Motor drive unit

Abstract

To provide a motor drive device that drives a motor having a plurality of coils respectively corresponding to a plurality of phases.SOLUTION: A motor drive device comprises: a first inverter that includes a plurality of first switching elements, being coupled with respective first ends of a plurality of coils; a second inverter that includes a plurality of second switching elements, being coupled with respective second ends of the plurality of coils; and a controller that decides an effective vector closest to a voltage vector corresponding to a voltage command of a motor that is set in advance as a duty of the plurality of second switching elements, and uses a value obtained by adding an effective vector corresponding to the duty of the second switching elements to the voltage command of the motor as a voltage command of the first inverter to perform pulse width modulation control of the first switching elements.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to a motor drive device, and more specifically to an open-end winding type motor drive device in which inverters are connected to both ends of the motor windings. [Background technology]

[0002] Generally, the windings of each phase in a motor are connected at one end to a single inverter, and the other ends are connected to each other to form a Y-connection.

[0003] During motor operation, the switching elements within the inverter are switched on and off by pulse width modulation control, and torque is generated by applying a line voltage to the Y-connected motor windings to produce an alternating current.

[0004] In environmentally friendly vehicles such as electric cars that use torque generated by such motors as their power source, the fuel efficiency (or electricity consumption) is determined by the power conversion efficiency of the inverter-motor. Therefore, to improve fuel efficiency, it is important to maximize the power conversion efficiency of the inverter and the efficiency of the motor.

[0005] The efficiency of an inverter-motor system is primarily determined by the voltage utilization rate of the inverter. When the vehicle's operating point is determined by the relationship between motor speed and torque in a section with a high voltage utilization rate, the vehicle's fuel efficiency can be improved.

[0006] However, increasing the number of windings in a motor to increase its maximum torque can lead to problems such as poor fuel efficiency, as the high-voltage utilization zone moves further away from the low-torque region, which is the vehicle's main operating point. Furthermore, designing the vehicle so that the main operating point is located within a high-voltage utilization zone for fuel efficiency reasons can restrict the motor's maximum torque, potentially reducing the vehicle's acceleration and starting performance.

[0007] To solve these problems, the field has proposed an open-end winding (OEW) motor drive technique, in which instead of short-circuiting one end of the motor winding with a Y-connection, inverters are connected to both ends of the motor winding and both inverters are driven.

[0008] This open-end winding motor drive technique has the advantage of being able to increase the phase voltage and improve voltage utilization compared to conventional Y-connection motor drive methods, thus enabling higher output power.

[0009] However, in open-end winding motor drive techniques, when a common DC power supply is applied to inverters connected to both ends of the motor windings, it is not possible to control the zero-phase component voltage to average to zero over the inverter switching period, thus generating a common-mode current. This common-mode current flows through the motor windings and acts as losses such as copper loss and iron loss, reducing motor efficiency and, in severe cases, can even cause the motor system to burn out.

[0010] The matters described above as background technology are intended solely to enhance understanding of the background of the present invention and should not be accepted as constituting prior art already known to those with ordinary skill in the art. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] U.S. Patent Publication No. 2009-0033253A1 [Patent Document 2] Patent No. 6285256B2 [Overview of the project] [Problems that the invention aims to solve]

[0012] Therefore, the technical problem of the present invention is to provide a motor drive device that can improve motor efficiency by eliminating the circulating current generated by the difference when driving a motor in an open-end winding type where inverters are connected to both ends of the motor winding, by setting the common mode voltage between the two inverters to be the same and controlling the zero-phase component voltage as desired.

[0013] In particular, the present invention aims to provide a motor drive device that can instantaneously reduce the difference between the zero-phase component voltages of both inverters to zero when driving a motor using an open-end winding method in which inverters are connected to both ends of the motor winding, so that both inverters instantly have the same zero-phase component voltage.

[0014] Furthermore, the present invention aims to solve the technical problem of providing a motor drive device that can eliminate the zero-phase component current and minimize the overall switching loss according to the type of switching element when the types of switching elements constituting the two inverters used in open-end winding type motor drive are different. [Means for solving the problem]

[0015] As a means to solve the aforementioned technical problems, the present invention provides a motor drive device for driving a motor having a plurality of windings corresponding to a plurality of phases, the motor drive device comprising: a first inverter including a plurality of first switching elements and connected to the first end of each of the plurality of windings; a second inverter including a plurality of second switching elements and connected to the second end of each of the plurality of windings; and a controller that determines the duty cycle of the plurality of second switching elements to be the effective vector closest to a voltage vector corresponding to a preset voltage command of the motor, and uses the value obtained by adding the effective vector corresponding to the duty cycle of the second switching elements to the voltage command of the motor as the voltage command of the first inverter to control the first switching elements by pulse width modulation.

[0016] In one embodiment of the present invention, the controller can control the first switching element using the RSPWM (Remote State Pulse Width Modulation) method.

[0017] In one embodiment of the present invention, the controller can synthesize a voltage command for the first inverter using a plurality of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element.

[0018] In one embodiment of the present invention, the controller can generate a three-phase voltage command by converting the motor's voltage command in reverse, and determine the effective vector that is closest to the voltage vector corresponding to the motor's voltage command based on the three-phase voltage command.

[0019] In one embodiment of the present invention, the controller is given by the following formula, D abc、inv2 =Sign(V abcn、lim * Using (Sign(x)=1 if x≧0, and Sign(x)=0 if x<0), the effective vector closest to the voltage vector corresponding to the voltage command of the motor can be determined. Here, Dabc、inv2 This is the duty cycle corresponding to the effective vector closest to the voltage vector corresponding to the voltage command of the motor, V abcn、lim * This is the aforementioned three-phase voltage command.

[0020] In one embodiment of the present invention, the controller can generate a voltage command for the first inverter by adding the result of rotational conversion of an effective vector corresponding to the duty cycle of the second switching element to the voltage command for the motor.

[0021] In one embodiment of the present invention, the controller can switch the first switching element such that a plurality of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element are repeated in a certain order.

[0022] In one embodiment of the present invention, the controller can switch the first switching element such that a plurality of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element appear symmetrically with respect to a predetermined midpoint of one switching cycle.

[0023] In one embodiment of the present invention, the controller can switch the first switching element such that the switching state having the longest duty cycle among a plurality of switching states of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element appears consecutively before and after the intermediate time point.

[0024] In one embodiment of the present invention, the controller can limit the voltage command of the motor, which has been set in advance, to an advance set upper limit and lower limit. [Effects of the Invention]

[0025] According to the motor drive device, the generation of common-mode current can be suppressed by controlling the zero-phase component voltages of the two inverters applied to the open-end winding method as desired.

[0026] Therefore, the motor drive device not only prevents distortion of the motor phase current due to common-mode current, making it easy to control the motor current, and prevents losses such as iron loss and copper loss in the motor caused by circulating current, thereby significantly improving the motor's driving efficiency, but it also prevents motor burnout in advance.

[0027] In particular, with the motor drive device described above, when driving a motor using an open-end winding method, the zero-phase component voltage is instantaneously reduced to zero, thereby eliminating motor losses due to instantaneous ripple in the zero-phase component current (common-mode current).

[0028] Furthermore, according to the motor drive device, spatial vector pulse width modulation is performed first based on the motor voltage command, and then pole voltage commands for each inverter are generated based on the output result. This minimizes the amount of calculation required for coordinate transformation, and therefore minimizes the discretization error caused by sine and cosine operations in the voltage modulation calculation.

[0029] Furthermore, with the motor drive device, when using an open-end winding drive method in which the motor is driven by simultaneously operating both inverters connected to both ends of the motor winding, the switching of inverters employing switching elements with high switching losses is minimized during voltage vector synthesis for spatial vector pulse width modulation. Instead, the switching is performed by inverters employing switching elements with relatively low switching losses, thereby reducing switching losses and improving the overall system efficiency.

[0030] The effects obtained by the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understandable to a person with ordinary skill in the art to which the present invention pertains from the following description. [Brief explanation of the drawing]

[0031] [Figure 1] This is a circuit diagram of a motor drive device according to one embodiment of the present invention. [Figure 2] This is a detailed block diagram showing a typical controller for controlling a motor using an open-end winding method. [Figure 3] Figure 2 is a voltage vector diagram illustrating the motor control technique applied to a typical controller. [Figure 4] Figure 2 shows the waveform diagram illustrating the voltage output of each inverter generated during motor control using a typical controller. [Figure 5] Figure 2 is a block diagram showing a more detailed spatial vector modulation section within a typical controller. [Figure 6] This is a block diagram showing in detail a controller applied to a motor drive device according to one embodiment of the present invention. [Figure 7] Figure 6 is a block diagram showing in more detail the spatial vector modulation section within the controller applied to a motor drive device according to one embodiment of the present invention. [Figure 8] Figure 6 shows waveform diagrams illustrating the voltage outputs of each inverter generated by the control of a motor drive device according to one embodiment of the present invention. [Figure 9] This is a block diagram showing in detail a controller applied to a motor drive device according to another embodiment of the present invention. [Figure 10] This voltage vector diagram illustrates an example in which, in the embodiment of the present invention shown in Figure 9, the phase voltage command of the first inverter is converted to precede the motor's rotation angle by 30 degrees, and the phase voltage command of the second inverter is converted to precede the motor's rotation angle by 150 degrees. [Figure 11] This voltage vector diagram illustrates an example in which, in the embodiment of the present invention shown in Figure 9, the phase voltage command of the first inverter is converted to 30 degrees behind the motor's rotation angle, and the phase voltage command of the second inverter is converted to 150 degrees behind the motor's rotation angle. [Figure 12] Figure 9 shows waveform diagrams illustrating the voltage output, zero-phase voltage component, and common-mode current of each inverter generated by the control of the motor drive device according to the embodiment of the present invention shown. [Figure 13] This is a block diagram showing in detail a controller applied to a motor drive device according to yet another embodiment of the present invention. [Figure 14] Figure 13 is a block diagram of the controller showing the spatial vector pulse width modulation section in more detail. [Figure 15] This is a block diagram showing a modified example of the controller of the embodiment shown in Figure 13. [Figure 16] This is a block diagram showing in detail a controller applied to a motor drive device according to yet another embodiment of the present invention. [Figure 17] This is a voltage vector diagram illustrating the voltages of each inverter and motor determined by the embodiment shown in Figure 16. [Figure 18] This waveform diagram shows the voltage output of each inverter generated by the control of the motor drive device according to the embodiment shown in Figure 16. [Figure 19-21] Figure 16 shows waveform diagrams illustrating various control methods for the first inverter that can be generated by the pulse width modulation unit for the first inverter. [Modes for carrying out the invention]

[0032] Hereinafter, motor drive devices according to various embodiments of the present invention will be described in detail based on the attached drawings.

[0033] Figure 1 is a circuit diagram of a motor drive device according to one embodiment of the present invention.

[0034] Referring to Figure 1, a motor drive device according to one embodiment of the present invention is a motor drive device that supplies drive power to a motor 100 having a plurality of windings L1-L3 corresponding to a plurality of phases, and may include a first inverter 10 including a plurality of first switching elements S11-S16 and connected to the first end of each winding of the motor 100, a second inverter 20 including a plurality of second switching elements S21-S26 and connected to the second end of each winding of the motor 100, and a controller 30 that pulse-width modulated control of the first switching elements S11-S16 and the second switching elements S21-S26 based on the required output of the motor 100.

[0035] The first inverter 10 and the second inverter 20 can convert the DC power stored in the battery 200 into three-phase AC power and supply it to the motor 100, or convert the regenerative braking energy generated by the regenerative braking torque of the motor 100 during regenerative braking into DC power and supply it to the battery 200. Such conversion between DC power and AC power can be performed by pulse width modulation control of a plurality of first switching elements S11-S16 and a plurality of second switching elements S21-S26 provided in the first inverter 10 and the second inverter 20, respectively.

[0036] The first inverter 10 may include a plurality of legs 11-13 to which a DC voltage formed on a DC link capacitor 300 connected between the ends of a battery 200 is applied. Each leg 11-13 can be electrically connected to a plurality of phases of a motor 100, respectively.

[0037] More specifically, the first leg 11 includes two switching elements S11 and S12 connected in series with respect to each other between the ends of a DC capacitor 300, and the connection node of both switching elements S11 and S12 can be connected to one end of a single-phase winding L1 in the motor 100 so that AC power corresponding to one phase among multiple phases is input and output.

[0038] Similarly, the second leg 12 includes two switching elements S13 and S14 connected in series with respect to each other between the ends of the DC capacitor 300, and the connection node of both switching elements S13 and S14 can be connected to one end of a single-phase winding L2 in the motor 100 so that AC power corresponding to one phase among multiple phases is input and output.

[0039] Furthermore, the third leg 13 includes two switching elements S15 and S16 connected in series with respect to each other between the ends of the DC capacitor 300, and the connection node of both switching elements S15 and S16 can be connected to one end of a single-phase winding L3 in the motor 100 so that AC power corresponding to one phase among multiple phases is input and output.

[0040] The second inverter 20 may also have a configuration similar to that of the first inverter 10. The second inverter 20 may include a plurality of legs 21-23 to which a DC voltage formed on a DC link capacitor 300 connected between the ends of the battery 200 is applied. Each leg 21-23 may be electrically connected to correspond to a plurality of phases of the motor 100.

[0041] More specifically, the first leg 21 includes two switching elements S21 and S22 connected in series with respect to each other between the ends of a DC capacitor 300, and the connection node of both switching elements S21 and S22 can be connected to the other end of a single-phase winding L1 in the motor 100 so that AC power corresponding to one phase among multiple phases is input and output.

[0042] Similarly, the second leg 22 includes two switching elements S23 and S24 connected in series with respect to each other between the ends of the DC capacitor 300, and the connection nodes of both switching elements S23 and S24 can be connected to the other end of a single-phase winding L2 in the motor 100 so that AC power corresponding to one phase among multiple phases is input and output.

[0043] Furthermore, the third leg 23 includes two switching elements S25 and S26 connected in series with respect to each other between the ends of the DC capacitor 300, and the connection node of both switching elements S25 and S26 can be connected to one end of a single-phase winding L3 in the motor 100 so that AC power corresponding to one phase among multiple phases is input and output.

[0044] The first inverter 10 is connected to one end of the motor winding L1-L3, and the second inverter 20 is connected to the other end of the motor winding L1-L3. In other words, open-end winding type electrical connections can be formed at both ends of the motor winding L1-L3, connecting to the first inverter 10 and the second inverter 20, respectively.

[0045] The controller 30 is basically an element that pulse-width modulated control of the switching elements S11-S16 and S21-S21 included in the first inverter 10 and the second inverter 20 so that the motor 100 is driven based on the required output demanded by the motor 100.

[0046] The controller 30 controls the DC voltage V applied to the first inverter 10 and the second inverter 20. dc The controller 30 receives the phase current supplied to the motor 100, detected by a current sensor (not shown), and the electrical angle of the motor, detected by a motor rotor sensor (not shown) provided on the motor 100, and switches the first switching elements S11-S16 of the first inverter 10 and the second switching elements S21-S26 of the second inverter 20 in a pulse width modulation manner to drive the motor 100. In particular, when the controller 30 controls the first switching elements S11-S16 and the second switching elements S21-S26 of the second inverter 20 in a pulse width modulation manner, it can apply the Space Vector Pulse Width Modulation (SVPWM) method.

[0047] To help achieve a clearer understanding of the motor drive device according to an embodiment of the present invention having the above-described configuration, the control technique of a normal open-end winding type motor drive device will first be described.

[0048] FIG. 2 is a block configuration diagram showing in detail a normal controller for controlling a motor in an open-end winding method, and FIG. 3 is a voltage vector diagram for explaining a motor control technique applied to the normal controller shown in FIG. 2. Further, FIG. 4 is a waveform diagram showing the voltage output of each inverter generated during motor control by the normal controller shown in FIG. 2, and FIG. 5 is a block configuration diagram showing in more detail the space vector modulation unit in the normal controller shown in FIG. 2.

[0049] As shown in FIG. 2, the controller of the conventional motor drive device can include a current command map 41, a current control unit 42, a first duty generation unit 43, and a second duty generation unit 44.

[0050] The current command map 41 can generate corresponding current commands I e * ), I -1 based on the required motor output (required motor torque T d * ), I q * generated by the operation of the driver or the like and the back electromotive force λ of the motor. The current command map 41 generates a current command of the motor reflecting the required motor output. In the example of FIG. 2, a map based on the required motor output and the back electromotive force is shown, but a map that generates a current command of the motor based on other factors can also be applied.

[0051] The current control unit 42 receives the current commands I d * ), I q * and compares them with the detected value of the current actually provided to the motor, and can reduce the difference to obtain a voltage command V d* , V q * , V n * It can generate the voltage command, which has a d-axis component V. d * , q-axis component V q * and zero-phase component V n * It can include...

[0052] The first duty cycle generation unit 43 is an element for generating the duty cycle of the switching elements in the first inverter 10 shown in Figure 1, and the voltage command V d * , V q * , V n * The first inverter voltage command V is applied to the first inverter 10 after being halved. d1 * , V q1 * , V n1 * A multiplier unit 431 that generates the first inverter voltage command V d1 * , V q1 * , V n1 * The first inverter phase voltage command V corresponds to each phase of the motor. as1 * , V bs1 * , V cs1 * A coordinate transformation unit 432 converts to and the first inverter phase voltage command V as1 * , V bs1 * , V cs1 * And the zero-phase component V in the first inverter voltage command n1 * It may include a first space vector pulse width modulation unit 433 that performs space vector pulse width modulation based on to generate the duty cycle of the switching elements in the first inverter 10.

[0053] Similar to the first duty generation unit 43, the second duty generation unit 44 is an element for generating the duty of the switching element in the second inverter 20 shown in FIG. 1, and the voltage command V d * , V q * , V n * is multiplied by -1 / 2 and applied to the second inverter 20. The multiple unit 441 for generating the second inverter voltage commands V d2 * , V q2 * , V n2 * , and the coordinate conversion unit 442 that converts the second inverter voltage commands V d2 * , V q2 * , V n2 * into the second inverter phase voltage commands V as2 * , V bs2 * , V cs2 * corresponding to each phase of the motor, and the second space vector pulse width modulation unit 443 that performs space vector pulse width modulation based on the second inverter phase voltage commands V as2 * , V bs2 * , V cs2 * and the zero-phase component V n2 * of the second inverter voltage command to generate the duty of the switching element in the second inverter 20 can be included.

[0054] Here, the coordinate conversion by the coordinate converters 432 and 442 is to convert the dq synchronous coordinates into the abc coordinates corresponding to the three phases of the motor, which corresponds to a known technique commonly known as the inverse rotation conversion (Inverse Clarke / Park Transformation) in the art. The opposite conversion, the rotation conversion (Clarke / Park Transformation), is also well-known in the art, and a separate detailed explanation thereof will be omitted hereinafter.

[0055] As shown in FIG. 2, the typical open-end winding type motor control technique distributes the voltage command of the motor equally to the first inverter and the second inverter.

[0056] That is, as shown in FIG. 3, in the motor control of the open-end winding structure, the motor voltage V shown on the vector diagram obtained by synthesizing the switching vector diagram for the first inverter and the switching vector diagram for the second inverter MOT is shown in the form of the difference between the voltage V INV1 by the first inverter and the voltage V INV1 by the first inverter and the voltage V INV2 by the second inverter having the same magnitude but opposite directions. Each vector diagram is shown on the dq plane, and the dq plane and the vector diagram for space vector pulse width modulation are matters well-known in the art, and a separate detailed explanation thereof will be omitted.

[0057] Thus, if the first inverter voltage and the second inverter voltage having the same magnitude but opposite directions are implemented by space vector pulse width modulation, an inverter output voltage waveform as shown in FIG. 4 can be obtained. In FIG. 4, T SW is the switching period of the switching element in the inverter, and V a1 , V b1 , V c1 , V n1 represent the phase voltages and the zero-phase component voltage of the first inverter, and V a2, V b2 , V c2 , V n2 This shows the phase voltages and zero-phase component voltage of the second inverter, V n This shows the difference between the zero-phase component voltage of the first inverter and the zero-phase component voltage of the second inverter, and represents the zero-phase component voltage applied to the motor by the first and second inverters.

[0058] As shown in Figure 4, the first inverter voltage and the second inverter voltage have the same magnitude on the dq plane, but their phases are different, resulting in each having different zero-phase component voltages. Therefore, the zero-phase component voltage V applied to the motor is n The magnitude cannot maintain a periodic average of 0.

[0059] The spatial vector modulation unit 433 or 443 in a typical controller shown in Figure 2 may include an offset voltage generation unit 51, an pole voltage command generation unit 52, an pole voltage command limiting unit 53, a division unit 54, and an addition unit 55, as shown in Figure 5.

[0060] The offset voltage generation unit 51 generates a 3-phase voltage command V as * , V bs * , V cs * Based on the offset voltage command V ns * The pole voltage command generation unit 52 generates this offset voltage command V ns * 0-phase component voltage V n * The value obtained by subtracting this is the 3-phase voltage command V as * , V bs * , V cs * Subtract from the pole voltage command V an * , V bn * , V cn * Generates.

[0061] Thus, in the case of motor control using a normal open-end winding method, the offset voltage command V ns * 3-phase voltage command V as * , V bs * , V cs * Since it is generated based on this, when the motor is actually driven by both inverters, there will be a difference between the offset voltage output from each inverter and the actual offset voltage. In particular, the first inverter and the second inverter have different offset voltage commands V ns * As a result, each inverter no longer outputs the offset voltage corresponding to the offset voltage command.

[0062] This can be expressed as shown in Equation 1 below.

number

[0063] Therefore, the zero-phase component voltage ultimately applied to the motor is given by Equation 2 below, and it is not possible to control the zero-phase component voltage as desired.

number

[0064] Thus, if the zero-phase component voltage cannot be controlled to zero on a periodic average, a common-mode current will be generated in the motor. This common-mode current increases the losses generated in the motor, and in severe cases, it can even cause the motor to burn out.

[0065] In Figure 5, the pole voltage command limiting unit 53 controls the DC voltage V applied to the first inverter and the second inverter. DC The pole voltage command is limited to a range of ±0.5, and the division unit 54 calculates the DC voltage V applied to the first inverter and the second inverter using the limited pole voltage command. DCThe division is performed, and the summing unit 55 adds 0.5 to the result of the division unit 54 to determine the duty cycle D of the switching element in the inverter. a , D b , D c It is possible to make a decision.

[0066] The pole voltage command limiting unit 53, the division unit 54, and the summing unit 55 correspond to known techniques applied to implement pulse width modulation control, and their detailed operation can be easily performed by an ordinary technician in the art; therefore, no further detailed explanation is provided.

[0067] Figure 6 is a detailed block diagram showing a controller applied to a motor drive device according to one embodiment of the present invention.

[0068] Referring to Figure 6, the controller 30 applied to a motor drive device according to one embodiment of the present invention may include a current command map 61, a current control unit 62, a first duty cycle generation unit 63, and a second duty cycle generation unit 64.

[0069] The current command map 61 is a motor command map that generates the motor required output (motor required torque T) through driver operations, etc. e * ) and the motor's back electromotive force λ -1 Based on that, the corresponding current command I d * , I q * It can generate [this].

[0070] The current control unit 62 controls the current command I d * , I q * The voltage command V can receive the detected current supplied to the motor and compare it with the actual current supplied to the motor, and reduce the difference. d * , V q * , V n * It can generate the voltage command, which has a d-axis component V. d* , q-axis component V q * and zero-phase component V n * It can include...

[0071] The current command map 61 and the current control unit 62 may be substantially identical to those applied to the typical motor control techniques shown in Figure 2.

[0072] The first duty cycle generation unit 63 is an element for generating the duty cycle of the switching elements in the first inverter 10, and the voltage command V d * , V q * , V n * The first inverter voltage command V is applied to the first inverter 10 after being halved. d1 * , V q1 * , V n1 * The multiplication unit 631 generates the first inverter voltage command V d1 * , V q1 * , V n1 * The first inverter phase voltage command V corresponds to each phase of the motor. as1 * , V bs1 * , V cs1 * The coordinate transformation unit 632 converts to and the first inverter phase voltage command V as1 * , V bs1 * , V cs1 * The first offset voltage command V generated based on ns1 * And the zero-phase component V in the first inverter voltage command n1 * and the second offset voltage command V generated by the second duty cycle generation unit 64 ns2 *Based on this, spatial vector pulse width modulation is performed on the duty cycle D of the switching elements in the first inverter 10. a1 , D b1 , D c1 It may include a first spatial vector pulse width modulation unit 633 that generates a first spatial vector pulse width modulation unit 633.

[0073] Similar to the first duty cycle generation unit 63, the second duty cycle generation unit 64 is an element for generating the duty cycle of the switching elements in the second inverter 20, and the voltage command V d * , V q * , V n * The second inverter voltage command V is applied to the second inverter 20 by multiplying it by -1 / 2. d2 * , V q2 * , V n2 * The multiplication unit 641 generates the second inverter voltage command V d2 * , V q2 * , V n2 * The second inverter phase voltage command V corresponds to each phase of the motor. as2 * , V bs2 * , V cs2 * The coordinate transformation unit 642 converts to and the second inverter phase voltage command V as2 * , V bs2 * , V cs2 * The second offset voltage command V generated based on ns2 * And the zero-phase component V in the second inverter voltage command n2 * and the first offset voltage command V generated by the first duty cycle generation unit 63 ns1 * Based on this, spatial vector pulse width modulation is performed on the duty cycle D of the switching element in the second inverter 20. a2 , Db2 , D c2 It may include a second spatial vector pulse width modulation unit 643 that generates the pulse width modulation.

[0074] In one embodiment of the present invention, the first duty cycle generation unit 63 and the second duty cycle generation unit 64 share their respective offset voltage commands, which are determined by the output voltages of the first inverter 10 and the second inverter 20, respectively, so that both inverters have the same zero-phase component voltage. That is, the first duty cycle generation unit 63 for controlling the first inverter 10 generates the first inverter phase voltage command V corresponding to the output voltage of the first inverter 10. as1 * , V bs1 * , V cs1 * Using the first offset voltage command V ns1 * After generating the second inverter phase voltage command V, which corresponds to the output voltage of the second inverter 20, the second inverter phase voltage command V can be provided to the second duty cycle generation unit 64 for controlling the second inverter 20. as2 * , V bs2 * , V cs2 * Using the second offset voltage command V ns2 * After generating it, it can be provided to the first duty cycle generation unit 63.

[0075] The first duty cycle generation unit 63 and the second duty cycle generation unit 64 generate the first offset voltage command V ns1 * and the second offset voltage command V ns2 * These are combined to generate a combined offset voltage command that has the same value as each other, and the combined offset voltage command and the 0-phase component voltage command of each inverter V n1 * , V n2 * This can be applied to the phase voltage command of each inverter to generate the pole voltage command for each inverter.

[0076] Figure 7 is a block diagram showing in more detail the spatial vector modulation section in a controller applied to a motor drive device according to one embodiment of the present invention. In particular, Figure 7 shows in detail the first spatial vector pulse width modulation section 643 in the first duty cycle generation section 63, and although not shown separately, the second spatial vector pulse width modulation section 644 in the second duty cycle generation section 64 can also be implemented with a corresponding configuration.

[0077] Referring to Figure 7, the first space vector pulse width modulation unit 634 within the first duty cycle generation unit 63 may include an offset voltage generation unit 71, an offset voltage command synthesis unit 711, an pole voltage command generation unit 72, an pole voltage command limiting unit 73, a division unit 74, and an addition unit 75.

[0078] The offset voltage generation unit 71 controls the three-phase voltage command V of the first inverter. as1 * , V bs1 * , V cs1 * Based on the offset voltage command V ns1 * It can generate [this].

[0079] In the example shown in Figure 7, the offset voltage generation unit 71 is a three-phase voltage command V as1 * , V bs1 * , V cs1 * The offset voltage command V of the first inverter 10 is the average of the maximum and minimum values ​​within that range. ns1 * Although it is shown as a calculation, this is a simple example, and the offset voltage command can be determined in a variety of ways known in the art.

[0080] The offset voltage command synthesis unit 711 generates the offset voltage command V of the first inverter 10 in the offset voltage generation unit 71. ns1 *and the offset voltage command V of the second inverter 20 generated by the second space vector pulse width modulation unit 644 in the second duty cycle generation unit 64. ns2 * The combined offset voltage command V is obtained by combining these two. ns、f * It can generate [this].

[0081] The offset voltage command synthesis unit 711 synthesizes offset voltage commands V in various ways. ns、f * It can generate the offset voltage command V of the first inverter 10. For example, the offset voltage command synthesis unit 711 generates the offset voltage command V of the first inverter 10. ns1 * and the offset voltage command V of the second inverter 20 ns2 * After applying weighted values ​​to each, the combined offset voltage command V is obtained by adding them together. ns、f * It can generate the offset voltage command V of the first inverter 10. ns1 * and the offset voltage command V of the second inverter 20 ns2 * The offset voltage command V is the average value of the above. ns,f * It is possible to make a decision.

[0082] The offset voltage command synthesis unit 711 synthesizes the offset voltage command V using the specified method. ns、f * Even if a composite offset voltage command V is generated by the first spatial vector pulse width modulation unit 634 and the second spatial vector pulse width modulation unit 644 respectively, ns、f * They must be embodied such that they have the same value as each other.

[0083] The offset voltage command V of the first inverter 10 is generated by the offset voltage command synthesis unit 711. ns1 * and the offset voltage command V of the second inverter 20 ns2 *When the average value with [object] is determined as the combined offset voltage command, the zero-phase component voltage output from each inverter is as shown in Equation 3 below.

Equation

[0084] According to Equation 3, the difference (V ns1 -V ns2 ) between the zero-phase component voltages of both inverters can be output as the video component voltage command V n * set by the current control unit 62. Here, when the combined offset voltage command V ns、f * finally applied to the modulation of both inverters is determined as the average of both offset voltage commands V ns1 * , V ns2 * , the margins of the output duties of both inverters become the same. Therefore, it is preferable that the combined offset voltage command V ns、f * is determined as the average of both offset voltage commands V ns1 * , V ns2 * .

[0085] In FIG. 7, the pole voltage command generation unit 72 subtracts the zero-phase component voltage command V! n1 ! * ! from the voltage commands of the first inverter 10 among the combined offset voltage command V! ns、f ! * ! and then subtracts the result from each of the three-phase voltage commands V! as1 ! * !, V! bs1 ! * !, V! cs1 ! * ! of the first inverter 10 to generate the pole voltage commands V! an1 ! * !, V! bn1 ! * !, V! cn1 ! * ! of the first inverter 10.

[0086] In FIG. 7, the pole voltage command limiting unit 73 limits the pole voltage command within the range of ±0.5 of the DC voltage V applied to the first inverter and the second inverter, and the division unit 74 divides the limited pole voltage command by the DC voltage V applied to the first inverter and the second inverter. The addition unit 75 adds 0.5 to the result of the division unit 74 to determine the duty D of the switching element in the inverter, D, D, D. DC The pole voltage command limiting unit 53, the division unit 54, and the addition unit 55 correspond to known technologies applied to implement pulse width modulation control. Since the detailed operation is fully implementable by an ordinary technician in the technical field, additional detailed explanations about this are omitted. DC Also, FIG. 7 shows the detailed configuration of the space vector pulse width modulation unit 633 in the first duty generation unit 63. However, an ordinary technician in the technical field can easily analogize the detailed configuration of the space vector pulse width modulation unit 643 in the second duty generation unit 64 from FIG. 7. Therefore, a separate explanation about the space vector pulse width modulation unit 643 in the second duty generation unit 64 is omitted. a b c

[0087]

[0088]

[0089] FIG. 8 is a waveform diagram showing the voltage output of each inverter generated by the control of the motor drive device according to an embodiment of the present invention.

[0090] Referring to FIG. 8, when comparing with the waveform of the ordinary motor drive device shown in FIG. 4, it can be confirmed that according to the motor drive device according to an embodiment of the present invention, the 0-phase component voltage V of the motor is determined to have an average value of 0 within one cycle. n

[0091] ​​​​​​Therefore, the motor drive device according to one embodiment of the present invention can perform desired control so as not to cause distortion of the zero-phase component voltage by spatial vector pulse width modulation, thereby suppressing common-mode current generated in the motor, reducing unnecessary motor losses, and preventing motor burnout.

[0092] The embodiments of the present invention shown in Figures 6 to 8 described above are embodiments that control the average of the zero-phase component voltage within the switching period to zero. While such embodiments can control the zero-phase component voltage to zero on a periodic average, instantaneous pulsation of the zero-phase component voltage can generate a common-mode current, and this instantaneous common-mode current can also cause motor losses. Below, we will describe other embodiments of the present invention that can eliminate even instantaneous common-mode current by suppressing the pulsation of the zero-phase component voltage.

[0093] Figure 9 is a block diagram showing in detail a controller applied to a motor drive device according to another embodiment of the present invention.

[0094] Referring to Figure 9, the controller 30 of the motor drive device according to another embodiment of the present invention may include a current command map 81, a current control unit 82, a first duty cycle generation unit 83, and a second duty cycle generation unit 84.

[0095] The current command map 81 is the motor required output (motor required torque T) generated by the driver's operation, etc. e * ) and the motor's back electromotive force λ -1 Based on that, the corresponding current command I d * , I q * It can generate [this].

[0096] The current control unit 62 controls the current command I d * , I q *The voltage command V can receive the detected current supplied to the motor and compare it with the actual current supplied to the motor, and reduce the difference. d * , V q * , V n * It can generate the voltage command, which has a d-axis component V. d * , q-axis component V q * and zero-phase component V n * It can include...

[0097] The current command map 81 and the current control unit 82 may be substantially identical to those applied to the typical motor control techniques shown in Figure 2.

[0098] JPEG0007867900000004.jpg57170

[0099] JPEG0007867900000005.jpg60170

[0100] It is known in the art that the rotation angle (θ) of a motor can be obtained from a rotation angle sensor (not shown) provided on the motor.

[0101] In one embodiment of the present invention, the first duty cycle generation unit 83 and the second duty cycle generation unit 84 perform a coordinate transformation such that there is a 120-degree difference between them in the process of converting the d-axis voltage command and the q-axis voltage command into a three-phase voltage command.

[0102] Figure 10 is a voltage vector diagram illustrating an example in the embodiment of the present invention shown in Figure 9, where the phase voltage command of the first inverter is converted to precede the motor's rotation angle by 30 degrees and the phase voltage command of the second inverter is converted to precede the motor's rotation angle by 150 degrees. Figure 11 is a voltage vector diagram illustrating an example in the embodiment of the present invention shown in Figure 9, where the phase voltage command of the first inverter is converted to lag behind the motor's rotation angle by 30 degrees and the phase voltage command of the second inverter is converted to lag behind the motor's rotation angle by 150 degrees.

[0103] JPEG0007867900000006.jpg31170

[0104] JPEG0007867900000007.jpg26170

[0105] Figure 12 is a waveform diagram showing the voltage output, zero-phase voltage component, and common-mode current of each inverter generated by the control of the motor drive device according to the embodiment of the present invention shown in Figure 9.

[0106] As shown in Figure 12, if the voltage vectors output by both inverters have a difference of 120 degrees, when performing modulation using both voltage vectors, the same zero-phase component voltage V will be instantaneously produced. n1 , V n2 It can be confirmed that this is the case. Therefore, the difference V in the zero-phase component voltage of both inverters. n It instantly becomes 0, and therefore we can confirm that the 0-phase component current ripple (common-mode current) due to the difference in 0-phase component voltage also becomes 0.

[0107] On the other hand, in one embodiment of the present invention, the zero-phase component voltage command V for each inverter n *They can also be distributed differently from each other. That is, in FIG. 9, the multiple value P1 for the first inverter set by the second multiple part 832 and the multiple value P2 for the second inverter can be determined to have different magnitudes from each other. Here, the sum of the magnitudes of both multiple values must be 1 (P1 + P2 = 1).

[0108] Zero-phase component voltage command V n * Since the distribution does not affect the output of the motor, it is the same from the perspective of the motor.

[0109] As an example, when the magnitudes of the zero-phase component voltages are distributed equally (when the magnitudes of P1 and P2 are the same), due to errors existing in the inverter such as switching dead time and the compensation for it, the final output duty ratios of both inverters change, and in some cases, one of the inverters may be the first to be subject to duty limit.

[0110] On the other hand, if freedom is given to the distribution of the zero-phase component voltage command for both inverters, it is possible to provide a means to adjust the maximum values of the duties that change with each other to be the same due to errors existing in the inverter such as dead time, thereby increasing the output of the motor. That is, by tuning the multiple values P1 and P2, the problems caused by the inevitable errors of the inverter itself can be appropriately improved, thereby improving the output of the motor.

[0111] Thus, in one embodiment of the present invention described based on FIGS. 9 to 12, by setting the phases of the voltage vectors of both inverters to have a 120-degree difference and generating the zero-phase component output voltages of both inverters by space vector pulse width modulation (SVPWM) to be the same, the zero-phase component switching pulsation between both inverters can be removed.

[0112] However, in such embodiments, the voltage command V for the entire motor drive system is dqn * This method involves separating the voltage required to drive each inverter and then performing calculations to drive each inverter using a spatial vector pulse width modulation scheme. This method requires many calculations for coordinate transformations, size constraints, etc., and discretization errors in cosine and sine operations can cause errors in the inverter output voltage.

[0113] Therefore, the present invention provides yet another embodiment that can resolve switching pulsation due to zero-phase component voltage through simpler calculations.

[0114] Figure 13 is a block diagram showing in detail a controller applied to a motor drive device according to yet another embodiment of the present invention, and Figure 14 is a block diagram of the controller showing in more detail the spatial vector pulse width modulation unit shown in Figure 13.

[0115] Referring to Figures 13 and 14, the controller 30 of the motor drive device according to yet another embodiment of the present invention may include a coordinate transformation unit 91, a spatial vector pulse width modulation unit 92, a multiplication unit 94, a first pole voltage command generation unit 961, and a second pole voltage command generation unit 962. The example controller shown in Figure 13 may naturally include the current command map 81 and current control unit 82 included in the embodiment shown in Figure 9. That is, the coordinate transformation unit 91 of the embodiment in Figure 13 generates the motor voltage command (dq voltage command in the synchronous coordinate system) V generated by the current control unit 82 of the embodiment shown in Figure 9. dr * , V qr * It can operate in response to [something].

[0116] The coordinate transformation unit 91 receives the motor voltage command V generated by the current control unit. dr * , V qr *The system receives this signal and converts it to 30 degrees behind the motor's rotation angle (θ), thereby creating a phase voltage command V that 30 degrees behind the motor's rotation angle (θ). as +* , V bs +* , V cs +* This can generate the coordinate transformation. The coordinate transformation performed by the coordinate transformation unit 91 can be carried out by applying the known technique of inverse Clarke / Park transformation.

[0117] The spatial vector pulse width modulation unit 92 outputs a phase voltage command V that is 30 degrees behind the motor rotation angle (θ) output from the coordinate transformation unit 91. as +* , V bs +* , V cs +* Based on this, a limited pole voltage command V is applied, which performs spatial vector pulse width modulation to lag the motor's rotation angle (θ) by 30 degrees. am_lim +* , V bm_lim +* , V cm_lim +* It can generate [this].

[0118] More specifically, the spatial vector pulse width modulation unit 92 controls a phase voltage command V that is 30 degrees behind the motor's rotation angle (θ). as +* , V bs +* , V cs +* An offset voltage generation unit 921 generates an offset voltage equivalent to the average of the maximum and minimum values ​​within the motor, and a phase voltage command V 30 degrees behind the motor's rotation angle (θ) sets the offset voltage. as +* , V bs +* , V cs +* Subtracting this from the command V, the pole voltage command is executed to set the motor's rotation angle (θ) 30 degrees behind. am +* , V bm +* , V cm+* A pole voltage command generation unit 922 generates a pole voltage command V that is 30 degrees behind the motor rotation angle (θ) generated by the pole voltage command generation unit 922. am +* , V bm +* , V cm +* A limited pole voltage command V that limits the magnitude and delays the motor's rotation angle (θ) by 30 degrees. am_lim +* , V bm_lim +* , V cm_lim +* It may include an pole voltage command limiting unit 923 that generates an pole voltage command limiting unit 923.

[0119] JPEG0007867900000008.jpg40170

[0120] JPEG0007867900000009.jpg31170

[0121] JPEG0007867900000010.jpg23170

[0122] The first pole voltage command generation unit 961 generates zero-phase component voltage commands V for the values ​​output from the multiplier unit 94. n * By multiplying these values ​​by 0.5 and adding them together, the final pole voltage command for the first inverter 10 can be generated.

[0123] The second pole voltage command generation unit 962 can generate pole voltage commands for the second inverter 20. If the voltage of the first inverter 10 lags behind the motor voltage by 30 degrees, the voltage command for the second inverter 20 will lag behind the voltage of the first inverter by an additional 120 degrees. This corresponds to shifting the a-phase command to the b-phase command, the b-phase command to the c-phase command, and the c-phase command to the a-phase command within the first pole voltage command.

[0124] In other words, the second pole voltage command generation unit 962 generates zero-phase component voltage commands V from the values ​​output from the multiplier unit 94.n * Subtracting this value by multiplying it by 0.5, the 0-phase component voltage command V is taken from the value corresponding to the a-phase among the values ​​output from the multiplier section 94. n * The value obtained by subtracting 1 / 2 of the value is used as the b-phase pole voltage command for the second inverter 20, and the 0-phase component voltage command V is derived from the value corresponding to the b-phase among the values ​​output from the multiplier unit 94. n * The value obtained by subtracting 1 / 2 of the value is used as the c-phase pole voltage command for the second inverter 20, and the 0-phase component voltage command V is derived from the value corresponding to the c-phase among the values ​​output from the multiplier unit 94. n * The value obtained by subtracting 1 / 2 of this value can be determined as the a-phase pole voltage command for the second inverter 20.

[0125] By generating a duty cycle based on the pole voltage commands output from the first pole voltage command generation unit 961 and the second pole voltage command generation unit 962, respectively, and controlling the switching elements in the first inverter 10 and the second inverter 20, as shown in the embodiment in Figure 9, the voltage of the first inverter lags behind the motor voltage command by 30 degrees, and the voltage of the second inverter has a phase difference of 120 degrees from the voltage of the first inverter, thereby eliminating the zero-phase component current.

[0126] In particular, the embodiments shown in Figures 13 and 14 first perform spatial vector pulse width modulation based on the motor voltage command, and then generate pole voltage commands for each inverter based on the output result. Therefore, compared to the embodiment shown in Figure 9, the amount of computation required for coordinate transformation can be minimized, and thus the discretization error due to sine and cosine operations in the voltage modulation calculation can be minimized.

[0127] On the other hand, Figures 13 and 14 show the zero-phase component voltage command V n * A multiplier 95 was applied to reduce it to 0.5 times, but as shown in Figure 15, the zero-phase component voltage command V for each inverter n * They can also be distributed differently from one another.

[0128] Figure 15 is a block diagram showing a modified example of the controller of the embodiment shown in Figure 13.

[0129] Referring to Figure 15, the multiple value P1 for the zero-phase component voltage command added to the first pole voltage command generation unit 961 and the multiple value P2 for the zero-phase component voltage command added to the second pole voltage command generation unit 962 can be determined to have different magnitudes. Here, the sum of the magnitudes of both multiple values ​​must be 1 (P1 + P2 = 1).

[0130] As already described in the description of the embodiment in Figure 9, the zero-phase component voltage command V n * Since the distribution does not affect the motor output, from the motor's perspective, they are identical. By giving both inverters a degree of freedom in the distribution of the zero-phase component voltage command, it is possible to provide a means to adjust the maximum duty cycles, which vary from one another due to errors present in the inverters such as dead time, to be the same, thereby increasing the motor's output.

[0131] In other words, the embodiment shown in Figure 15 can appropriately improve the problems caused by errors that are unavoidable in the inverter itself by tuning the multiple values ​​P1 and P2, thereby improving the output of the motor.

[0132] On the other hand, in Figures 13 to 15, reference numeral '93' indicates an anti-windup calculation unit that generates and provides a signal to be fed back to the integrator (corresponding to the current controller 82 in Figure 9).

[0133] In the embodiments shown in Figures 13 to 15, the motor voltage command V corresponds to the output of the current controller 82. d r* , V q r*The voltage is limited by the pole voltage command limiting unit 923 within the spatial vector pulse width modulation unit 92, and then the switching control for each inverter is performed by the limited command. In other words, for the current controller 82 to perform accurate feedback control, the voltage command it outputs must be fed back to a limited extent when it is actually applied to the inverter control.

[0134] The anti-wind-up calculation unit 93 sets a limited pole voltage command V that is 30 degrees behind the motor's rotation angle (θ). am_lim +* , V bm_lim +* , V cm_lim +* A rotational transformation (Clarke / Park Transformation) can be performed to set the motor's rotation angle (θ) 30 degrees backward, and this can be fed back to the current controller.

[0135] In addition, in yet another embodiment of the present invention, the voltage of the first inverter 10 can precede the motor voltage command by 30 degrees. In this case, the voltage of the second inverter 20 can precede the voltage of the first inverter 10 by 120 degrees. Therefore, the second pole voltage command generation unit 962 generates zero-phase component voltage commands V for the values ​​output from the multiplier unit 94. n * The values ​​are multiplied by 0.5 and added together, and the value corresponding to the a-phase among the values ​​output from the multiplier section 94 is set to the 0-phase component voltage command V n * The sum of 1 / 2 of the above values ​​is used as the c-phase pole voltage command for the second inverter 20, and the value corresponding to the b-phase among the values ​​output from the multiplier unit 94 is used as the 0-phase component voltage command V n * The sum of 1 / 2 of the above values ​​is used as the a-phase pole voltage command for the second inverter 20, and the value corresponding to the c-phase among the values ​​output from the multiplier unit 94 is used as the 0-phase component voltage command V n * The sum of 1 / 2 of these values ​​can be used to determine the b-phase pole voltage command for the second inverter 20.

[0136] The voltage phase relationship between the first inverter and the second inverter is shown in Figure 10. Figure 10 shows an example where the voltage of the first inverter precedes the motor voltage by 30 degrees, but an ordinary technician in the art can easily infer from the example in Figure 10 an embodiment in which the voltage of the first inverter follows the motor voltage by 30 degrees.

[0137] In the embodiment described above, the switching elements corresponding to each phase of the first inverter 10 and the second inverter 20 perform switching once each within one switching cycle. Here, one switching means that the switching element switches from the off state to the on state and then switches back to the off state, or switches from the on state to the off state and then switches back to the on state.

[0138] This switching method for switching elements within an inverter is efficient when the first switching elements S11-S16 in the first inverter 10 and the second switching elements S21-S26 in the second inverter 20 are of the same type.

[0139] However, if the first switching elements S11-S16 in the first inverter 10 and the second switching elements S21-S26 in the second inverter 20 are of different types, for example, if the first switching elements S11-S16 are MOSFETs made from SiC, a material with relatively low switching loss, and the second switching elements S21-S26 are IGBTs made from Si, a material with relatively high switching loss but low cost, then it is inefficient for the first switching elements S11-S16 and the second switching elements S21-S26 to switch at the same rate. This can result in situations where the motor is controlled with high switching loss, even though it would be possible to reduce the switching loss.

[0140] Therefore, yet another embodiment of the present invention provides a novel control technique that can reduce switching losses and improve system efficiency when the first switching elements S11-S16 and the second switching elements S21-S26 in the second inverter 20 are different switching elements made from different materials.

[0141] Figure 16 is a block diagram showing in detail a controller applied to a motor drive device according to yet another embodiment of the present invention. In the following description, we will explain as an example the case in which the second switching elements S21-S26 constituting the second inverter 20 are elements with relatively large switching losses, such as IGBTs made from Si, and the first switching elements S11-S16 constituting the first inverter 10 are elements with relatively small switching losses, such as MOSFETs made from SiC.

[0142] Referring to Figure 16, the controller 30 of the motor drive device according to yet another embodiment of the present invention may include a current command map 1010, a current control unit 1020, a voltage limiting unit 1030, a duty cycle generation unit 1040 for the second inverter, a coordinate transformation unit 1050, and a pulse width modulation unit 1060 for the first inverter.

[0143] The current command map 1010 and the current control unit 1020 may be substantially identical to the current command map and current control unit applied to the embodiment shown in Figure 6 or Figure 9.

[0144] In other words, the current command map 1010 is the motor required output (motor required torque T) generated by the driver's operation, etc. e * and the motor's back electromotive force λ -1 Based on that, the corresponding current command I d * , I q * It can generate a current command I. d * , I q *The voltage command V can be used to reduce the difference between the detected value and the actual current supplied to the motor. d * , V q * , V n * It can generate the voltage command, which is the d-axis component V. d * , q-axis component V q * and zero-phase component V n * It can include...

[0145] The voltage limiting unit 1030 controls the voltage command V generated by the current control unit 1020. d * , V q * , V n * The upper and lower limits are restricted to the limited voltage command V d、lim * , V q、lim * , V n、lim * The voltage limiting unit 1030 can store in advance pre-set upper and lower limits for a voltage command, and these upper and lower limits can be predetermined by the upper and lower limits of the motor voltage that can be generated by controlling the switching elements in the first inverter 10 and the second inverter 20.

[0146] The duty cycle generation unit 1040 for the second inverter generates a limited voltage command V d、lim * , V q、lim * Based on this, the switching duty cycles of the second switching elements S21-S26 in the second inverter 20 can be determined.

[0147] The embodiment shown in Figure 16 illustrates an example of a controller 30 that can be applied when the second switching elements S21-S26 applied to the second inverter 20 have a larger switching loss than the first switching elements S11-S16 applied to the first inverter 10. In other words, the embodiment shown in Figure 16 is an example in which the switching loss of the second switching elements S21-S26, which have a relatively larger switching loss, can be reduced by not switching the second switching elements S21-S26 of the second inverter 20 within one switching cycle and only switching the first switching elements S11-S16 of the first inverter 10.

[0148] The duty cycle generation unit 1040 for the second inverter generates a limited voltage command V d、lim * , V q、lim * The duty cycle of the second inverter can be determined based on the active voltage vector that is closest to the negative value of the function.

[0149] Figure 17 is a voltage vector diagram illustrating the voltages of each inverter and the motor voltage determined by the embodiment shown in Figure 16.

[0150] Referring to Figure 17, as mentioned above, the motor voltage is equivalent to the voltage of the second inverter minus the voltage of the first inverter, so the voltage command V d、lim * , V q、lim * Corresponding voltage vector V ref The voltage vector V of the first inverter 10 INV1 Voltage vector V from the second inverter 20 INV2 It can be generated by subtracting [something].

[0151] The duty cycle generation unit 1040 for the second inverter can determine the voltage vector of the second inverter as the effective voltage vector corresponding to one of the vertices of a hexagon on the vector diagram. In particular, the duty cycle generation unit 1040 for the second inverter generates a voltage command V for optimal calculation. d、lim * , V q、lim * Corresponding voltage vector V ref The voltage vector closest to the voltage vector corresponding to the negative value (

[0001] in Figure 17) can be determined as the voltage vector of the second inverter. Therefore, the second inverter can maintain a high state only for the c-phase voltage during one switching cycle (corresponding to the case where the upper switching elements S21 and S23 of the a-phase and b-phase legs of the second inverter 20 are off, the lower switching elements S22 and S24 of the a-phase and b-phase legs of the second inverter 20 are on, the upper switching element S25 of the c-phase leg of the second inverter 20 is on, and the lower switching element S26 of the c-phase leg of the second inverter 20 is off).

[0152] The duty cycle generation unit 1040 for the second inverter generates a voltage command V d、lim * , V q、lim * Corresponding voltage vector V ref There are various ways to determine the closest effective vector, but the voltage command V d、lim * , V q、lim * The simplest and most effective method is to determine the sign of each corresponding three-phase voltage using the sign of the corresponding voltage.

[0153] The duty cycle generation unit 1040 for the second inverter uses inverse Clarke / Park transformation to generate a voltage command V d、lim * , V q、lim *The values ​​are converted to abc coordinates corresponding to the three phases of the motor, and the voltage vector of the second inverter 20, i.e., the duty cycle of the second inverter 20, can be determined by the sign of the converted abc coordinates, as shown in Equation 4 below.

number

[0154] The coordinate transformation unit 1050 can convert the voltage vector corresponding to the duty cycle of the second inverter 20 back into dq coordinates by rotational transformation (Clarke / Park Transformation).

[0155] The pulse width modulation unit 1060 for the first inverter receives a voltage command V d、lim * , V q、lim * , V n、lim * The voltage vectors corresponding to the duty cycle of the second inverter 20, which have been transformed by the coordinate transformation unit 1050, are added together to form the voltage command V of the first inverter. d、INV1 * , V q、INV2 * , V n、INV3 * The voltage command V of the first inverter is received as follows: d、INV1 * , V q、INV2 * , V n、INV3 * Based on this, pulse width modulation is performed and the duty cycle of the first inverter D a1 , D b1 , D c1 It is possible to make a decision.

[0156] The pulse width modulation unit 1060 for the first inverter can apply RSPWM (Remote State Pulse Width Modulation) to enable switching using an effective vector having the same zero-phase component voltage so that the first inverter and the second inverter can maintain the same zero-phase component voltage within the switching cycle.

[0157] It is known that the zero-phase component voltage for each switching state of a three-phase inverter is determined as shown in the table below. [Table 1]

[0158] For example, as shown in Figure 17, if the duty cycle or voltage command of the second inverter 20 is determined to

[0001] , the voltage command of the first inverter 10 can be determined using

[0010] ,

[0001] , and

[0100] , which have the same zero-phase component voltage as the zero-phase component voltage due to the switching state of the second inverter.

[0159] The hexagon at the bottom of Figure 17 shows, with a dotted line, the range of the first inverter voltage that can be combined by the effective vectors having switching states

[0010] ,

[0001] , and

[0100] in the first inverter. Furthermore, when the voltage range of the first inverter 10, whose 0-phase component voltage can be determined in the same way as the second inverter by the effective vectors determined by the duty cycle of the second inverter 20, is applied to the overall motor voltage obtained by combining the first and second inverters, the motor voltage can be determined within the range shown by the dotted line in the hexagon at the top of Figure 17.

[0160] The pulse width modulation unit 1060 for the first inverter controls the voltage V of the first inverter 10. INV1 To enable synthesis, the duty cycle can be determined for a switching state having the same zero-phase component voltage as the switching state of the second inverter.

[0161] Figure 18 is a waveform diagram showing the voltage output of each inverter generated by the control of the motor drive device according to the embodiment of Figure 16.

[0162] As shown in Figure 18, the second inverter 20 has a switching period T sw Of these, only state

[0001] is maintained, and it can be confirmed that the first inverter 10 performs switching that shows

[0001] ,

[0100] , and

[0010] , which have the same zero-phase component voltage as

[0001] , with a constant duty cycle. The zero-phase component voltages of both inverters V n1 , V n2 Since they are identical to each other, the difference between the two zero-phase component voltages corresponds to the zero-phase component voltage V of the entire motor drive system. n We can confirm that it is also 0, and therefore the zero-phase component current I n It can be confirmed that this does not occur.

[0163] Figures 19 to 21 are waveform diagrams showing various control methods for the first inverter that can be generated by the pulse width modulation unit for the first inverter shown in Figure 16.

[0164] According to the table above, once the duty cycle of the second inverter 20 is determined, the pulse width modulation unit 1060 for the first inverter can determine the duty cycle of the first inverter 10 using the switching states of three active voltage vectors having the same zero-phase component voltage.

[0165] First, as shown in Figure 19, the pulse width modulation unit 1060 for the first inverter can be configured to switch the first switching elements S11-S16 of the first inverter 10 by repeatedly switching the three determined switching states in a fixed order.

[0166] Furthermore, as shown in Figure 20, the pulse width modulation unit 1060 for the first inverter can be configured to symmetrically distribute the three determined switching states based on a predetermined midpoint of one switching cycle.

[0167] Furthermore, as shown in Figure 21, when the pulse width modulation unit 1060 for the first inverter applies a method of symmetrically distributing the three determined switching states with respect to the midpoint of one switching cycle, it can apply a method to reduce the number of switching cycles and reduce switching losses by ensuring that the switching state with the longest duty cycle appears consecutively before and after the midpoint of one switching cycle.

[0168] As explained above, the embodiment described with reference to Figures 16 to 21 allows for minimizing the switching of the inverter using a switching element with high switching loss when the types of switching elements constituting the two inverters applied to the open-end winding method are different. This reduces switching loss and thereby significantly improves system efficiency.

[0169] Although specific embodiments of the present invention have been described with illustrations above, it will be apparent to those with ordinary skill in the art that the present invention can be improved and modified in various ways within the scope of the claims. [Explanation of symbols]

[0170] 10. First Inverter 20 Second Inverter 30 controllers 100 motors 200 batteries 61, 81 Current Command Map 62, 82 Current control unit 63, 64, 83, 84 Duty cycle generation unit Multiples of 631, 641, 831, 832, 841, 842 632, 642, 833, 843 Coordinate transformation section 633, 634, 834, 844 Spatial vector pulse width modulation section 71 Offset voltage generation unit 711 Offset Voltage Command Synthesis Unit 72-pole voltage command generation unit 73-pole voltage command limiting unit 74 Division Section 75 Combined section 91 Coordinate Transformation Unit 92 Spatial vector pulse width modulation section 921 Offset voltage generation unit 922 Pole Voltage Command Generation Unit 923 Pole Voltage Command Limiting Unit 93 Anti-wind-up calculation unit Multiples of 94, 95, 951, 952 961 First pole voltage command generation unit 962 Second pole voltage command generation unit 1010 Current Command Map 1020 Current Control Unit 1030 Voltage limiting section 1040 Duty cycle generation unit for the second inverter 1050 Coordinate Transformation Unit 1060 Pulse width modulation section for the first inverter S11-S16 First switching element S21-S26 Second switching element S31-S33 Third switching element L1-L3 winding

Claims

1. A motor drive device for driving a motor having multiple windings corresponding to multiple phases, A first inverter comprising a plurality of first switching elements, connected to the first end of each of the plurality of windings, A second inverter comprising a plurality of second switching elements, connected to the second end of each of the plurality of windings, A controller that determines the duty cycle of the plurality of second switching elements to be the effective vector closest to the voltage vector corresponding to the voltage command of the motor which has been set in advance, and uses the value obtained by adding the effective vector corresponding to the duty cycle of the second switching elements to the voltage command of the motor as the voltage command of the first inverter to control the first switching element with pulse width modulation, A motor drive system, including a motor drive device.

2. The motor drive device according to claim 1, characterized in that the controller controls the first switching element using the RSPWM (Remote State Pulse Width Modulation) method.

3. The motor drive device according to claim 1, characterized in that the controller synthesizes the voltage command of the first inverter using a plurality of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element.

4. The motor drive device according to claim 1, characterized in that the controller generates a three-phase voltage command by converting the motor's voltage command in reverse, and determines the effective vector closest to the voltage vector corresponding to the motor's voltage command based on the three-phase voltage command.

5. The aforementioned controller is given by the following equation: D ａｂｃ、ｉｎｖ２ =Sign(V ａｂｃｎ、ｌｉｍ ＊ ) The motor drive device (D) according to claim 4, characterized in that it determines the effective vector closest to the voltage vector corresponding to the voltage command of the motor using (Sign(x) = 1 if x ≥ 0, Sign(x) = 0 if x < 0). ａｂｃ、ｉｎｖ２ : The duty cycle, V, that corresponds to the effective vector closest to the voltage vector corresponding to the voltage command of the motor. ａｂｃｎ、ｌｉｍ ＊ (The three-phase voltage command mentioned above).

6. The motor drive device according to claim 1, characterized in that the controller generates a voltage command for the first inverter by adding the result of rotational conversion of an effective vector corresponding to the duty cycle of the second switching element to the voltage command for the motor.

7. The motor drive device according to claim 3, characterized in that the controller switches the first switching element such that a plurality of effective vectors having the same zero-phase component voltage as the effective vector corresponding to the duty cycle of the second switching element are repeated in a certain order.

8. The motor drive device according to claim 3, characterized in that the controller switches the first switching element such that a plurality of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element appear symmetrically with respect to a predetermined midpoint of one switching period.

9. The motor drive device according to claim 8, characterized in that the controller switches the first switching element such that the switching state having the longest duty cycle among a plurality of switching states of active vectors having the same zero-phase component voltage as the active vector corresponding to the duty cycle of the second switching element appears consecutively before and after the intermediate time point.

10. The motor drive device according to claim 1, characterized in that the controller limits the voltage command of the motor, which has been set in advance, to an upper and lower limit value, which has been set in advance.

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