JP5109354B2 - Motor inverter device and control method thereof - Google Patents

Description

  The present invention relates to an inverter device for controlling a three-phase AC motor and a control method thereof.

  As a control method for driving a three-phase AC motor, there is PWM (Pulse Width Modulation) control for controlling the on-time of six switching elements. Further, a two-phase modulation method is generally used in which only two of the three phases are controlled to be turned on and off, and the remaining one phase is fixed only on the upper phase or only on the lower phase. In PWM control, the ON periods of the respective phases may overlap, and there is a problem that the ripple current flowing through the smoothing capacitor becomes large at that time.

  In order to improve the above problems, we previously proposed an inverter device in which the ripple current is reduced by shifting the phase of the two-phase reference triangular wave to be turned on and off by 180 degrees in the two-phase modulation method. (See Patent Document 2).

In Patent Document 1, in an inverter apparatus having a motor inverter and a generator inverter, the first pulse width modulation signal for driving the motor and the second pulse width modulation signal for driving the generator are turned on / off. It describes that the timing of off is different.
JP 2000-78850 A JP 2005-51838 A

  By the way, when driving a plurality of three-phase AC motors by converting the output voltage of the DC power supply with a DC / AC converter using an inverter, the ripple current flowing through the smoothing capacitor further increases than when driving a single three-phase AC motor. .

  Further, if the rotation speeds of the plurality of three-phase AC motors driven by the inverter are different, the electric angles of the respective motors are also different. Therefore, it is conceivable that the ripple current increases in the same control method as that for one motor.

  The subject of this invention is providing the inverter apparatus which can reduce the ripple current of the smoothing capacitor connected to DC power supply.

  In the motor inverter device of the present invention, the output voltage of one DC power source is smoothed by a smoothing capacitor and converted into a plurality of three-phase AC voltages, and each of the three-phase AC voltages drives a motor, Control means for generating a drive signal for two-phase modulation control of the motor, and a switching element group for supplying a three-phase AC voltage that is on / off-controlled by the drive signal for each of the motors. Two phases to be modulated are generated based on carrier signals having different phases.

  According to the present invention, the peak value of the output current of the motor inverter device can be suppressed and the ripple current flowing through the smoothing capacitor can be reduced by performing two-phase modulation control on a plurality of motors based on carrier signals having different phases. .

  In the motor inverter device of the above invention, the control means is a carrier signal generating means for generating carrier signals having different phases, and the driving for performing two-phase modulation control based on a command value of each motor and the carrier signal. Drive signal generating means for generating a signal.

  With this configuration, the peak value of the output current of the motor inverter device is suppressed by performing two-phase modulation control based on carrier signals having different phases generated by the carrier signal generating means, and the ripple current flowing in the smoothing capacitor is reduced. Can be reduced.

  In the motor inverter device of the above invention, the carrier signals corresponding to the two phases to be modulated among the drive signals for each motor are 180 ° out of phase with each other and the phases of all carrier signals are equally different.

  In this way, the carrier signal phase is changed by 180 °, and the phase of all the carrier signals is changed equally, so that the switching timing of the switching element group is changed equally, and the peak value of the output current of the motor inverter device is suppressed. Can do.

In the motor inverter device of the above invention, there are two motors.
In the motor inverter device according to the above invention, the drive signal generation means generates a second drive signal for performing two-phase modulation control of each motor instead of the drive signal in accordance with the relationship of the command values between the motors. The two phases to be generated and modulated for each of the motors are generated based on two carrier signals having different phases, and the phases of the two carrier signals are equal between the motors.

  In this case, for example, in the case of two motors, the two phases to be modulated among the second drive signals of one motor are different in phase, and the two phases to be modulated among the second drive signals of the other motor are Although the phases are different from each other, one of the two phases modulated by one motor and one of the two phases modulated by the other motor are equal in phase, and the other of the two phases modulated by one motor and the other The other of the two phases modulated by the motor has the same phase.

  With this configuration, the second drive signal is generated instead of the drive signal according to the relationship between the command values of the motors, and the switching element group is controlled by the second drive signal. The peak value of the output current of the inverter device can be suppressed.

In the motor inverter device of the above invention, the two carrier signals are 180 ° out of phase with each other.
Thus, by using the carrier signal having a 180 ° phase difference, the switching timing of the switching element group can be shifted, and the peak value of the output current of the motor inverter device can be suppressed.

  In the motor inverter device according to the invention described above, the number of the motors is two, and the drive signal generation unit is configured such that a command value of one phase of one motor is a constant positive value and a command of one phase of the other motor. When the value is a negative constant value, the second drive signal is generated.

  With this configuration, when the command value of one motor is a positive constant value and the command value of the other motor is a negative constant value, the motor is controlled by controlling the switching element group with the second drive signal. The peak value of the output current of the inverter device can be suppressed.

  The motor inverter device control method of the present invention smoothes the output voltage of one DC power source with a smoothing capacitor and converts it into a plurality of three-phase AC voltages, and each of the three-phase AC voltages drives a motor. In this control method, a drive signal for two-phase modulation control of each motor is generated, the drive signal is supplied to a control terminal of a switching element group of a motor inverter device, and two phases of the drive signal to be modulated are in phase. Generated based on different carrier signals.

According to the control method of the present invention, the peak value of the output current of the motor inverter device can be suppressed, and the ripple current flowing through the smoothing capacitor can be reduced.
In the control method of the motor inverter device of the above invention, a second drive signal for performing two-phase modulation control of each motor is generated instead of the drive signal in accordance with a relationship of command values between the motors, For each motor, two phases to be modulated among the second drive signals are generated based on two carrier signals having different phases, and the phases of the two carrier signals are the same between the motors.

  With this configuration, the second drive signal is generated instead of the drive signal according to the relationship between the command values of the motors, and the switching element group is controlled by the second drive signal. The peak value of the output current of the inverter device can be suppressed.

  According to the present invention, the ripple current flowing through the smoothing capacitor can be reduced.

  Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an inverter device according to an embodiment. In the following description, “ON” and “OFF” indicate a switch of an upper arm (or a lower arm) in particular for each phase switching element of the inverter bridge. The switching element of the lower arm (or upper arm) is complementary to the switching element of the upper arm (or lower arm), such as OFF when the upper arm (or lower arm) is “ON” and ON when it is “OFF”. Behave as if

  This inverter device 11 supplies drive signals to two inverter bridges 14a and 14b (corresponding to a switching element group) for supplying a drive voltage to two three-phase AC motors 12 and 13, and inverter bridges 14a and 14b. And a control circuit 15 (corresponding to the control means). A voltage obtained by smoothing the output voltage of the DC power supply E with the smoothing capacitor C1 is input to the inverter device 11. As shown by a dotted line in FIG. 1, three or more three-phase AC motors may be used and three or more inverter bridges may be provided.

  The inverter bridge 14a includes MOS transistors TR1 and TR2, TR3 and TR4, TR5 and TR6 connected in series between the positive potential side and the negative potential side of the DC power supply E. MOS transistors TR1 and TR2, TR3 and TR4, and TR5 and TR6 are connected in parallel to each other.

  The connection point between the MOS transistors TR1 and TR2 is connected to the U phase of the three-phase AC motor 12, the connection point between the MOS transistors TR3 and TR4 is connected to the V phase, and the connection point between the MOS transistors TR5 and TR6 is connected to the W phase. ing.

  Similarly, the inverter bridge 14b includes MOS transistors TR1 ′ and TR2 ′, TR3 ′ and TR4 ′, TR5 ′ and TR6 ′ connected in series between the positive potential side and the negative potential side of the DC power supply E. Become.

  The connection point between the MOS transistors TR1 ′ and TR2 ′ is connected to the U phase of the three-phase AC motor 13, the connection point between the MOS transistors TR3 ′ and TR4 ′ is connected to the V phase, and the connection point between the MOS transistors TR5 ′ and TR6 ′. Are connected to the W phase.

  A drive signal is supplied from the control circuit 15 to the gates of the MOS transistors TR1 to TR6 and TR1 'to TR6' of the inverter bridges 14a and 14b. A DC voltage is converted into two three-phase AC voltages by turning on and off the MOS transistors of the inverter bridges 14a and 14b by this drive signal.

  The control circuit 15 includes a triangular wave generator (corresponding to carrier signal generating means) 16 that generates four types of triangular waves (carrier signals), which will be described later, and MOS transistors TR1 to TR6, TR1 based on the triangular wave and the command value of each phase. And a PWM control unit (corresponding to drive signal generating means) 17 for generating a pulse width control signal (drive signal) for determining an ON period of “˜TR6”.

  In this embodiment, a two-phase modulation method is employed in which one of the three phases is fixed on or off for a certain period and the on-time of the remaining two-phase MOS transistors is variably controlled. From the PWM control unit 17, a signal for fixing the switching element of one phase of the inverter bridges 14a and 14b to ON or OFF for a certain period and a pulse width control for controlling the ON width of the switching elements of the other two phases. A signal is output.

FIG. 2 is a diagram showing the relationship between the command value for controlling the three-phase AC motors 12 and 13 and the electrical angle of the motor.
The vertical axis in FIG. 2 indicates the magnitude (voltage value) of the command value, the horizontal axis indicates the electrical angle, and the electrical angle of the three-phase AC motor 12 is shown based on 0 to 360 degrees. In FIG. 2, thick lines indicate U, V, and W phase command values of the three-phase AC motor 12, thick solid lines indicate U phase command values, dotted lines indicate V phase command values, and alternate long and short dash lines indicate W phase commands. Indicates the value. The thin line indicates the U, V, and W phase command values of another three-phase AC motor 13. The thin solid line indicates the U phase command value, the thin dotted line indicates the V phase command value, and the thin one-dot chain line indicates the W line. Indicates the command value of the phase. Furthermore, while the command value of the three-phase AC motor 12 indicated by a solid line changes by 360 degrees in electrical angle, the command value of the three-phase AC motor 13 indicated by a thin line shows a state in which it changes by 180 degrees, which is a half electrical angle. ing. That is, in this state, while the rotor of the three-phase AC motor 12 rotates once, the rotor of the three-phase AC motor 13 rotates 1/2.

Next, FIG. 3 is a diagram showing four types of triangular waves generated by the triangular wave generator 16. The vertical axis in FIG. 3 indicates the voltage value, and the horizontal axis indicates time.
In FIG. 3, a triangular wave a indicated by a thick line and a triangular wave b indicated by a thick dotted line are signals having the same frequency and a constant phase difference (for example, 90 degrees). A triangular wave c indicated by a thin solid line is an inverted signal of the triangular wave a, and a triangular wave d indicated by a dotted dotted line is an inverted signal of the triangular wave b. The frequencies of the triangular waves a to d are set to a frequency that is sufficiently higher than the frequencies of the U, V, and W phase command values shown in FIG.

  The PWM control unit 17 compares the command value of each phase shown in FIG. 2 with the amplitude value of a specific triangular wave among the four types of triangular waves a to d shown in FIG. 3, and when the value of the triangular wave is equal to or greater than the command value, for example, A drive signal for turning on the MOS transistor is output, and when the value of the triangular wave is less than the command value, a drive signal for turning off the MOS transistor is output.

  Therefore, in the section of the electrical angle where the magnitude of the command value shown in FIG. 2 changes, a pulse width modulation signal is generated in which the period during which the triangular wave is equal to or greater than the command value is on. It should be noted that in the section of the electrical angle where the command value is a positive constant value (for example, “1”), the triangular wave is set to be less than the command value, and a drive signal for turning off the switching element is generated in that section. Is done.

  Next, the operation of the inverter device 11 according to the first embodiment of the present invention will be described with reference to the flowchart of FIG. The first embodiment is an example in which the rotation of two three-phase AC motors 12 and 13 is controlled using four types (or two types) of triangular waves a to d. In the following description of the flowchart, the three-phase AC motor 12 is referred to as the first motor 12, and the three-phase AC motor 13 is referred to as the second motor 13.

  The position of the rotor of the first motor 12 is detected by a position detector (not shown) (S11 in FIG. 4). Next, an electrical angle and a rotational speed are calculated from the position of the rotor detected by the position detector (S12).

  Next, from the command value of the first motor 12, the phase in which the command value is fixed to “1” or “−1” at the calculated electrical angle and the other phases are determined. The command values of the two phases (two phases to be modulated) whose command values are not fixed values are compared with the amplitude values of the triangular wave a shown in FIG. A period longer than the command value is calculated, and a pulse width control signal (PWM value) that is ON during that period is obtained. Further, a pulse width control signal (PWM value) for fixing on or off for a phase in which the command value is fixed to “1” or “−1” is obtained. (S13). By this process, a drive signal for controlling the switching element of the inverter bridge 14a is determined.

Next, the drive signal (three-phase PWM signal) generated by the above processing is output to the control terminals (gates of TR1 to TR6) of the switching element of the inverter bridge 14a (S14).
The same process is executed for the second motor 13. The position of the rotor of the second motor 13 is detected by a position detector (not shown) (S15). The electrical angle and rotational speed at the detected position are calculated (S16).

  Next, from the command values of the three phases of the second motor 13, the phase in which the command value is fixed at “1” or “−1” at the calculated electrical angle and the other phases are determined. A command value of two phases (two phases to be modulated) whose command value is not a fixed value is compared with an amplitude value of a triangular wave b having a phase difference of 90 degrees with respect to the triangular wave a and a triangular wave d which is an inverted signal thereof. A period in which the amplitude values of b and d are equal to or greater than the command value is calculated, and a pulse width control signal (PWM value) that is ON during that period is generated. Further, a pulse width control signal (PWM value) for fixing on or off for a phase in which the command value is fixed to “1” or “−1” is obtained. (S17). By this process, a drive signal for controlling the switching element of the inverter bridge 14b is determined.

Next, the three-phase drive signal generated by the above processing is output to the control terminal of the switching element of the inverter bridge 14a (S18).
As a result, drive signals are generated based on the triangular waves a, b, c, and d which are carrier signals having different phases for the two phases modulated by the inverter bridge 14a and the two phases modulated by the inverter bridge 14b.

  Further, for each of the first motor 12 and the second motor 13, the triangular waves a and c and the triangular waves b and d, which are carrier signals corresponding to the two phases to be modulated among the driving signals, are 180 degrees out of phase with each other, and all The phases of the triangular waves a, b, c, d, which are carrier signals, are equally different by 90 °.

The phase difference between the triangular wave a and the triangular wave b is not limited to 90 degrees, and a triangular wave having a phase difference in the range of 0 to 180 degrees can be used.
Here, when driving current is supplied from the inverter device 11 to the two three-phase AC motors 12 and 13, (1) when the switching timing of the inverter bridges 14a and 14b is controlled using one type of triangular wave, 2) The switching timing of the inverter bridge 14a is controlled using two types of triangular waves (for example, triangular wave a and triangular wave c) having a phase difference of 180 degrees, and similarly, two types of triangular waves having a phase difference of 180 degrees ( For example, when the switching timing of the inverter bridge 14b is controlled using the triangular wave a and the triangular wave c), (3) two types of triangular waves (for example, the triangular wave a and the four of the four types of triangular waves having a phase difference of 90 degrees or 180 degrees). The switching timing of the inverter bridge 14a is controlled using the triangular wave c), and four types of triangular waves are used. Another two of the triangular wave (e.g. triangular wave b and the triangular wave d) when controlling the switching timing of the inverter bridge 14b using the, illustrating a simulation result of ripple ratio of the current flowing through the smoothing capacitor C1. The ripple rate is the ratio of the peak value to the average current flowing through the smoothing capacitor C1.

The ripple rate in the case of (1) was about “0.775”.
The ripple rate in the case of (2) was about “0.481”.
The ripple rate in the case of (3) was about “0.401”.

  From the above results, when two three-phase AC motors 12 and 13 are driven by the inverter bridges 14a and 14b, an inverter bridge using two types of triangular waves having a phase difference or four types of triangular waves having a phase difference. It has been confirmed that the ripple rate of the current flowing through the smoothing capacitor C1 can be improved by shifting the switching timing of 14a and the inverter bridge 14b.

  According to the first embodiment described above, the switching timings of the two phases of the inverter bridge 14a are shifted using four types of triangular waves having phase differences, and the switching timings of the two phases of the inverter bridge 14b are shifted simultaneously. Thus, the ripple current of the smoothing capacitor C1 can be reduced. In particular, the triangular wave a shown in FIG. 3 and the triangular wave c of the inverted signal of the triangular wave a are used to control the switching timing of the inverter bridge 14a, the triangular wave b having a phase difference of 90 degrees from the triangular wave a and the triangular wave d of the inverted signal thereof. Is used to control the switching timing of the inverter bridge 14b, the switching timing of the inverter device 11 can be evenly shifted at intervals of 90 degrees.

Next, FIG. 5 is a flowchart showing the operation of the inverter device 11 according to the second embodiment.
In the second embodiment, when two-phase modulation control is performed, one phase of one three-phase AC motor is turned on for a certain period, and at the same time, one phase of the other three-phase AC motor is turned off for a certain period. In such a case, the pulse width control is performed by switching the triangular wave from four types to two types. Thus, when the ripple rate of the smoothing capacitor C1 when the control for switching the triangular wave for generating the pulse width control signal from four types to two types is performed by simulation, the ripple rate of the current flowing through the smoothing capacitor C1 is calculated. It was confirmed that it could be improved.

  First, when the command value of one phase of one three-phase AC motor is fixed to a positive specific value and the command value of one phase of the other three-phase AC motor is fixed to a negative specific value, This will be described with reference to FIG.

  The command value of the W phase of the three-phase AC motor 12 is fixed to a negative value “−1” in the section where the electrical angle is 120 degrees to 160 degrees as shown by a thick dashed line in FIG. At this time, the command value of the U phase of the other three-phase AC motor 13 is fixed to a positive value “1” as shown by a thin solid line in FIG.

Therefore, in this section, the command value of the three-phase AC motor 12 is fixed to a negative value “−1”, and the command value of another three-phase AC motor 13 is fixed to a positive value “1”.
Hereinafter, in the description of the flowchart of FIG. 5, the same processes as those in the flowchart of FIG.

In step S21 of FIG. 5, the output values of the three phases are determined with reference to the command values of the respective phases of the first motor 12.
In step S22, the output values of the three phases are determined with reference to the command values of the respective phases of the second motor 13.

  Next, in step S23, it is determined whether or not the output values for any phase of the two three-phase AC motors 12 and 13 are simultaneously fixed to a positive value or a negative value. That is, the determination is made according to the command value between the first motor 12 and the second motor 13. When the output value of one three-phase AC motor is fixed to a specific value that is positive for a certain period and at the same time the output value of the other three-phase AC motor is fixed to a specific value that is negative, 2 types of reference triangular wave are selected. That is, as in (2), which is a comparative example of the first embodiment, the three-phase AC motors 12 and 13 are selected to be controlled by the same two types of triangular waves. In other cases, as in (3) of the first embodiment, two of the four types of triangular waves are selected to be used for controlling the three-phase AC motor 12, and the remaining two types are three. It selects so that it may be used for control of the phase alternating current motor 13. FIG.

  Next, in step S24 and step S25, the pulse width control signals (PWM values) of the two inverter bridges 14a and 14b are calculated using the selected reference triangular wave. Here, what is calculated when the three-phase AC motors 12 and 13 are controlled by the same two types of triangular waves corresponds to the second drive signal.

Here, the simulation result of the ripple rate of the smoothing capacitor C1 when the inverter device 11 is controlled by the control method of the second embodiment will be described.
As a result of the simulation, the ripple rate of the smoothing capacitor C1 when the switching timing was controlled using four types of triangular waves (first embodiment) was about “0.401”.

  On the other hand, in the section where the command value of one phase of one three-phase AC motor is “1” and one command value of the other three-phase AC motor is “−1”, the triangular wave a in FIG. Is used to control the switching timing of the inverter bridge 14a, and when the switching timing of the inverter bridge 14b is controlled using the triangular wave c having a phase difference of 180 degrees from the triangular wave a, the ripple rate of the smoothing capacitor C1 is about “0. 367 ".

  From the above results, it can be confirmed that the ripple rate of the smoothing capacitor C1 can be improved by controlling the switching timing of the inverter bridge 14a and the inverter bridge 14b by switching between four types of triangular waves and two types of triangular waves having different phases. It was.

  In the second embodiment described above, the command value (or three-phase output value) of each motor is obtained from the electrical angle of the two three-phase AC motors 12 and 13, and the command value of the two three-phase AC motors. On the basis of (or output value), switching is performed between four types of triangular waves having a phase difference or two types of triangular waves having a phase difference for control. Thereby, the peak value of the output current of the inverter device 11 can be reduced, and the ripple rate of the current flowing through the smoothing capacitor C1 can be reduced.

  In the second embodiment, the output value of one phase of one three-phase AC motor is fixed to a specific value that is positive, and the output value of one phase of the other three-phase AC motor is negative. During a period fixed to a specific value, the switching timing of the inverter bridge 14a and the inverter bridge 14b is controlled using two types of triangular waves a and c having a phase difference of 180 degrees. Thereby, the switching timing of the inverter bridge 14a and the switching timing of the inverter bridge 14b can be shifted, and the peak value of the output current of the inverter device 11 can be suppressed. By suppressing the peak value of the output current of the inverter device 11, the ripple rate of the current flowing through the smoothing capacitor C1 can be improved.

  Next, FIG. 6 shows a case where the inverter device 11 is controlled by the conventional control method and the control methods of the first and second embodiments when the electrical angles of the two three-phase AC motors are changed. It is a figure which shows the simulation result of a ripple rate.

  The vertical axis in FIG. 6 represents the ripple rate, and the horizontal axis represents the difference in electrical angle between the two three-phase AC motors. The graph connecting white diamond points (one type of triangular wave) shows the ripple rate when the switching timing of the inverter bridges 14a and 14b is controlled using one type of triangular wave ((1) of the first embodiment). Is shown.

  The graphs connecting the black square points (two types of triangular waves) are obtained when the switching timings of the inverter bridge 14a and the inverter bridge 14b are shifted using two types of triangular waves having a phase difference of 180 degrees (first phase). The simulation result of the ripple rate of Embodiment (2) is shown.

  Further, a graph connecting black triangular points (four types of triangular waves) uses two types of triangular waves having a phase difference of 180 degrees to shift the switching timing of the two phases of the inverter bridge 14a and When the switching timings of the two phases of the inverter bridge 14b are shifted using two types of triangular waves having a phase difference and a phase difference of 180 degrees from each other (the first embodiment (3)), the ripple rate The simulation result is shown.

  Further, a graph (points of 4 + 2 triangle waves) connecting the points marked with x is a case where the switching timings of the inverter bridges 14a and 14b are shifted by switching between the four kinds of triangle waves and the two kinds of triangle waves (second embodiment). ) Ripple rate simulation results.

  When the switching timing of the inverter bridge 14a and the inverter bridge 14b is shifted using four types of triangular waves (see FIG. 3) having phase differences of 90 degrees and 180 degrees as shown by black triangular points in FIG. The ripple rate is less than "0.4" when the difference in electrical angle between the two three-phase AC motors is in the range of 0 degrees to 360 degrees, and the average value of the ripple ratio is improved compared to the case of using two types of triangular waves Has been.

  Furthermore, as shown by the point of x in FIG. 6, the ripple rate when the switching timing of the inverter bridge 14a and the inverter bridge 14b is shifted by switching between the four types of triangular waves and the two types of triangular waves is about “0.35”. The average value of the ripple rate is improved as compared with the case where four types of triangular waves are used when the difference in electrical angle between the two three-phase AC motors is in the range of 0 degree to 360 degrees.

  As described above, the ripple of the current flowing in the smoothing capacitor C1 by shifting the switching timing of the inverter bridge 14a and the switching timing of the inverter bridge 14b by the control method of the first embodiment or the control method of the second embodiment. The rate can be improved.

The present invention is not limited to the embodiment described above, and may be configured as follows, for example.
In the embodiment, the case where two three-phase AC motors are controlled has been described.
The functions of the triangular wave generator 16 and the PWM control unit 17 of the control unit 15 of the embodiment may be realized by a CPU.
The carrier signal for generating the drive signal is not limited to the triangular wave, and other signals such as a sawtooth wave may be used.
In the embodiment, the case where the control unit 15 calculates two types or four types of triangular waves has been described. The controller (CPU) 15 may calculate the drive signal based on the pulse width data stored in the memory.
The switching element of the inverter device is not limited to a MOS transistor but may be a bipolar transistor, IGBT, or the like.

It is a circuit diagram of the inverter apparatus of an embodiment. It is a figure which shows the command value of two three-phase alternating current motors. It is a wave form diagram of a triangular wave. It is a flowchart which shows operation | movement of the inverter apparatus of 1st Embodiment. It is a flowchart which shows operation | movement of the inverter apparatus of 2nd Embodiment. It is a figure which shows the relationship between the phase difference of a three-phase alternating current motor, and a ripple rate.

Explanation of symbols

E DC power supply C1 Smoothing capacitors TR1 to TR6 MOS transistors TR1 ′ to TR6 ′ MOS transistors 11 Inverter devices 12 and 13 Three-phase AC motors 14a and 14b Inverter bridge 15 Control unit 16 Triangular wave generator 17 PWM control unit

Claims (4)

In the motor inverter device in which the output voltage of one DC power supply is smoothed by a smoothing capacitor and converted into a plurality of three-phase AC voltages, and each of the three-phase AC voltages drives two motors.
Carrier signal generating means for generating carrier signals having different phases, and a drive signal for performing two-phase modulation control of the two motors based on the command values of the two motors and the carrier signals, and 1 of one motor When the command value of one phase is a positive constant value and the command value of one phase of the other motor is a negative constant value, a second drive signal for two-phase modulation control of the two motors is the drive signal. Control means having drive signal generation means for generating instead of;
For each motor, a switching element group that is on / off controlled by the drive signal or the second drive signal and supplies a three-phase AC voltage;
Have
Two phases to be modulated among the drive signals are generated based on carrier signals having different phases ,
Of the second drive signal, two phases to be modulated for each of the two motors are generated based on two carrier signals having different phases, and the phase of the two carrier signals is between the two motors. equal,
The motor inverter apparatus characterized by the above-mentioned. 2. The motor inverter device according to claim 1, wherein the carrier signals corresponding to two phases to be modulated among the drive signals for each motor are different in phase from each other by 180 °, and the phases of all carrier signals are equally different. 3. The motor inverter device according to claim 1, wherein two carrier signals corresponding to two phases to be modulated among the second drive signals have a phase difference of 180 ° from each other. In the control method of the motor inverter device in which the output voltage of one DC power supply is smoothed by a smoothing capacitor and converted into a plurality of three-phase AC voltages, and each of the three-phase AC voltages drives two motors.
Generate carrier signals with different phases,
Generating a drive signal for two-phase modulation control of the two motors based on the command values of the two motors and the carrier signal ;
Second drive for two-phase modulation control of the two motors when the command value of one phase of one motor is a positive constant value and the command value of one phase of the other motor is a negative constant value Generating a signal instead of the drive signal,
Two phases to be modulated among the drive signals are generated based on carrier signals having different phases,
Of the second drive signal, two phases to be modulated for each of the two motors are generated based on two carrier signals having different phases, and the phase of the two carrier signals is between the two motors. equally,
A control method for a motor inverter device, wherein the drive signal or the second drive signal is supplied to a control terminal of a switching element group of the motor inverter device.

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