JP5538657B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device such as a brushless motor, and more particularly to a motor control device that limits a power supply current supplied to the motor.

In an electric power steering apparatus that applies a steering assist force to a steering system of a vehicle by a motor, the assist force is applied to the steering shaft or the rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer. It is supposed to be.
As a motor of such an electric power steering apparatus, a multiphase motor such as a brushless motor is used.
With an increase in the output demand of the brushless motor, when an excessive current is supplied to the brushless motor, there is a possibility of causing problems such as heat generation on the power supply path and destruction of the switching element.
Further, in the vehicle, electric power is not excessively applied from the outside, and only constant electric power is supplied. Therefore, in a motor drive system that consumes excessive power, most of the power is consumed, and in a battery that supplies a constant voltage, the power consumption consumes excessive current. Since an overcurrent is generated in the system line, an excessive load is applied.
In addition, excessive power consumption causes a decrease in voltage, and power may not be supplied to other systems supplied from the same power source. In order to prevent this, it is necessary to limit the current consumption.

  In the case where heat generation of the power supply current energizing section becomes a problem due to excessive power supply current, it is necessary to limit the power supply current. For this purpose, a power supply current detector for detecting the power supply current is provided, and control for limiting the power supply current is performed based on the detected current. However, having a power supply current detector inevitably increases the cost, and if the accuracy of the power supply current detector to be installed or a shunt resistor is attached, the power supply current detector itself Loss also becomes an issue.

In order to solve such a problem, a steering assist command limit value corresponding to a predetermined power supply current is calculated from the power supply voltage, the motor rotation speed, and the input / output energy balance of the electric power steering device, and the calculated steering assist command limit value is calculated. There is known an electric power steering device that limits a steering assist command value so as not to draw a power supply current that exceeds a predetermined power supply current (see Patent Document 1).
In addition, the motor current value corresponding to the maximum power supply current value is calculated based on the power supply voltage and the motor rotation angular velocity, and the motor current command value is limited to the calculated power supply current maximum value or less, so that the power supply current becomes overcurrent. There is known a motor control device that does not become necessary (see Patent Document 2).

JP 2008-49910 A JP 2009-78711 A

  However, since the calculation for obtaining the steering assist command limit value in Patent Document 1 is to solve the quadratic expression for the steering assist command limit value, it takes a considerable amount of calculation processing time. In order to solve this processing load problem, a lookup table is used to solve the quadratic expression. However, even with this measure, calculation processing takes time. Further, the calculation formula used when calculating the steering assist command limit value includes many motor-specific parameters such as motor resistance and torque constant, and includes temperature-dependent parameters. In particular, the resistance value greatly varies depending on the temperature, so that the accuracy of the limit value deteriorates in a situation where the environmental temperature changes.

Further, the restriction by the steering assist command limit value means that the limit is applied by the motor current command value, and there is a delay from the determination of the motor current command limit value to the limitation of the motor current. Therefore, depending on the responsiveness of the motor current control and the cycle of referring to the motor current command value during motor current control, when the motor current limit is necessary, the motor current limit is delayed and a power supply current larger than the predetermined power supply current flows. May occur.
Since Patent Document 2 also calculates a motor current limit value corresponding to the maximum power supply current value and limits the motor current command value, there is a delay until the motor current is limited, as in Patent Document 1. However, depending on the responsiveness of the motor current control and the cycle of referring to the motor current command value during the motor current control, the motor current limitation may be delayed when the motor current limitation is required.

  The present invention has been made in order to solve the above-described problems, is inexpensive because it does not require a power source current detector, reduces the calculation load of the control device, and speeds up the response of motor current control. An object of the present invention is to provide a motor control device that limits the power supply current supplied to the motor.

A motor control device according to the present invention includes a rotation speed calculation unit that detects a rotation position of a motor and calculates a motor rotation speed from the motor rotation position, a motor current detection unit that detects a current supplied to the motor, a motor A motor voltage command value calculating means for calculating a motor voltage command value for driving the motor based on a current command value applied to the motor and a motor current detected by the motor current detecting means, and supplying a constant power such as a battery In the motor control device of the electric power steering apparatus , the power supply voltage detection means for detecting the power supply voltage supplied to the motor, the power supply voltage detected by the power supply voltage detection means, and the motor rotation speed calculated by the rotation speed calculation means, motor voltage command limit value calculation for calculating a d-axis voltage command limit value for limiting only d-axis voltage command value of the motor voltage command value And stage, the d-axis voltage command limit value, in which a motor voltage command value limiting means for limiting the motor voltage command value.

According to the present invention, even when there is an excessive current supply request to the motor when the motor is driven due to an increase in the output demand of the motor, the control device is configured at low cost without having a power supply current detector. It is possible to reduce the processing load of the microcomputer and limit the motor voltage command value to suppress the supply of excessive power supply current to the motor.
In addition, since it is limited not by the motor current command value but by the motor voltage command value, even when sudden limitation is required, the motor current control response is better than when the current command value is limited. It is possible to suppress the supply of excessive power supply current to the power source. Furthermore, since the motor voltage saturation state can be prevented, the stability of the system is also improved.
In the electric power steering apparatus, the heat supply problem due to the increase in the output demand of the motor is effective by limiting the motor power supply current. In addition, there is an effect of reducing and suppressing the vibration problem by reducing the processing load of the microcomputer constituting the control device and ensuring the system stability by limiting the motor voltage.
In particular, in an electric power steering device, the assist power is suddenly reduced due to excessive current consumption. This can be prevented by the present application.

It is a block diagram of the motor control apparatus in Embodiment 1 of this invention. It is a figure explaining the voltage restriction map in Embodiment 1 of this invention. It is a figure explaining the relationship between the power consumption of a motor, and a torque characteristic. It is a figure explaining the method to restrict | limit the motor voltage command value in Embodiment 1 of this invention. It is a block diagram of the motor control apparatus in Embodiment 2 of this invention. It is a figure explaining the voltage restriction map in Embodiment 2 of this invention. It is a block diagram of the motor control apparatus in Embodiment 3 of this invention. It is a figure explaining the method to restrict | limit the motor voltage command value in Embodiment 3 of this invention. It is a block diagram of the motor control apparatus in Embodiment 4 of this invention. It is a figure explaining the example of the voltage limitation map in Embodiment 5 of this invention. It is a figure explaining the method to restrict | limit the motor voltage command value in Embodiment 6 of this invention.

Embodiment 1 FIG.
Hereinafter, a motor control apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a motor control device according to Embodiment 1 of the invention, FIG. 2 is a diagram illustrating a voltage limit map according to Embodiment 1 of the present invention, and FIG. 3 is a diagram illustrating a relationship between motor power consumption and torque characteristics. FIG. 4 is a diagram for explaining a method of limiting the motor voltage command value in the first embodiment of the invention.

  In FIG. 1, a motor 1 such as a three-phase DC brushless motor that is a driving source, an in-vehicle battery that is a DC power source, and the like, a power source 2 that supplies power to the motor 1, and power of the motor 1 and the power source 2 A PWM (pulse width modulation) inverter 3 as a drive circuit that is provided in the middle of the supply path and generates drive power to be supplied to the motor 1, and a microcontroller that controls the operation of the PWM inverter 3 according to the output of the motor control signal And a control device (ECU) 4.

The PWM inverter 3 is a well-known device in which three arms corresponding to each phase are connected in parallel with a pair of switching elements connected in series as a basic unit (arm), and a motor control signal output from the control device 4 is The duty ratio of the switching element of the PWM inverter 3 is defined.
The control device 4 includes a position sensor 5 for detecting the magnetic pole position of the rotor of the motor 1, a current detection circuit 6 for detecting each phase current Iu, Iv, Iw energized to the motor 1, and a power source 2. And a power supply voltage detection circuit 7 for detecting the voltage between the PWM inverters 3 are connected.

  Further, the control device 4 is built in the microcontroller, and an A / D converter 8 for converting the phase currents Iu, Iv, Iw detected by the current detection circuit 6 into digital values, and the A / D converter 8 A three-phase / two-phase coordinate converter 9 that converts the three-phase AC coordinates of the phase currents Iu, Iv, and Iw converted in step 1 into a d-axis coordinate d-axis current value Id and a q-axis current value Iq, and a position sensor 5. Is provided with a rotation speed calculator 10 for calculating the motor rotation speed from the motor rotation position of the motor.

Further, a d-axis current command value Id * and a q-axis current command value Iq * are input to the control device 4 as command values of control signals for driving the motor 1, and these d-axis current command values Id * are input. The q-axis current command value Iq * and the d-axis current value Id and the q-axis current value Iq, which are outputs from the three-phase / two-phase coordinate converter 9, are input to the corresponding subtractors 11a and 11b, respectively.
The d-axis current deviation ΔId and q-axis current deviation ΔIq calculated in the subtractors 11a and 11b are input to the corresponding PI control units 12a and 12b, respectively. In the PI control units 12a and 12b, feedback control for causing the d-axis current value Id and the q-axis current value Iq, which are actual currents, to follow the d-axis current command value Id * and the q-axis current command value Iq * is performed. .

Specifically, the PI control units 12a and 12b multiply the input d-axis current deviation ΔId and q-axis current deviation ΔIq by a predetermined PI gain to thereby drive a d-axis voltage command for driving the motor 1. It functions as a motor voltage command value calculation means for calculating the value Vd * and the q-axis voltage command value Vq *.
On the other hand, the motor voltage command limit value calculator 13 for calculating the motor voltage command limit value for limiting the power supply current supplied to the motor 1 is the power supply voltage detected by the power supply voltage detection circuit 7 and the rotation speed calculator 10. The motor rotation speed calculated in step S3 and the motor current d-axis current value Id and q-axis current value Iq, which are outputs from the three-phase / two-phase coordinate converter 9, are input, and the motor voltage command value limit value Vlimit Is calculated. The motor voltage command limit value Vlimit is determined by map processing as will be described later, but may be obtained by calculation.

The motor voltage command value limiter 14 uses the motor voltage command values (d-axis voltage command value Vd * and q-axis voltage command value Vq *) input from the PI controllers 12a and 12b as the motor voltage command limit value calculator 13. From the motor voltage command limit value Vlimit.
The motor voltage command values of the d-axis voltage command value Vd ** and the q-axis voltage command value Vq ** restricted by the motor voltage command value limiter 14 are converted into two-phase / three-phase coordinates together with the rotation angle from the position sensor 5. The two-phase / three-phase coordinate converter 15 converts the voltage into a three-phase voltage command value.

Each phase voltage command value from the two-phase / three-phase coordinate converter 15 is input to the PWM controller 16, and the PWM controller 16 generates a motor control signal corresponding to each phase voltage command value. The PWM inverter 3 is driven to control the supply of driving power to the motor 1.
Of the configuration of the control device 4, the configuration other than the A / D converter 8 is realized as software in the microcontroller.

Next, a description will be given based on the flow of motor control in the first embodiment of the present invention.
The U-phase current Iu, the V-phase current Iv, and the W-phase current Iw, which are the respective phase currents of the motor 1, are detected by the current detection circuit 6, converted into predetermined currents, and input to the control device 4 of the microcontroller. Each phase current input to the control device 4 is discretized by the A / D converter 8 and delivered to software processing.

Next, the operation of the program installed in the control device 4 of the microcontroller will be described. This program is called at a predetermined fixed cycle. Further, it is assumed that the d-axis current command value Id * and the q-axis current command value Iq * of the motor are separately provided.
First, the motor rotation speed calculator 10 calculates the motor rotation speed by detecting a difference between the motor angle detected by the position sensor 5 and the motor angle detected last time by the motor rotation speed calculator 10 every predetermined time. calculate.

Next, the U-phase current Iu, V-phase current Iv and W-phase current Iw digitally converted by the A / D converter 8 and the motor position (angle) detected by the position sensor 5 are converted into three-phase / 2-phase coordinates. The three-phase / two-phase coordinate converter 9 converts the three-phase AC coordinates of the phase currents Iu, Iv, and Iw into coordinates consisting of two axes, d-axis and q-axis, and detects the detected d. An axial current Id and a q-axis current Iq are obtained.
The detected d-axis current Id and q-axis current Iq are respectively input to the subtracters 11a and 11b. In the subtractors 11a and 11b, the deviation between the d-axis current Id and the d-axis current command value Id *, and the q-axis current Deviations between Iq and q-axis current command value Iq * are obtained, and d-axis voltage command value Vd * and q-axis voltage command value Vq * are calculated from the deviations by PI controllers 12a and 12b for d-axis and q-axis, respectively. Is done.

Here, the motor voltage command limit value calculation unit 13 calculates the motor voltage from the power supply voltage between the power supply 2 and the PWM inverter 3 detected by the power supply voltage detection circuit 7 and the motor rotation speed calculated by the rotation speed calculator 10. Calculate the maximum allowable voltage command value. For example, as shown in FIG. 2, the motor voltage command limit value calculation unit 13 determines a motor voltage command limit value with respect to the motor rotation speed and the power supply voltage in advance in a motor to be controlled, and maps it to a map. Thus, the motor voltage command limit value Vlimit which is the maximum allowable value is determined as the motor voltage command value.
The motor voltage command limit value calculation unit 13 uses the map as described above to calculate the motor voltage command limit value. This is because the map has a merit that the calculation load is reduced and the processing is accelerated. is there. However, it is also possible to obtain the motor voltage command limit value by calculation instead of map processing. In this case, although attention to the calculation load is necessary, the motor voltage limit is compared to the conventional method of current limitation. Therefore, the responsiveness is improved over the conventional method.

Here, a case where the motor voltage command limit value is obtained by calculation will be briefly described.
The motor voltage command limit value is obtained from the following power balance equation.
Pin = Pout + Ploss
Vin × Iin = Kt × Iq × ω + R × Im ²
Vin = (K × Iq × ω + R × Im ² ) / Iin
Vmax is obtained by substituting Imax for Iin. This Vmax is set as a motor voltage command limit value Vlimit.
Where Pin: Input power from the power supply (battery)
Pout: Output power to the motor
Ploss: Motor loss
Vin: Power supply voltage (battery voltage)
Iin: Input current from the power supply (battery)
Kt: Torque constant
Iq: q-axis detection current
Im motor current sqrt (Iq ² + Id ² )
ω: angular velocity of motor rotation
R: Motor resistance

  As shown in FIG. 3, the power consumption of the brushless motor 1 is represented by a curve-like characteristic such that the horizontal axis is the motor rotation speed. In FIG. 3, the point at which the power consumption curve reaches its peak is near the rated speed of the motor, as can be seen from the speed-torque curve. The power consumption is the largest in the vicinity of the rated speed, and thereafter, the motor voltage is saturated and the torque output decreases as the rotational speed increases, so the power consumption also decreases.

Since the power consumption of the brushless motor 1 is as shown in FIG. 3, it is possible to limit the power consumption by limiting the motor voltage command value near the peak of the power consumption. In other words, since the power supply power from the power source 2 is large at the power consumption peak when the efficiency is low, limiting the motor voltage command value may result in an excessive power supply state from the power source 2. Can be prevented.
Since the power consumption increases at the time of high torque output, if the limit on the motor voltage command value is set based on the point at which the power consumption at the maximum torque output peaks, the torque output is It will not be an excessive power supply state from.

  In other words, if the target brushless motor drive system, including the motor usage conditions, is determined in advance, the power consumption characteristics as shown in FIG. 3 are uniquely determined by the system. The map shown in FIG. 2 in which the output is generated as the motor voltage command limit value limits the motor output according to the motor rotation speed, so that an excessive current supply to the brushless motor does not occur. The map will limit the command value.

  Next, in the motor voltage command value limiter 14, the motor voltage command limit value calculation unit 13 performs the target d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the PI controllers 12 a and 12 b. When the d-axis voltage command value Vd * and the q-axis voltage command value Vq * exceed the motor voltage command limit value Vlimit by comparing with the calculated motor voltage command limit value Vlimit, the d-axis voltage command value Vd * The q-axis voltage command value Vq * is limited to the motor voltage command limit value Vlimit.

  As an example of the limiting method, a method of limiting from the combined voltage of the d-axis voltage and the q-axis voltage will be described. As shown in FIG. 4 as a method of limiting the combined voltage, a description will be given of the case where the voltage phase is fixed and the limitation is performed. In the method of fixing the voltage phase, the phase of the voltage command is fixed and only the amplitude is reduced to the limit voltage. The motor voltage command limit value is Vlimit, and the d-axis voltage command value Vd * and q-axis voltage command value Vq * before the limit, and the d-axis voltage command value Vd ** and the q-axis voltage command value Vq ** after the limit are The relationship is as shown in the following equation.

式（１）はモータ電圧の絶対値を求める式であり、式（２）によってｄ軸電圧指令値Ｖｄ＊＊、数（３）によってｑ軸電圧指令値Ｖｑ＊＊は表される。

Expression (1) is an expression for obtaining the absolute value of the motor voltage. Expression (2) represents the d-axis voltage command value Vd **, and expression (3) represents the q-axis voltage command value Vq **.

At this time, calculations of equations (1) to (3) occur, but the processing load for solving the quadratic equation as in the conventional method does not occur. Motor control is performed using the obtained d-axis voltage command value Vd ** and q-axis voltage command value Vq ** after limitation.
By limiting the motor voltage command value in this way, even if sudden supply of excessive current to the brushless motor suddenly becomes necessary, the motor output is limited according to the motor rotation speed. Excessive current supply to the battery does not occur.

  As described above, the motor voltage command value limited to a predetermined value or less by the motor voltage command value limiter 14 is converted into the U-phase voltage and V-phase voltage from the dq axis coordinates by the 2-phase / 3-phase coordinate converter 15. , The coordinates are converted into a three-phase voltage of the W-phase voltage and input to the PWM controller 16. The PWM controller 16 controls the duty ratio of the switching element of the PWM inverter 3 using the motor voltage command value as a motor control signal, and the PWM inverter 3 responds accordingly from the power source 2 to the U phase, V phase, W of the motor 1. Electric power is supplied to each phase, and the motor 1 is driven to rotate.

In the above description, as an example of the operation of the motor voltage command value limiter 14, the method of limiting from the combined voltage of the d-axis voltage and the q-axis voltage has been described.
The q-axis voltage command limit value for limiting the axis voltage command value and the d-axis voltage command limit value for limiting the d-axis voltage command value are calculated. The motor voltage command value limiter 14 calculates the q-axis voltage command value Vq *. This is the same as limiting the q-axis voltage command limit value and limiting the d-axis voltage command value Vd * to the d-axis voltage command limit value.

Further, in the dq axis coordinates, since the d axis voltage is an excitation component and the q axis voltage is a component corresponding to the load torque, the d axis voltage command limit value is set to 0 when the rotation speed is important. A method of limiting only the q-axis voltage command value Vq * is effective. In this case, the motor voltage command limit value calculator 13 calculates a q-axis voltage command limit value that limits the q-axis voltage command value of the motor voltage command value.
On the other hand, when it is desired to focus on the torque as opposed to the rotation speed, a method of limiting the q-axis voltage command limit value to 0 and limiting only the d-axis voltage command value Vd * becomes effective. In this case, the motor voltage command limit value calculator 13 calculates a d-axis voltage command limit value that limits the d-axis voltage command value of the motor voltage command value.

  As described above, according to the first embodiment, both the d-axis voltage command value and the q-axis voltage command value of the motor voltage command value, or either the d-axis or q-axis voltage command value depending on the purpose. By limiting the motor voltage command value, even when there is an excessive current supply request to the brushless motor, it is possible to quickly limit the motor current in order to prevent excessive current supply to the brushless motor.

Embodiment 2. FIG.
Next, the motor control apparatus in Embodiment 2 of this invention is demonstrated based on FIGS. FIG. 5 is a configuration diagram of the motor control device according to the second embodiment of the present invention, and FIG. 6 is a diagram illustrating a voltage limit map according to the second embodiment of the present invention.
In FIG. 5, the environmental temperature from the environmental temperature detector 17 for detecting the environmental temperature around the installation of the motor control device is added as an input to the motor voltage command limit value calculator 13, and other configurations are implemented. It attaches | subjects the same code | symbol as the structure shown in FIG. 1 of the form 1, and abbreviate | omits description.

The motor voltage command limit value calculator 13 is a power supply voltage between the power supply 2 and the PWM inverter 3 detected by the power supply voltage detection circuit 7, a motor rotational speed calculated by the rotational speed calculator 10, and an environmental temperature detector. As shown in FIG. 6, the maximum motor voltage command value is obtained from a map in which the input is the motor rotation speed, the power supply voltage, and the environmental temperature, and the output is the motor voltage command limit value, as shown in FIG. A motor voltage command limit value Vlimit which is an allowable value is determined.
Since the motor voltage command limit value calculation unit 13 calculates the motor voltage command limit value using the map shown in FIG. 6 as described above, there is an advantage that the calculation load is reduced and the processing is accelerated.

Next, in the motor voltage command value limiter 14, the motor voltage command limit value calculation unit 13 performs the target d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the PI controllers 12 a and 12 b. When the d-axis voltage command value Vd * and the q-axis voltage command value Vq * exceed the motor voltage command limit value Vlimit by comparing with the calculated motor voltage command limit value Vlimit, the d-axis voltage command value Vd * Further, limiting the q-axis voltage command value Vq * to the motor voltage command limit value Vlimit is the same as in the first embodiment.
The motor voltage command value limited to a predetermined value or less by the motor voltage command value limiter 14 is coordinate-converted from the dq axis coordinate to the three-phase voltage by the two-phase / three-phase coordinate converter 15, and the PWM controller. 16 controls the PWM inverter 3 to drive the motor 1 to rotate.

  As described above, according to the second embodiment, the motor voltage command limit value Vlimit for limiting the motor voltage command value is determined from the motor rotation speed, the power supply voltage, and the environmental temperature. Even in such a situation, the accuracy of the motor voltage command limit value does not deteriorate. Therefore, by limiting the motor voltage command value with this motor voltage command limit value, even if there is an excessive current supply request to the brushless motor, the motor current is promptly prevented to prevent excessive current supply to the brushless motor. Can be limited.

Embodiment 3 FIG.
Next, a motor control apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 7 is a block diagram of a motor control apparatus according to Embodiment 3 of the present invention, and FIG. 8 is a diagram for explaining a method for limiting a motor voltage command value according to Embodiment 3 of the present invention.
In FIG. 7, the target d-axis voltage command value Vd * and the q-axis voltage command value Vq * calculated by the PI controllers 12a and 12b are converted into three-phase voltages from the dq-axis coordinates by the two-phase / three-phase coordinate converter 15. The coordinate conversion is performed, and the phase voltages after the conversion are limited by the motor voltage command value limiter 14, and the other configurations are the same as those shown in FIG. The reference numerals are attached and the description is omitted.

  In the invention of the third embodiment, when limiting the motor voltage command value, a method of limiting using the d-axis voltage command value Vd * and the q-axis voltage command value Vq * as in the first and second embodiments. Instead, the three-phase voltage itself is limited, such as a U-phase voltage command value Vu *, a V-phase voltage command value Vv *, and a W-phase voltage command value Vw *. In the case of limiting each phase voltage, it means that the range of the power supply voltage that can be used by the motor control device is limited, and the motor current can be suppressed by this voltage limitation.

  In FIG. 7, the d-axis voltage command value Vd * and the q-axis voltage command value Vq * output from the PI controllers 11a and 11b are converted into three-phase voltages from the dq-axis coordinates by the two-phase / three-phase coordinate converter 15. To U phase voltage command value Vu *, V phase voltage command value Vv *, and W phase voltage command value Vw *. In the motor voltage command value limiter 14, the motor voltage command limit value calculation unit 13 calculates the U phase voltage command value Vu *, the V phase voltage command value Vv *, and the W phase voltage command value Vw *. If the U-phase voltage command value Vu *, V-phase voltage command value Vv *, and W-phase voltage command value Vw * exceed the motor voltage command limit value Vlimit in comparison with the motor voltage command limit value Vlimit, Voltage command value Vu *, V phase voltage command value Vv *, and W phase voltage command value Vw * are limited to motor voltage command limit value Vlimit.

As an example of the limiting method, as shown in FIG. 8, the motor voltage command limit value calculation unit 13 calculates the U-phase voltage command limit value Vu **, V-phase as the motor voltage command limit value Vlimit from the motor rotation speed and the power supply voltage. Voltage command limit value Vv ** and W-phase voltage command limit value Vw ** are output. In the motor voltage command value limiter 14, the U-phase voltage command value Vu *, the V-phase voltage command value Vv *, and the W-phase voltage command value Vw * before the restriction are the U-phase voltage command value Vu **, V after the restriction. The phase voltage command value Vv ** and the W phase voltage command value Vw ** are set and output to the PWM controller 16.
The motor voltage command value of each phase limited to a predetermined value or less by the motor voltage command value limiter 14 controls the PWM inverter 3 by the PWM controller 16 to drive the motor 1 to rotate.

  As described above, according to the invention of the third embodiment, when there is an excessive current supply request to the brushless motor by limiting the motor voltage command value of each phase of the U phase, the V phase, and the W phase. However, in order to prevent an excessive current supply to the brushless motor, the motor current can be quickly limited.

Embodiment 4 FIG.
Next, a motor control apparatus according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 9 is a configuration diagram of a motor control device according to Embodiment 4 of the present invention.
The configuration shown in FIG. 9 is the same as the configuration shown in FIG. 7 of the third embodiment, from the environmental temperature detector 17 that detects the environmental temperature around the installation of the motor control device as an input to the motor voltage command limit value calculator 13. Other configurations are the same as those in FIG. 7, and the same reference numerals are given and description thereof is omitted.

  The motor voltage command limit value calculator 13 is a power supply voltage between the power supply 2 and the PWM inverter 3 detected by the power supply voltage detection circuit 7, a motor rotational speed calculated by the rotational speed calculator 10, and an environmental temperature detector. As shown in FIG. 6, the maximum motor voltage command value is obtained from a map in which the input is the motor rotation speed, the power supply voltage, and the environmental temperature, and the output is the motor voltage command limit value. A motor voltage command limit value Vlimit which is an allowable value is determined.

  In the motor voltage command value limiter 14, the U-phase voltage command value Vu *, the V-phase voltage command value Vv *, which are coordinate-converted from the dq axis coordinate to the three-phase voltage by the 2-phase / 3-phase coordinate converter 15, The W-phase voltage command value Vw * is compared with the motor voltage command limit value Vlimit calculated by the motor voltage command limit value calculation unit 13, and the U-phase voltage command values Vu * and Vu are compared with those in the third embodiment. When phase voltage command value Vv * and W phase voltage command value Vw * exceed motor voltage command limit value Vlimit, U phase voltage command value Vu *, V phase voltage command value Vv *, and W phase voltage command value Vw * is limited to the motor voltage command limit value Vlimit.

  The method for limiting the motor voltage command value is the same as that shown in FIG. 8, and the motor voltage command value of each phase limited to a predetermined value or less by the motor voltage command value limiter 14 is input to the PWM controller 16. The PWM controller 16 controls the PWM inverter 3 to drive the motor 1 to rotate.

Embodiment 5 FIG.
Next, a motor control apparatus according to Embodiment 5 of the present invention will be described with reference to FIG. The configuration diagram of the motor control device in the fifth embodiment is the same as that shown in FIGS. 1, 5, 7, and 9. FIG. 10 is a diagram for explaining a voltage limit map according to the motor rotation speed in the fifth embodiment of the invention, and shows a motor voltage command limit value output from the motor voltage command limit value calculator 13.
In the motor voltage command limit value calculator 13, the map for determining the voltage command limit value that is the maximum allowable value of the motor voltage command value is the motor rotation speed, power supply voltage, and environmental temperature in the inventions of the first to fourth embodiments. By preparing several types as shown in FIG. 2 and FIG. 6, it is possible to arbitrarily set a limit value for changes in the usage environment (changes in power supply voltage, power consumption, environmental temperature). I made it.

However, the curve for setting the limit value is not limited to the method of focusing on the place where the power consumption is large as shown in FIG. 3. For example, as shown in FIG. A method of making the limit value constant (limit curve pattern 1), a method of loosening the limit in the high motor speed range (limit curve pattern 2), or a method of loosening the limit as the motor rotation speed increases (limit curve pattern 3) ) And other maps can be set as desired according to the purpose. These limit curve patterns 1, 2, and 3 are determined by factors of the motor rotation speed and the power supply voltage, and several types of maps of the limit curve patterns 1, 2, and 3 are prepared depending on the power supply voltage. For example, in the limit curve pattern 1, a plurality of patterns in which the motor voltage command limit value Vlimit changes depending on the power supply voltage as shown by an arrow, and the motor voltage command limit value Vlimit is increased if the power supply voltage is large. Keep it.
In the motor voltage command value limiter 14, the motor voltage command value is limited by the motor voltage command limit value Vlimit based on these limit curve patterns 1, 2, and 3.

Embodiment 6 FIG.
In the motor control devices of the third and fourth embodiments, each phase voltage itself is limited like the U-phase voltage command value Vu *, the V-phase voltage command value Vv *, and the W-phase voltage command value Vw *. The motor voltage command value limiter 14 may limit the duty value of each phase after the conversion to the three-phase voltage.
That is, the voltage command limit value calculation means 13 calculates a duty command limit value that limits the PWM command duty value to each phase motor voltage of the U phase, the V phase, and the W phase based on the motor rotation speed and the power supply voltage. Then, the motor voltage command value limiter 14 limits the PWM command duty value by the duty command limit value.
In this case, as an example of the limiting method, when the motor voltages of the U phase, V phase, and W phase are limited, the motor voltage command limit value Vlimit is represented by a hexagon as shown in FIG. The motor voltage command limit value Vlimit for limiting the PWM command Duty value to each phase motor voltage is represented by a circle as shown in FIG.

  As described above, according to the present invention, an excessive current supply request to the brushless motor is achieved by switching the map creation method and the motor voltage limiting method according to the purpose of the control and limiting the motor voltage command value. Even in the case where there is, the motor current can be limited in order to prevent an excessive current supply to the brushless motor.

In the above description, the rotational position of the motor 1 is detected by the position sensor 5 and the rotational speed calculator 10 calculates the rotational speed of the motor 1 from the rotational position of the motor. A rotation angle sensor that detects the angle θ may be provided, and a rotation angle speed calculator that calculates the rotation angle speed by differentiating the rotation angle θ may be provided instead of the rotation speed calculator 10.
In short, both the position sensor 5 that detects the rotational position of the motor 1 and the rotational angle sensor that detects the rotational angle θ detect the rotational position in a broad sense, and the rotational speed calculator 10 that calculates the rotational speed also has the rotational angular speed. In a broad sense, the rotational angular velocity computing unit that computes also computes the rotational velocity, and these are substantially the same.

1: Motor 2: Power supply 3: PWM inverter 4: Control device (microcontroller)
5: Position sensor 6: Current detection circuit 7: Power supply voltage detection circuit 8: A / D converter 9: 3-phase / 2-phase coordinate converter 10: Rotational speed calculator 11a, 11b: Subtractor 12a, 12b: PI control Unit 13: Motor voltage command limit value calculator 14: Motor voltage command value limiter 15: 2-phase / 3-phase coordinate converter 16: PWM controller 17: Environmental temperature detector

Claims (3)

Rotation speed calculation means for detecting a rotation position of the motor and calculating a motor rotation speed from the motor rotation position; motor current detection means for detecting a current supplied to the motor; and a current command value applied to the motor And a motor voltage command value calculating means for calculating a motor voltage command value for driving the motor based on the motor current detected by the motor current detecting means, and an electric power steering for a vehicle for supplying a constant power such as a battery. In the motor control device in the device,
The d-axis voltage of the motor voltage command value is calculated from the power supply voltage detection means for detecting the power supply voltage supplied to the motor, the power supply voltage detected by the power supply voltage detection means, and the motor rotation speed calculated by the rotation speed calculation means. Motor voltage command limit value calculating means for calculating a d-axis voltage command limit value for limiting only the command value; and motor voltage command value limiting means for limiting the motor voltage command value by the d-axis voltage command limit value. A motor control device characterized by that. The motor voltage command limit value calculating means has a plurality of limit patterns in which the limit value increases, maintains, or decreases as the motor rotation speed increases, and selects those limit values according to the power supply voltage. The motor control device according to claim 1, wherein a voltage command limit value is calculated .   2. The motor control device according to claim 1, wherein the motor voltage command limit value calculation unit includes a map in which a maximum value allowable as the motor voltage command value is determined in advance by the motor rotation speed and the power supply voltage. .

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