JP5511885B2 - Motor control device and motor control method - Google Patents

Description

  The present invention relates to a motor control device and a motor control method, and more particularly, to a PWM control brushless motor switching circuit and a motor control device and a motor control method for preventing an element that generates heat from being overheated by a current flowing through a battery. is there.

  The current flowing through the motor coil of the brushless motor is controlled by an inverter circuit. The inverter circuit is composed of a plurality of switching elements, and each switching element is turned on / off to control the current flowing in each phase of the motor coil. However, since the switching element is damaged by overheating, the current flowing through each switching element (current flowing through the motor coil of each phase) is constantly monitored, and the current flowing through the switching element before each switching element is overheated. Must be restricted or blocked.

  As means for limiting the current flowing through each switching element, there is one in which a current detection means is connected to the switching element of each phase to limit the current of each phase (see, for example, Patent Document 1).

JP 2006-254618 A

  However, the current limiting means provided in the conventional motor control device limits the current only by the motor current detected by the current detection means for each phase, and the battery current, which is one of the factors causing the overheat state, is Not detected. For this reason, the limit value according to the motor current is set so that each element does not enter an overheated condition, for example, under the condition that the battery current flows most frequently under the actual usage conditions. As a result, when the battery current is small, there is a problem that overprotection occurs and the current is limited more than necessary.

  The present invention has been made to solve such a problem, and based on the current value flowing through the battery and the current value flowing through the switching circuit, the current value flowing through each of them is limited separately, so that it is more than necessary. It is an object of the present invention to provide a motor control device and a motor control method capable of overheating protection of an element that generates heat due to a current flowing through a switching circuit and a battery without limiting the current.

This invention relates to a motor controller for controlling the switching circuit the current flowing from the battery by PWM control based on the duty ratio to the multi-phase motor, a current detecting means for detecting a current flowing through the switching circuit as a motor current, the Based on the duty ratio and the motor current detected by the current detection means, current calculation means for estimating the battery current flowing through the battery and outputting it as a battery current estimated value; torque command value and magnetic flux input from the outside A current command value calculating means for calculating a motor current command value based on the command value; and a first determination value for limiting the motor current command value based on the motor current detected by the current detecting means. If the motor current command value is greater than the first determination value, the motor current command value Is limited to the first judgment value, otherwise, the transformation and the first current limiting means for directly outputting the motor current command value, the output from the first current limiting means to a motor voltage command value A first motor voltage command value output means for outputting as a first motor voltage command value, and when the battery current estimated value calculated by the current calculation means is larger than a predetermined second determination value set in advance. Restricts the battery current estimated value to the second determination value; otherwise, the second current limiting means for outputting the battery current estimated value as it is, and the battery current flowing through the battery is the second current value. determine the maximum allowable value of the motor voltage command value that is less than or equal to the output of the current limiting means, and a second motor voltage command value output means for outputting a second motor voltage command value, the first motor voltage command By comparing the output from the output and the second motor voltage command value output means from the output means, the motor command value limiting means for controlling the current flowing in the polyphase motor based on the motor voltage command value of the smaller And a motor control device.

This invention relates to a motor controller for controlling the switching circuit the current flowing from the battery by PWM control based on the duty ratio to the multi-phase motor, a current detecting means for detecting a current flowing through the switching circuit as a motor current, the Based on the duty ratio and the motor current detected by the current detection means, current calculation means for estimating the battery current flowing through the battery and outputting it as a battery current estimated value; torque command value and magnetic flux input from the outside A current command value calculating means for calculating a motor current command value based on the command value; and a first determination value for limiting the motor current command value based on the motor current detected by the current detecting means. If the motor current command value is greater than the first determination value, the motor current command value Is limited to the first judgment value, otherwise, the transformation and the first current limiting means for directly outputting the motor current command value, the output from the first current limiting means to a motor voltage command value A first motor voltage command value output means for outputting as a first motor voltage command value, and when the battery current estimated value calculated by the current calculation means is larger than a predetermined second determination value set in advance. Restricts the battery current estimated value to the second determination value; otherwise, the second current limiting means for outputting the battery current estimated value as it is, and the battery current flowing through the battery is the second current value. determine the maximum allowable value of the motor voltage command value that is less than or equal to the output of the current limiting means, and a second motor voltage command value output means for outputting a second motor voltage command value, the first motor voltage command By comparing the output from the output and the second motor voltage command value output means from the output means, the motor command value limiting means for controlling the current flowing in the polyphase motor based on the motor voltage command value of the smaller Therefore, the current value flowing through the battery and the current value flowing through the switching circuit are individually limited based on the current value flowing through the battery and the current value flowing through the switching circuit, so that more current than necessary is required. Without being limited, overheating protection of the element that generates heat due to the current flowing through the switching circuit and the battery can be performed.

It is a block diagram of the motor control apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the operation | movement of the program of the software built in the microcontroller of FIG. It is explanatory drawing which shows the motor current limiting value of the motor control apparatus which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the synthetic | combination drive current with respect to the motor control apparatus which concerns on Embodiment 1 of this invention vs the motor current limiting value change speed about the time of rotation of a motor, and a stop. It is a figure explaining battery current estimation in Embodiment 1 of this invention. It is a figure explaining the method to restrict | limit the motor voltage command value in Embodiment 1 of this invention.

Embodiment 1 FIG.
The present invention is a motor control device for preventing a PWM-controlled brushless motor switching circuit and an element that generates heat due to a current flowing through a battery from being overheated. More specifically, based on the current value flowing through the battery and the current value flowing through each switching element, the current value flowing through the switching circuit and the current value flowing through the battery are limited. This is a motor control device that determines whether or not to prevent overheating of an element that generates heat due to a current flowing through a switching circuit and a battery.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding members and parts will be described with the same reference numerals.

  FIG. 1 is a block diagram showing a motor control device according to Embodiment 1 of the present invention together with peripheral devices. In FIG. 1, this motor control device is connected to a three-phase brushless motor 1 (hereinafter abbreviated as “motor 1”) which is a multiphase motor.

  The motor control device includes a position sensor (position detection means) 2 that detects the magnetic pole position of the rotor of the motor 1, a PWM inverter (inverter device) 3 that drives the motor 1 by obtaining drive power from the battery BT, and a PWM inverter 3. Based on a current detector (current detection means) 4 for detecting three-phase motor drive currents Iu, Iv, and Iw input to the motor 1, and a torque command value T * and a magnetic flux command value F * given from the outside. A current command value calculation unit 5 for generating a d-axis (magnetic flux axis) command current Id * and a q-axis (torque axis) command current Iq *, which are motor current command values of the motor 1, and a motor current command value (Id *, And a microcontroller 6 (motor control means) for controlling the PWM inverter 3 using Iq *).

  The microcontroller 6 limits the motor current command values (Id *, Iq *) to prevent overheating, and A / D converters 8u, 8v for converting the output of the current detector 4 into digital values. , 8w (hereinafter collectively referred to as “A / D converter 8”), the output of the A / D converter 8 is changed from a three-phase AC coordinate to a dq coordinate consisting of a d axis and a q axis (perpendicular to the d axis). A three-phase-dq coordinate conversion unit 9 (abbreviated as “coordinate conversion unit 9” in FIG. 1) to be converted, an output of a motor current limiting unit 14 described later, and an output of the three-phase-dq coordinate conversion unit 9 Current control units 10d and 10q (hereinafter collectively referred to as “current control unit 10”) that perform feedback control on the dq coordinate based on outputs from subtractors 19d and 19q (hereinafter collectively referred to as “subtractor 19”) that output a difference. The output of the current control unit 10 from the dq coordinate A dq-3-phase coordinate conversion unit 11 for converting the coordinates (in Fig. 1 shown by abbreviated as "coordinate conversion unit 11"), and a.

  The microcontroller 6 further estimates the battery current Ib flowing through the battery BT based on the duty ratios Du, Dv, Dw of each phase of UVW and the phase currents Iu, Iv, Iw flowing through the motor 1 to estimate the battery current. The battery current estimating unit (current calculating means) 15 that outputs the value Ib * and the battery current estimated value Ib * are limited so as to be equal to or less than a predetermined battery current limit value Ibr that is set in advance. The battery current limit value calculation unit 16 that outputs * and the motor voltage command limit value Vlimit that is the maximum allowable value for the motor voltage command value so that the battery current Ib flowing through the battery BT is equal to or less than the current Ibr * after the battery limit. U-phase voltage command output from the motor voltage command limit value calculator 17 to be obtained and the dq-3 phase coordinate converter 11 The Vu, V-phase voltage command value Vv, and W-phase voltage command value Vw are compared with the motor voltage command limit value Vlimit calculated by the motor voltage command limit value calculation unit 17, and the U-phase voltage command value Vu and V-phase are compared. When the voltage command value Vv and the W-phase voltage command value Vw exceed the motor voltage command limit value Vlimit, the U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw are set as the motor voltage command. And a motor voltage command value limiter 18 that limits the limit value Vlimit.

  The overheat protection unit 7 includes a motor rotation speed calculation unit 12 that calculates the rotation speed R1 of the motor 1 from the magnetic pole position of the rotor, a preset predetermined overheat protection determination threshold value, and a three-phase-dq coordinate conversion unit 9 Subtractors 20d and 20q (hereinafter collectively referred to as "subtractor 20") that output the difference from the output, the motor rotation speed R1 output from the motor rotation speed calculator 12 and the output of the subtractor 20 are input, and the motor Motor current limit value calculation unit 13 for calculating motor current limit values Idr and Iqr for limiting current command values (Id *, Iq *), motor current limit value Idr output from motor current limit value calculation unit 13 Based on Iqr, motor current limiting units 14d and 14q that limit motor current command values (Id *, Iq *) (hereinafter collectively referred to as “motor current limiting unit 14”), and the output of the motor current limiting unit 14 And a subtractor 19 described above outputs a difference between the output of the three-phase -dq coordinate converter 9 when.

  Here, the 3-phase-dq coordinate conversion unit 9, the current control unit 10, the dq-3 phase coordinate conversion unit 11, the motor rotation speed calculation unit 12, the motor current limit value calculation unit 13, the motor current limit unit 14, and the subtraction The devices 19 and 20 are built in the microcontroller 6 as software.

  FIG. 2 is a flowchart showing the operation of the software program built in the microcontroller 6 of FIG. This program is called repeatedly at regular intervals.

The operation of the motor control device having the above configuration will be described below with reference to FIG.
First, the position sensor 2 detects the magnetic pole position of the rotor of the motor 1 every predetermined time, and the motor rotation speed calculation unit 12 calculates the difference between the magnetic pole position detected this time and the magnetic pole position detected last time by the position sensor 2. The motor rotational speed R1 is calculated from the difference and output (step S21).

  The current detector 4 detects the u-phase drive current Iu, the v-phase drive current Iv, and the w-phase drive current Iw of the three-phase motor drive current input from the PWM inverter 3 to the motor 1. Three-phase motor drive currents Iu, Iv, and Iw are output (step S22).

  The three-phase motor drive currents Iu, Iv, and Iw are converted into digital signals by the A / D converter 8, and then converted into dq coordinates by the three-phase-dq coordinate conversion unit 9, and d-axis drive shown in FIG. The current (d-axis component current) Id and the q-axis drive current (q-axis component current) Iq are output (step S23).

  In the motor current limit value calculation unit 13, the d-axis drive current Id and the q-axis drive current Iq are vector-synthesized by the following equation (1) to obtain a combined drive current (synthesized current) Is (step S24).

  Here, when the combined drive current Is is constant, a circle with a constant radius indicated by a broken line in FIG. 3 can be expressed as a motor current limit value. This indicates that the result of combining the three-phase motor drive currents Iu, Iv, and Iw is a constant current value. The combined drive current Is is not affected by the magnetic pole position of the rotor of the motor 1, that is, the phase angle θ formed by the q axis and the combined drive current Is (hereinafter abbreviated as “current phase angle θ”). The current value energized to the motor 1 can be represented.

  The d-axis drive current Id and the q-axis drive current Iq output from the dq-3 phase coordinate conversion unit 9 are respectively compared with the threshold value for overheat protection determination by the subtracter 20 to obtain a deviation. The maximum value of each deviation is output as the motor current limit value change speed Vm, for example, according to the same characteristics as in FIG. At this time, the horizontal axis shown in FIG. 4 is read from the combined drive current Is to the above deviation. In FIG. 4, the broken line is the value of the motor current limit value change speed Vm used when the motor 1 is rotating, and the solid line is the value of the motor current limit value change speed Vm used when the motor 1 is stopped. It is. Whether the motor 1 is rotating or stopped is determined by determining a threshold value of the motor rotation speed R1. The motor current limit value calculation unit 13 selects a motor current limit value change speed Vm from two types based on the rotation / stop of the motor 1 and integrates the selected motor current limit value change speed Vm, Motor current limit values (Idr, Iqr) are calculated (step S25). The detailed operation of step S25 will be described later.

  The motor current limiter 14 receives the d-axis command current Id * and the q-axis command current Iq * from the current command value calculator 5 and the d-axis motor current limit values Idr and q from the motor current limit value calculator 13. The shaft motor current limit value Iqr is input, and the d-axis command current Id * and the q-axis command current Iq * are limited to be equal to or less than the d-axis motor current limit value Idr and the q-axis motor current limit value Iqr, respectively. It is output as the d-axis limited current Idr * and the q-axis limited current Iqr * (step S26, step S27). Specifically, if the d-axis command current Id * and the q-axis command current Iq * are equal to or less than the d-axis motor current limit value Idr and the q-axis motor current limit value Iqr, the values are output as they are, If the d-axis motor current limit value Idr and the q-axis motor current limit value Iqr are exceeded, the values of the d-axis motor current limit value Idr and the q-axis motor current limit value Iqr are output.

  In the subtracter 19, the d-axis limited current Idr * and the q-axis limited current Iqr * are input from the motor current limiting unit 14, and the d-axis driving current Id and the q-axis driving current Iq are input from the dq-3 phase coordinate conversion unit 9. Is calculated, and the difference between the d-axis limited current Idr * and the d-axis drive current Id and the difference between the q-axis limited current Iqr * and the q-axis drive current Iq are calculated and input to the current control unit 10. In the current control unit 10, feedback control is performed based on the output of the subtracter 19 (step S28, step S29).

  In the dq-3 phase coordinate conversion unit 11, the output of the current control unit 10 is converted from the dq coordinate to the three-phase AC coordinate, and is output to the PWM inverter 3 via the motor voltage command value limiting unit 18 (step S30). ). The motor 1 is driven by the output of the PWM inverter 3.

Next, the operation of the motor current limit value calculation unit 13 in step S25 will be described in detail.
The motor current limit value calculation unit 13 uses the motor rotation speed R1 from the motor rotation speed calculation unit 12 and the combined drive current Is calculated by itself, based on the characteristics (predetermined function) shown in FIG. A motor current limit value changing speed Vm that gradually decreases or gradually increases the maximum current allowed to 1 is calculated. Subsequently, the motor current limit value change speed Vm is integrated, and motor current limit values (Idr, Iqr) are calculated. The motor current limit values (Idr, Iqr) limit the motor current command values (Id *, Iq *) on the dq coordinates.

  Here, the motor current limit value calculation unit 13 determines that the motor 1 is rotating when the motor rotation speed R1 is equal to or higher than a predetermined rotation speed ξ that is arbitrarily set. A motor current limit value (Idr, Iqr) is calculated using the change speed Vm (see FIG. 4).

  Further, the motor current limit value calculation unit 13 determines that the motor 1 is stopped when the motor rotation speed R1 is less than a predetermined rotation speed ξ that is arbitrarily set, and the solid line motor current limit value change speed is determined. A motor current limit value (Idr, Iqr) is calculated using Vm (see FIG. 4).

  Therefore, since the gradient when gradually decreasing the maximum current allowed for the motor 1 can be switched according to the motor rotation speed R1, the gradient of gradual decrease can be made smaller when the motor 1 is rotating than when the motor 1 is stopped. Can do.

  When the motor current limit values (Idr, Iqr) are gradually increased, the motor current limit values (Idr, Iqr) are determined by the heat dissipation characteristics of the microcontroller 6 or the motor 1 regardless of whether the motor 1 is rotating or stopped. 1 is set as the same parameter when rotating and stopping.

  The motor current limit values (Idr, Iqr) are decomposed into the d-axis current limit value Idr and the q-axis current limit value Iqr so that the current phase angle θ (see FIG. 3) is constant, and the motor current limit unit 14 Is output. For example, the d-axis current limit value Idr and the q-axis current limit value Iqr have the same characteristics as those shown in FIG. 4 when the motor rotates and stops.

  According to the motor control device according to the first embodiment of the present invention, the motor current limit values (Idr, Iqr) can be calculated according to the motor rotation speed R1, so that the motor 1 can be appropriately overheat protected. it can.

  Further, since the motor current limit values (Idr, Iqr) are calculated according to the combined drive current Is, it is possible to cope with heat concentration on a specific motor phase when the motor 1 is stopped, and to generate heat when the motor 1 rotates. It is possible to cope with the situation where is averaged.

  The motor current limit values (Idr, Iqr) calculated by the motor current limit value calculation unit 13 limit the motor current command values (Id *, Iq *) on the dq coordinates, and are three-phase AC coordinates. Since the motor current command values (Id *, Iq *) are limited before the coordinate conversion is performed, the current can be gradually reduced without losing the current balance of each motor phase depending on the rotation state of the motor 1.

  The battery current estimation unit 15 estimates the battery current Ib flowing through the battery BT.

A method for estimating the battery current will be described below.
FIG. 5 is a block diagram showing a motor driving apparatus related to battery current estimation. As shown in FIG. 5, the PWM inverter 3 is provided with a total of six switching elements 30. Specifically, three switching elements 30UU, 30VU, 30WU (hereinafter referred to as “upper switching elements 30UU, 30VU, 30WU”) corresponding to each phase are provided on the upper side, and each phase is provided on the lower side. Three corresponding switching elements 30UL, 30VL, and 30WL (hereinafter referred to as “lower switching elements 30UU, 30VU, and 30WU”) are provided. These switching elements are comprised from semiconductor elements, such as FET, for example. In each switching element, an upper switching element and a lower switching element are directly connected for each phase, and a total of three series bodies are formed.

  In FIG. 5, assuming that the duty ratio of each phase of UVW is Du, Dv, Dw, and the phase current flowing through the motor is Iu, Iv, Iw, the average current (Iuu, Ivu, Iwu) flowing through each upper switching element 3UU, 3VU, 3WU ) Can be expressed by the following formula (2).

Iuu = Iu * Du (2-1)
Ivu = Iv * Dv (2-2)
Iwu = Iw * Dw (2-3)

  Since battery current Ib is the sum of the currents flowing through upper switching elements 3UU, 3VU, and 3WU, it can be expressed by the following equation (3).

    Ib = Iuu + Ivu + Iwu (3)

  Therefore, the battery current Ib can be expressed by the following equation (4) from the equations (2) and (3).

    Ib = Iu * Du + Iv * Dv + Iw * Dw (4)

  Therefore, the estimated battery current value Ib * is obtained by substituting the values of Iu, Iv, and Iw for the duty ratios Du, Dv, and Dw of each phase of UVW and the phase current that flows through the motor into Equation (4). Can do.

  The battery current limit value calculation unit 16 limits the battery current estimated value Ib * estimated by the battery current estimated value 15 to be equal to or lower than a predetermined battery current limit value Ibr set in advance, and the battery current limited current Ibr * Is output. Specifically, if the battery current estimated value Ib * is equal to or less than the battery current limit value Ibr, the value is output as it is. On the other hand, if the battery current limit value Ibr exceeds the battery current limit value Ibr, the value of the battery current limit value Ibr is output. Is output.

  The motor voltage command limit value calculation unit 17 determines a motor voltage command limit value Vlimit which is a maximum allowable value as a motor voltage command value so that the battery current Ib flowing through the battery BT is equal to or less than the battery limit current Ibr *.

  The motor voltage command value limiting unit 18 is a motor voltage command limit value for the U phase voltage command value Vu, the V phase voltage command value Vv, and the W phase voltage command value Vw output from the dq-3 phase coordinate conversion unit 11. The U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw exceed the motor voltage command limit value Vlimit by comparing with the motor voltage command limit value Vlimit calculated by the calculation unit 17. In this case, the U-phase voltage command value Vu, the V-phase voltage command value Vv, and the W-phase voltage command value Vw are limited to the motor voltage command limit value Vlimit. In other words, the motor voltage command value control unit 18 compares the output from the current control unit 10 with the output from the battery current limit value calculation unit 16 and applies the motor 1 to the motor 1 based on the smaller current value. It means controlling the flowing current.

  The method for limiting the motor voltage command value is the same as that shown in FIG. 6, and the motor voltage command value limiting unit 18 limits the motor voltage command value to the motor voltage command limit value Vlimit (Vu **, Vv **, Vw **) or less. The motor voltage command values Du, Dv, and Dw for each phase are input to the PWM controller 16, and the PWM controller 16 controls the PWM inverter 3 to rotate the motor 1.

  As described above, according to the first embodiment of the present invention, the motor that controls the current flowing from the battery BT to the motor 1 by performing the PWM control based on the duty ratio by the PWM inverter 3 (switching circuit). A control device that estimates current flowing through the PWM inverter 3 (switching circuit) as a motor current value (current detector 4) and current flowing through the PWM inverter 3 (switching circuit) as a battery current value. Current calculation means (battery current estimation unit 15) to perform, and when the motor current value is larger than a predetermined first determination value (Idr, Iqr), first current limiting means (motor current limit value) for limiting the motor current The calculation unit 13 and the motor current control unit 14) and the estimated battery current value is larger than a predetermined second determination value (Ibr). Includes a second current limiting unit (battery current limit value calculation unit 16) that limits the battery current, and separates and limits the motor current value flowing through the PWM inverter 3 and the battery current value flowing through the battery BT. Thus, the overheat protection of the switching element 30 that generates heat due to the current flowing through the PWM inverter 3 (switching circuit) and the overheat protection of the switching element 30 that generates heat due to the current flowing through the battery BT can be separated.

  Therefore, by separating the overheat protection means according to the current flowing through the element, the overprotection of the element can be eliminated, and the continuous energization time can be made longer than before by performing the optimum overheat protection.

  Further, the motor command value limiting means (motor voltage command value limiting unit 18) compares the motor current limit value calculated from the current flowing through the PWM inverter with the battery current limit value calculated from the current flowing through the battery, and is small. By limiting the current with the current value of the one, more optimal overheat protection can be performed for the element that generates heat due to the current.

  1 3-phase brushless motor, 2 position sensor, 3 PWM inverter, 4 current detector, 5 current command value calculation unit, 6 microcontroller, 7 overheat protection unit, 8 A / D converter, 9 3-phase-dq coordinate conversion unit 10 current control unit, 11 dq-3 phase coordinate conversion unit, 12 motor rotation speed calculation unit, 13 motor current limit value calculation unit, 14 motor current limit unit, 15 battery current estimation unit, 16 battery current limit value calculation unit, 17 motor voltage command limit value calculator, 18 motor voltage command value limiter, 19, 20 subtractor, Id d axis drive current, Iq q axis drive current, Id * d axis command current, Iq * q axis command current, Idr d-axis motor current limit value, Iqr q-axis motor current limit value, Idr * q-axis limit current, Iqr * q-axis limit current, Vu U phase command voltage, Vv V phase Decree voltage, Vw W-phase command voltage, Du U-phase PWM driving Duty, Dv V-phase PWM driving Duty, Dw W-phase PWM driving Duty, BT battery.

Claims (4)

A motor control device for controlling a current flowing from a battery to a multiphase motor by a switching circuit by PWM control based on a duty ratio,
Current detection means for detecting a current flowing through the switching circuit as a motor current;
Current calculation means for estimating a battery current flowing in the battery based on the duty ratio and the motor current detected by the current detection means, and outputting the estimated battery current value;
Current command value calculating means for calculating a motor current command value based on a torque command value and a magnetic flux command value input from the outside;
Based on the motor current detected by the current detection means, a first determination value for limiting the motor current command value is obtained, and when the motor current command value is larger than the first determination value, the motor First current limiting means for limiting a current command value to the first determination value; otherwise, outputting the motor current command value as it is;
A first motor voltage command value output means for converting the output from the first current limiting means into a motor voltage command value and outputting it as a first motor voltage command value;
If the battery current estimated value calculated by the current calculating means is larger than a predetermined second determination value set in advance, the battery current estimated value is limited to the second determination value, otherwise, the battery current estimated value is limited to the second determination value. Second current limiting means for outputting the battery current estimated value as it is;
Second motor voltage command value output means for obtaining a maximum allowable value of the motor voltage command value at which the battery current flowing through the battery is less than or equal to the output of the second current limiting means, and outputting it as a second motor voltage command value When,
The output from the first motor voltage command value output means and the output from the second motor voltage command value output means are compared, and the current flowing through the multiphase motor based on the smaller motor voltage command value And a motor command value limiting means for controlling the motor control device. A rotation speed detecting means for detecting a rotation speed of the multiphase motor;
The first current limiting means determines the presence or absence of rotation of the multiphase motor from the rotation speed detected by the rotation speed detection means, and the first current limiting means determines the first current according to the presence or absence of rotation of the multiphase motor. The motor control device according to claim 1, wherein a determination value is calculated. The apparatus further comprises coordinate conversion means for converting the motor current detected by the current detection means into a d-axis (magnetic flux axis) component current and a q-axis (torque axis) component current orthogonal to the d-axis component current. ,
The first current limiting unit obtains a combined drive current of the d-axis component current and the q-axis component current, and calculates the first determination value based on the combined drive current. Item 3. The motor control device according to Item 1 or 2. A motor control method for controlling a current flowing from a battery to a multiphase motor by a switching circuit by PWM control based on a duty ratio,
A current detection step of detecting a current flowing through the switching circuit as a motor current;
A current calculation step of estimating a battery current flowing in the battery based on the duty ratio and the motor current detected in the current detection step, and outputting the estimated battery current value;
A current command value calculation step for calculating a motor current command value based on a torque command value and a magnetic flux command value input from the outside;
Based on the motor current detected in the current detection step, a first determination value for limiting the motor current command value is obtained, and when the motor current command value is larger than the first determination value, the motor A first current limiting step of limiting a current command value to the first determination value; otherwise, outputting the motor current command value as it is;
A first motor voltage command value output step of converting an output of the first current limiting step into a motor voltage command value and outputting the motor voltage command value as a first motor voltage command value;
When the battery current estimated value calculated in the current calculating step is larger than a predetermined second determination value set in advance, the battery current estimated value is limited to the second determination value; A second current limiting step for outputting the battery current estimated value as it is;
A second motor voltage command value output step for obtaining a maximum allowable value of the motor voltage command value at which the battery current flowing through the battery is less than or equal to the output of the second current limiting step, and outputting the maximum motor voltage command value as a second motor voltage command value When,
The output from the first motor voltage command value output step is compared with the output from the second motor voltage command value output step, and the current flowing to the multiphase motor is controlled based on the smaller motor voltage command value A motor control method comprising: a motor command value limiting step.

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