JP2005117869A - Two-phase modulation control inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-phase modulation control inverter device that can perform two-phase modulation control properly, even if a three-phase modulation voltage command value is small and extensively distorted by the effect of a counter electromotive force and the like, in such cases as slow revolutions and low torque in a power state and a regeneration state. <P>SOLUTION: A two-phase modulation voltage command value generating means 74 is made up of a fixed mode calculating means 742 that calculates a fixed mode based on a three-phase modulation voltage command value, a mode counter 743 that determines whether the fixed mode calculated by the fixed mode calculating means 742 complies with ideal change order or not, and a voltage command value calculating means 744 that calculates a two-phase modulation voltage command value based on the fixed mode that is changed when a coincidence signal is outputted from the mode counter 743. As a result, since the fixed mode is changed in accordance with the ideal change order, the two-phase modulation control can be performed properly. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a two-phase modulation control type inverter device.

  Against the background of environmental problems in recent years, there is an increasing demand for loss reduction in various fields, and inverter devices are no exception. A general inverter device for driving a three-phase AC motor is a three-phase modulation control type inverter device, but a two-phase modulation control type inverter device is known as an inverter device capable of reducing loss. Here, the three-phase modulation control type inverter device is an inverter device that performs control while sequentially modulating the frequencies of all three phases. The two-phase modulation control type inverter device is an inverter device controlled by a system in which any one of the three phases called two-phase modulation is sequentially fixed, and at the same time, only the other two phases are modulated. The two-phase modulation is described in pages 110, 111, 125, etc. of the book “Semiconductor Power Conversion Circuit” published by the Institute of Electrical Engineers of Japan in March 1987. Note that fixing one phase means that the switching element of the corresponding phase is always turned on or off.

  As a conventional inverter device, for example, Japanese Patent No. 3395920 discloses an inverter device that performs two-phase modulation control when a three-phase AC motor is in a power running state. This controls the inverter circuit by calculating the two-phase modulation voltage command value based on the three-phase modulation voltage command value in the power running state.

By the way, when performing two-phase modulation control, a so-called fixed mode indicating which phase is set as a modulation phase is determined based on a three-phase modulation voltage command value. There is a need to. For example, the fixed mode is changed every time the command value of each phase of the three-phase voltage command value passes through the zero cross point.
Japanese Patent No. 3395920

  Thus, for example, when the fixed mode is changed based on the zero cross point, if the three-phase modulation voltage command value is a relatively large value, the fixed mode is changed according to an appropriate order. However, when the three-phase modulation voltage command value is small, the fixed mode may not be changed according to an appropriate order. This is because, for example, a large distortion occurs in the three-phase modulation voltage command value due to the influence of the back electromotive force or the like, and it is difficult to accurately detect the zero cross of the three-phase voltage command. This is because there is a case where the order of is different. If such a fixed mode is not changed according to an appropriate order, two-phase modulation control cannot be performed. This is because if the fixed mode is not changed according to an appropriate order, the three-phase AC motor cannot be appropriately controlled, for example, by suddenly changing the phase current and generating abnormal noise from the three-phase AC motor.

  Here, in the power running state, especially when the operating point of the motor is low rotation and low torque, the three-phase modulation voltage command value is a small value. This is because the dq axis current command value is also small because the motor output is small. Further, in the regenerative state, the three-phase modulation voltage command value is a small value in almost the entire region of the motor operating point. This is because, for example, when driving a magnet type three-phase AC motor in a regenerative state, the regenerative state has a three-phase voltage command value when driven with the same current amplitude as the power running state as can be seen from the voltage equation of the motor. This is because the amplitude of is small.

  That is, there is a problem that the two-phase modulation control cannot be performed because the three-phase voltage command value is small in the power running state, particularly in the case of low rotation and low torque and in the regenerative state.

  The present invention has been made in view of such circumstances, and can perform appropriate two-phase modulation control even in the case of low rotation and low torque in a power running state and in the case of a regenerative state. An object is to provide a phase modulation control type inverter device.

  Therefore, the present inventor has intensively studied to solve this problem, and as a result of repeated trial and error, has come up with the idea of changing the order of the fixed modes to match the ideal order, and has completed the present invention. It was.

  That is, the two-phase modulation control type inverter device of the present invention includes a three-phase inverter circuit that drives and controls a three-phase AC motor, and a three-phase modulation voltage command that generates a three-phase modulation voltage command value to be applied to the three-phase AC motor. Two-phase modulation for fixing an on / off state of a predetermined one-phase switching element of the three-phase inverter circuit and modulating an on / off state of another two-phase switching element based on the value generation means and the three-phase modulation voltage command value Two-phase modulation voltage command value generating means for generating a voltage command value and PWM signal generating means for generating a PWM signal for PWM control of the three-phase inverter circuit based on the two-phase modulation voltage command value In the modulation control type inverter device, the two-phase modulation voltage command value generating means sets any one of the three phases to an on state or an off state of the switching element. Fixed mode storage means for storing a plurality of fixed modes indicating which two phases are to be modulated as fixed phases to be fixed, and fixed mode change order storage means for storing the ideal change order of each of the fixed modes And a fixed mode calculation means for calculating the fixed mode based on the three-phase modulation voltage command value and a predetermined condition stored in advance, and when the calculated fixed mode is changed, the fixed mode before the change is changed A change order determining means for determining whether or not a subsequent order to the fixed mode matches the ideal change order; and a change order determining means that determines that the order matches the ideal change order. A two-phase modulation voltage instruction for calculating the two-phase modulation voltage command value based on a phase modulation voltage command value and the changed fixed mode calculated by the fixed mode calculation means Characterized by comprising a value calculating means, the (claim 1).

  The two-phase modulation control type inverter device further includes current detection means for detecting at least two currents of the three-phase AC motor, electric angle detection means for detecting an electric angle of the three-phase AC motor, Dq-axis current command value generating means for generating a dq-axis current command value for a three-phase AC motor, and the three-phase voltage command value generated by the three-phase modulation voltage command value generating means is generated by the current detecting means. It may be calculated based on the detected current, the electrical angle detected by the electrical angle detection means, and the dq-axis current generated by the dq-axis current command value generation means.

  According to the two-phase modulation control type inverter device of the present invention, the fixed mode can be changed according to an ideal change order. This is achieved by changing the fixed mode to the next fixed mode only when the two-phase modulation voltage command value calculating means determines that the change order determining means matches the ideal change order. Specifically, when the change of the fixed mode is output from the fixed mode calculation means, if the fixed mode after the change is a fixed mode according to the ideal change order, the fixed mode is changed, and the changed When the fixed mode is a fixed mode that does not follow the ideal change order, the fixed mode before the change is maintained.

  That is, according to the present invention, even if the three-phase modulation voltage command value is a small value, the fixed mode is changed according to the ideal change order, so that appropriate two-phase modulation control can be performed. That is, appropriate two-phase modulation control can be performed even when the three-phase AC motor has a low rotation and low torque in a power running state and a regenerative state. As a result, it is possible to provide an inverter device that can reliably reduce the loss.

  Next, the present invention will be described in more detail with reference to embodiments.

  The ideal change order when the three-phase AC motor rotates in the forward direction may be opposite to the ideal change order when the three-phase AC motor rotates in the reverse direction. For example, if the ideal change order in the forward rotation is the order of A → B → C → D, the ideal change order in the reverse rotation is the order of D → C → B → A. Thus, the two-phase modulation control can be reliably performed regardless of whether the three-phase AC motor is rotating forward or rotating backward. The fixed mode change order storage means may store the ideal change order of either the forward rotation or the reverse rotation (Claim 2).

  The predetermined condition in the fixed mode calculation means may be changed based on a zero cross point of the three-phase modulation voltage command value. For example, if the fixed mode is changed every time the three-phase modulation voltage command value passes the zero cross point, the change order of the fixed mode may not match the ideal change order. As described above, even when the fixed mode is changed based on the zero cross point, according to the present invention, the change order of the fixed mode can be surely matched with the ideal change order.

  The fixed mode storage means stores each of the fixed modes as a corresponding mode number, and the ideal change order stored in the fixed mode change order storage means is a change order of each of the mode numbers, The change order determination means is a counter that increases or decreases the mode number when the fixed mode calculated by the fixed mode calculation means is changed, and the changed mode number matches the ideal change order. It may be determined whether or not (Claim 4).

  That is, the mode numbers stored in the fixed mode storage means are added or decreased according to the ideal change order. In this case, the fixed mode storage unit and the fixed mode change order storage unit are integrally configured. For example, when the change mode of the fixed mode is A → B → C → D is an ideal change order, the mode number of the fixed mode A is set to 1, the mode number of the fixed mode B is set to 2, and the mode of the fixed mode C is set. The number is 3, and the mode number of the fixed mode D is 4, which is stored in the fixed mode storage means. Since the change order determination unit is a counter that increases or decreases the mode number, for example, when the fixed mode is to be changed by the fixed mode calculation unit, the counter is increased by, for example, one. Then, it is determined whether or not the mode number of the changed fixed mode output from the fixed mode calculation means matches the mode number of the counter. That is, by using the mode number obtained by numbering the fixed mode and the counter, it is possible to easily determine whether or not it is the ideal change order.

  The two-phase modulation voltage command value calculating means may calculate the two-phase modulation voltage command value when the three-phase AC motor is in a regenerative state. As described above, the three-phase modulation voltage value is smaller in the regenerative state than in the powering state. That is, if two-phase modulation control is performed in the regenerative state, there is a high possibility that the change order of the fixed mode does not match the ideal change order. Therefore, by applying the present invention especially in the regenerative state, it becomes possible to perform the two-phase modulation control even in the regenerative state where the conventional two-phase modulation control has been difficult, thereby achieving higher efficiency. it can. Further, unlike the prior art, it is not necessary to change the three-phase modulation control and the two-phase modulation control between the power running state and the regenerative state, so that controllability can be improved (claim 5).

  Further, the fixed mode stored in the fixed mode storage means may be any of six types, twelve types, and three types. The case where there are six types of fixed modes is performed, for example, by switching the fixed mode only when the three-phase modulation voltage passes through the zero cross point. For example, when the U-phase voltage value is positive and the V-phase and W-phase voltage values are negative, the U-phase is set as the positive phase on the positive side. The case where there are 12 types of fixed modes is performed, for example, by switching the fixed mode when the three-phase modulation voltage passes through the zero-cross point and when the three-phase voltage passes through the intersecting points. The case where there are three types of fixed modes is performed, for example, by switching the fixed mode when passing through a point where three-phase voltages cross each other on the positive electrode side (claims 6, 7, and 8). ).

  The two-phase modulation control type inverter device may be used for a three-phase AC motor mounted on an automobile. When the two-phase modulation control type inverter is used for the three-phase AC motor mounted on an automobile, the loss can be surely reduced in the entire operation region of the three-phase AC motor, particularly in the regenerative state. (Claim 9).

  Next, an Example is given and this invention is demonstrated more concretely.

(Overall configuration of two-phase modulation control type inverter device)
A motor drive device using the two-phase modulation control type inverter device 1 in the present embodiment will be described with reference to FIG. In addition, the motor drive apparatus shown here is an apparatus which drives the three-phase alternating current motor mounted in a motor vehicle.

  As shown in FIG. 1, the motor drive device includes a two-phase modulation control type inverter device 1, a three-phase AC motor 2, a DC power source (battery) 3, a current sensor 4, and a rotational position detection sensor 5. Has been. The current sensor 4 is a sensor that detects at least two-phase currents (for example, currents Iv and Iw flowing in the V phase and the W phase) of the armature coils of the three-phase AC motor 1. The rotational position detection sensor 5 is a sensor that detects the rotational position of the rotor of the three-phase AC motor 1. The rotational position detection sensor 5 can be omitted by calculating the electrical angle θ (phase) based on the currents Iv, Iw and the like.

  The two-phase modulation control type inverter device 1 includes a three-phase inverter circuit 6, a control circuit 7, and a smoothing capacitor 8. A three-phase inverter circuit (hereinafter simply referred to as “inverter circuit”) 6 is a circuit that converts a DC voltage into a three-phase AC voltage and applies it to an armature coil of the three-phase AC motor 2. This inverter circuit 6 has a U-phase inverter 61, a V-phase inverter 62, and a W-phase inverter 63. Each of the phase inverters 61 to 63 includes IGBT elements 601 to 603 as upper arm side switching elements, and lower arm side switching elements. IGBT elements 604 to 606 are individually provided. Further, flywheel diodes 64 are connected to the IGBT elements 601 to 606 in antiparallel.

  The upper end sides of the upper arm side switching elements 601 to 603 of the inverter circuit 6 are connected to the DC power source 3 and the positive side of the smoothing capacitor 8. On the other hand, the lower end sides of the lower arm side switching elements 604 to 606 of the inverter circuit 6 are connected to the DC power supply 3 and the negative side of the smoothing capacitor 8. And between the upper arm side switching element 601 and the lower arm side switching element 604 of the U-phase inverter 61 is connected to the U-phase armature coil of the three-phase AC motor 2. A space between the upper arm side switching element 602 and the lower arm side switching element 605 of the V phase inverter 62 is connected to a V phase armature coil of the three-phase AC motor 2. A space between the upper arm side switching element 603 and the lower arm side switching element 606 of the W phase inverter 63 is connected to a W phase armature coil of the three-phase AC motor 2.

(Configuration of control circuit)
The control circuit 7 inputs a torque command value trq * from the vehicle ECU, inputs V-phase and W-phase currents Iv and Iw from the current sensor 4, and further rotates the three-phase AC motor 2 from the rotational position detection sensor 5. The child rotation position signal is input. Based on these input signals, the on / off states of the switching elements 601 to 606 of the inverter circuit 6 are controlled. Specifically, the gate voltage applied to the gate terminals of the switching elements 601 to 606 is controlled.

  The control circuit 7 will be described in detail with reference to FIG. As shown in FIG. 2, the control circuit 7 includes a motor rotational position detecting means 71, a dq-axis current command generating means 72, a three-phase voltage command generating means 73, a two-phase modulation voltage command generating means 74, and a PWM signal. The generating unit 75, the switching gate driver 76, and the motor rotation direction detecting unit 77 are configured.

  The motor rotational position detection means 71 calculates the electrical angle θ of the three-phase AC motor 2 and the motor rotational speed Nmot based on the rotational position signal of the rotor of the three-phase AC motor 2 input from the rotational position detection sensor 5. The dq-axis current command generating means 72 calculates dq-axis current command values Id and Iq based on the torque command value trq * input from the vehicle ECU and the motor rotational speed Nmot calculated by the motor rotation position detecting means 71. The three-phase voltage command generation means (three-phase modulation voltage command value generation means) 73 has an electrical angle θ calculated by the motor rotation position detection means 71 and a dq-axis current command value Id calculated by the dq-axis current command generation means 72. , Iq and the motor currents Iv, Iw detected by the current sensor 4, the three-phase modulation voltage command values U, V, W applied to the armature coils of the respective phases of the three-phase AC motor 2 are calculated. The three-phase modulation voltage command values U, V, and W are voltage command values when performing three-phase modulation control. The two-phase modulation voltage command generation means (two-phase modulation voltage command value generation means) 74 performs two-phase modulation based on the three-phase modulation voltage command values U, V, and W calculated by the three-phase voltage command generation means 73 Voltage command values U ′, V ′, and W ′ at are calculated. Details of the two-phase modulation voltage command generation means 74 will be described later.

  The PWM signal generation means 75 is based on the two-phase modulation voltage command values U ′, V ′, W ′ calculated by the two-phase modulation voltage command generation means 74, and the U-phase inverter 61 and the V-phase inverter 62 of the inverter circuit 6. , PWM signals Vu, Vv, and Vw serving as drive command signals for the W-phase inverter 63 are generated by comparing the carrier wave (triangular wave) with the magnitude.

  The switching gate driver (drive circuit) 76 is based on the PWM signals Vu, Vv, and Vw output from the PWM signal generating means 75, and the gate voltages Uu and Ul of the switching elements 601 and 604 of the U-phase inverter 61 and the V-phase inverter. 62, the gate voltages Vu and Vl of the switching elements 602 and 605 and the gate voltages Wu and Wl of the switching elements 603 and 606 of the W-phase inverter 63 are generated. These gate voltages Uu, Ul, Vu, Vl, Wu, and Wl can be expressed by a duty that is a time ratio of an ON state in a predetermined time. The switching elements 601 to 606 of the inverter circuit 6 are driven on and off based on the gate voltages Uu, Ul, Vu, Vl, Wu, and Wl output from the switching gate driver 76. That is, when the gate voltage is turned on (predetermined voltage value), the transistor is turned on, and when the gate voltage is turned off (zero), the transistor is turned off. The switching gate driver 76 is a circuit for applying a gate voltage to the IGBT based on a PWM (Pulse Width Modulation) signal when the switching elements 601 to 606 are IGBTs (Insulated Gate Bipolar Transistors), for example. , Logic ICs, transistors and the like.

  The motor rotation direction detection unit 77 detects the rotation direction R / L of the three-phase AC motor 2 based on the electrical angle change Δθ of the three-phase AC motor 2 output from the motor rotation position detection unit 71. That is, it detects whether the three-phase AC motor 2 is rotating forward or reversely. This rotational direction R / L is used by the two-phase modulation voltage command generation means 74.

(Two-phase modulation voltage command generation means)
(First embodiment)
The two-phase modulation voltage command generation means 74 includes a fixed mode storage means (fixed mode storage means, fixed mode change order storage means) 741, a fixed mode calculation means (fixed mode calculation means) 742, and a mode counter (change order determination means). 743 and voltage command calculation means (two-phase modulation voltage command value calculation means) 744.

  The fixed mode storage unit 741 stores a plurality of fixed modes indicating which one of the three phases is a fixed phase and which two phases are modulation phases. Here, the stationary phase refers to a phase that fixes any one of the phase inverters 61 to 63 to the on state or the off state. The modulation phase refers to the remaining two phases other than the stationary phase, and the switching element of this modulation phase modulates the on / off state.

  The fixed mode stored in the fixed mode storage unit 741 will be described in more detail with reference to FIG. The fixed mode in the first embodiment consists of six types of fixed modes. FIG. 3A shows an ideal state diagram of the three-phase modulation voltage command values U, V, and W output from the three-phase voltage command generation means 73. FIG. 3B is a diagram for explaining the fixed mode when the three-phase modulation voltage command value is in an ideal state. In FIG. 3 (b), the numerical value of the mode number is shown on the upper side, and the voltage command value for each phase is shown on the lower side. FIG. 3C will be described later.

  As shown in FIG. 3A, the three-phase modulation voltage command values U, V, and W in the ideal state are represented by sine waves whose phases are shifted by an electrical angle of 60 °. In the fixing mode in the first embodiment, as shown in FIG. 3B, one phase having a different polarity is fixed to the polarity side. Specifically, in the mode number 1 of the fixed mode, only the V phase has a negative polarity and the U phase and the W phase have a positive polarity as shown in FIG. In this case (in the case of mode number 1), as shown in FIG. 3B, the fixed mode is a mode in which the V phase is fixed as a negative voltage (−VDC / 2) and the U phase and the W phase are modulated. Become. In mode number 2 of the fixed mode, as shown in FIG. 3A, only the U phase has a positive polarity, and the V phase and the W phase have a negative polarity. In this case (in the case of mode number 2), as shown in FIG. 3B, the fixed mode is a mode in which the U phase is fixed as a positive voltage (+ VDC / 2) and the V phase and the W phase are modulated. . In the mode number 3 of the fixed mode, as shown in FIG. 3A, only the W phase has a negative polarity, and the U phase and the V phase have a positive polarity. In this case (in the case of mode number 3), as shown in FIG. 3B, the fixed mode is a mode in which the W phase is fixed as a negative voltage (−VDC / 2) and the U phase and the V phase are modulated. Become. In the mode number 4 of the fixed mode, as shown in FIG. 3A, only the V phase has a positive polarity, and the U phase and the W phase have a negative polarity. In this case (in the case of mode number 4), as shown in FIG. 3B, the fixed mode is a mode in which the V phase is fixed as a positive voltage (+ VDC / 2) and the U phase and the W phase are modulated. . In mode number 5 of the fixed mode, as shown in FIG. 3A, only the U phase has a negative polarity, and the V phase and the W phase have a positive polarity. In this case (in the case of mode number 5), as shown in FIG. 3B, the fixed mode is a mode in which the U phase is fixed as a negative voltage (−VDC / 2) and the V phase and the W phase are modulated. Become. In the mode number 6 of the fixed mode, as shown in FIG. 3A, only the W phase has a positive polarity, and the U phase and the V phase have a negative polarity. In this case (mode number 6), the fixed mode is a mode in which the W phase is fixed as a positive voltage (+ VDC / 2) and the U phase and the V phase are modulated as shown in FIG. .

  Furthermore, the mode number is a numerical value from 1 to 6, as described above. Here, this numerical order is an ideal change order. That is, when the fixed modes are composed of the six types described above, the order of the stationary phases “V−”, “U +”, “W−”, “V +”, “U−”, and “W +” is the ideal change order. Then, the mode number is increased in accordance with this ideal change order. That is, the fixed mode storage unit 741 also stores an ideal change order of the fixed mode.

  The fixed mode calculation unit 742 includes the three-phase modulation voltage command values U, V, and W output from the three-phase voltage command generation unit 73, preset predetermined conditions, and a fixed mode stored in the fixed mode storage unit 741. Based on the above, the fixed mode is calculated. Here, the calculation process of the fixed mode will be described with reference to FIGS.

  A description will be given assuming that the three-phase modulation voltage command value shown in FIG. The predetermined condition in the first embodiment is whether or not only one of the three phases has a different polarity. That is, it is determined whether or not the zero-cross point of the three-phase modulation voltage command values U, V, and W has passed, and whether the polarity of each phase is positive or negative.

  Specifically, as shown in FIG. 3A, first, the U-phase voltage command value passes through the zero cross point. As for the polarities of the respective phases at this time, the U phase and the W phase are positive electrodes, and the V phase is a negative electrode. Therefore, in this case, the mode number 1 of the fixed mode is selected and output. Subsequently, when rotating by a predetermined angle, the W phase passes through the zero cross point. As for the polarities of the respective phases at this time, the U phase is a positive electrode, and the V phase and the W phase are negative electrodes. Therefore, the mode number 2 of the fixed mode is selected and output. Subsequently, when rotating by a predetermined angle, the V phase passes through the zero cross point. As for the polarities of each phase at this time, the U phase and the V phase are positive electrodes, and the W phase is a negative electrode. Therefore, the mode number 3 of the fixed mode is selected and output.

  Next, the mode counter 743 will be described with reference to FIG. The mode counter 743 determines whether or not the change order from the mode number before change to the mode number after change matches the ideal change order based on the mode number of the fixed mode after change output from the fixed mode calculation means 742. Determine whether.

  Here, a description will be given with reference to FIG. 3 in which the three-phase modulation voltage command value is an ideal state. Then, the mode counter 743 determines whether to increase or decrease the counter value based on the rotation direction R / L output from the motor rotation direction detection unit 77 for the rotation direction of the three-phase AC motor 2. For example, the count value is increased when the rotation direction of the three-phase AC motor 2 is forward rotation, and the count value is decreased when the rotation direction is reverse.

  Here, it is assumed that the two-phase modulation voltage command generation means 74 is currently outputting to the PWM signal generation means 75 in the state of the mode number “1” in the fixed mode, and the rotation direction of the three-phase AC motor 2 is positive rotation. . Therefore, the mode counter 743 stores “2”, which is incremented by 1 to the currently executed mode number, as a count value.

  When the three-phase AC motor 2 rotates positively by a predetermined angle (electrical angle 60 °), the fixed mode calculation unit 742 outputs the mode number “2” of the fixed mode. Subsequently, it is determined whether or not the mode number output from the fixed mode calculation means 742 matches the count value currently stored in the mode counter 743. Here, as described above, the mode number output from the fixed mode computing means 742 and the count value of the mode counter 743 are both “2”, and therefore coincide. Subsequently, when the mode number and the count value match, a match signal is output to a voltage command calculation means 744 described later, and the mode counter 743 currently increments the count value stored by “1”. That is, the count value currently stored in the mode counter 743 is “3”. If the mode number and the count value do not match, a match signal is not output to the voltage command calculation means 744 until they match, and the count value is also maintained as it is.

  Subsequently, when the three-phase AC motor 2 rotates positively by a predetermined angle (electrical angle 60 °), the fixed mode calculation unit 742 outputs the mode number “3” of the fixed mode. Subsequently, it is determined whether or not the mode number output from the fixed mode calculation means 742 matches the count value currently stored in the mode counter 743. Here, as described above, the mode number output from the fixed mode computing means 742 and the count value of the mode counter 743 are both “3”, and therefore match. Subsequently, the coincidence signal is output to the voltage command calculation means 744 and the count value currently stored in the mode counter 743 is incremented by “1”.

  In this way, it is determined whether or not the mode number of the fixed mode output from the fixed mode calculation means 742 matches the increased count value. In the case of the ideal three-phase modulation voltage command value shown in FIG. 3, the mode number of the fixed mode always output from the fixed mode calculation means 742 matches the count value currently stored in the mode counter 743. To do.

  When the count value stored in the mode counter 743 is “6”, the count value is increased to “1” next time. When the three-phase AC motor 2 rotates in the reverse direction, the mode counter 743 decreases the count value. That is, the count value is sequentially changed as “1 → 6 → 5 → 4 → 3 → 2 → 1”.

  The voltage command calculation means 744 outputs the three-phase modulation voltage command values U, V, W output from the three-phase voltage command generation means 73, the fixed mode output from the fixed mode calculation means 742, and the mode counter 743. The two-phase modulation voltage command values U ′, V ′, W ′ are calculated based on the coincidence signal. That is, the two-phase modulation voltage command value is calculated so that the fixed mode output from the fixed mode calculation means 742 when the coincidence signal output from the mode counter 743 is output.

  Here, a description will be given with reference to FIG. 3 in which the three-phase modulation voltage command value is an ideal state. When the mode number output from the fixed mode calculation means 742 in the mode counter 743 matches the count value currently stored in the mode counter 743 by “2”, the voltage command calculation means 744 returns from the mode counter 743. Input a coincidence signal.

  Then, the fixed mode output from the fixed mode calculation means 742 when the coincidence signal is input is input. Here, since the mode number and the count value are “2”, the fixed mode output from the fixed mode calculation unit 742 is a mode in which the U phase is fixed to the plus side and the V phase and the W phase are modulated.

  Then, based on the three-phase modulation voltage command values U, V, W output from the three-phase voltage command generation means 73 so that the fixed mode is set, the two-phase modulation voltage command values U ′, V ′, W ′ are calculate. That is, in this case, the two-phase modulated voltage command values U ′, V ′, and W ′ output from the voltage command generation unit 744 are the voltage command values of the respective phases with the U phase fixed to the plus side.

  Note that while the coincidence signal is not output from the mode counter 743, the currently executed fixed mode is maintained. That is, even if a signal for changing the fixed mode is output from the fixed mode calculation means 742, if the coincidence signal is not output from the mode counter 743, the fixed mode is not changed.

  Up to this point, the description has been made based on the ideal three-phase modulation voltage command value of FIG. 3A, but the following description will be given with reference to FIG. 4 which is the actual waveform of the three-phase modulation voltage command value. FIG. 4A shows an ideal three-phase modulation voltage command value, and FIG. 4B shows a three-phase modulation voltage command value when the three-phase AC motor 2 has low rotation and low torque in a power running state. Show. In the case of low rotation and low torque in the power running state, the three-phase modulation voltage command value becomes small and further has a large distortion due to the influence of the counter electromotive force and the like. Moreover, it shows about the stationary phase in an ideal state in the lower side of Fig.4 (a). 4B shows the fixed phase of the output information of the fixed mode calculation means 742, and the upper side of FIG. 4B shows the fixed phase of the input information of the voltage command calculation means 744.

  FIG. 4A shows an ideal state for comparison and is the same as that described above with reference to FIG. Here, it is assumed that the electrical angle shown in the leftmost part of FIG. That is, it is assumed that the two-phase modulation voltage command generation means 74 outputs to the PWM signal generation means 75 in the state of the mode number “1” in the fixed mode, and the rotation direction of the three-phase AC motor 2 is positive rotation. Therefore, the mode counter 743 stores “2”, which is incremented by 1 to the currently executed mode number, as a count value.

  Then, when the three-phase AC motor 2 rotates forward by a predetermined angle (up to about an electrical angle of about 100 ° in FIG. 4B), the W phase passes through the zero cross point. As for the polarities of the respective phases at this time, the U phase is a positive electrode, and the V phase and the W phase are negative electrodes. Accordingly, the fixed mode calculation means 742 selects and outputs the mode number “2” of the fixed mode. Subsequently, the mode counter 743 determines whether or not the mode number output from the fixed mode calculation unit 742 matches the count value currently stored in the mode counter 743. Here, since the mode number output from the fixed mode calculation means 742 and the count value of the mode counter 743 are both “2”, they coincide. When the mode number and the count value match, the mode counter 743 outputs a match signal to the voltage command calculation means 744 and increases the count value currently stored in the mode counter 743 by “1”. That is, the count value currently stored in the mode counter 743 is “3”. Subsequently, the voltage command calculation unit 744 inputs a coincidence signal from the mode counter 743. Then, the voltage command calculation unit 744 inputs the fixed mode output from the fixed mode calculation unit 742. That is, during this period, as shown in FIG. 4B, the fixed phase of the fixed mode output from the fixed mode calculation unit 742 is “U +”, and the fixed mode fixed to which the voltage command generating unit 744 is input is fixed. The phase is also “U +”.

  Subsequently, when the three-phase AC motor 2 is rotated forward by a predetermined angle (up to about 115 ° electrical angle in FIG. 4B), the V phase passes through the zero cross point. As for the polarities of each phase at this time, the U phase and the V phase are positive electrodes, and the W phase is a negative electrode. Accordingly, the fixed mode calculation means 742 selects and outputs the mode number “3” of the fixed mode. Subsequently, the mode counter 743 determines whether or not the mode number output from the fixed mode calculation unit 742 matches the count value currently stored in the mode counter 743. Here, since the mode number output from the fixed mode calculation means 742 and the count value of the mode counter 743 are both “3”, they match. When the mode number and the count value match, the mode counter 743 outputs a match signal to the voltage command calculation means 744 and increases the count value currently stored in the mode counter 743 by “1”. That is, the count value currently stored in the mode counter 743 is “4”. Subsequently, the voltage command calculation unit 744 inputs a coincidence signal from the mode counter 743. Then, the voltage command calculation unit 744 inputs the fixed mode output from the fixed mode calculation unit 742. That is, during this period, as shown in FIG. 4B, the fixed phase of the fixed mode output from the fixed mode calculating unit 742 is “W−”, and the fixed mode of the fixed mode in which the voltage command generating unit 744 is input. The stationary phase is also “W−”.

  Subsequently, when the three-phase AC motor 2 is rotated forward by a predetermined angle (up to about an electrical angle of about 130 ° in FIG. 4B), the V phase passes through the zero cross point again. As for the polarities of the respective phases at this time, the U phase is a positive electrode, and the V phase and the W phase are negative electrodes. Accordingly, the fixed mode calculation means 742 selects and outputs the mode number “2” of the fixed mode. Subsequently, the mode counter 743 determines whether or not the mode number output from the fixed mode calculation unit 742 matches the count value currently stored in the mode counter 743. Here, while the mode number output from the fixed mode calculation means 742 is “2”, the count value of the mode counter 743 is “4”, so they do not match. If the mode number does not match the count value, the mode counter 743 maintains the count value currently stored in the mode counter 743 without outputting a match signal to the voltage command calculation means 744. That is, the count value currently stored in the mode counter 743 remains “4”. At this time, the voltage command calculation means 744 does not input a coincidence signal from the mode counter 743. Then, the voltage command calculation unit 744 does not input the fixed mode output from the fixed mode calculation unit 742. In other words, during this period, as shown in FIG. 4B, the fixed phase of the fixed mode output from the fixed mode calculating unit 742 is “U +”, but the fixed phase of the fixed mode of the voltage command generating unit 744 is “ "W-" remains.

  Subsequently, when the three-phase AC motor 2 rotates forward by a predetermined angle (up to about an electric angle of about 155 ° in FIG. 4B), the V phase passes through the zero cross point again. As for the polarities of each phase at this time, the U phase and the V phase are positive electrodes, and the W phase is a negative electrode. Accordingly, the fixed mode calculation means 742 selects and outputs the mode number “3” of the fixed mode. Subsequently, the mode counter 743 determines whether or not the mode number output from the fixed mode calculation unit 742 matches the count value currently stored in the mode counter 743. Here, while the mode number output from the fixed mode calculation means 742 is “3”, the count value of the mode counter 743 is “4”, so they do not match. If the mode number and the count value do not match, the mode counter 743 maintains the count value currently stored in the mode counter 743 without outputting a match signal to the voltage command calculation means 744. That is, the count value currently stored in the mode counter 743 remains “4”. At this time, the voltage command calculation means 744 does not input a coincidence signal from the mode counter 743. Then, the voltage command calculation unit 744 does not input the fixed mode output from the fixed mode calculation unit 742. That is, during this period, as shown in FIG. 4B, the fixed phase of the fixed mode output from the fixed mode calculation unit 742 is “W−”, and the fixed phase of the fixed mode of the voltage command generating unit 744 is “W”. -".

  Subsequently, when the three-phase AC motor 2 rotates forward by a predetermined angle (up to about an electrical angle of about 180 ° in FIG. 4B), the U phase passes through the zero cross point. As for the polarities of the respective phases at this time, the V phase is a positive electrode, and the U phase and the W phase are negative electrodes. Therefore, the fixed mode calculation means 742 selects and outputs the mode number “4” of the fixed mode. Subsequently, the mode counter 743 determines whether or not the mode number output from the fixed mode calculation unit 742 matches the count value currently stored in the mode counter 743. Here, since the mode number output from the fixed mode calculation means 742 and the count value of the mode counter 743 are both “4”, they match. When the mode number and the count value match, the mode counter 743 outputs a match signal to the voltage command calculation means 744 and increases the count value currently stored in the mode counter 743 by “1”. That is, the count value currently stored in the mode counter 743 is “5”. Subsequently, the voltage command calculation unit 744 inputs a coincidence signal from the mode counter 743. Then, the voltage command calculation unit 744 inputs the fixed mode output from the fixed mode calculation unit 742. That is, during this period, as shown in FIG. 4B, the fixed phase of the fixed mode output from the fixed mode calculation unit 742 is “V +”, and the fixed mode fixed to which the voltage command generating unit 744 is input is fixed. The phase is also “V +”.

  That is, the mode number of the fixed mode output from the fixed mode calculation means is changed in the order of “1 → 2 → 3 → 2 → 3 → 4 → 3 → 4 → 5 → 4”, whereas the voltage command The mode number of the fixed mode input by the generating means 744 is changed in the order of “1 → 2 → 3 → 4 → 5 → 6 → 1”. That is, the mode number of the fixed mode output from the fixed mode calculation means does not match the ideal change order, but the change order of the mode number of the fixed mode input by the voltage command generation means 744 is the same as the ideal change order. I'm doing it.

  Therefore, when the three-phase modulation voltage command value is a small value and the three-phase modulation voltage command value is greatly distorted due to the influence of the counter electromotive force, as in the case of low rotation and low torque in the power running state or the regenerative state. Even in this case, the change order of the fixed mode can be matched with the ideal change order. As a result, even when the three-phase modulation voltage command value becomes a small value, the two-phase modulation control can be performed.

(Second embodiment)
The fixed mode stored in the fixed mode storage unit 741 in the second embodiment will be described with reference to FIG. The fixed mode in the second embodiment consists of three types of fixed modes. FIG. 5 is a diagram for explaining the fixed mode when the three-phase modulation voltage command value is ideal.

  In the fixed mode in the second embodiment, as shown in FIG. 5, the phase having the highest voltage value among the voltage command values U, V, W of each phase of the three-phase modulation voltage command value is set as the fixed phase. That is, the fixed mode is changed every time the voltage command value of each phase of the three-phase modulation voltage command value passes through the intersection.

  Specifically, in the mode number 1 of the fixed mode, the U phase has a larger voltage value than the other two phases, the V phase and the W phase. The fixed mode in this case (in the case of mode number 1) is a mode in which the U phase is fixed as a positive voltage (+ VDC / 2) and the V phase and the W phase are modulated as shown in FIG. In the mode number 2 of the fixed mode, the V phase has a larger voltage value than the other two phases U and W. The fixed mode in this case (in the case of mode number 2) is a mode in which the V phase is fixed as a positive voltage (+ VDC / 2) and the U phase and the W phase are modulated, as shown in FIG. In the mode number 3 of the fixed mode, the W phase has a larger voltage value than the other two phases U and V. The fixed mode in this case (in the case of mode number 3) is a mode in which the W phase is fixed as a positive voltage (+ VDC / 2) and the U phase and V phase are modulated, as shown in FIG.

  Further, the mode number is a numerical value from 1 to 3 as described above. Here, this numerical order is an ideal change order. That is, when the fixed modes are the above-described three types, the order of the stationary phases “U +”, “V +”, and “W +” is the ideal change order. The mode number is increased or decreased according to this ideal change order.

(Third embodiment)
The fixed mode stored in the fixed mode storage means 741 in the third embodiment will be described with reference to FIG. The fixed mode in the third embodiment includes three types of fixed modes. FIG. 6 is a diagram for explaining the fixed mode when the three-phase modulation voltage command value is in an ideal state.

  In the fixed mode in the third embodiment, as shown in FIG. 6, the phase having the lowest voltage value among the voltage command values U, V, W of each phase of the three-phase modulation voltage command value is set as the fixed phase. That is, the fixed mode is changed every time the voltage command value of each phase of the three-phase modulation voltage command value passes through the intersection.

  Specifically, in the mode number 1 of the fixed mode, the U phase has a smaller voltage value than the other two phases, the V phase and the W phase. In this case (in the case of mode number 1), the fixed mode is a mode in which the U phase is fixed as a negative voltage (−VDC / 2) and the V phase and the W phase are modulated, as shown in FIG. In the mode number 2 of the fixed mode, the V phase has a smaller voltage value than the other two phases U phase and W phase. In this case (in the case of mode number 2), as shown in FIG. 6, the fixed mode is a mode in which the V phase is fixed as a negative voltage (−VDC / 2) and the U phase and the W phase are modulated. In the mode number 3 of the fixed mode, the W phase has a smaller voltage value than the other two phases, the U phase and the V phase. In this case (mode number 3), the fixed mode is a mode in which the W phase is fixed as a negative voltage (−VDC / 2) and the U phase and the V phase are modulated, as shown in FIG.

  Further, the mode number is a numerical value from 1 to 3 as described above. Here, this numerical order is an ideal change order. That is, when the fixed modes are the above-described three types, the order of the stationary phases “U−”, “V−”, and “W−” is the ideal change order. The mode number is increased or decreased according to this ideal change order.

(Fourth embodiment)
The fixed mode stored in the fixed mode storage means 741 in the fourth embodiment will be described with reference to FIG. The fixed mode in the fourth embodiment includes 12 types of fixed modes. FIG. 7 is a diagram for explaining the fixed mode when the three-phase modulation voltage command value is in an ideal state.

  In the fixed mode in the fourth embodiment, as shown in FIG. 7, the phase having a large absolute value of the three-phase modulation voltage command value is set as the fixed phase among the two phases having the same polarity. That is, the fixed mode is changed each time the voltage command value of each phase of the three-phase modulation voltage command value crosses the zero cross point.

  Specifically, in mode number 1 in the fixed mode, the U-phase and W-phase two phases have the same polarity, and the absolute value of the W-phase voltage value is larger than the absolute value of the U-phase voltage value. In this case (in the case of mode number 1), as shown in FIG. 7, the fixed mode is a mode in which the W phase is fixed as a positive voltage (+ VDC / 2) and the V phase and the W phase are modulated. In the mode number 2 of the fixed mode, the U-phase and W-phase two phases have the same polarity, and the absolute value of the U-phase voltage value is larger than the absolute value of the W-phase voltage value. The fixed mode in this case (in the case of mode number 2) is a mode in which the U phase is fixed as a positive voltage (+ VDC / 2) and the V phase and the W phase are modulated as shown in FIG. In the mode number 3 in the fixed mode, the two-phase polarities of the V-phase and the W-phase are common, and the absolute value of the V-phase voltage value is larger than the absolute value of the W-phase voltage value. In this case (in the case of mode number 3), as shown in FIG. 7, the fixed mode is a mode in which the V phase is fixed as a negative voltage (−VDC / 2) and the U phase and the W phase are modulated.

  In the fixed mode mode number 4, the two-phase polarities of the V-phase and the W-phase are common, and the absolute value of the W-phase voltage value is larger than the absolute value of the V-phase voltage value. The fixed mode in this case (in the case of mode number 4) is a mode in which the W phase is fixed as a negative voltage (−VDC / 2) and the U phase and the V phase are modulated as shown in FIG. In the mode number 5 of the fixed mode, the U-phase and V-phase two-phase polarities are common, and the absolute value of the U-phase voltage value is larger than the absolute value of the V-phase voltage value. In this case (in the case of mode number 5), as shown in FIG. 7, the fixed mode is a mode in which the U phase is fixed as a positive voltage (+ VDC / 2) and the V phase and the W phase are modulated. In the mode number 6 of the fixed mode, the U-phase and V-phase two-phase polarities are common, and the absolute value of the V-phase voltage value is larger than the absolute value of the U-phase voltage value. In this case (in the case of mode number 6), as shown in FIG. 7, the fixed mode is a mode in which the V phase is fixed as a plus voltage (+ VDC / 2) and the U phase and the W phase are modulated.

  Furthermore, the mode number is a numerical value from 1 to 12, as described above. Here, this numerical order is an ideal change order. That is, when the fixed modes are the above-described 12 types, the order of the stationary phases “W +” “U +” “V−” “W−” “U +” “V +”. . The mode number is increased or decreased according to this ideal change order.

It is a figure which shows a two-phase modulation control type inverter apparatus. It is a block diagram which shows a control circuit. It is a figure which shows the fixed mode of 1st Example. It is a figure explaining the fixed mode of 1st Example based on an actual three-phase modulation voltage command value. It is a figure which shows the fixed mode of 2nd Example. It is a figure which shows the fixed mode of 3rd Example. It is a figure which shows the fixed mode of 4th Example.

Explanation of symbols

1: two-phase modulation control type inverter device, 2: three-phase AC motor, 3: DC power supply, 4: current sensor, 5: rotational position detection sensor, 6: three-phase inverter circuit, 7: control circuit, 8: smoothing capacitor 61: U-phase inverter, 62: V-phase inverter, 63: W-phase inverter, 64: flywheel diode, 71: motor rotation position detection means, 72: dq-axis current command generation means, 73: three-phase voltage command generation means 74: Two-phase modulation voltage command generation means, 75: PWM signal generation means, 76: Switching gate driver, 601 to 603: Upper arm side switching element, 604 to 606: Lower arm side switching element, 741: Fixed mode storage means , 742: Fixed mode calculation means, 743: Mode counter, 744: Voltage command calculation means (Compensated two-phase voltage command value calculation means)

Claims (9)

A three-phase inverter circuit for driving and controlling a three-phase AC motor;
Three-phase modulation voltage command value generating means for generating a three-phase modulation voltage command value to be applied to the three-phase AC motor;
Based on the three-phase modulation voltage command value, generates a two-phase modulation voltage command value for fixing the on / off state of a predetermined one-phase switching element of the three-phase inverter circuit and modulating the on / off state of another two-phase switching element. Two-phase modulation voltage command value generating means,
PWM signal generating means for generating a PWM signal for PWM control of the three-phase inverter circuit based on the two-phase modulation voltage command value;
In the two-phase modulation control type inverter device provided with
The two-phase modulation voltage command value generating means is
Fixed mode storage means for storing a plurality of fixed modes indicating which one of three phases is a modulation phase for modulating which two phases are fixed as a fixed phase for fixing the switching element to an on state or an off state;
Fixed mode change order storage means for storing an ideal change order of each of the fixed modes;
Fixed mode calculation means for calculating the fixed mode based on the three-phase modulation voltage command value and a predetermined condition stored in advance;
A change order determination means for determining whether the order from the fixed mode before change to the fixed mode after change matches the ideal change order when the calculated fixed mode is changed;
The two-phase modulation voltage command based on the three-phase modulation voltage command value and the fixed mode after the change calculated by the fixed mode calculation device when the change order determination unit determines that the ideal change order is matched. Two-phase modulation voltage command value calculation means for calculating a value;
A two-phase modulation control type inverter device comprising:   2. The ideal change order when the three-phase AC motor rotates in the forward direction is opposite to the ideal change order when the three-phase AC motor rotates in the reverse direction. Two-phase modulation control type inverter device.   2. The two-phase modulation control type inverter device according to claim 1, wherein the predetermined condition is changed based on a zero cross point of the three-phase modulation voltage command value. The fixed mode storage means stores each of the fixed modes as a corresponding mode number,
The ideal change order stored in the fixed mode change order storage means is a change order of each mode number,
The change order determination means is a counter that increases or decreases the mode number when the fixed mode calculated by the fixed mode calculation means is changed, and the changed mode number matches the ideal change order. 2. The two-phase modulation control type inverter device according to claim 1, wherein it is determined whether or not.   2. The two-phase modulation control type inverter device according to claim 1, wherein the two-phase modulation voltage command value calculation means calculates the two-phase modulation voltage command value when the three-phase AC motor is in a regenerative state.   The two-phase modulation control type inverter device according to claim 1, wherein the fixed modes stored in the fixed mode storage means are of six types.   The two-phase modulation control type inverter device according to claim 1, wherein the fixed modes stored in the fixed mode storage means are 12 types.   2. The two-phase modulation control type inverter device according to claim 1, wherein the fixed modes stored in the fixed mode storage means are of three types.   2. The two-phase modulation control type inverter device according to claim 1, wherein the two-phase modulation control type inverter device is used for the three-phase AC motor mounted in an automobile.

Images