC power source 1 and outputs it, and the output DC voltage of the Z source booster circuit 2 is converted into a three-phase AC voltage. And a three-phase voltage command calculation unit 32 that calculates the three-phase voltage commands Vu ^* , Vv ^* , and Vw ^* and calculates the active power command P ^*. And two-phase modulation conversion of the three-phase voltage commands Vu ^* , Vv ^* , Vw ^* based on the rotation angle θ of the motor 4 to generate two-phase modulation conversion voltage commands Vu ^** , Vv ^** , Vw ^** And two-phase modulation state signals Vu ^** min, Vu ^** max, Vv ^** min, Vv ^** max, Vw indicating the states of the two-phase modulation conversion voltage commands Vu ^** , Vv ^** , Vw ^{**. **} min, Vw ^** Based on the two-phase modulation conversion unit 33 that generates max, the two-phase modulation conversion voltage commands Vu ^** , Vv ^** , Vw ^**, and a predetermined carrier signal, the basic gate signals Gup0, Gun0, Gvp0, Gvn0, Gwp0, A basic gate signal generator 34 for generating Gwn0, a short-circuit duty calculator 36 for calculating a short-circuit duty Du based on the voltage Vc of the capacitor 14 of the Z-source booster circuit 2 and the DC voltage command Vc ^* , and an active power command Based on P ^* , power supply voltage Ve of DC power supply 1, and maximum load power of motor 4, reactor minimum current value IL_lim_min, which is the minimum value of current flowing through reactor 13 of Z source booster circuit 2, and current flowing through reactor 13 Current limit value calculation unit 51 for calculating reactor maximum current value IL_lim_max which is the maximum value of Based on the minimum reactor current value IL_lim_min, the maximum reactor current value IL_lim_max, and the current IL flowing through the reactor 13, the short-circuit duty limit coefficient calculation unit 52 that calculates the short-circuit duty limit coefficient Lim_Du, and the short-circuit duty Du in the short-circuit duty limit coefficient Lim_Du Based on the limited short-circuit duty Du_lim and the carrier signal, the boosting gate signal generation unit 37 that generates the boosting gate signal Gz, and the two-phase modulation state signals Vu ^** min, Vu ^** max, Vv ^** min , Vv ^** max, Vw ^** min, Vw ^** max, and switching for generating boosting gate signals Gzup, Gzun, Gzvp, Gzvn, Gzwp, Gzwn for each switching element based on the boosting gate signal Gz The basic gate signal so that the boost gate operation is performed in the phase where the element-specific boost gate signal generation unit 38 and the two-phase modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** become the lower limit value or the upper limit value. Based on Gup0, Gun0, Gvp0, Gvn0, Gwp0, Gwn0, and boosting gate signals Gzup, Gzun, Gzvp, Gzvn, Gzwp, Gzwn for each switching element, a final gate signal generation unit that generates a gate signal for each switching element 39.

Corresponds to the phase for which the two-phase modulation conversion voltage commands Vu ^** , Vv ^** , and Vw ^** obtained by performing two-phase modulation conversion on the three-phase voltage commands Vu ^* , Vv ^* , and Vw ^* are the lower limit value or the upper limit value. By performing the boosting gate operation by short-circuiting the switching element, the boosting gate operation can always be performed using the switching element corresponding to one of the phases. Therefore, it is possible to increase the boosting rate. In addition, since one of the switching elements constituting the inverter circuit 3 is continuously turned on or off, switching loss can be reduced.

  Further, the short-circuit duty limit coefficient Lim_Du is determined based on the minimum reactor current value IL_lim_min, the maximum reactor current value IL_lim_max, and the current IL flowing through the reactor 13, and the short-circuit duty limit coefficient Lim_Du is used to limit the short-circuit duty Du. The converter 100 can operate in a continuous mode in which a constant current or more always flows through the reactor 13. By operating the power conversion device 100 in the continuous mode, the voltage (capacitor voltage) of the capacitor 14 of the Z source booster circuit 2 can be stabilized, and the output of the inverter circuit 3 can be prevented from becoming unstable.

  In the present embodiment, the example in which the basic gate signal generation unit 34 and the boosting gate signal generation unit 37 use the same carrier signal a has been described. However, the present invention is not limited to this, and the basic gate signal generation unit 34 is not limited thereto. The boosting gate signal generator 37 may use different carrier signals (for example, carrier signals having different frequencies). By doing so, switching loss can be further reduced.

  The switching element-specific boosting gate signal generation unit 38 includes boosting gates for one or more switching elements among a plurality (two) of switching elements constituting each of the U-phase, V-phase, and W-phase. A signal may be generated. For example, the switching element boosting gate signal generation unit 38 generates the boosting gate signal Gzup for the switching element 16 out of the switching elements 16 and 17 constituting the U phase, and the switching element 18 constituting the V phase. The 19-minute boost gate signals Gzvp and Gzvn may be generated, and the boost gate signal Gzwn for the switching element 21 among the switching elements 20 and 21 constituting the W phase may be generated. By doing so, switching loss can be further reduced.

  Although the present invention has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various variations or modifications based on the present disclosure. Therefore, it should be noted that these variations or modifications are included in the scope of the present invention. For example, functions included in each block or the like can be rearranged so that there is no logical contradiction, and a plurality of blocks can be combined into one or divided.

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Z source booster circuit 3 Inverter circuit 4 Motor 5, 10 Voltage sensor 6, 7, 9 Current sensor 8 Rotation angle sensor 11 Diode 12, 13 Reactor 14, 15 Capacitor 16-21 Switching element 22-27 Freewheel diode 31 Control Unit 32 Three-Phase Voltage Command Calculation Unit 33 Two-Phase Modulation Conversion Unit 34 Basic Gate Signal Generation Unit 35 Subtractor 36 Short-Cut Duty Calculation Unit 37 Boosting Gate Signal Generation Unit 38 Switching Element-Specific Boosting Gate Signal Generation Unit 39 Final Gate Signal generator 51 Current limit value calculator 52 Short-circuit duty limit coefficient calculator 53 Multiplier 41 3-phase-dq coordinate converter 42 Current command generator 43, 44 Subtractor 45, 46 PI controller 47 dq coordinate-3 phase conversion 48 Active power command calculator

Claims (3)

A first reactor having one end connected to the positive electrode side of the DC power source, a second reactor having one end connected to the negative electrode side of the DC power source, one end connected to one end of the first reactor, and the other end Is connected to the other end of the second reactor, one end is connected to the other end of the second reactor, and the other end is connected to one end of the first reactor. A Z-source booster circuit having a capacitor;
A plurality of switching elements, connected to the other end of the first reactor and the other end of the second reactor, which are outputs of the Z source booster circuit, and the Z source booster is switched by switching the plurality of switching elements; An inverter circuit that converts the output DC voltage of the circuit into a three-phase AC voltage and outputs it to an AC motor;
A three-phase voltage command calculation unit for calculating a three-phase voltage command for instructing an output voltage of the inverter circuit, and for calculating an active power command;
Based on the rotation angle of the AC motor, the three-phase voltage command calculated by the three-phase voltage command calculation unit is subjected to two-phase modulation conversion to generate a two-phase modulation conversion voltage command, and the two-phase modulation conversion voltage command A two-phase modulation conversion unit for generating a two-phase modulation state signal indicating the state of
A basic gate signal generation unit that generates a basic gate signal based on the two-phase modulation conversion voltage command generated by the two-phase modulation conversion unit and a predetermined carrier signal;
A short-circuit duty calculating unit that calculates a short-circuit duty, which is a time for short-circuiting the output of the Z-source booster circuit, based on the voltage of the first capacitor and the command value of the voltage of the first capacitor;
Reactor minimum which is the minimum value of the current flowing through the second reactor based on the active power command calculated by the three-phase voltage command calculation unit, the power supply voltage of the DC power supply, and the maximum load power of the AC motor A current limit value calculating unit that calculates a current value and a reactor maximum current value that is a maximum value of a current flowing through the second reactor;
A short-circuit duty limit coefficient calculator that calculates a short-circuit duty limit coefficient based on the reactor minimum current value and the reactor maximum current value calculated by the current limit value calculator and the current flowing through the second reactor;
A boosting gate that generates a boosting gate signal based on a limited short-circuit duty obtained by limiting the short-circuit duty calculated by the short-circuit duty calculating unit with a limiting coefficient calculated by the short-circuit duty limiting coefficient calculating unit and a carrier signal A signal generator;
A switching element that generates a boosting gate signal for each switching element based on the two-phase modulation state signal generated by the two-phase modulation conversion unit and the boosting gate signal generated by the boosting gate signal generation unit A separate boosting gate signal generator,
The basic gate signal generated by the basic gate signal generation unit, and the switching element-specific boost gate signal so that the boost gate operation is performed in a phase in which the two-phase modulation conversion voltage command is a lower limit value or an upper limit value. And a final gate signal generation unit that generates a gate signal for each of the switching elements based on the boosting gate signal for each of the switching elements generated by the generation unit. The power conversion device according to claim 1,
The power conversion apparatus according to claim 1, wherein a carrier signal used by the basic gate signal generation unit is different from a carrier signal used by the boosting gate signal generation unit. In the power converter device according to claim 1 or 2,
The switching element boosting gate signal generator generates a boosting gate signal for one or more switching elements among a plurality of switching elements constituting the same phase.

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