Power conversion device

Abstract

To provide a power conversion device capable of improving responsiveness while stably controlling a secondary side voltage of a GND common type dual inverter, and driving a motor having a winding of an open end structure.SOLUTION: A primary side inverter is connected to a DC power supply, a secondary side inverter is connected to a capacitor, a negative side power supply line of the primary side inverter and the secondary side inverter is shared, and a control device 6 for controlling a secondary side voltage which is a charging voltage of the capacitor is provided. The control device 6 includes a secondary-side voltage control system 23 that generates a zero phase voltage command value for flowing a zero phase current necessary for controlling the secondary-side voltage to the secondary-side voltage command value. The secondary-side voltage control system 23 includes a feedforward control unit that outputs a feedforward control amount of the zero phase voltage command value on the basis of the secondary-side voltage command value and the primary-side voltage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power conversion device that applies AC output to a motor having open-ended windings with both ends open, using two inverters, a primary inverter and a secondary inverter. [Background technology]

[0002] For example, when driving an electric compressor used in an air conditioning system for an electric vehicle such as an electric car or a hybrid car, a three-phase permanent magnet synchronous motor is used. However, the existing motor control method using an inverter controls the d-axis current i d and q-axis current i q Vector control, which controls the above, is common.

[0003] It is possible to design a controller by modeling the controller and the controlled object (plant model) as shown in Figure 26. In other words, modeling the controlled object is important for designing a controller.

[0004] On the other hand, when the input voltage drops, the motor driven by the inverter tends to have a narrower range of high-speed operation because the rotational speed at which it can be driven decreases or the torque that can be output at high rotational speeds decreases.In the above-mentioned electric compressor for vehicle use, which drives the compression mechanism with a motor housed in a housing, the required range of input voltage was not wide in the past, but in recent years, the requirements for the range in which electric compressors can be operated in response to changes in input voltage have become stricter.

[0005] However, in-vehicle electric compressors use the battery of the electric vehicle as a DC power source, which can cause a drop in input voltage. If the input voltage drops, the torque that can be output will decrease in the high rotation speed range.

[0006] Therefore, as a method of increasing the output voltage to the motor relative to the input voltage, various dual inverter power conversion devices have been proposed, in which a motor with a so-called open-end winding structure (a motor with the neutral point of the motor not connected but extended to the outside) having multiple stator windings with both ends open is sandwiched between two inverters, one on the primary side and one on the secondary side, and the differential voltage between the primary inverter and the secondary inverter is applied to the motor to drive it (see, for example, Patent Document 1 and Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-149153 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-33984 Summary of the Invention [Problem to be solved by the invention]

[0008] In a dual inverter power conversion device that drives a motor with an open-end winding structure, there are two inverters, one on the primary side and one on the secondary side, so there is a degree of freedom in how the voltage command value is distributed to the two inverters.

[0009] Conventional dual inverter power conversion devices can be broadly divided into three types, as shown in Figures 27 to 29. Figure 27 shows a typical common power supply dual inverter power conversion device. In Figure 27, M is a motor equipped with the open-end structure windings described above, INV1 is a primary side inverter, and INV2 is a secondary side inverter, which sandwich the stator winding of motor M.

[0010] The common power supply dual inverter is the simplest method, sharing the same power supply for the primary and secondary sides. Because there is only one power supply, the withstand voltage of all semiconductor elements and passive elements (capacitors, etc.) on the primary and secondary sides must be set according to the power supply voltage. Also, because there is a path through which zero-phase current flows, measures must be taken to prevent zero-phase current, but both the primary and secondary sides can output active power and reactive power.

[0011] In this method, since a common power supply is used for the primary and secondary sides, half of the voltage command value is output from each of the inverters INV1 and INV2.

[0012] Next, Figure 28 shows a power conversion device with an isolated power supply type dual inverter. In Figure 28, M is a motor with open-end structure windings, INV1 is the primary-side inverter, and INV2 is the secondary-side inverter, which sandwich the stator winding of motor M, but with this method, two isolated power supplies are placed on the primary and secondary sides, respectively. The need to prepare two isolated power supplies raises concerns about an increase in size, but it has the advantage that zero-phase current does not flow and that both the primary and secondary sides can output active power and reactive power.

[0013] In this method, the primary and secondary sides are driven by separate power supplies (voltages), so the output is determined according to the voltage ratio. For example, if the voltage V of the primary power supply is dc1 is the voltage of the secondary power supply, V dc2 If the voltage command value is 1 / 2 of the voltage command value, the primary side inverter INV1 outputs 1 / 3 of the voltage command value, and the secondary side inverter INV2 outputs 2 / 3 of the voltage command value.

[0014] Next, Figure 29 shows a floating capacitor type dual inverter power conversion device. In Figure 29, M is a motor with open-end structure windings, INV1 is the primary side inverter, and INV2 is the secondary side inverter, which sandwich the stator winding of motor M, but in this method, a floating capacitor C is placed in the secondary side inverter, and the secondary side voltage is controlled by charging and discharging the capacitor from the motor side.

[0015] The floating capacitor method has the advantage that the secondary side voltage can be controlled and no zero-phase current flows, but on the other hand, it is necessary to prepare an additional drive power supply to drive the switching elements of the secondary side inverter.

[0016] In addition, since the power supply for the secondary inverter is a capacitor, it can only supply reactive power. Therefore, the primary inverter INV1 outputs the active voltage of the voltage command value, and the secondary inverter INV2 outputs the reactive voltage. In addition, the reactive voltage that cannot be output by the secondary inverter INV2 is also borne by the primary inverter INV1.

[0017] Here, the above active power is P, reactive power is Q, and active voltage is V real , reactive voltage is V imag Then, the relationship between them is as shown in the vector diagram of FIG. 30 and is defined by the following formulas (I) to (III). That is, the apparent power S is proportional to the motor current I as shown in formula (I). m and the motor applied voltage V m It is defined as the product (cross product for vectors) of

[0018] Also, the effective power P is calculated by the motor applied voltage V as shown in formula (II). m Motor current I m The effective voltage V real and the motor current I m Furthermore, the reactive power Q is defined as the product of the motor applied voltage V as shown in formula (III). m Motor current I m The reactive voltage V is the component perpendicular to the imag and the motor current Im It is defined as the product of

[0019]

number

[0020] In the floating capacitor type dual inverter power conversion device shown in Figure 29, as described above, the primary side inverter INV1 can output active power P and reactive power Q, and the secondary side inverter INV2 can output only reactive power Q, so with control as shown in the block diagram of Figure 31, the voltage command values ​​of the primary side inverter INV1 and secondary side inverter INV2 are distributed using the following formulas (IV) and (V) to drive the motor M.

[0021]

number

[0022] In addition, in Figure 31, formula (IV) and formula (V), v d ref is the d-axis voltage command value, v q ref is the q-axis voltage command value, i d is the d-axis current, i q is the q-axis current, θ Im is the motor current phase, v d1 ref is the d-axis voltage command value of the primary inverter INV1, v q1 ref is the q-axis voltage command value of the primary inverter INV1, v d2 ref is the d-axis voltage command value of the secondary inverter INV2, v q2 ref is the q-axis voltage command value of the secondary side inverter INV2.

[0023] Furthermore, in a floating capacitor type dual inverter power conversion device, in addition to driving the motor M, it is necessary to control the DC link voltage of the secondary side inverter INV2, i.e., the secondary side voltage Vdc2, which adds the component of the voltage vector required to charge the capacitor C.

[0024] In this case, the floating capacitor type dual inverter power conversion device does not have a zero-phase current, so the motor current I m and the voltage vector, the secondary voltage V dc2 That is, as shown in FIG. 32, the phase difference of the voltage vector between the primary inverter INV1 and the secondary inverter INV2 is controlled to control the secondary voltage V dc2 Control the charging and discharging modes of the battery.

[0025] Specifically, when the output voltage vector V2 of the secondary inverter INV2 is advanced by 90 degrees relative to the current phase and brought closer to the current phase (+β), the charging mode is achieved, and when the phase is further advanced (-β), the discharging mode is achieved. In addition to this method, there are many other ways to create a phase difference and distribute vectors. This type of floating capacitor-type dual inverter power conversion device has the advantage of being able to drive the motor M while boosting the capacitor C provided in the secondary inverter INV2, thereby enabling the voltage that can be applied to the motor M to be even higher than with a common power supply type.

[0026] However, the conventional dual inverter power conversion devices described above all require a large number of components, making it difficult to reduce cost and size. In particular, in a floating capacitor type dual inverter power conversion device, the secondary inverter INV2 has a floating potential, so it is necessary to create a gate drive power supply (isolated power supply) for the switching elements of the secondary inverter INV2, which has a different reference potential, in addition to the gate drive power supply for the switching elements of the primary inverter INV1. This makes it difficult to adopt this type of power conversion device in devices with limited board area, such as automotive electric compressors, due to the component mounting area and cost considerations.

[0027] Therefore, the applicant previously proposed a power conversion device as shown in Figure 1. In this system, the positive side power supply line of the common power supply type shown in Figure 27 is separated between the primary side inverter INV1 and the secondary side inverter INV2, and only the negative side power supply line is shared, with a capacitor placed on the secondary side as in the floating capacitor type shown in Figure 29. Hereinafter, a power conversion device of this type will be referred to as a GND common type dual inverter. In this system, the secondary side voltage can be controlled in the same way as the floating capacitor type dual inverter power conversion device described in Figures 30 to 32.

[0028] Furthermore, in a common GND type dual inverter power conversion device, it is possible to share the power supply for the drive circuit of the secondary-side inverter INV2, just like in the common power supply type.The primary-side inverter INV1 on the power supply side can be configured with high-voltage components, and the controllable secondary-side inverter INV2 can be configured with low-voltage components.The common GND type, which can share the power supply for the drive circuit of the secondary-side inverter INV2 with the primary-side inverter INV1, has great advantages in applications where the power supply voltage fluctuates greatly.

[0029] However, such a common-ground dual inverter power conversion device requires zero-phase current control due to the flow of zero-phase current. This means that secondary-side voltage control, like that of the floating capacitor inverter, cannot be applied due to the nature of the zero-phase current. Furthermore, the need to simultaneously control the secondary-side voltage and the motor requires complex control. Furthermore, like the floating capacitor inverter, the primary-side inverter INV1 can output both the active and reactive voltages of the voltage command value, while the secondary-side inverter INV2 can only output the reactive voltage. However, until now, a common-ground control theory for driving a motor with an open-end winding structure while stably controlling the secondary-side voltage has not been established.

[0030] The present invention has been made to solve the above-mentioned conventional technical problems, and provides a power conversion device that can stably control the secondary side voltage of the above-mentioned common GND type dual inverter while improving responsiveness and driving a motor having open-end structure windings. [Means for solving the problem]

[0031] In order to stably control the power conversion device of the above-mentioned common GND type dual inverter, the existing vector control of dq axis current as shown in Figure 26 is applied to the control of the secondary side voltage, and modeling is performed, and feedforward control is also introduced.

[0032] That is, the power conversion device of the present invention comprises a primary inverter connected to one end of an open-ended winding of a motor, and a secondary inverter connected to the other end of the winding, and applies a differential voltage between the primary inverter and the secondary inverter to the motor, the primary inverter being connected to a DC power source, the secondary inverter being connected to a capacitor, the negative power supply lines of the primary inverter and the secondary inverter being common, and the secondary voltage V, which is the charging voltage of the capacitor, dc2 The control device controls the secondary voltage V dc2 is the secondary voltage command value V dc2 ref The zero-phase voltage command value v that flows the secondary DC link current required to control z ref This secondary voltage control system generates a secondary voltage command value V dc2 ref and the primary voltage V dc1 Based on this, the zero-phase voltage command value v z ref The feedforward control amount v z refFF , or the control variable v to derive it m ref The present invention is characterized by having a feedforward control section that outputs:

[0033] A power conversion device of a second invention is characterized in that in the above invention, the primary side inverter and the secondary side inverter are each composed of upper and lower arm switching elements of each phase connected in series, the positive side input terminal of the primary side inverter is connected to a positive side power supply line of the DC power supply, the negative side input terminal of the primary side inverter is connected to a negative side power supply line of the DC power supply, the output terminal of the primary side inverter is connected to one end of a winding, the output terminal of the secondary side inverter is connected to the other end of the winding, a capacitor is connected between the positive side input terminal and the negative side input terminal of the secondary side inverter, the positive side input terminal of the secondary side inverter is not connected to the positive side power supply line of the DC power supply, and the negative side input terminal of the secondary side inverter is connected to the negative side power supply line of the DC power supply, and the control device generates an AC output from the DC power supply by switching on and off the upper and lower arm switching elements of each phase.

[0034] In a power conversion device according to a third aspect of the present invention, the secondary voltage control system further includes a feedback control unit, and the feedback control unit controls the secondary voltage V dc2 a secondary voltage control unit that generates a secondary DC link current command value required to control the secondary DC link current; and a zero-phase voltage command value v based on the secondary DC link current command value and the secondary DC link current to control the secondary DC link current to the secondary DC link current command value. z ref Feedback control amount v z refFB The secondary DC link current control unit outputs the

[0035] In the power conversion device of the fourth invention, in the above invention, the control device employs a capacitor current flowing through the capacitor as the secondary side DC link current, or employs a zero-phase current i z The present invention is characterized by the adoption of the following.

[0036] The power conversion device of the fifth invention is the power conversion device of the above inventions, wherein the secondary side voltage control system is a feedforward control variable v z refFF The zero-phase voltage command value v z ref, or feedforward control amount v z refFF to the feedback control amount v z refFB The zero-phase voltage command value v obtained by adding z ref Based on this, the primary side output voltage command value v for switching the primary side inverter is uvw1 ref and the secondary-side output voltage command value v for switching the secondary-side inverter. uvw2 ref The present invention is characterized in that it further comprises an output voltage command generating unit that generates an output voltage command.

[0037] In the power conversion device of the sixth invention, in the above invention, the output voltage command generating unit generates a dq-axis voltage command value v dq ref The primary side output voltage vector command value and the secondary side output voltage vector command value are generated from the primary side output voltage vector command value, and the primary side output voltage command value v uvw1 ref is generated, and the secondary output voltage command value v is calculated from the secondary output voltage vector command value. uvw2 ref and the zero-phase voltage command value v is generated as the primary side output voltage vector command value and / or the secondary side output voltage vector command value. z ref By adding uvw1 ref and the secondary output voltage command value v uvw2 ref The present invention is characterized by generating

[0038] The power conversion device of the seventh aspect of the present invention is the power conversion device of the above aspect, wherein the control device controls the primary side output voltage command value v uvw1 ref a primary-side modulator that generates a primary-side inverter switching signal for switching the primary-side inverter from the secondary-side output voltage command value v uvw2 ref The inverter further comprises a secondary side modulation section for generating a secondary side inverter switching signal for switching the secondary side inverter from the inverter.

[0039] The power conversion device of the eighth invention is characterized in that in the second invention, the control device has a primary side modulation unit that generates a primary side inverter switching signal for switching the primary side inverter, and a secondary side modulation unit that generates a secondary side inverter switching signal for switching the secondary side inverter, and the primary side modulation unit or the secondary side modulation unit performs two-phase modulation in which an upper arm switching element of one phase is turned on to stop switching, or a lower arm switching element of one phase is turned on to stop switching.

[0040] In a power conversion device according to a ninth aspect of the present invention, in the above-mentioned invention, the primary side modulation unit or the secondary side modulation unit is configured to provide a primary side output voltage command value v for each phase for switching the primary side inverter in two-phase modulation. uvw1 ref , or the secondary-side output voltage command value v of each phase for switching the secondary-side inverter uvw2 ref The same primary side zero-phase voltage command value v z1 ref , or secondary side zero-phase voltage command value v z2 ref The modulation value V com By adding as above, the primary side output voltage command value v uvw1 ref , or secondary output voltage command value v uvw2 ref The upper arm switching element of the phase where v is the maximum is turned on to stop switching, or the primary side output voltage command value v uvw1 ref , or secondary output voltage command value v uvw2 ref The lower arm switching element of the phase in which the value of the current is smallest is turned on to stop switching.

[0041] The power conversion device of the tenth aspect of the invention is the power conversion device of the above aspect, wherein the primary side modulation unit is configured to input a primary side zero-phase voltage command value v z1 ref The modulation value V com The primary output voltage command value v uvw1 refThe two-phase modulation is performed by adding to the zero-phase voltage command value v z ref The feedforward control amount v z refFF The control variable to derive is the primary side output voltage command value v uvw1 ref The primary output voltage swing V m ref It is characterized in that:

[0042] In the power conversion device of the eleventh aspect of the present invention, in the above-mentioned invention, the secondary side voltage control system is z1 ref The secondary side zero-phase voltage command value v z2 ref The ripple component cancellation control unit generates the dq-axis voltage command value v dq ref The secondary side output voltage vector command value generated based on the secondary side zero-phase voltage command value v z2 ref is added to obtain the secondary output voltage command value v uvw2 ref The present invention is characterized by generating

[0043] In the power conversion apparatus of the twelfth aspect of the present invention, in the above-mentioned invention, the ripple component cancellation control section is z1 ref and the primary side output voltage amplitude V m ref Based on this, the secondary side zero-phase voltage command value v z2 ref The method is characterized by calculating and outputting the following.

[0044] The power conversion device of the thirteenth aspect of the present invention is the power conversion device of the eleventh aspect of the present invention, wherein the ripple component cancellation control unit is configured to receive the primary side zero-phase sequence voltage command value v via a low-pass filter. z1 ref and the primary side zero-phase voltage command value v z1 ref The difference between this and the secondary side zero-phase voltage command value v z2 ref The present invention is characterized in that it outputs the signal as

[0045] A power conversion device according to a fourteenth aspect of the present invention is any of the eleventh to thirteenth aspects, wherein the secondary voltage control system further includes a feedback control unit, and the feedback control unit controls the secondary voltage V dc2 a secondary voltage control unit that generates a secondary DC link current command value required to control the secondary DC link current; and a zero-phase voltage command value v based on the secondary DC link current command value and the secondary DC link current to control the secondary DC link current to the secondary DC link current command value. z ref Feedback control amount v z refFB The secondary DC link current control unit outputs a feedback control amount v z refFB , the secondary side zero-phase voltage command value v z2 ref The present invention is characterized in that it adds to

[0046] In the power conversion device of the fifteenth aspect of the present invention, the control device controls a secondary side voltage command value V dc2 ref The feature is that it has a function of limiting the rate of change of [Effects of the Invention]

[0047] According to the present invention, in a power conversion device that includes a primary side inverter connected to one end of an open-ended winding of a motor and a secondary side inverter connected to the other end of the winding, and that applies the differential voltage between the primary side inverter and the secondary side inverter to the motor, the primary side inverter is connected to a DC power supply, the secondary side inverter is connected to a capacitor, and the negative side power supply lines of the primary side inverter and the secondary side inverter are shared, thereby using the above-mentioned common GND dual inverter, the capacitor is charged by the secondary side inverter from the DC power supply via the motor, and AC output is applied to the motor using the voltage charged in the capacitor by the secondary side inverter, making it possible to expand the drivable range in response to changes in input voltage.

[0048] Furthermore, in a power conversion device with a common GND dual inverter, as in the second invention, the positive input terminal of the secondary inverter is not connected to the positive power line of the DC power supply, and the negative input terminal of the secondary inverter is connected to the negative power line of the DC power supply, so the secondary inverter does not have a floating potential, and the reference voltages of the primary inverter and the secondary inverter are aligned.

[0049] This eliminates the need to create a gate drive power supply (insulated power supply) for the switching elements of the secondary inverter separately from the gate drive power supply (insulated power supply) for the switching elements of the primary inverter, and the switching elements of the primary inverter and the switching elements of the secondary inverter can be switched using a common gate drive power supply, making it possible to expand the drivable range in response to changes in input voltage without using a separate boost converter, etc.

[0050] Furthermore, since there is no longer a need to create a gate drive power supply for each inverter, the increase in component mounting area can be suppressed, and miniaturization and cost reduction can be achieved. This is extremely effective for devices such as automotive electric compressors, where the input voltage varies greatly, there is a strong demand for cost reduction, and the board area is limited, requiring the power conversion device to be miniaturized.

[0051] Furthermore, in the present invention, the secondary voltage V dc2 A control device is provided to control the secondary voltage V dc2 is the secondary voltage command value V dc2 ref The zero-phase voltage command value v that flows the secondary DC link current required to control z ref Since the secondary voltage control system is configured to generate the secondary voltage V dc2 This allows modeling and control system design of the secondary voltage V dc2 This makes it possible to design the response of the secondary voltage and motor drive control in a stable manner.

[0052] In particular, the secondary voltage V dc2 In this invention, the secondary voltage command value V dc2 ref and the primary voltage V dc1 Based on this, the zero-phase voltage command value v z ref The feedforward control amount v z refFF , or the control variable v to derive it m ref Since a feedforward control section that outputs the above is provided, it is possible to realize even faster response by feedforward control.

[0053] In addition, as in the third aspect of the present invention, a feedback control section is further provided in the secondary voltage control system, and the feedback control section is configured to control the secondary voltage V dc2 a secondary voltage control unit that generates a secondary DC link current command value required to control the secondary DC link current; and a zero-phase voltage command value v based on the secondary DC link current command value and the secondary DC link current to control the secondary DC link current to the secondary DC link current command value. z ref Feedback control amount v z refFB By providing a secondary DC link current control unit that outputs the above, it becomes possible to prevent runaway of the secondary DC link current by feedback control.

[0054] This makes it possible to perform feedforward control by the feedforward control unit and feedback control by the feedback control unit in parallel, thereby realizing a power conversion device that combines the high-speed response performance of feedforward control with the disturbance suppression performance of feedback control, and is therefore both responsive and accurate.

[0055] In the above case, the control device uses the capacitor current flowing through the capacitor as the secondary side DC link current as in the fourth aspect of the invention, or uses the zero-phase current i as an index showing the secondary side DC link current. zThe capacitor current is the secondary DC link current itself, and the zero-phase current i z However, when using the capacitor current, a separate sensor is required to detect the current flowing through the capacitor. z If so, each phase current i uvw The control device can detect this.

[0056] Furthermore, as in the fifth aspect of the present invention, the secondary voltage control system is z refFF The zero-phase voltage command value v z ref , or feedforward control amount v z refFF to the feedback control amount v z refFB The zero-phase voltage command value v obtained by adding z ref Based on this, the primary side output voltage command value v for switching the primary side inverter is uvw1 ref and the secondary-side output voltage command value v for switching the secondary-side inverter. uvw2 ref The output voltage command generating unit generates the dq-axis voltage command value v as in the sixth aspect of the present invention. dq ref The primary side output voltage vector command value and the secondary side output voltage vector command value are generated from the primary side output voltage vector command value, and the primary side output voltage command value v uvw1 ref is generated, and the secondary output voltage command value v is calculated from the secondary output voltage vector command value. uvw2 ref and the zero-phase voltage command value v is generated as the primary side output voltage vector command value and / or the secondary side output voltage vector command value. z ref By adding uvw1 ref and the secondary output voltage command value v uvw2 refBy using a configuration that generates the above, it is possible to realize more stable secondary side voltage control and motor drive control.

[0057] In this case, as in the seventh aspect of the present invention, the control device controls the primary side output voltage command value v uvw1 ref a primary-side modulator that generates a primary-side inverter switching signal for switching the primary-side inverter from the secondary-side output voltage command value v uvw2 ref The secondary side inverter may further include a secondary side modulation section that generates a secondary side inverter switching signal for switching the secondary side inverter from the secondary side inverter.

[0058] Furthermore, as in the eighth aspect of the present invention, if the primary side modulation unit or secondary side modulation unit of the control device performs two-phase modulation in which the upper arm switching element of one phase is turned on to stop switching, or the lower arm switching element of one phase is turned on to stop switching, the number of times the upper and lower arm switching elements of the primary side inverter or secondary side inverter are switched can be reduced compared to the case of three-phase modulation, thereby significantly reducing switching losses and suppressing heat generation.

[0059] In this case, as in the ninth aspect of the present invention, the primary side modulation unit or the secondary side modulation unit is used for two-phase modulation, and the primary side output voltage command value v uvw1 ref , or the secondary-side output voltage command value v of each phase for switching the secondary-side inverter uvw2 ref The same primary side zero-phase voltage command value v z1 ref , or secondary side zero-phase voltage command value v z2 ref The modulation value V com By adding as above, the primary side output voltage command value v uvw1 ref , or secondary output voltage command value v uvw2 refThe upper arm switching element of the phase where v is the maximum is turned on to stop switching, or the primary side output voltage command value v uvw1 ref , or secondary output voltage command value v uvw2 ref The lower arm switching element of the phase where the value of is smallest is turned on to stop switching.

[0060] In addition, as in the tenth aspect of the present invention, the primary side modulation unit z1 ref The modulation value V com The primary output voltage command value v uvw1 ref When two-phase modulation is performed by adding to the zero-phase voltage command value v z ref The feedforward control amount v z refFF The control variable to derive is the primary side output voltage command value v uvw1 ref The primary output voltage swing V m ref This becomes:

[0061] On the other hand, when the primary side modulation unit performs two-phase modulation as described above, the primary side zero-phase voltage command value v z1 ref Therefore, as in the eleventh aspect of the present invention, the primary side zero-phase sequence voltage command value v z1 ref The secondary side zero-phase voltage command value v z2 ref A ripple component cancellation control unit is provided to generate the dq-axis voltage command value v dq ref The secondary side output voltage vector command value generated based on the secondary side zero-phase voltage command value v z2 ref is added to obtain the secondary output voltage command value v uvw2 ref By generating the primary side zero-phase voltage command value v z1 refThis compensates for the ripple component of the rectifier, making it possible to suppress the generation of electromagnetic noise and noise due to the ripple current.

[0062] In this case, as in the twelfth aspect of the present invention, the ripple component cancellation control section controls the primary side zero-phase voltage command value v z1 ref and the primary side output voltage amplitude V m ref Based on this, the secondary side zero-phase voltage command value v z2 ref This allows instantaneous compensation for the ripple component.

[0063] In addition, as in the thirteenth aspect of the present invention, the ripple component cancellation control section outputs the primary side zero-phase voltage command value v via a low-pass filter. z1 ref and the primary side zero-phase voltage command value v z1 ref The difference between this and the secondary side zero-phase voltage command value v z2 ref This makes it possible to compensate for the ripple component with a relatively simple configuration.

[0064] In addition, as in the fourteenth aspect of the present invention, a feedback control section is further provided in the secondary voltage control system, and the feedback control section is configured to control the secondary voltage V dc2 a secondary voltage control unit that generates a secondary DC link current command value required to control the secondary DC link current; and a zero-phase voltage command value v based on the secondary DC link current command value and the secondary DC link current to control the secondary DC link current to the secondary DC link current command value. z ref Feedback control amount v z refFB A secondary DC link current control unit is provided to output a feedback control amount v z refFB , the secondary side zero-phase voltage command value v z2 ref By adding this to the feedback control, it becomes possible to prevent runaway of the secondary DC link current.

[0065] This makes it possible to perform feedforward control by the feedforward control unit and feedback control by the feedback control unit in parallel, thereby realizing a power conversion device that combines the high-speed response performance of feedforward control with the disturbance suppression performance of feedback control, and is therefore both responsive and accurate.

[0066] Here, when performing the above feedforward control, the secondary voltage command value V dc2 ref When the secondary voltage V changes, the high-speed response dc2 Therefore, as in the fifteenth aspect of the present invention, the control device controls the secondary side voltage command value V dc2 ref If the secondary voltage V dc2 This reduces the excitation of vibrations, making it possible to achieve both high responsiveness and low vibration. [Brief explanation of the drawings]

[0067] [Figure 1] 1 is an electrical circuit diagram of a common-GND dual inverter power conversion device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of a control device for the power conversion device of FIG. [Figure 3] 2 is a diagram illustrating an equivalent circuit of a zero-phase sequence component of the power conversion device of FIG. 1. FIG. [Figure 4] FIG. 2 is a diagram showing a model of secondary voltage control (feedforward control) of the power conversion device of FIG. 1 (Example 1). [Figure 5] 3 is a block diagram of a secondary side voltage control system, a primary side modulation unit, and a secondary side modulation unit in FIG. 2. FIG. [Figure 6] 10A and 10B are diagrams illustrating voltage command values ​​and voltages when feedforward control is not executed. [Figure 7] 7 is an enlarged view of FIG. 6 showing a change in the secondary side voltage when the secondary side voltage command value is changed. [Figure 8] 3 is a diagram showing voltage command values ​​and voltages when the control device of FIG. 2 executes feedforward control. FIG. [Figure 9] 9 is an enlarged view of FIG. 8 showing a change in the secondary-side voltage when the secondary-side voltage command value is changed. [Figure 10] FIG. 9 is a diagram showing a state after vibration countermeasures have been implemented in FIG. 8. [Figure 11] 11 is an enlarged view of FIG. 10 showing a change in the secondary side voltage when the secondary side voltage command value is changed. [Figure 12] FIG. 2 is a diagram showing a model of secondary-side voltage control (feedback control) of the power conversion device of FIG. 1 (Example 2). [Figure 13] 3 is a block diagram of the secondary-side voltage control system, primary-side modulation unit, and secondary-side modulation unit of FIG. 2 when a feedback control unit is added. [Figure 14] FIG. 3 is a block diagram of the secondary-side voltage control system, primary-side modulation unit, and secondary-side modulation unit of FIG. 2 when two-phase modulation is performed in the primary-side inverter (third embodiment). [Figure 15] 15 is a diagram for explaining superscript two-phase modulation performed in the primary side inverter of FIG. 14. FIG. [Figure 16] 15 is a diagram for explaining superscript two-phase modulation performed in the primary side inverter of FIG. 14. FIG. [Figure 17] 15 is a diagram for explaining superscript two-phase modulation performed in the primary side inverter of FIG. 14. FIG. [Figure 18] 15 is a diagram for explaining subscript two-phase modulation performed in the primary side inverter of FIG. 14. FIG. [Figure 19] 15 is a diagram for explaining the subscript two-phase modulation performed in the primary side inverter of FIG. 14. FIG. [Figure 20] 15 is a diagram for explaining the subscript two-phase modulation performed in the primary side inverter of FIG. 14. FIG. [Figure 21] 15 is a diagram showing voltage command values ​​and voltages when the feedforward control of the control device of FIG. 2 is executed in the case of FIG. 14. FIG. [Figure 22] 22 is an enlarged view of FIG. 21 showing a change in the secondary side voltage when the secondary side voltage command value changes. FIG. [Figure 23] FIG. 22 is a diagram showing the state of FIG. 21 after vibration countermeasures have been implemented. [Figure 24] FIG. 24 is an enlarged view of FIG. 23 showing a change in the secondary side voltage when the secondary side voltage command value changes. [Figure 25] FIG. 15 is a block diagram of the secondary-side voltage control system, primary-side modulation unit, and secondary-side modulation unit of FIG. 2 when a feedback control unit is added in FIG. 14 (Example 4). [Figure 26] FIG. 1 is a diagram illustrating a model of vector control of a general power conversion device. [Figure 27] FIG. 1 is an electrical circuit diagram of a conventional common power supply type dual inverter power conversion device. [Figure 28] FIG. 1 is an electrical circuit diagram of a conventional insulated power supply type dual inverter power conversion device. [Figure 29] FIG. 1 is an electrical circuit diagram of a conventional floating capacitor type dual inverter power conversion device. [Figure 30] 30 is a diagram defining active power, reactive power, active voltage and reactive voltage for explaining the operation of the floating capacitor type dual inverter power conversion device of FIG. 29. FIG. [Figure 31] FIG. 30 is a block diagram for explaining a drive control method for the floating capacitor type dual inverter power conversion device of FIG. 29. [Figure 32] 30 is a diagram for explaining a charging mode and a discharging mode of the capacitor of the floating capacitor type dual inverter power conversion device of FIG. 29. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0068] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0069] (1) Power conversion device 1 1 is an electrical circuit diagram of a power conversion device 1 of a common-GND type dual inverter according to an embodiment of the present invention. The power conversion device 1 of the embodiment converts a DC voltage V dc(for example, DC 500V) is converted into a three-phase AC voltage (AC output) and supplied to the motor M. The motor M in this embodiment is a three-phase interior permanent magnet synchronous motor that is composed of a stator with windings and a rotor with a built-in magnet that rotates inside the stator, and drives an electric compressor used in an air conditioning system for electric vehicles such as electric cars and hybrid cars. dc is the primary voltage V dc1 is.

[0070] In this embodiment, the power conversion device 1 is configured with a three-phase primary-side inverter INV1 consisting of upper and lower arm switching elements 3A to 3F, a secondary-side inverter INV2 also consisting of upper and lower arm switching elements 4A to 4F, a control device 6 (FIG. 2), etc. In this embodiment, each of the switching elements 3A to 3F and 4A to 4F is configured with an insulated gate bipolar transistor (IGBT) incorporating a MOS structure in the gate portion.

[0071] In this invention, the DC voltage V of the DC power supply 2 is generated by the primary side inverter INV1 and the secondary side inverter INV2. dc is converted into a three-phase AC voltage (AC output), and the difference voltage between the primary inverter INV1 and the secondary inverter INV2 is applied to the windings (stator windings) 7U, 7V, and 7W of the motor M. Here, the windings 7U, 7V, and 7W of the motor M have an open-end structure that is not bundled at the neutral point.

[0072] (2) Primary side inverter INV1 The primary-side inverter INV1 has a U-phase half-bridge circuit 9U, a V-phase half-bridge circuit 9V, and a W-phase half-bridge circuit 9W, and each of the half-bridge circuits 9U to 9W has the upper-arm switching elements 3A to 3C and lower-arm switching elements 3D to 3F described above. Furthermore, each of the switching elements 3A to 3F has a built-in freewheeling diode connected in antiparallel.

[0073] The collector electrodes of the upper arm switching elements 3A to 3C, which are the positive input terminals of the primary side inverter INV1, are connected to a positive side power supply line 11 (HV+) of the DC power supply 2. On the other hand, the emitter electrodes of the lower arm switching elements 3D to 3F, which are the negative input terminals of the primary side inverter INV1, are connected to a negative side power supply line 12 (HV-) of the DC power supply 2. In the figure, reference numeral 13 denotes a capacitor connected between the positive side power supply line 11 and the negative side power supply line 12, which constitutes a noise filter.

[0074] The primary side inverter INV1 is connected to the emitter electrode of the upper arm switching element 3A and the collector electrode of the lower arm switching element 3D of the U-phase half bridge circuit 9U, and their connection point (arm midpoint: output terminal of the primary side inverter INV1) is connected to one end of the U-phase winding 7U of the motor M.

[0075] In addition, the emitter electrode of the upper arm switching element 3B and the collector electrode of the lower arm switching element 3E of the V-phase half-bridge circuit 9V are connected, and their connection point (arm midpoint: output terminal of the primary side inverter INV1) is connected to one end of the V-phase winding 7V of the motor M.

[0076] Furthermore, the emitter electrode of the upper arm switching element 3C and the collector electrode of the lower arm switching element 3F of the W-phase half-bridge circuit 9W are connected, and their connection point (arm midpoint: output terminal of the primary side inverter INV1) is connected to one end of the W-phase winding 7W of the motor M.

[0077] (3) Secondary side inverter INV2 The secondary-side inverter INV2 also includes three half-bridge circuits 16U, 16V, and 16W corresponding to the UV phases. The neutral points of the phases of the motor M are not bundled together, and the windings 7U to 7W of the motor M are sandwiched between the half-bridge circuits 9U to 9W of the primary-side inverter INV1 and the half-bridge circuits 16U to 16W of the secondary-side inverter INV2.

[0078] The half-bridge circuits 16U to 16W of the secondary-side inverter INV2 also have upper-arm switching elements 4A to 4C and lower-arm switching elements 4D to 4F, respectively. Each of the switching elements 4A to 4F also has a built-in freewheeling diode connected in antiparallel.

[0079] A capacitor C is connected between the collector electrodes of the upper arm switching elements 4A to 4C, which are the positive input terminals of the secondary inverter INV2, and the emitter electrodes of the lower arm switching elements 4D to 4F, which are the negative input terminals of the secondary inverter INV2.

[0080] However, the collector electrodes of the upper arm switching elements 4A to 4C, which are the positive input terminals of the secondary side inverter INV2, are not connected to but separated from the positive power supply line 11 of the DC power supply 2. On the other hand, in the present invention, the emitter electrodes of the lower arm switching elements 4D to 4F, which are the negative input terminals of the secondary side inverter INV2, are connected to the negative power supply line 12 of the DC power supply 2.

[0081] The emitter electrode of the upper arm switching element 4A and the collector electrode of the lower arm switching element 4D of the U-phase half-bridge circuit 16U are connected, and their connection point (arm midpoint: output terminal of the secondary side inverter INV2) is connected to the other end of the U-phase winding 7U of the motor M.

[0082] In addition, the emitter electrode of the upper arm switching element 4B and the collector electrode of the lower arm switching element 4E of the V-phase half-bridge circuit 16V are connected, and their connection point (arm midpoint: output terminal of the secondary side inverter INV2) is connected to the other end of the V-phase winding 7V of the motor M.

[0083] Furthermore, the emitter electrode of the upper arm switching element 4C and the collector electrode of the lower arm switching element 4F of the W-phase half-bridge circuit 16W are connected, and their connection point (arm midpoint: output end of the secondary-side inverter INV2) is connected to the other end of the W-phase winding 7W of the motor M. In other words, the power conversion device 1 of the present invention has the above-mentioned common-GND dual inverter configuration.

[0084] (4) Control device 6 2 shows a block diagram of the control device 6. The control device 6 of the embodiment is composed of a microcomputer having a processor, and receives a speed command value ω rm ref and the secondary voltage command value V dc2 ref and the phase current of the motor M is input from a current sensor (not shown), and based on these, the ON / OFF states of the switching elements 3A to 3F and 4A to 4F of the primary inverter INV1 and the secondary inverter INV2 are controlled (switching).

[0085] Specifically, it controls the gate voltages applied to the gates of the switching elements 3A to 3F and 4A to 4F. The control device 6 of the embodiment includes a speed control unit 21, a dq-axis current control unit 22, a secondary side voltage control system 23, a primary side modulation unit 24, a secondary side modulation unit 26, etc.

[0086] The speed control unit 21 performs PI calculation and q-axis current i q The q-axis current command value i q ref The dq-axis current control unit 22 calculates and outputs the d-axis voltage command value v d ref and the q-axis voltage command value v q ref In this case, the d-axis current control unit 22 basically calculates and outputs the d-axis current command value i d ref and d-axis current i d (estimated value), q-axis current command value i q ref and q-axis current iq The d-axis voltage command value v in the direction that eliminates the deviation from the (estimated value) d ref and the q-axis voltage command value v q ref is calculated.

[0087] The secondary voltage control system 23 controls the secondary voltage V dc2 is the secondary voltage command value V dc2 ref The secondary DC link current required for controlling the z The zero-phase voltage command value v z ref Then, the d-axis current i d (estimated value) and q-axis current i q (estimated value), the d-axis voltage command value v output by the dq-axis current control unit 22 d ref and the q-axis voltage command value v q ref , the zero-phase voltage command value v z ref The primary side output voltage command value v for switching each of the switching elements 3A to 3F of the primary side inverter INV1 is u1 ref , v v1 ref , v w1 ref and a secondary-side output voltage command value v for switching each of the switching elements 4A to 4F of the secondary-side inverter INV2. u2 ref , v v2 ref , v w2 ref The configuration and operation of the secondary side voltage control system 23 will be described in detail later.

[0088] In this embodiment, the primary side modulation unit 24 modulates the primary side output voltage command value v u1 ref , v v1 ref , v w1 refThe inverter circuit 100 generates and outputs primary-side inverter switching signals (PWM signals) for performing typical three-phase modulation to switch (PWM control) each of the switching elements 3A to 3F of the primary-side inverter INV1.

[0089] In this embodiment, the secondary side modulation unit 26 also converts the secondary side output voltage command value v u2 ref , v v2 ref , v w2 ref The inverter circuit 100 generates and outputs secondary-side inverter switching signals (PWM signals) for switching (PWM-controlling) each of the switching elements 4A to 4F of the secondary-side inverter INV2 by performing general three-phase modulation from the inverter circuit 100.

[0090] (5) Secondary voltage control system 23 Next, the detailed configuration and operation of secondary side voltage control system 23 of the embodiment will be described with reference to Figures 3 to 11. In this embodiment, secondary side voltage control system 23 is configured to include a secondary side voltage / zero-phase voltage command conversion unit 27 and an output voltage command generation unit 29.

[0091] Here, the equivalent circuit of the zero-phase component of the power conversion device 1 in FIG. 1 is shown in the lower part of FIG. 3. This equivalent circuit in the lower part of FIG. 3 can be regarded as a chopper circuit of a step-down chopper and a step-up chopper. dc1 is the primary voltage mentioned above, which is the DC voltage of the DC power supply 2. dc2 is the capacitance of the capacitor C, and L z is the self-inductance of the z-axis of the motor M, R a is the internal resistance.

[0092] From this equivalent circuit, the zero-phase voltage v of the primary inverter INV1 z1 and the zero-phase voltage v of the secondary inverter INV2 z2 The zero-phase voltage v is the potential difference between z (=v z1 -v z2 ) the zero-phase current i z By controlling the secondary voltage vdc2 Therefore, the control device 6 of this embodiment can control the zero-phase current i z is used as an index of the secondary DC link current. This is the zero-phase current i z This is based on the fact that the DC link current is approximately equal to the secondary DC link current.

[0093] As mentioned above, assuming that the zero-phase component (z-axis) of the power conversion device 1 can be expressed equivalently to a chopper circuit, the feedforward control controller and the controlled object (plant model) for the power conversion device 1 in Figure 1 can be modeled as shown in Figure 4. In this case, the plant model of the controlled object is the voltage (v z -e z ) to the current (zero-phase current i z ) model (shown as 31 in the figure), we assume an LR load as in the dq axis, and the zero-phase current i z to secondary voltage V dc2 The model for e (shown as 32 in the figure) is modeled as a simple capacitor. z is the induced voltage component excited on the z-axis by the rotation of the motor M, ω re is the electrical angular velocity, θ re is the rotor position.

[0094] Regarding the control system, a feedforward control system 25 constituting a feedforward control unit 20 (FIG. 5) that controls the secondary side voltage is z ref The feedforward control amount v z refFF The feedforward control unit 20 is included in the secondary side voltage / zero-phase voltage command conversion unit 27 shown in FIG.

[0095] The feedforward control system 25 controls the secondary voltage command value V dc2 ref and the primary voltage V dc1 Based on this, the zero-phase voltage command value v is calculated using the following formula (VI). z ref The feedforward control amount v z refFFCalculate and output the G in this formula (VI). V is the secondary voltage command value V dc2 ref , the zero-phase voltage command value v z ref The feedforward control amount v z refFF This function has superior responsiveness compared to feedback control, and is calculated directly by the feedforward control system 25.

[0096]

number

[0097] The rotation of the motor M induces the induced voltage component e z The feedforward control amount v z refFF and the feedforward control unit 20 outputs the zero-phase voltage command value v z ref This makes it possible to design a controller for the power conversion device 1 of FIG.

[0098] A block diagram of the secondary voltage control system 23 designed by the above modeling is shown in Fig. 5. In the upper left of Fig. 5, the feedforward control system 25 of Fig. 4 constitutes the feedforward control unit 20 of the secondary voltage / zero-phase voltage command conversion unit 27 of Fig. 2, and this feedforward control unit 20 controls the zero-phase current i z (secondary DC link current in this invention) is expressed as the zero-phase current command value i z ref (The secondary voltage V dc2 (the secondary DC link current command value required to control the zero-phase voltage command value v z ref Output.

[0099] The block shown below is the output voltage command generating unit 29 of Fig. 2. The basic control block of this output voltage command generating unit 29 is the same as that of the floating capacitor type dual inverter power conversion device shown in Fig. 31. That is, the output voltage command generating unit 29 of this embodiment has an active / inactive decomposition unit 36, and this active / inactive decomposition unit 36 ​​calculates the d-axis voltage command value v d ref and the q-axis voltage command value v q ref , the effective voltage V real and reactive voltage V imag This effective voltage V real is an example of the primary side output voltage vector command value in the present invention, and the reactive voltage V imag is an example of a secondary side output voltage vector command value in the present invention.

[0100] The output voltage command generator 29 calculates the effective voltage V decomposed as above using the above-mentioned formula (V). real The d-axis voltage command value v of the primary inverter INV1 d1 ref The q-axis voltage command value v of the primary inverter INV1 is q1 ref is set to 0. Also, the d-axis voltage command value v of the secondary inverter INV2 d2 ref is set to 0, and the reactive voltage V imag The q-axis voltage command value v of the secondary inverter INV2 q2 ref Let's say.

[0101] Next, the dq-uvw conversion unit 37 of the output voltage command generation unit 29 converts the d-axis voltage command value v d1 ref and the q-axis voltage command value v of the primary inverter INV1. q1 ref is converted into the output voltage command values ​​of the uv and w phases of the primary inverter INV1, and the dq-uvw conversion unit 38 converts it into the d-axis voltage command value v d2 ref and the q-axis voltage command value v of the secondary inverter INV2 q2 refis converted into output voltage command values ​​for each phase uv and w of the secondary side inverter INV2.

[0102] The output voltage command generator 29 also includes a zero-phase-sequence voltage distributor 39. The zero-phase-sequence voltage distributor 39 distributes the zero-phase-sequence voltage command value v z ref to the primary inverter INV1 and the secondary inverter INV2 with a gain M1 for distributing to the primary inverter INV1 and a gain M2 for distributing to the secondary inverter INV2. Then, an adder 41 multiplies the output voltage command values ​​of the uv and w phases of the primary inverter INV1 output from the dq-uvw converter 37 by the gain M1 to obtain the zero-phase voltage command value v z ref and the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref and an adder 42 multiplies the output voltage command values ​​of the uv and w phases of the secondary inverter INV2 output from the dq-uvw conversion unit 38 by a gain M2 to obtain a zero-phase voltage command value v z ref and the secondary output voltage command value v u2 ref , v v2 ref , v w2 ref Output as

[0103] That is, the effective voltage V as the primary side output voltage vector command value real and the reactive voltage V as the secondary output voltage vector command value. imag (Actually, these are converted into output voltage command values ​​for each phase of uvw) z ref By distributing and adding these, the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref and the secondary output voltage command value v u2 ref , v v2ref , v w2 ref Generate and output.

[0104] Here, gain M1+gain M2=1. The zero-phase voltage distribution unit 39 has two cases: gain M1=1 and gain M2=0, and gain M1=0 and gain M2=1. Therefore, the zero-phase voltage command value v is added to the output voltage command values ​​of the u, v, and w phases of either one of the inverters INV1 and INV2. z ref In some cases, one is added to the other and the other is not.

[0105] Basically, the zero-phase voltage command value v z ref However, since a zero-phase voltage is added, it is better that the primary-side inverter INV1, which has a higher voltage, should bear the zero-phase voltage command value v only in the primary-side inverter INV1, taking into consideration the operating range, etc. In this case, the zero-phase voltage distribution unit 39 sets the gain M1=1 and the gain M2=0, and the zero-phase voltage command value v z ref to impose a burden.

[0106] The zero-phase voltage command value v multiplied by the gain M2 added in the adder 42 is z ref The sign of is - (i.e., subtraction) because the zero-phase voltage v z This is because it is necessary to create a potential difference of the zero-phase voltage command value v multiplied by the gain M2. z ref The negative value of is added to the output voltage command value of each uvw phase.

[0107] In this way, the output voltage command generator 29 calculates the zero-phase voltage command value v z ref Based on this, the primary side output voltage command value v for switching the primary side inverter INV1 is u1 ref , vv1 ref , v w1 ref and the secondary-side output voltage command value v for switching the secondary-side inverter INV2. u2 ref , v v2 ref , v w2 ref Generate and output.

[0108] The primary side modulator 24 modulates the primary side output voltage command value v output by the output voltage command generator 29. u1 ref , v v1 ref , v w1 ref The secondary-side modulator 26 generates and outputs a primary-side inverter switching signal (PWM signal) for performing three-phase modulation from the output voltage command generator 29 to switch (PWM control) each of the switching elements 3A to 3F of the primary-side inverter INV1. u2 ref , v v2 ref , v w2 ref The inverter circuit 100 generates and outputs secondary-side inverter switching signals (PWM signals) for performing three-phase modulation from the inverter circuit 100 to perform PWM control on the switching elements 4A to 4F of the secondary-side inverter INV2.

[0109] Next, the effect of the feedforward control by the control device 6 of the power conversion device 1 described above will be described with reference to Fig. 6 to Fig. 11. Fig. 6 is a diagram showing voltage command values ​​and voltages when feedforward control is not executed, and Fig. 7 is a diagram showing the secondary side voltage command value V dc2 ref When the secondary voltage V changes dc2 6 shows an enlarged view of the change in the voltage command value V. FIG. 8 shows the voltage command values ​​and voltages when the feedforward control of the control device 6 of FIG. 2 is executed. FIG. 9 shows the secondary side voltage command value V. dc2 ref When the secondary voltage V changes dc2 8 showing the change in .

[0110] The top row of each diagram shows the voltages v of each phase of the primary inverter INV1. u1 , v v1 , v w1 and the zero-phase voltage v z1 The second row from the top shows the voltages v of each UVW phase of the secondary inverter INV2. u2 , v v2 , v w2 and the zero-phase voltage v z2 The third row from the top shows the zero-phase voltage v of the primary inverter INV1. z1 and the zero-phase voltage v of the secondary inverter INV2 z2 The second row from the bottom shows the primary voltage (primary DC link voltage) V dc1 , the bottom row is the secondary voltage (secondary DC link voltage) V dc2 and the secondary voltage command value V dc2 ref This shows:

[0111] As is clear from a comparison of Fig. 7 and Fig. 9, when feedforward control is performed (Fig. 9), the secondary voltage command value V dc2 ref Changes in secondary voltage V dc2 It can be seen that the response is extremely high.

[0112] However, as is clear from Figure 9, the secondary voltage V dc2 Therefore, the control device 6 controls the secondary side voltage command value V dc2 ref 10 and 11. Note that FIG. 10 shows a case where the feedforward control of the control device 6 in FIG. 2 is executed and the secondary side voltage command value V dc2 ref 11 shows the voltage command values ​​and voltages when the rate of change of the secondary voltage command value V dc2 ref When the secondary voltage V changes dc2 10 showing the change in

[0113] However, this limitation is based on the secondary voltage Vdc2 This is done in a range at least faster than the change in the secondary voltage V dc2 The vibrations can be eliminated or suppressed.

[0114] As described above, according to the present invention, by configuring the power conversion device 1 as the aforementioned common-GND dual inverter, the capacitor C is charged by the secondary-side inverter INV2 from the DC power supply 2 via the motor M, and an AC output is applied to the motor M using the voltage charged in the capacitor C by the secondary-side inverter INV2, thereby making it possible to expand the drivable range in response to changes in the input voltage.

[0115] Furthermore, in the power conversion device 1 of the common GND type dual inverter, the positive input terminal of the secondary side inverter INV2 is not connected to the positive side power supply line 11 of the DC power supply 2 as in the embodiment, and the negative input terminal of the secondary side inverter INV2 is connected to the negative side power supply line 12 of the DC power supply 2, so the secondary side inverter INV2 does not have a floating potential, and the reference voltages of the primary side inverter INV1 and the secondary side inverter INV2 are the same.

[0116] This eliminates the need to create a gate drive power supply (insulated power supply) for the switching elements 4A to 4F of the secondary inverter INV2 in addition to the gate drive power supply (insulated power supply) for the switching elements 3A to 3F of the primary inverter INV1. The switching elements 3A to 3F of the primary inverter INV1 and the switching elements 4A to 4F of the secondary inverter INV2 can be switched by a common gate drive power supply, which makes it possible to expand the drivable range in response to changes in input voltage without using a separate boost converter or the like.

[0117] Furthermore, since there is no need to create a gate drive power supply for each inverter INV1, INV2, the increase in component mounting area can be suppressed, and miniaturization and cost reduction can be achieved. This is extremely effective for devices such as automotive electric compressors, where the input voltage varies greatly, there is a strong demand for cost reduction, and the board area is limited, requiring the miniaturization of the power conversion device.

[0118] Furthermore, in the present invention, the secondary voltage V, which is the charging voltage of the capacitor C, dc2 A control device 6 is provided to control the secondary voltage V dc2 is the secondary voltage command value V dc2 ref The zero-phase voltage command value v that flows the secondary DC link current required to control z ref Since the secondary voltage control system 23 is configured to generate the secondary voltage V dc2 This allows modeling and control system design of the secondary voltage V dc2 This makes it possible to design the response of the secondary voltage and drive control of the motor M in a stable manner.

[0119] In particular, the secondary voltage V dc2 and designing the control system. In the present invention, the secondary voltage control system 23 is provided with a secondary voltage command value V dc2 ref and the primary voltage V dc1 Based on this, the zero-phase voltage command value v z ref The feedforward control amount v z refFF Since the feedforward control section 20 that outputs the signal is provided, it is possible to realize even faster response by feedforward control.

[0120] In the embodiment, the control device 6 determines the secondary voltage command value V dc2 ref Since the rate of change of the secondary voltage V dc2 This reduces the excitation of vibrations, making it possible to achieve both high responsiveness and low vibration. [Example]

[0121] (6) Feedback control Next, another embodiment of the present invention will be described with reference to Figures 12 and 13. In this embodiment, the secondary side voltage V dc2 Feedback control is added to the feedforward control of Fig. 12. Fig. 12 is a diagram modeling the secondary-side voltage control (feedback control) of the power conversion device 1 of Fig. 1, and Fig. 13 is a block diagram of the secondary-side voltage control system 23, primary-side modulation unit 24, and secondary-side modulation unit 26 of Fig. 2 when a feedback control unit 30 is added.

[0122] The feedback control controller and the controlled object (plant model) of the power conversion device 1 in Fig. 1 are modeled as shown in Fig. 12. In this figure, the same reference numerals as in Fig. 4 denote the same or similar functions. In this case, the plant model of the controlled object is the same as that in Fig. 4.

[0123] On the other hand, in the control system, the voltage PI control system 33 that controls the secondary side voltage controls the zero-phase current command value i z ref and outputs the zero-phase current i z The current PI control system 34 controls the zero-phase voltage command value v z ref Feedback control amount v z refFB The rotation of the motor M generates an induced voltage component e z The decoupling voltage command value e that compensates for z est The feedback control amount v z refFB This similarly makes it possible to design a feedback control controller for the power conversion device 1 of FIG.

[0124] In addition, the secondary voltage V dc2 The control of the zero-phase current i zIn the model in Figure 12, PI control is applied, so the secondary voltage V dc2 However, the decoupling voltage command value e z est Due to parameter errors, etc., the zero-phase current i z When a ripple occurs in the secondary voltage V dc2 Since ripples are also excited, advanced current control can be achieved by adopting a controller that suppresses AC components (periodic disturbance components) from the viewpoint of voltage quality, such as periodic disturbance suppression control, sine wave tracking control, or repetitive control.

[0125] Fig. 13 shows a block diagram in which a feedback control unit 30 is added to the secondary-side voltage / zero-phase-sequence voltage command conversion unit 27 of the embodiment in Fig. 5. In the figure, the same reference numerals as in Fig. 5 denote the same or similar functions. In the upper left of Fig. 13, the feedback control unit 30 of the secondary-side voltage control system 23 in this case has a secondary-side voltage control unit 35 and a secondary-side DC link current control unit 28. The voltage PI control system 33 in Fig. 12 constitutes the secondary-side voltage control unit 35, and this secondary-side voltage control unit 35 controls the zero-phase-sequence current command value i z ref (The secondary voltage V dc2 The secondary DC link current command value required to control the

[0126] 12 constitutes the secondary DC link current control unit 28, which controls the zero-phase current i z (secondary DC link current in this invention) is expressed as the zero-phase current command value i z ref (the secondary DC link current command value in this invention) z ref Feedback control amount v z refFB Output.

[0127] In this embodiment, the current PI control system 34 constituting the secondary side DC link current control unit 28 receives the zero-phase current command value i z ref From the zero-phase current i z The current PI control system 34 of the secondary side DC link current control unit 28 receives the zero-phase current command value i z ref and zero-phase current i z The zero-phase voltage command value v in the direction to eliminate the difference z ref Feedback control amount v z refFB Calculate the zero-phase current i z is the zero-phase current command value i z ref It operates to control the

[0128] The zero-phase voltage command value v output by the feedforward control unit 20 is z ref The feedforward control amount v z refFF and the zero-phase voltage command value v output by the feedback control unit 30. z ref Feedback control amount v z refFB , the decoupling voltage command value e z est is added, and the zero-phase voltage command value v z ref From then on, the effective voltage V as the primary side output voltage vector command value is output as in the case of Fig. 5. real and the reactive voltage V as the secondary output voltage vector command value. imag (Actually, these are converted into output voltage command values ​​for each phase of uvw) z ref By distributing and adding these, the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref and the secondary output voltage command value v u2 ref , v v2ref , v w2 ref Generate and output.

[0129] As in this embodiment, a feedback control unit 30 is provided in the secondary voltage control system 23, and the feedback control unit 30 controls the secondary voltage V dc2 a secondary-side voltage control unit 35 that generates a secondary-side DC link current command value required to control the zero-phase current command value (secondary-side DC link current command value) i z ref and the zero-phase current (secondary DC link current) i z Based on this, the zero-phase current i z is the zero-phase current command value i z ref The zero-phase voltage command value v z ref Feedback control amount v z refFB By providing a secondary side DC link current control unit 28 that outputs the zero-phase current i z This will make it possible to prevent runaway.

[0130] This allows feedforward control by the feedforward control unit 20 and feedback control by the feedback control unit 30 to be performed in parallel, making it possible to realize a power conversion device 1 that combines the high-speed response performance of feedforward control with the disturbance suppression performance of feedback control, thereby providing both responsiveness and accuracy. [Example]

[0131] (7) Two-phase modulation Next, another embodiment of the present invention will be described with reference to Figures 14 to 24. In this embodiment, two-phase modulation is performed by either the primary-side modulator 24 or the secondary-side modulator 26, and three-phase modulation is performed by the other. In each figure, components denoted with the same reference numerals as in Figures 1 to 13 perform the same or similar functions. In the following description, it is assumed that two-phase modulation is performed by the primary-side modulator 24, and three-phase modulation is performed by the secondary-side modulator 26.

[0132] (7-1) Boost operation First, the superscript two-phase modulation performed by the primary side modulation unit 24 will be described with reference to Figures 15 and 16. When the secondary side inverter INV2 performs a voltage step-up operation, the primary side modulation unit 24 performs the superscript two-phase modulation. Note that the numerical values ​​shown in each figure are plus or minus V dc1 This is a value normalized to plus or minus 1 by / 2.

[0133] The superscript two-phase modulation in the primary side modulation unit 24 is performed by using the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref The same primary side zero-phase voltage command value v z1 ref The modulation value V com As shown in Figure 16, the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph By generating the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref In this case, the upper arm switching elements 3A to 3C of one phase where the maximum value is reached are fixed to the ON state, and the lower arm switching elements 3D to 3F are fixed to the OFF state, thereby stopping switching (PWM operation). This reduces the number of times the switching elements are switched compared to three-phase modulation, and makes it possible to significantly reduce switching loss.

[0134] Modulation value V in general superscript biphase modulation com is the difference between the primary output voltage command value of the maximum phase and "1" (Fig. 15), and this is the primary output voltage command value of all phases v u1 ref , v v1 ref , v w1 refBy adding to the modulation value V com , that is, the primary side zero-phase voltage command value v z1 ref Therefore, in this embodiment, the primary side modulation unit 24 takes on part of the function of the secondary side voltage / zero-phase sequence voltage command conversion unit 27.

[0135] However, when the primary side modulation unit 24 performs two-phase modulation, the calculated primary side zero-phase voltage command value v z1 ref As shown in Figures 15 and 16, the zero-phase current i z (secondary DC link current) and secondary voltage V dc2 A large ripple is excited in the

[0136] Therefore, in this embodiment, a ripple component cancellation control unit 46 is provided in the secondary voltage control system 23. Figure 14 shows a block diagram of the secondary voltage control system 23, the primary side modulation unit 24, and the secondary side modulation unit 26 in this case. In this case, the secondary side voltage V dc2 is the primary side output voltage amplitude v of the primary side inverter INV1 m ref (FIG. 15), the feedforward control system 25 constituting the feedforward control unit 20 of the secondary side voltage / zero-phase voltage command conversion unit 27 in this embodiment is dc2 ref and the primary voltage V dc1 Based on this, the primary side output voltage amplitude v m ref Calculate and output.

[0137]

number

[0138] This primary side output voltage amplitude v m ref is the zero-phase voltage command value v z refThe reason is that the primary side output voltage amplitude v m ref is the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref These are values ​​for generating the primary side zero-phase voltage command value v z1 ref The modulation value V com By adding the above, the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph That is, the zero-phase voltage command value v z ref (v z ref =v z1 ref +v z2 ref ) The primary side zero-phase voltage command value v z1 ref is the primary side output voltage amplitude v m ref This is because it is determined by

[0139] In addition, the primary side output voltage amplitude v m ref When it is 0, the voltage is doubled, and when it is 1.2, the voltage is doubled.

[0140] Then, the output voltage command generating unit 29 calculates the primary side output voltage amplitude v m ref Based on this, the primary side output voltage command value v is calculated using the following formula (VIII). u1 ref , v v1 ref , v w1 ref is calculated and output to the primary side modulation unit 24. re is the rotor position, θ Vmis the voltage phase difference with respect to rotor position.

[0141]

number

[0142] As described above, the primary side modulator 24 calculates the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref , the primary side zero-phase voltage command value v z1 ref The modulation value V com By adding as above, the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph Furthermore, the uvw-αβ conversion unit 47 generates the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref to the primary side α-axis voltage command value vα1 ref and the primary side β-axis voltage command value vβ1 ref Generate.

[0143] Furthermore, the dq-αβ conversion unit 48 included in the output voltage command generation unit 29 converts the d-axis voltage command value v d ref and the q-axis voltage command value v q ref is converted to the αβ axis, and the converted value is the primary side α axis voltage command value vα1 ref and the primary side β-axis voltage command value vβ1 ref The value obtained by the subtraction is converted into a secondary side output voltage vector command value by an αβ-uvw converter 49.

[0144] On the other hand, the ripple component cancellation control unit 46 of the embodiment of FIG. 14 is configured to cancel the primary side output voltage command value v u1 2ph , v v12ph , v w1 2ph After adding these, the primary side zero-phase voltage command value v z1 ref (feedforward control amount). Then, this primary side zero-phase voltage command value v z1 ref From the above, the primary side zero-phase voltage command value v z1 ref By subtracting the value that has passed through the low-pass filter 51 (resulting in the action of a high-pass filter), the secondary side zero-phase sequence voltage command value v z2 ref (which also serves as a feedforward control variable) is derived.

[0145] Next, the secondary side zero-phase voltage command value v z2 ref is added to the secondary output voltage vector command value output by the αβ-uvw conversion unit 49 in the adder 52, thereby obtaining the secondary output voltage command value v u2 ref , v v2 ref , v w2 ref is generated and output to the secondary side inverter INV2.

[0146] Figure 17 shows the secondary side zero-phase voltage command value v z2 ref and the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph and the primary side zero-phase voltage command value v z1 ref The secondary side zero-phase voltage command value v z2 ref is the primary side zero-phase voltage command value v z1 ref Since it is added negatively to the zero-phase voltage command value v z ref is constant at 0.5 in the figure, and the primary side zero-phase voltage command value v z1 refThat is, the secondary side inverter INV2 is supplied with the secondary side zero-phase sequence voltage command value v so as to cancel out the ripple component superimposed by the primary side inverter INV1. z2 ref will be superimposed.

[0147] In this way, the ripple component cancellation control unit 46 outputs the primary side zero-phase sequence voltage command value v z1 ref and the primary side zero-phase voltage command value v z1 ref The difference between this and the secondary side zero-phase voltage command value v z2 ref By outputting the signal as a ripple component, it becomes possible to compensate for the ripple component with a relatively simple configuration.

[0148] The ripple component cancellation control unit 46 shown in FIG. 14 uses a low-pass filter 51 to cancel the secondary side zero-phase voltage command value v z2 ref However, the primary side zero-phase voltage command value v z1 ref and the primary side output voltage amplitude V m ref Based on this, the secondary side zero-phase voltage command value v is calculated using the following formula (IX). z2 ref may be calculated.

[0149]

number

[0150] In this way, the ripple component cancellation control unit 46 controls the primary side zero-phase sequence voltage command value v z1 ref and the primary side output voltage amplitude V m ref Based on this, the secondary side zero-phase voltage command value v z2 ref If the above formula is calculated and output, it becomes possible to instantaneously compensate for the ripple component.

[0151] (7-2) Step-down operation Next, the subscript two-phase modulation executed by the primary side modulation unit 24 will be described with reference to Figures 18 and 19. When the secondary side inverter INV2 performs a step-down operation, the primary side modulation unit 24 executes the subscript two-phase modulation. Similarly, each figure shows the phase difference between plus and minus V dc1 This is a value normalized to plus or minus 1 by / 2.

[0152] The subscripted two-phase modulation in the primary side modulation unit 24 is performed by using the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref The same primary side zero-phase voltage command value v z1 ref The modulation value V com By adding the above, the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph By generating the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref The lower arm switching elements 3D to 3F of one phase for which the value of is smallest are fixed to the ON state, and the upper arm switching elements 3A to 3C are fixed to the OFF state, thereby stopping switching (PWM operation).

[0153] Modulation value V in general subscript biphase modulation com is the difference between the primary output voltage command value of the minimum phase and "-1" (Fig. 18), and is used as the primary output voltage command value of all phases v u1 ref , v v1 ref , v w1 ref By adding to this, the lower arm switching element of the minimum phase is fixed to the ON state. In this case, the primary side zero-phase voltage command value v z1 ref18 and 19, the ripple component is cancelled by the ripple component cancellation control section 46.

[0154] In this case, the secondary voltage V dc2 is the primary side output voltage amplitude v of the primary side inverter INV1 m ref (FIG. 18), the feedforward control system 25 constituting the feedforward control unit 20 of this embodiment determines the secondary side voltage command value V dc2 ref and the primary voltage V dc1 Based on this, the primary side output voltage amplitude v in this case is calculated using the following formula (X): m ref Calculate and output.

[0155]

number

[0156] In addition, the primary side output voltage amplitude v m ref When it is 0, it is 0V, when it is 1.2 it is 1x voltage drop, and when it is 0.6 it is 1 / 2x voltage drop.

[0157] Then, the output voltage command generating unit 29 calculates the primary side output voltage amplitude v m ref Based on this, the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref and outputs it to the primary side modulation unit 24.

[0158] As described above, the primary side modulator 24 calculates the primary side output voltage command value v u1 ref , v v1 ref , v w1 ref , the primary side zero-phase voltage command value v z1 ref The modulation value V comBy adding as follows, the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph Furthermore, the ripple component cancellation control unit 46 generates the secondary side zero-phase sequence voltage command value v z2 ref The secondary side zero-phase voltage command value v z2 ref is added to the secondary output voltage vector command value output by the αβ-uvw conversion unit 49 in the adder 52, thereby obtaining the secondary output voltage command value v u2 ref , v v2 ref , v w2 ref is generated and output to the secondary side inverter INV2.

[0159] Figure 20 shows the secondary side zero-phase voltage command value v z2 ref and the primary side output voltage command value v u1 2ph , v v1 2ph , v w1 2ph and the primary side zero-phase voltage command value v z1 ref The secondary side zero-phase voltage command value v z2 ref is the primary side zero-phase voltage command value v z1 ref Since it is added negatively to the zero-phase voltage command value v z ref is constant at -0.5 in the figure, and the primary side zero-phase voltage command value v z1 ref The ripple component of

[0160] During this voltage step-down operation, the ripple component cancellation control unit 46 in FIG. 14 does not use the low-pass filter 51, but instead uses the secondary side zero-phase sequence voltage command value v z2 ref Similarly, when calculating the primary side zero-phase voltage command value v z1 refand the primary side output voltage amplitude V m ref Based on this, the secondary side zero-phase voltage command value v is calculated using the following formula (XI). z2 ref Calculate.

[0161]

number

[0162] Next, the effect of the feedforward control by the control device 6 of the power conversion device 1 of this embodiment will be described with reference to Figs. 21 to 24. Fig. 21 is a diagram showing the voltage command values ​​and voltages when the feedforward control of the control device 6 of this embodiment is executed, and Fig. 22 is a diagram showing the secondary side voltage command value V dc2 ref When the secondary voltage V changes dc2 21 showing the change in the parameter values. The parameters in each figure are the same as those in FIGS.

[0163] As is clear from a comparison of FIG. 7 and FIG. 22, when the feedforward control of this embodiment is executed (FIG. 22), the secondary voltage command value V dc2 ref Changes in secondary voltage V dc2 It can be seen that the response is extremely high.

[0164] However, as is clear from Figure 22, the secondary voltage V dc2 Therefore, in this case, the control device 6 also controls the secondary side voltage command value V dc2 ref 23 and 24. Note that FIG. 23 shows the control device 6 of this embodiment that executes feedforward control and limits the rate of change of the secondary side voltage command value V dc2 ref 24 shows the voltage command values ​​and voltages when the rate of change of the secondary side voltage command value V dc2 ref When the secondary voltage V changes dc223 showing the change in

[0165] However, this limitation also applies to the secondary voltage V shown in Figures 7 and 8. dc2 This is done in a range at least faster than the change in the secondary voltage V dc2 The vibrations can be eliminated or suppressed.

[0166] As described above, if the primary side modulation unit 24 of the control device 6 performs two-phase modulation in which the upper arm switching elements 3A to 3C of one phase are turned on to stop switching, or the lower arm switching elements 3D to 3F of one phase are turned on to stop switching, the number of times that the upper and lower arm switching elements 3A to 3F of the primary side inverter INV1 are switched can be reduced compared to the case of three-phase modulation, thereby significantly reducing switching losses and suppressing heat generation.

[0167] In addition, the secondary side voltage control system 23 receives the primary side zero-phase voltage command value v z1 ref The secondary side zero-phase voltage command value v z2 ref A ripple component cancellation control unit 46 is provided to generate a d-axis voltage command value v d ref and the q-axis voltage command value v q ref The secondary side output voltage vector command value generated based on the secondary side zero-phase voltage command value v z2 ref is added to obtain the secondary output voltage command value v u2 ref , v v2 ref , v w2 ref is generated, the primary side zero-phase voltage command value v z1 ref This compensates for the ripple component of the rectifier, making it possible to suppress the generation of electromagnetic noise and noise due to the ripple current.

[0168] In this case, the control device 6 also calculates the secondary voltage command value V dc2 refBy incorporating a function to limit the rate of change of the secondary voltage V dc2 This reduces the excitation of vibrations, making it possible to achieve both high responsiveness and low vibration. [Example]

[0169] (8) Two-phase modulation + feedback control Next, still another embodiment of the present invention will be described with reference to Fig. 25. In this embodiment, the secondary side zero-phase sequence voltage command value v z2 ref A control amount of feedback control is added to the (feedforward control amount). Figure 25 is a block diagram of the secondary side voltage control system 23, primary side modulation unit 24, and secondary side modulation unit 26 of Figure 2 when a feedback control unit 30 is added. In this figure, elements denoted with the same reference numerals as those in Figures 13 and 14 have the same or similar functions.

[0170] In this case, the zero-phase voltage command value v outputted by the secondary DC link current control unit 28 configured by the current PI control system 34 z ref Feedback control amount v z refFB , the secondary side zero-phase voltage command value v z2 ref (feedforward control amount). In this case, the secondary DC link current control unit 28 also adds the zero-phase current i z (secondary DC link current in this invention) is expressed as the zero-phase current command value i z ref (the secondary DC link current command value in this invention) z ref Feedback control amount v z refFB Also, the feedback control amount v z refFB is set to a negative value (-) for the same reason as above, and the secondary side zero-phase voltage command value v z2 ref (feedforward control amount).

[0171] In this way, the control device 6 is further provided with a feedback control section 30, and the feedback control section 30 is dc2 The zero-phase current command value i required to control z ref and a secondary voltage control unit 35 that generates a zero-phase current command value i z ref and zero-phase current i z Based on this, the zero-phase current i z is the zero-phase current command value i z ref The zero-phase voltage command value v z ref Feedback control amount v z refFB A secondary DC link current control unit 28 is provided to output a feedback control amount v z refFB , the secondary side zero-phase voltage command value v z2 ref By adding to the zero-phase current i z This will make it possible to prevent runaway.

[0172] This makes it possible to perform feedforward control by the feedforward control unit and feedback control by the feedback control unit in parallel, thereby realizing a power conversion device that combines the high-speed response performance of feedforward control with the disturbance suppression performance of feedback control, and is therefore both responsive and accurate.

[0173] In each embodiment, the zero-phase current i is used as an index indicating the secondary DC link current. z However, it is not limited to this, and a capacitor current may be used as the secondary DC link current. However, when a capacitor current is used, a separate sensor is required to detect the current flowing through the capacitor C. However, the zero-phase current i z If so, each phase current i u , i v , i w From i z =(i u +i v +i w ) / 3, the control device 6 can detect it.

[0174] Furthermore, in the second and fourth embodiments, the secondary side DC link current control unit 28 is provided in the secondary side voltage control system 23, but this is also effective for a power conversion device that does not have the secondary side DC link current control unit 28.

[0175] Furthermore, in the first and second embodiments, the output voltage command generating unit 29 generates an effective voltage V real and reactive voltage V imag However, the method for determining the primary side output voltage vector command value and the secondary side output voltage vector command value can be changed in various ways. That is, the zero-phase sequence voltage command value v z ref As one of the methods for determining the primary side output voltage vector command value and secondary side output voltage vector command value before adding real and reactive voltage V imag There is a method to divide it into

[0176] Furthermore, in the third and fourth embodiments, two-phase modulation is performed in the primary-side modulation unit 24 and three-phase modulation is performed in the secondary-side modulation unit 26, but this is not limiting, and three-phase modulation may be performed in the primary-side modulation unit 24 and two-phase modulation may be performed in the secondary-side modulation unit 26. In this case, the voltage step-up operation is performed with subscript two-phase modulation and the voltage step-down operation is performed with superscript two-phase modulation.

[0177] In addition, although the switching elements in the embodiments are IGBTs, MOSFETs may also be used. In particular, the specific configurations and numerical values ​​shown in the embodiments are not limited to these and may be changed within the scope of the present invention. [Explanation of symbols]

[0178] 1 Power conversion device 2 DC power supply 3A~3F, 4A~4F switching elements 6. Control device 7U, 7V, 7W winding 11 Positive power supply line 12 Negative power supply line 20 Feedforward control section 21 Speed ​​control section 22 dq axis current control section 23 Secondary voltage control system 24 Primary side modulation section 25 Feedforward control system 26 Secondary side modulation section 27 Secondary voltage / zero-phase voltage command conversion unit 28 Secondary DC link current control section 29 Output voltage command generator 30 Feedback control section 33 Voltage PI control system 34 Current PI control system 35 Secondary voltage control section 36 Effective / ineffective resolution section 39 Zero-phase voltage distribution section 46 Ripple component cancellation control section 51 Low-pass filter C capacitor INV1 Primary side inverter INV2 Secondary side inverter Medium motor

Claims

1. A power conversion device includes a primary inverter connected to one end of an open-ended winding of a motor, and a secondary inverter connected to the other end of the winding, and applies a voltage difference between the primary inverter and the secondary inverter to the motor, The primary side inverter is connected to a DC power source; the secondary side inverter is connected to a capacitor; The negative power supply line of the primary inverter and the negative power supply line of the secondary inverter are shared, a control device for controlling a secondary side voltage that is a charging voltage of the capacitor; The control device a secondary-side voltage control system that generates a zero-phase sequence voltage command value that causes a secondary-side DC link current required to flow in order to control the secondary-side voltage to a secondary-side voltage command value; The secondary voltage control system includes: A power conversion device comprising a feedforward control unit that outputs a feedforward control amount of a zero-phase voltage command value or a control amount for deriving the same, based on the secondary side voltage command value and the primary side voltage.

2. The primary side inverter and the secondary side inverter are each configured with upper and lower arm switching elements of each phase connected in series, a positive input terminal of the primary inverter connected to a positive power supply line of the DC power supply, a negative input terminal of the primary inverter connected to the negative power supply line of the DC power supply, and an output terminal of the primary inverter connected to one end of the winding; an output terminal of the secondary inverter is connected to the other end of the winding, and the capacitor is connected between a positive input terminal and a negative input terminal of the secondary inverter; A positive input terminal of the secondary inverter is connected to a positive power supply line of the DC power supply, and a negative input terminal of the secondary inverter is connected to a negative power supply line of the DC power supply; 2. The power conversion device according to claim 1, wherein the control device generates an AC output from the DC power supply by switching the upper and lower arm switching elements of each phase.

3. the secondary side voltage control system further includes a feedback control unit, The feedback control unit a secondary-side voltage control unit that generates a secondary-side DC link current command value required to control the secondary-side voltage; 2. The power conversion apparatus according to claim 1, further comprising a secondary DC link current control unit that outputs a feedback control amount of the zero-phase sequence voltage command value based on the secondary DC link current command value and the secondary DC link current so as to control the secondary DC link current to the secondary DC link current command value.

4. The control device 4. The power conversion device according to claim 3, wherein a capacitor current flowing through the capacitor is used as the secondary DC link current, or a zero-phase current is used as an index indicating the secondary DC link current.

5. The secondary side voltage control system includes: an output voltage command generating unit that generates a primary-side output voltage command value for switching the primary-side inverter and a secondary-side output voltage command value for switching the secondary-side inverter, based on the zero-phase-sequence voltage command value, which is the feedforward control amount, or the zero-phase-sequence voltage command value obtained by adding the feedforward control amount to the feedback control amount; 5. The power conversion device according to claim 1, further comprising:

6. The output voltage command generation unit A primary-side output voltage vector command value and a secondary-side output voltage vector command value are generated from the dq-axis voltage command values, the primary-side output voltage command value is generated from the primary-side output voltage vector command value, and the secondary-side output voltage command value is generated from the secondary-side output voltage vector command value; 6. The power conversion device according to claim 5, wherein the primary side output voltage command value and the secondary side output voltage command value are generated by adding the zero-phase voltage command value to the primary side output voltage vector command value and / or the secondary side output voltage vector command value.

7. The control device a primary-side modulation unit that generates a primary-side inverter switching signal for switching the primary-side inverter from the primary-side output voltage command value; a secondary-side modulation unit that generates a secondary-side inverter switching signal for switching the secondary-side inverter from the secondary-side output voltage command value; 7. The power conversion device according to claim 6, further comprising:

8. The control device a primary side modulation unit that generates a primary side inverter switching signal for switching the primary side inverter; a secondary-side modulation unit that generates a secondary-side inverter switching signal for switching the secondary-side inverter; 3. The power conversion device according to claim 2, wherein the primary side modulation unit or the secondary side modulation unit performs two-phase modulation in which the upper arm switching element of one phase is turned on to stop switching, or the lower arm switching element of one phase is turned on to stop switching.

9. 9. The power conversion device according to claim 8, wherein the primary-side modulation unit or the secondary-side modulation unit adds, as a modulation value, the same primary-side zero-phase voltage command value or the secondary-side zero-phase voltage command value to the primary-side output voltage command value of each phase for switching the primary-side inverter or the secondary-side output voltage command value of each phase for switching the secondary-side inverter, thereby turning on the upper arm switching element of the phase where the primary-side output voltage command value or the secondary-side output voltage command value is maximum to stop switching, or turning on the lower arm switching element of the phase where the primary-side output voltage command value or the secondary-side output voltage command value is minimum to stop switching.

10. the primary-side modulation unit performs the two-phase modulation by adding the primary-side zero-phase sequence voltage command value as the modulation value to the primary-side output voltage command value of each phase; 10. The power conversion device according to claim 9, wherein a control amount for deriving a feedforward control amount of the zero-phase voltage command value output by the feedforward control unit is a primary-side output voltage amplitude for generating the primary-side output voltage command value.

11. 11. The power conversion device according to claim 10, wherein the secondary side voltage control system includes a ripple component cancellation control unit that generates a secondary side zero-phase-sequence voltage command value that cancels a ripple component of the primary side zero-phase-sequence voltage command value, and generates the secondary side output voltage command value by adding the secondary side zero-phase-sequence voltage command value to a secondary side output voltage vector command value generated based on dq-axis voltage command values.

12. 12. The power conversion device according to claim 11, wherein the ripple component cancellation control unit calculates and outputs the secondary side zero-phase sequence voltage command value based on the primary side zero-phase sequence voltage command value and the primary side output voltage amplitude.

13. 12. The power conversion device according to claim 11, wherein the ripple component cancellation control unit outputs, as the secondary side zero-phase-sequence voltage command value, a difference between a value of the primary side zero-phase-sequence voltage command value that has passed through a low-pass filter and a value of the primary side zero-phase-sequence voltage command value that has not passed through the low-pass filter.

14. the secondary side voltage control system further includes a feedback control unit, The feedback control unit a secondary-side voltage control unit that generates a secondary-side DC link current command value required to control the secondary-side voltage; a secondary DC link current control unit that outputs a feedback control amount of the zero-phase sequence voltage command value based on the secondary DC link current command value and the secondary DC link current so as to control the secondary DC link current to the secondary DC link current command value; 14. The power conversion device according to claim 11, wherein the feedback control amount is added to the secondary side zero-phase sequence voltage command value.

15. The control device The power conversion device according to claim 1 , further comprising a function of limiting a rate of change of the secondary voltage command value.

Images