JP6503277B2 - Controller and AC motor drive - Google Patents

Description

  The present invention relates to a controller that controls an AC motor having electrically separated multi-phase windings, and an AC motor drive device.

  One end and the other end of the multi-phase winding of an AC motor (hereinafter referred to as an open winding alternating current motor) having an electrically separated multi-phase winding for the purpose of increasing the capacity of electric power supplied to the motor Patent Document 1 discloses a technique for driving an open-winding alternating current motor by connecting an inverter to each.

  FIG. 6 shows a configuration example of a controller 60 for controlling a first inverter and a second inverter (not shown) respectively connected to one end and the other end of the multi-phase winding of the open winding alternating current motor. FIG. Here, each of the first inverter and the second inverter includes, for example, a plurality of switching elements, and is a multiphase voltage type PWM (Pulse Width Modulation) inverter that converts DC power into AC power by controlling the plurality of switching elements. It is.

  The controller 60 shown in FIG. 6 includes a zero phase current detection unit 61, a subtractor 62, a zero phase current adjustment unit 63, an adder 64, and a PWM signal generation unit 65.

The zero-phase current detection unit 61 is a zero-phase current i from the sum of the U-phase current i _u flowing in the U-phase of the open winding AC motor, the V-phase current i _v flowing in the V phase, and the W-phase current i _w flowing in the W phase. ₀ is detected, and the detection result is output to the subtractor 62.

Subtractor 62 obtains the deviation (i ₀ ^* -i ₀₎ by subtracting the zero-phase current i ₀ which is detected by the zero-phase current detection unit 61 from the zero-phase current command i ₀ ^*, zero-phase current controller 63 Output to

Zero-phase current adjustment unit 63 sets zero-phase voltage command v ₀ ^* instructing an output voltage to the open-winding alternating current motor such that the deviation (i ₀ ^* −i ₀ ) output from subtractor 62 is _zero ^. It is generated and output to the adder 64.

The adder 64 adds the zero-phase voltage command v ₀ ^* output from the zero-phase current adjustment unit 63 and the voltage command v ^* to command the voltage of each phase for causing the open-winding AC motor to generate a desired torque. The addition is performed to generate an inverter output voltage command v _INV ^*, which is output to the PWM signal generation unit 65.

The PWM signal generation unit 65 causes the first inverter and the second inverter to make the voltage applied from the first inverter and the second inverter to the open winding AC motor coincide with the inverter output voltage command v _INV ^*. The PWM signal PWM ₁ and the PWM signal PWM ₂ that control the respective switching elements are generated. Then, the PWM signal generating unit 65 outputs the generated PWM signal PWM ₁ to the first inverter, and outputs the generated PWM signal PWM ₂ in a second inverter.

Patent 4788949

  In patent document 1, it is premised to use an induction motor as an open winding alternating current motor. Here, in the case where a permanent magnet synchronous motor is used as the open winding AC motor, the technique disclosed in Patent Document 1 has a problem that it is difficult to suppress the zero-phase current. The following describes the causes of this problem.

  When a permanent magnet synchronous motor is used as the open winding AC motor, in particular, when the open winding AC motor is configured using the rotor structure of a star-connected permanent magnet synchronous motor as it is, when the open winding AC motor is driven, A 3n-order harmonic component tends to appear as a zero-phase component of the induced voltage. This harmonic component corresponds to the disturbance voltage for zero-phase current adjustment unit 63 shown in FIG.

In general, the zero-phase current adjustment unit 63 generates a zero-phase voltage command v ₀ ^* such that the deviation (i ₀ ^* −i ₀ ) becomes zero by general proportional integral control. Here, proportional integral control has a characteristic that high control performance (gain) can not be obtained in a high frequency region. Therefore, the disturbance voltage due to the 3n harmonic component appearing in the high frequency region can not be compensated by the technique disclosed in Patent Document 1, and the zero phase current can not be controlled as the zero phase current command i ₀ ^* . When a zero-phase current including a 3n-order harmonic component flows due to the disturbance voltage, a loss due to the zero-phase current occurs, which leads to an increase in loss when driving the open-winding alternating current motor, and the efficiency decreases. Since this disturbance voltage increases in frequency and increases in size in proportion to the number of revolutions of the motor, the above-mentioned problems become remarkable particularly in an open-winding permanent magnet synchronous motor driven at high speed.

  Also, although the zero-phase current does not directly affect the torque, there is an interference relationship between the torque current and the flux current used for torque control of the open-winding AC motor and the zero-phase current, and depending on the rotor structure, the zero-phase current Ripples in the torque current and the magnetic flux current cause the torque ripple to increase.

  An object of the present invention is to provide a controller and an AC motor drive device capable of solving the above-mentioned problems and reducing the zero-phase current.

  In order to solve the above-mentioned subject, the controller concerning the present invention is connected to one end and the other end of the winding of the above-mentioned plurality of phases of the permanent magnet synchronous motor which has the winding of a plurality of phases electrically separated mutually, respectively. A controller generating an applied voltage command for controlling an output voltage of the first inverter and the second inverter, the zero-phase current detection unit detecting a zero-phase current flowing through the permanent magnet synchronous motor; and the applied voltage command A zero-phase voltage estimation unit for estimating a zero-phase voltage generated by the permanent magnet synchronous motor based on a zero-phase voltage command which is a zero-phase component of the first phase and a zero-phase current detected by the zero phase current detection section; Zero that generates an adjusted zero-phase voltage command that controls the output voltage of the first inverter and the second inverter such that the deviation between the zero-phase current and the zero-phase current command detected by the current detection unit becomes zero. phase A flow adjustment unit, a zero-phase voltage estimated by the zero-phase voltage estimation unit, and the adjusted zero-phase voltage command generated by the zero-phase current adjustment unit to generate the zero-phase voltage command And a first voltage command obtained by converting the zero-phase voltage command generated by the first adder into a multi-phase voltage command, and generating a predetermined torque in the permanent magnet synchronous motor. And an adder for adding the second voltage command which is a multiphase voltage command for generating the applied voltage command.

  In the controller according to the present invention, the zero-phase voltage estimation unit is an inverse model of a zero-phase model representing the permanent magnet synchronous motor, which has a zero-phase voltage as an input and a zero-phase current as an output, represented by zero phase. A zero-phase inverse model unit that calculates an estimated zero-phase voltage corresponding to the zero-phase current detected by the zero-phase current detection unit based on a certain zero-phase inverse model, and a zero phase that is a zero-phase component of the applied voltage command The first subtractor for calculating the deviation between the voltage command and the estimated zero-phase voltage calculated by the zero-phase inverse model unit, the plurality of low pass filters, and the plurality of low pass filters A selection unit for selecting any one of the low pass filters according to the electrical angle of the permanent magnet synchronous motor and inputting the deviation calculated by the first subtracter to the selected low pass filter; Low pass filter for each output A second subtraction that subtracts the average value stored in the storage unit from the storage unit that stores the average value and the output of the low-pass filter selected by the selection unit, and outputs the result as the zero-phase voltage It is desirable to provide the

  Further, in the controller according to the present invention, the selection unit divides one cycle of the phase by the number of the plurality of low pass filters, and any one of the plurality of low pass filters in each region of the divided phases. And the phase of the suppression target harmonic is calculated by multiplying the electrical angle of the permanent magnet synchronous motor by the order of the suppression target harmonic generating the zero phase current, and calculating the phase of the suppression target harmonic It is desirable to select the low pass filter assigned to the region that contains

  Further, in the controller according to the present invention, when the operating frequency of the permanent magnet synchronous motor is equal to or less than a predetermined value, a carrier signal having a constant frequency is generated, and the operating frequency of the permanent magnet synchronous motor is higher than the predetermined value. It is desirable to further include a carrier signal generation unit that generates a carrier signal of a frequency that is proportional to the operating frequency of the permanent magnet synchronous motor when it becomes larger, and operates at an operating frequency according to the frequency of the carrier signal.

  Further, in order to solve the above problems, an AC motor drive device according to the present invention is provided for each of one end and the other end of the multi-phase winding of a permanent magnet synchronous motor having multi-phase windings electrically separated from each other. A first inverter and a second inverter connected to each other, and any of the controllers described above.

  According to the controller and the AC motor drive device of the present invention, it is possible to reduce the zero phase current.

It is a figure showing composition of an exchange motor drive concerning one embodiment of the present invention. It is a figure which shows the structure of the controller shown in FIG. It is a figure which shows the structure of the zero phase voltage estimation part shown in FIG. It is a figure which shows an example of the output of the filter group shown in FIG. It is a figure for demonstrating the operating frequency of the controller shown in FIG. It is a figure which shows the structure of the conventional controller.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a view showing the configuration of an AC motor drive device 10 according to an embodiment of the present invention. The AC motor drive device 10 according to the present embodiment is a DC power supplied from a DC power supply 2 to an open-winding AC motor 1 having a plurality of electrically separated (neutral-point separated) multiple-phase windings. Is converted into AC power and supplied to drive the open winding AC motor 1. In the present embodiment, it is assumed that the open winding alternating current motor 1 is a permanent magnet synchronous motor.

  An AC motor drive device 10 shown in FIG. 1 includes inverters 11-1 and 11-2 (first inverter and second inverter), a current detector 12, and a controller 13.

  The inverters 11-1 and 11-2 are connected in parallel to the DC power supply 2, and are, for example, three-phase voltage type PWM inverters. As the DC power supply 2, a secondary power supply such as a battery, or one obtained by rectifying an AC power supply with a bridge diode or the like can be used.

  The output terminal of the inverter 11-1 is connected to one end of the winding of the open winding AC motor 1, and the DC voltage from the DC power supply 2 is an AC voltage (U phase voltage U1, V phase voltage V1, W phase voltage W1) And apply to the open winding alternating current motor 1.

  Specifically, inverter 11-1 includes smoothing capacitor C1 for smoothing the output of DC power supply 2, and switching elements S11 to S16 such as IGBT (Insulated Gate Bipolar Transistor). Switching element S11 and switching element S12 are connected in series between the positive electrode and the negative electrode of DC power supply 2, switching element S13 and switching element S14 are connected in series, and switching element S15 and switching element S16 are in series It is connected to the. The voltage at the connection point between switching element S11 and switching element S12, the voltage at the connection point between switching element S13 and switching element S14, and the voltage at the connection point between switching element S15 and switching element S16 are U-phase voltage U1. The V-phase voltage V1 and the W-phase voltage W1 are applied to the open winding AC motor 1. A desired output voltage can be obtained by controlling the on / off of the switching elements S11 to S16.

  The output terminal of the inverter 11-2 is connected to the other end of the winding of the open winding AC motor 1, and the DC voltage from the DC power supply 2 is converted to an AC voltage (U phase voltage U2, V phase voltage V2, W phase voltage W2 ) And apply to the open winding AC motor 1.

  Specifically, inverter 11-2 includes a smoothing capacitor C2 for smoothing the output of DC power supply 2, and switching elements S21 to S26 such as IGBT. Switching element S21 and switching element S22 are connected in series between the positive electrode and the negative electrode of DC power supply 2, switching element S23 and switching element S24 are connected in series, and switching element S25 and switching element S26 are in series It is connected to the. The voltage at the connection point between switching element S21 and switching element S22, the voltage at the connection point between switching element S23 and switching element S24, and the voltage at the connection point between switching element S25 and switching element S26 are U phase voltage U2 respectively. The V-phase voltage V2 and the W-phase voltage W2 are applied to the open winding AC motor 1, respectively. A desired output voltage can be obtained by controlling the on / off of the switching elements S21 to S26.

The current detector 12 detects a U-phase current i _u flowing in the U-phase of the open winding AC motor 1, a V-phase current i _v flowing in the V-phase, and a W-phase current i _w flowing in the W phase, and controls the detection result Output to the output unit 13.

The controller 13 controls the switching elements S11 to S16 of the inverter 11-1 based on the U-phase current i _u , the V-phase current i _v , the W-phase current i _w detected by the current detector 12 and the like. generating a ₁ and the PWM signal PWM ₂ for controlling the switching element S21~S26 inverter 11-2. Then, the controller 13 outputs the generated PWM signal PWM ₁ to the inverter 11-1, and outputs the generated PWM signal PWM ₂ to the inverter 11-2.

  Next, the configuration of the controller 13 will be described with reference to FIG.

  The controller 13 shown in FIG. 2 includes a zero-phase current detection unit 21, a subtractor 22, a zero-phase current adjustment unit 23, adders 24 and 27, a zero-phase voltage estimation unit 25, and zero-phase three-phase conversion. A unit 26, multipliers 28 and 29, a carrier signal generator 30, and PWM signal generators 31-1 and 31-2 are provided. The adder 24 is a first adder, and the adder 27 is a second adder.

The zero-phase current detection unit 21 receives the detection result (U-phase current i _u , V-phase current i _v , W-phase current i _w ) of the current detector 12 and detects the zero-phase current i ₀ based on the detection result. Do. Specifically, the zero phase current detection unit 21 detects the zero phase current i ₀ from the U phase current i _u , the V phase current i _v and the W phase current i _w by Equation 1. The zero phase current detection unit 21 outputs the detected zero phase current i ₀ to the subtractor 22 and the zero phase voltage estimation unit 25.

Subtractor 22 obtains a by subtracting the zero-phase current i ₀ detected by the zero-phase current command i ₀ ^* from the zero-phase current detection unit 21 zero-phase current deviation ^{_{i 0err (= i 0 * -i}} 0), It is output to the zero phase current adjustment unit 23.

The zero-phase current adjustment unit 23 sets the zero-phase current so that the zero-phase current deviation i _0err output from the subtractor 22 becomes zero (as the zero-phase current i ₀ approaches the zero-phase current command i ₀ ^* ). Feedback control (for example, proportional integral integral amplification) is _performed on deviation i _0err to generate zero-phase voltage command v _0pi ^* (adjusted zero-phase voltage command) by feedback control. The zero phase current adjustment unit 23 outputs the generated zero phase voltage command v 0 _pi ^* to the adder 24.

The adder 24 _{generates the} zero-phase voltage command v _0pi ^* output from the zero-phase current adjustment unit 23 and the alternating current component i _0rip of the zero-phase current i ₀ output from the zero-phase voltage estimation unit 25 described later. The zero-phase voltage command v ₀ ^* is generated by adding the zero-phase voltage v _{0 rip} ^* that is _present, and is output to the zero-phase voltage estimation unit 25 and the zero-phase three-phase conversion unit 26.

The zero-phase voltage estimation unit 25 generates the open-winding alternating current motor 1 based on the zero-phase current i ₀ output from the zero-phase current detection unit 21 and the zero-phase voltage command v ₀ ^* output from the adder 24. A zero-phase voltage (a zero-phase voltage v _0rip generating an alternating current component i _0rip of the zero-phase current i ₀ ) is estimated and output to the adder 24. As described above, since the zero-phase voltage generated by the open winding AC motor 1 is caused by the 3n-order harmonic component that appears as the zero-phase component of the induced voltage, the zero-phase voltage v _0rip is open It changes according to the electrical angle of the winding AC motor 1.

The zero-phase to three-phase conversion unit 26 has an array structure of the U-phase voltage v _u0 , the V-phase voltage v _u0, and the W-phase voltage v _u0 from the zero-phase voltage command v ₀ ^* output from the adder 24 according to Equation 2. The phase voltage command V _uvw ^* is generated and output to the adder 27.

The adder 27 _generates a three-phase voltage command V _uvw ^* output from the zero-phase three-phase converter 26 and a U-phase voltage command and a V-phase voltage command for causing the open winding AC motor 1 to generate a desired torque. The three-phase voltage command v ^* having the W-phase voltage command array structure is added to generate an inverter output voltage command v _m ^* (applied voltage command), which is output to the multiplier 28. Thus, in the inverter output voltage command v _m ^* (applied voltage command), the zero-phase voltage command v ₀ ^* generated by the adder 24 is a voltage of multiple phases (three phases) by the zero-phase to three-phase converter 26. It is generated by adding the three-phase voltage command V _uvw ^* converted to the command (first voltage command) and the three-phase voltage command v ^* (second voltage command). Therefore, the zero-phase voltage command v ₀ ^* generated by the adder 24 corresponds to the zero-phase component of the inverter output voltage command v _m ^* .

The multiplier 28 multiplies the inverter output voltage command v _m ^* output from the adder 27 by 1⁄2 and outputs the result to the multiplier 29 and a PWM signal as an inverter output voltage command v _m1 ^* for the inverter 11-1 It is output to the generation unit 31-1.

The multiplier 29 multiplies the output of the multiplier 28 by −1 and outputs the result to the PWM signal generator 31-2 as an inverter output voltage command v _m2 ^* for the inverter 11-2. The inverter output voltage command v _m2 ^* is obtained by multiplying the inverter output voltage command v _m ^* by −1⁄2.

Carrier signal generating unit 30 is input electrical angle F _e open winding AC motor 1 generates a carrier signal having a frequency corresponding to the input electric angle F _e, PWM signal generating unit 31-1,31- Output to 2.

The PWM signal generation unit 31-1 generates the PWM signal PWM ₁ based on the inverter output voltage command v _m1 ^* output from the multiplier 28 and the carrier signal output from the carrier signal generation unit 30, and the inverter 11 Output to -1.

The PWM signal generation unit 31-2 generates the PWM signal PWM ₂ based on the inverter output voltage command v _m2 ^* output from the multiplier 29 and the carrier signal output from the carrier signal generation unit 30, and generates the inverter 11. Output to -2.

  Next, the configuration of zero-phase voltage estimation unit 25 will be described with reference to FIG.

  The zero-phase voltage estimation unit 25 shown in FIG. 3 includes a zero-phase inverse model unit 32, a subtractor 33 (first subtractor), switches 34a and 34b, and a plurality (Nf) of low-pass filters (Nf). A filter group 35 including an LPF (Low Pass Filter), a storage unit 36, a subtractor 37 (second subtractor), a proportional unit 38, and a switching signal generator 39 are provided. The proportional unit 38 and the switching signal generator 39 constitute a selection unit 40.

The zero-phase inverse model unit 32 is an inverse model of a zero-phase model in which an open-winding AC motor 1 having a zero-phase voltage as an input and an zero-phase current as an output is represented by zero phase Holds a zero-phase inverse model which is a model having a function Here, the zero-phase inverse model is a model that does not depend on the electrical angle θ _e (= F _e ) of the open winding AC motor 1. The zero-phase inverse model unit 32 receives the zero-phase current i ₀ from the zero-phase current detection unit 21 shown in FIG. 2 and corresponds to the inputted zero-phase current i ₀ based on the zero-phase inverse model held. The estimated value v _0p (estimated zero-phase voltage) of the zero-phase voltage is calculated and output to the subtractor 33.

Subtractor 33, zero-phase voltage command v ₀ ^* from the zero-phase voltage output from the zero-phase inverse model 32 estimates v _0p subtraction to disturbance zero-phase voltage output from the adder 24 shown in FIG. 2 v Calculate _0d . As described above, the zero-phase inverse model zero phase inverse model unit 32 holds is represented in the model that is not dependent on the electrical angle theta _e open winding AC motor 1. Resulting Therefore, by subtracting the estimated value v _0p of zero-phase voltage command v ₀ ^* from the zero-phase voltage, an open winding AC motor 1 of the electric angle θ zero-phase voltage disturbance zero-phase voltage that changes by _e v _0d Be

The switch 34a selects one of a plurality of low pass filters (LPF ₁ , LPF ₂ ,..., LPF _Nf ) included in the filter group 35 according to a switching signal output from the switching signal generator 39 described later. And one of the low pass filters and the subtractor 33 are connected. By connecting the subtractor 33 and the low pass filter via the switch 34a, the disturbance zero-phase voltage v _0d output from the subtracter 33 is input to the connected low pass filter.

The switch 34 b is a part of the plurality of low pass filters (LPF ₁ , LPF ₂ ,..., LPF _Nf ) included in the filter group 35 according to the switching signal output from the switching signal generator 39 described later. , And one of the low pass filters and the subtractor 37 are connected. By connecting the low pass filter and the subtractor 37 via the switch 34 b, the output of the low pass filter is input to the subtractor 37.

The low-pass filters included in the filter group 35 are each connected to the subtractor 33 via the switch 34a to remove high frequency components of the disturbance zero-phase voltage v _0d input from the subtractor 33, thereby eliminating the disturbance zero. The phase voltage v _{0 d} is averaged and output to the subtractor 37 via the switch 34 b. Each of the low-pass filters constituting the filter group 35 is a digital filter that performs filter processing by performing a predetermined operation, and when not connected to the switches 34a and 34b, the switches 34a and 34b and the switches 34a and 34b Hold the data used in the calculation when connecting.

  The storage unit 36 calculates and stores the average value of the outputs of the low pass filters included in the filter group 35, and outputs the stored average value to the subtractor 37. The average value of the output of each low pass filter corresponds to the DC component of the zero phase voltage.

The subtractor 37 subtracts the average value output from the storage unit 36 from the output of the low pass filter included in the filter group 35, and outputs the result as the zero phase voltage V _0rip ^* to the adder 24 shown in FIG. As described above, the average value stored in the storage unit 36 corresponds to the DC component of the zero phase voltage. Therefore, the AC component (zero-phase voltage v _0rip ) of the zero-phase voltage can be estimated by subtracting the average value from the output of the low-pass filter.

In feedback control (for example, proportional integral control) by the zero-phase current adjustment unit 23, high control performance can be obtained in the low frequency region, but high control performance can not be obtained in the high frequency region. Therefore, the DC component (low frequency component) of the zero phase voltage can be compensated by the feedback control by the zero phase current adjustment unit 23. Therefore, the zero-phase voltage estimation unit 25 estimates an AC component (zero-phase voltage v _0rip ) of the zero-phase voltage, and outputs the same to the adder 24. Then, the adder 24, the zero-phase voltage command _v 0pi ^* and adds the zero-phase voltage _v 0rip ^* to produce a zero-phase voltage command v ₀ ^*, to compensate for the alternating current component of the zero-phase voltage, zero-phase Generation of current can be suppressed.

The proportional unit 38 receives the electrical angle θ _e of the open-winding AC motor 1, and generates the zero-order voltage at the input electrical angle θ _e. The order of the harmonics to be suppressed (harmonics to be suppressed) The multiplication is performed to calculate the phase θ _h of the suppression target harmonic, and the phase θ _h is output to the switching signal generator 39.

The switching signal generator 39 divides one cycle of the phase θ _h by the number Nf of low-pass filters included in the filter group 35, and includes the low levels included in the filter group 35 in each region of the phases of the divided target harmonics. Assign one of the low pass filters. For example, assuming that the order of harmonics to be suppressed is third and the number Nf of low pass filters is 4, the switching signal generator 39 generates the low pass filter LPF _{1 in} the region of 0 ° ≦ θ _h <90 °. The low pass filter LPF ₂ is assigned to the region of 90 ° ≦ θ _h <180 °, and the low pass filter LPF ₃ is assigned to the region of 180 ° ≦ θ _h <270 °, and 270 ° ≦ θ _h A low pass filter LPF ₄ is assigned to the region of <360 °.

Then, the switching signal generator 39 selects a low pass filter assigned to a region including the phase θ _h of the suppression target harmonic output from the proportional unit 38. Therefore, each low pass filter included in the filter group 35 is selected at least once in one period of the phase. The switching signal generator 39 outputs, to the switches 34a and 34b, a switching signal such that the selected low pass filter and the switches 34a and 34b are connected.

As described above, the proportional unit 38 and the switching signal generator 39 constitute the selection unit 40. Therefore, the selection unit 40 selects one of the low pass filters from the plurality of low pass filters included in the filter group 35 in accordance with the electrical angle θ _e of the open winding AC motor 1, The disturbance zero phase voltage v _0d calculated by 33 is input to the selected low pass filter. Here, the selection unit 40 causes each low pass filter included in the filter group 35 to be selected at least once in one cycle of the phase.

  If there is a low pass filter that is not selected during one phase of the phase, the weight of each low pass filter included in the filter group 35 becomes unbalanced, and the output of the zero phase voltage estimation unit 25 is distorted. The zero-phase current can not be suppressed. As in the present embodiment, suppression of the zero-phase current is achieved by selecting each low-pass filter included in the filter group 35 at least once in one cycle of the phase of the suppression target harmonic. be able to.

FIG. 4 is a diagram showing an example of an output from the filter group 35 shown in FIG. In FIG. 4, one period of the phase of the harmonic to be suppressed 41 is divided into four regions (region 1 to region 4), and low pass filters LPF _{1 to} LPF ₄ are assigned to regions 1 to 4 respectively. It shall be.

When the phase θ _{h of the} harmonic to be suppressed is included in the region 1, the low pass filter LPF ₁ is selected. Low-pass filter LPF ₁ removes the high frequency component of the disturbance zero-phase voltage v _0d, outputs a signal 42 to the disturbance zero-phase voltage v _0d averaged. Similarly, when the phase θ _h of the suppression target harmonic is included in the region 2, the low pass filter LPF ₂ is selected, and when the phase θ _h of the suppression target harmonic is included in the region 3, low. When the low pass filter LPF ₃ is selected and the phase θ _{h of the} harmonic to be suppressed is included in the region 4, the low pass filter LPF ₄ is selected. Then, high frequency components of the disturbance zero phase voltage v _{0 d} are removed by each of the selected low-pass filters, and a signal obtained by averaging the disturbance zero phase voltage v _{0 d} is output. As a result, as shown in FIG. 4, the output of the filter group 35 (each low pass filter included in the filter group 35) is the phase θ _{h of the} harmonic to be suppressed (the electrical angle θ _{e of the} open winding AC motor 1 It becomes a discrete value according to).

As described above, the zero-phase voltage generated by the open winding AC motor 1 changes in accordance with the electrical angle θ _e of the open winding AC motor 1. In the present embodiment, a plurality of low pass filters are provided, and the disturbance zero phase voltage v _0d is passed through different low pass filters according to the electrical angle θ _e of the open winding AC motor 1 to obtain the zero phase voltage v _{Since 0 rip} is estimated, zero-phase voltage v 0 _rip generated according to each electrical angle θ _e can be estimated with high accuracy. As a result, it is possible to suppress the zero phase current.

When the open winding AC motor 1 operates at high speed, it is necessary to increase the operating frequency of the controller 13 in order to suppress the zero-phase current with high accuracy. However, when the carrier frequency (the frequency of the carrier signal) is increased in synchronization with the operating frequency of the controller 13, the switching loss of the inverter increases. Therefore, in the present embodiment, when the input frequency to the open winding AC motor 1 is equal to or less than the predetermined value F, the carrier signal generation unit 30 makes the carrier frequency F _c constant (for example, 6 kHz) and performs control. vessel 13, the operating frequency F _s is twice the carrier frequency F _c.

On the other hand, when the input frequency to open winding AC motor 1 is larger than predetermined value F, carrier signal generation unit 30 determines the operating frequency of open winding AC motor 1 (input frequency to open winding AC motor 1). Depending on the carrier frequency. Specifically, when the number of low-pass filters included in the filter group 35 and N _f, the degree of suppression target harmonics and N _h, the frequency of the electrical angle of the open winding AC motor 1 and F _e, The carrier signal generation unit 30 sets the carrier frequency F _c to N _f × N _h × F _e / 2, and the controller 13 doubles the operating frequency F _s to the carrier frequency F _c (N _f × N _h × F _e And).

Accordingly, as shown in FIG. 5, in the area input frequency is lower than a predetermined value F to open winding AC motor 1, controller 13 operates at a constant operating frequency F _s (asynchronous operation region), open wound input frequency to the line AC motor 1 is at a predetermined value F larger area, it operates at the operating frequency F _s which varies in synchronization with the operation frequency of the open-winding AC motor 1 (synchronous operation region). In this way, when the open winding AC motor 1 is operating at low speed, the increase in switching loss of the inverters 11-1 and 11-2 is suppressed, and for high speed operation of the open winding AC motor 1, the zero phase current is high. It can be suppressed to the accuracy.

In the present invention, it is desirable that the present invention is applied in an operation range where the zero-phase voltage of the inverters 11-1 and 11-2 can be arbitrarily controlled. That is, in the overmodulation operation region where the inverter output voltage commands v _m1 ^* and v _m2 ^{* of the} inverters 11-1 and 11-2 become larger than the voltage of the DC power supply 2, the zero phase for controlling the zero phase current Not only the margin of the voltage is lost, but the output voltage waveform of the inverters 11-1 and 11-2 is distorted, so that an unintended zero-phase voltage component is included in the output voltage, and the zero-phase current is increased. As measures against such an increase in zero-phase current, zero-phase current can be suppressed by inserting a zero-phase inductance on the input side or the output side of the inverter 11-1 and the inverter 11-2.

  Although the present invention has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various changes or modifications based on the present disclosure. Therefore, it should be noted that these variations or modifications are included in the scope of the present invention. For example, functions included in each block can be rearranged so as not to be logically inconsistent, and a plurality of blocks can be combined into one or divided.

DESCRIPTION OF SYMBOLS 1 open winding AC motor 2 DC power supply 10 AC motor drive device 11 -1, 11-2 inverter 12 electric current detector 13 controller 21 zero phase current detection part 22 subtractor 23 zero phase current adjustment part 24, 27 adder 25 Zero-phase voltage estimation unit 26 Zero-phase three-phase conversion unit 28, 29 Multiplier 30 Carrier signal generation unit 31-1, 31-2 PWM signal generation unit 32 Zero-phase inverse model unit 33, 37 Subtractor 34a, 34b Switch 35 Filter group 36 Storage unit 38 Proportioner 39 Switching signal generator 40 Selection unit

Claims (5)

Application controlling an output voltage of a first inverter and a second inverter respectively connected to one end and the other end of the multi-phase winding of the permanent magnet synchronous motor having the multi-phase winding electrically separated from each other A controller that generates a voltage command,
A zero-phase current detection unit that detects a zero-phase current flowing in the permanent magnet synchronous motor;
A zero-phase voltage estimation unit for estimating a zero-phase voltage generated by the permanent magnet synchronous motor based on a zero-phase voltage command which is a zero-phase component of the applied voltage command and a zero-phase current detected by the zero-phase current detector; ,
The adjusted zero-phase voltage command for controlling the output voltage of the first inverter and the second inverter such that the deviation between the zero-phase current and the zero-phase current command detected by the zero-phase current detection unit becomes zero A zero-phase current adjustment unit to generate
A first adder that generates the zero-phase voltage command by adding the zero-phase voltage estimated by the zero-phase voltage estimation unit and the adjusted zero-phase voltage command generated by the zero-phase current adjustment unit; ,
A first voltage command in which the zero-phase voltage command generated by the first adder is converted into a multi-phase voltage command, and a multi-phase voltage for causing the permanent magnet synchronous motor to generate a predetermined torque A second adder that adds the second voltage command that is the command to generate the applied voltage command;
A controller comprising: In the controller according to claim 1,
The zero-phase voltage estimation unit
A zero-phase current detection unit is detected based on a zero-phase inverse model that is an inverse model of a zero-phase model in which the zero-phase voltage is input and the zero-phase current is output using a zero-phase inverse motor. A zero phase inverse model unit that calculates an estimated zero phase voltage corresponding to the zero phase current;
A first subtractor that calculates a deviation between a zero-phase voltage command that is a zero-phase component of the applied voltage command and an estimated zero-phase voltage calculated by the zero-phase inverse model unit;
With multiple low pass filters,
One of the low pass filters is selected from the plurality of low pass filters according to the electrical angle of the permanent magnet synchronous motor, and the low pass selected by the first subtractor is the deviation calculated by the first subtractor. A selection unit to be input to the pass filter,
A storage unit that stores an average value of outputs of each of the plurality of low pass filters;
A second subtractor that subtracts the average value stored in the storage unit from the output of the low-pass filter selected by the selection unit, and outputs the result as the zero-phase voltage;
A controller comprising: In the controller according to claim 2,
The selection unit divides one cycle of the phase by the number of the plurality of low pass filters, assigns any one of the plurality of low pass filters to each area of the divided phase, and the permanent magnet synchronous motor A low frequency band assigned to a region including the phase of the suppression target harmonic calculated by calculating the phase of the suppression target harmonic by multiplying the electrical angle by the order of the suppression target harmonic generating the zero phase current A controller characterized by selecting a pass filter. The controller according to any one of claims 1 to 3.
When the operating frequency of the permanent magnet synchronous motor is less than a predetermined value, a carrier signal of a fixed frequency is generated, and when the operating frequency of the permanent magnet synchronous motor becomes larger than the predetermined value, the operation of the permanent magnet synchronous motor And a carrier signal generator for generating a carrier signal of a frequency proportional to the frequency,
A controller operating at an operating frequency according to the frequency of the carrier signal. A first inverter and a second inverter connected to one end and the other end of the multi-phase winding of the permanent magnet synchronous motor having the multi-phase winding electrically separated from each other;
An AC motor drive apparatus comprising: the controller according to any one of claims 1 to 4.

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