JP2021005943A - Position determination device - Google Patents

Abstract

To provide a position determination device that can achieve accurate vector control starting at a time a rotor starts rotation.SOLUTION: In a position determination device 13, a rotation position acquisition unit 131 acquires a rotation position θ of a rotor. A torque estimation unit 132 estimates a torque generated in a motor on the basis of a current supplied to the motor. An angular acceleration estimation unit 133 estimates an angular acceleration 22 of the rotor on the basis of the torque estimated by the torque estimation unit 132. A position compensation unit 137 compensates the acquired rotation position θ on the basis of the rotation position θ acquired by the rotation position acquisition unit 131 and of the angular acceleration 22 estimated by the angular acceleration estimation unit 133.SELECTED DRAWING: Figure 3

Description

The present invention relates to a position specifying device for specifying a rotation position of a rotor included in a motor.

In a permanent magnet synchronous motor, the rotor comprises a permanent magnet and the stator comprises a coil. By supplying three-phase alternating current to the coil, the coil generates a rotating magnetic field. The rotor rotates in synchronization with the rotating magnetic field generated by the coil. Permanent magnet synchronous motors are sometimes referred to as brushless DC (Direct Current) motors.

When driving a permanent magnet synchronous motor using a DC power supply, an inverter is used. The inverter includes a plurality of switching elements such as transistors, and converts a direct current into an alternating current. An inverter control device is used to control a plurality of switching elements included in the inverter. The inverter control device uses vector control to switch on / off of a plurality of switching elements. The parameters used in vector control are the angular velocity of the rotor and the rotational position of the rotor.

The inverter control device includes a position specifying device for specifying the rotation position of the rotor. The positioning device identifies the rotational position based on, for example, output signals from a plurality of Hall elements arranged around the rotor. When the three Hall elements are arranged around the rotor at intervals of 120 degrees, the positioning device can specify the rotational position of the rotor in units of 60 degrees.

The positioning device compensates for the rotational position of the rotor in order to improve the accuracy of the rotational position of the rotor. For example, the motor control device disclosed in Patent Document 1 is set at a second time after the control cycle has elapsed from the first time, based on the length of the control cycle and the angular velocity and acceleration of the rotor at the first time. Compensate for the rotational position of the rotor. The motor control device performs vector control based on the compensated rotation position.

However, at the start of rotation of the rotor, the motor control device cannot acquire the angular acceleration unless it acquires at least three rotation positions. That is, the motor control device cannot execute highly accurate vector control from the start of rotation of the rotor until the rotation positions of at least three rotors are acquired.

JP-A-2018-133890

In view of the above problems, an object of the present invention is to provide a position specifying device capable of realizing highly accurate vector control from the time when the rotor starts rotating.

In order to solve the above problems, the first invention is a position specifying device for specifying a rotation position of a rotor included in a motor, which includes a rotation position acquisition unit, a torque estimation unit, an angular acceleration estimation unit, and position compensation. It has a part. The rotation position acquisition unit acquires the rotation position of the rotor. The torque estimation unit estimates the torque generated by the motor based on the current supplied to the motor. The angular acceleration estimation unit estimates the angular acceleration of the rotor based on the torque estimated by the torque estimation unit. The position compensating unit compensates for the acquired rotation position based on the rotation position acquired by the rotation position acquisition unit and the angular acceleration estimated by the angular acceleration estimation unit.

The first invention estimates the torque based on the current supplied to the motor, estimates the angular acceleration of the rotor based on the estimated torque, and compensates for the acquired rotational position using the estimated angular acceleration. According to the first invention, compensation for the rotational position can be started before the angular acceleration based on the rotational position of the rotor can be calculated. Therefore, in the first invention, highly accurate vector control can be realized from the time when the rotor starts rotating.

The second invention is the first invention, and further includes an angular velocity estimation unit. The angular velocity estimation unit estimates the angular velocity of the rotor using the estimated angular acceleration. The position compensation unit compensates for the acquired rotational position based on the angular velocity estimated by the angular velocity estimation unit.

In the second invention, the angular velocity is estimated based on the estimated angular acceleration, and the rotational position is compensated based on the estimated angular velocity. In the second invention, compensation for the rotational position can be started before the angular velocity can be calculated based on the rotational position of the rotor. Therefore, the second invention can execute vector control with higher accuracy.

The third invention is the first or second invention, and when the motor is driven, the rotation position acquisition unit acquires the range of the rotation position of the rotor, and the initial rotation position of the rotor is based on the acquired range. To determine. The position compensating unit compensates for the rotation position after the rotor starts rotating based on the initial rotation position determined by the rotation position acquisition unit.

The third invention specifies the initial rotation position of the rotor based on the range of rotation positions of the rotor. As a result, even if the rotation position of the rotor cannot be specified at the start of rotation of the rotor, the rotation position of the rotor can be compensated.

A fourth invention is a position specifying method for specifying a rotation position of a rotor included in a motor, and includes a rotation position acquisition step, a torque estimation step, an angular acceleration estimation step, and a position compensation step. The rotation position acquisition step acquires the rotation position of the rotor. The torque estimation step estimates the torque generated by the motor based on the current supplied to the motor. The angular acceleration estimation step estimates the angular acceleration of the rotor based on the torque estimated by the torque estimation step. The position compensation step compensates for the acquired rotation position based on the rotation position acquired by the rotation position acquisition step and the angular acceleration estimated by the angular acceleration estimation step.

The fourth invention is used in the first invention.

According to the present invention, it is possible to provide a position specifying device capable of realizing highly accurate vector control from the time when the rotor starts rotating.

It is a functional block diagram which shows the structure of the motor control system which concerns on embodiment of this invention. It is a functional block diagram which shows the structure of the inverter control device shown in FIG. It is a functional block diagram which shows the structure of the position specifying apparatus shown in FIG. It is a flowchart which shows the operation of the position specifying apparatus shown in FIG. It is a graph of the compensation rotation position calculated by the position specifying apparatus shown in FIG. It is a figure which shows the CPU bus configuration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

[1. Constitution]
[1.1. Configuration of motor control system 100]
FIG. 1 is a functional block diagram showing a configuration of a motor control system 100 according to an embodiment of the present invention. With reference to FIG. 1, the motor control system 100 includes a motor 1, an inverter 2, current sensors 3 and 4, a rotation position sensor 5, and an inverter control device 10.

The motor 1 is a permanent magnet synchronous motor and includes a rotor 1R. The rotor 1R is rotated by the three-phase alternating current 50 supplied from the inverter 2. The three-phase alternating current 50 has a U phase 50U, a V phase 50V, and a W phase 50W.

The inverter 2 generates a three-phase AC 50 by switching on / off of a switching element (not shown) such as a transistor based on a switching signal 20 received from the inverter control device 10. The inverter 2 supplies the generated three-phase alternating current 50 to the motor 1.

The current sensor 3 is provided on the wiring for supplying the U-phase 50U from the inverter 2 to the motor 1, and detects the current of the U-phase 50U. The current sensor 3 outputs the current detection value Iu to the inverter control device 10 as the current detection result of the U phase 50U.

The current sensor 4 is provided on the wiring for supplying the W phase 50W from the inverter 2 to the motor 1, and detects the current of the W phase 50W. The current sensor 4 outputs the current detection value Iw to the inverter control device 10 as the current detection result of the W phase 50W.

The rotation position sensor 5 detects the magnetic field of the permanent magnet included in the rotor 1R, and outputs an output signal 5M indicating the detection result of the magnetic field to the inverter control device 10. In FIG. 1, the rotation position sensor 5 is arranged outside the motor 1. However, in reality, the rotation position sensor 5 is arranged in the motor 1 so as to surround the rotor 1R. In the present embodiment, the rotation position sensor 5 is three Hall elements. Each of the three Hall elements outputs an output signal of 5M to the inverter control device 10.

The inverter control device 10 controls the inverter 2 based on the torque command value 60. Specifically, the inverter control device 10 uses feedback using the current detection value Iu received from the current sensor 3, the current detection value Iw received from the current sensor 4, and the output signal 5M received from the rotation position sensor 5. By control, the current target value based on the torque command value 60 is adjusted. The inverter control device 10 generates a switching signal 20 based on the adjusted current target value, and supplies the generated switching signal 20 to the inverter 2.

[1.2. Configuration of inverter control device 10]
FIG. 2 is a functional block diagram showing the configuration of the inverter control device 10 shown in FIG. With reference to FIG. 2, the inverter control device 10 includes a control unit 11, a PWM signal generation device 12, and a position identification device 13.

The control unit 11 receives the current detection values Iu and Iw from the current sensors 3 and 4, and receives the compensation rotation position θc from the position identification device 13. The control unit 11 controls the inverter control device 10 by using the received current detection values Iu and Iw, the received compensation rotation position θc, and the torque command value 60 input to the inverter control device 10. The control unit 11 generates a U-phase voltage target value Vu *, a V-phase voltage target value Vv *, and a W-phase voltage target value Vw * in order to control the inverter control device 10. The configuration of the control unit 11 will be described later.

The PWM signal generation device 12 receives the U-phase voltage target value Vu *, the V-phase voltage target value Vv *, and the W-phase voltage target value Vw * from the control unit 11. The PWM signal generation device 12 generates a switching signal 20 from the received U-phase voltage target value Vu *, V-phase voltage target value Vv *, and W-phase voltage target value Vw *.

For example, the PWM signal generation device 12 generates a PWM signal corresponding to the U phase by comparing the received U-phase voltage target value Vu * with a carrier (not shown). Similarly, PWM signals corresponding to each of the V phase and the W phase are generated. The PWM signal generation device 12 generates a switching signal 20 including a PWM signal corresponding to each of the U phase, the V phase, and the W phase, and supplies the generated switching signal 20 to the inverter 2.

The position specifying device 13 receives an output signal 5M from the rotation position sensor 5, and identifies the rotation position of the rotor 1R based on the received output signal 5M. The position specifying device 13 generates the compensated rotation position θc by compensating for the specified rotation position based on the current detection values Iu and Iw received from the current sensors 3 and 4.

[1.3. Configuration of control unit 11]
The control unit 11 includes a current target value calculation unit 111, a vector conversion unit 112, a current control unit 113, and a vector inverse conversion unit 114.

The current target value calculation unit 111 generates a d-axis current target value Id * and a q-axis current target value Iq * based on the torque command value 60 input to the inverter control device 10. The d-axis current target value Id * is a d-axis component of the current target value in the rotating coordinate system with the rotation axis of the rotor 1R as the origin. The q-axis current target value Iq * is a q-axis component of the current target value in the rotating coordinate system.

The vector conversion unit 112 acquires the current detection value Iu received from the current sensor 3 as the current value of the U phase 50U. The vector conversion unit 112 acquires the current detection value Iw received from the current sensor 4 as the current value of the W phase 50W. The vector conversion unit 112 calculates the current value of the V phase 50V based on the acquired current value of the U phase 50U and the acquired current value of the W phase 50W. The vector conversion unit 112 uses the compensation rotation position θc received from the position specifying device 13 to perform coordinate conversion between the current value of the U phase 50U, the current value of the V phase 50V, and the current value of the W phase 50W. As a result of the coordinate transformation, the d-axis current detection value Id and the q-axis current detection value Iq are generated.

The current control unit 113 receives the d-axis current target value Id * and the q-axis current target value Iq * from the current target value calculation unit 111. The current control unit 113 receives the d-axis current detection value Id and the q-axis current detection value Iq from the vector conversion unit 112. The current control unit 113 executes PI (Proportional-Integral) control so that the received d-axis current detection value Id matches the received d-axis current target value Id *. As a result of PI control, the current control unit 113 generates a d-axis voltage target value Vd *. The current control unit 113 executes PI control so that the received q-axis current detection value Iq matches the received q-axis current target value Iq *. As a result of PI control, the current control unit 113 generates the q-axis voltage target value Vq *.

The vector inverse conversion unit 114 receives the d-axis voltage target value Vd * and the q-axis voltage target value Vq * from the current control unit 113. The vector inverse conversion unit 114 receives the compensation rotation position θc from the position specifying device 13. The vector inverse conversion unit 114 sets the U-phase voltage target value Vu * and the V-phase voltage target from the received d-axis voltage target value Vd * and the received q-axis voltage target value Vq * based on the received compensation rotation position θc. A value Vv * and a W-phase voltage target value Vw * are generated. The vector inverse conversion unit 114 outputs the U-phase voltage target value Vu *, the V-phase voltage target value Vv *, and the W-phase voltage target value Vw * to the PWM signal generator 12.

[1.4. Configuration of position identification device 13]
FIG. 3 is a functional block diagram showing the configuration of the position specifying device 13 shown in FIG. With reference to FIG. 3, the position specifying device 13 includes a rotation position acquisition unit 131, a torque estimation unit 132, an angular acceleration estimation unit 133, an angular velocity estimation unit 134, an angular velocity calculation unit 135, and an angular acceleration calculation unit 136. And a position compensation unit 137.

The rotation position acquisition unit 131 receives the output signal 5M from the rotation position sensor 5, and acquires the rotation position θ or the position range 40 based on the received output signal 5M. The rotation position θ is a specific value indicating the rotation angle of the rotor 1R. The position range 40 indicates a range in which the rotation position θ of the rotor 1R will be included. The rotation position acquisition unit 131 acquires the position range 40 when the rotation position θ cannot be acquired.

The torque estimation unit 132 receives the d-axis current detection value Id and the q-axis current detection value Iq from the vector conversion unit 112. The torque estimation unit 132 estimates the torque generated by the rotor 1R based on the received d-axis current detection value Id and the q-axis current detection value Iq, and generates a torque estimation value 21 indicating the estimation result.

The angular acceleration estimation unit 133 receives the torque estimation value 21 from the torque estimation unit 132, and estimates the angular acceleration 22 of the rotor 1R based on the received torque estimation value 21. In the following description, the angular acceleration 22 may be referred to as "estimated angular acceleration 22".

The angular velocity estimation unit 134 receives the estimated angular acceleration 22 from the angular acceleration estimation unit 133, and estimates the angular velocity 23 of the rotor 1R based on the received estimated angular acceleration 22. In the following description, the angular velocity 23 may be described as "estimated angular velocity 23".

The angular velocity calculation unit 135 receives the rotation position θ from the rotation position acquisition unit 131, and calculates the angular velocity 33 of the rotor 1R based on the received rotation position θ. In the following description, the angular velocity 33 may be described as "calculated angular velocity 33".

The angular acceleration calculation unit 136 receives the calculated angular velocity 33 from the angular velocity calculation unit 135, and calculates the angular acceleration 32 of the rotor 1R based on the received calculated angular velocity 33. In the following description, the angular acceleration 32 may be described as "calculated angular acceleration 32".

The position compensation unit 137 receives the rotation position θ or the position range 40 from the rotation position acquisition unit 131. The position compensation unit 137 receives the estimated angular acceleration 22 from the angular acceleration estimation unit 133 and the estimated angular velocity 23 from the angular velocity estimation unit 134. The position compensation unit 137 receives the calculated angular acceleration 32 from the angular acceleration calculation unit 136 and the calculated angular velocity 33 from the angular velocity calculation unit 135. The position compensation unit 137 received either one of the received rotation position and the received position range 40, one of the received estimated angular acceleration 22 and the received calculated angular acceleration 32, the received estimated angular velocity 23, and the received calculation. The compensation rotation position θc is calculated using either one of the angular velocities 33.

[2. Operation of position identification device 13]
FIG. 4 is a flowchart showing the operation of the position specifying device 13 shown in FIG. Hereinafter, the operation of the position specifying device 13 is started with reference to FIG. When a torque command value 60 larger than zero is input to the inverter control device 10, the position specifying device 13 starts the process shown in FIG.

(Initialize)
The position specifying device 13 executes steps S11 to S12 to initialize the position specifying device 13. Specifically, the rotation position acquisition unit 131 initializes the number of acquisitions of the rotation position θ to zero (step S11). The number of acquisitions is used for determining whether or not each of the calculated angular acceleration 32 and the calculated angular velocity 33 can be calculated, as will be described later.

The rotation position acquisition unit 131 determines the initial rotation position, which is the rotation position of the rotor 1R at the start of rotation (step S12). The rotation position acquisition unit 131 outputs the determined initial rotation position to the position compensation unit 137.

The method of determining the initial rotation position in step S12 differs depending on whether or not the rotation position θ has been acquired. Hereinafter, a specific description will be given.

When the level of any one of the three output signals 5M from the three Hall elements changes, the rotation position acquisition unit 131 can specify the rotation position θ. The rotation position θ is specified based on the Hall element that outputs the output signal 5M whose level has changed and the increase / decrease in the level of the output signal 5M. The rotation position θ is one of six angles of 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees. When the rotation position θ can be acquired, the rotation position acquisition unit 131 determines the rotation position θ as the initial rotation position and increments the acquisition number. For example, when the rotation position θ is 120 degrees, the rotation position acquisition unit 131 determines the initial rotation position to 120 degrees.

The rotation position acquisition unit 131 cannot acquire the rotation position θ when the levels of the three output signals 5M do not change. In this case, the rotation position acquisition unit 131 acquires the position range 40 based on the level of each of the three output signals 5M. The rotation position acquisition unit 131 determines the median value of the acquired position range 40 as the initial rotation position. As a result, the position specifying device 13 can start compensation for the rotation position θ even when the rotation position θ cannot be specified. When the initial rotation position is the median value of the position range 40, the rotation position acquisition unit 131 does not increment the acquisition number.

FIG. 5 is a graph showing an example of a time change of the compensation rotation position θc calculated by the position specifying device 13 shown in FIG. In FIG. 5, the rotation position acquisition unit 131 acquires the position range 40 of 0 degrees or more and 60 degrees or less instead of the rotation position θ in the period A from the time t0 to the time t4. The rotation position θ is acquired for the first time at time t4 in the graph shown in FIG. Therefore, the rotation position θ is not shown in the graph shown in FIG. 5 during the period A. The ideal curve L1 shows an example of the actual rotation position of the rotor 1R. The ideal curve L1 is 15 degrees at time t0.

The rotation position acquisition unit 131 acquires the rotation position θ at each of the times t4, t5, and t6. The rotation position θ is 60 degrees at time t4, 120 degrees at time t5, and 180 degrees at time t6.

In the example shown in FIG. 5, the rotor 1R starts rotating at time t0. At time t0, the rotation position acquisition unit 131 specifies a position range 40 indicating 0 degrees or more and 60 degrees or less, and determines 30 degrees, which is the median value of the specified position range 40, as the initial rotation position.

(Estimation of angular acceleration)
Each time the rotation position acquisition unit 131 receives the three output signals 5M from the rotation position sensor 5, the rotation position θ or the position range 40 is acquired based on the three output signals 5M received. The rotation position acquisition unit 131 determines whether or not the rotation position θ has been acquired (step S13).

When the rotation position acquisition unit 131 acquires the position range 40 (No in step S13), the angular acceleration estimation unit 133 determines whether or not the calculated angular acceleration 32 of the rotor 1R has been acquired (step S21).

When the number of acquisitions is 3 or more, the angular acceleration estimation unit 133 determines that the calculated angular acceleration 32 has already been acquired (Yes in step S21). This is because the angular acceleration calculation unit 136 can calculate the angular acceleration 32 when three or more rotation positions θ are acquired. In this case, the position specifying device 13 proceeds to step S23.

When the number of acquisitions is less than 3, the angular acceleration estimation unit 133 determines that the calculated angular acceleration 32 has not been acquired (No in step S21). The angular acceleration estimation unit 133 estimates the angular acceleration 22 by using the torque estimation value 21 estimated by the torque estimation unit 132 (step S22).

Specifically, the torque estimation unit 132 calculates the torque estimation value 21 based on the d-axis current detection value Id and the q-axis current detection value Iq received from the vector conversion unit 112. The angular acceleration estimation unit 133 receives the torque estimation value 21 from the torque estimation unit 132, and calculates the estimated angular acceleration 22 using the following equation (1). The angular acceleration estimation unit 133 outputs the calculated estimated angular acceleration 22 to the angular velocity estimation unit 134 and the position compensation unit 137.

In equation (1), T is the torque estimate 21. J is the inertia (moment of inertia) of the rotor 1R. α is the estimated angular acceleration 22. D is the load torque. Each of the inertia and the load torque is a constant and is preset in the angular acceleration estimation unit 133. The angular acceleration estimation unit 133 calculates the estimated angular acceleration 22 by solving the equation (1) to which the above parameters are substituted for α.

In the example shown in FIG. 5, the rotation position θ is acquired at times t4, t5, and t6. The angular acceleration calculation unit 136 cannot calculate the calculated angular acceleration 32 in the period F from the time t0 to the time t6. Therefore, the angular acceleration estimation unit 133 repeatedly calculates the estimated angular acceleration 22 in the period F.

(Estimation of angular velocity)
The angular velocity estimation unit 134 determines whether or not the calculated angular velocity 33 has already been acquired (step S23).

When the number of acquisitions is 2 or more, the angular velocity estimation unit 134 determines that the calculated angular acceleration 32 has already been acquired (Yes in step S23). This is because the angular velocity calculation unit 135 can calculate the angular velocity 33 when two or more rotation positions θ are acquired. In this case, the position specifying device 13 proceeds to step S25.

When the number of acquisitions is less than 2, the angular velocity estimation unit 134 determines that the calculated angular velocity 33 has not been acquired (No in step S23). The angular velocity estimation unit 134 receives the estimated angular acceleration 22 from the angular acceleration estimation unit 133, and estimates the angular velocity 23 using the received estimated angular acceleration 22 (step S24). Specifically, the angular velocity estimation unit 134 calculates the estimated angular velocity 23 by integrating the received estimated angular acceleration 22 over time.

In the example shown in FIG. 5, since the number of acquisitions is less than 2 in the period E from the time t0 to the time t5, the angular velocity calculation unit 135 cannot calculate the calculated angular velocity 33 in the period E. Therefore, the angular velocity estimation unit 134 estimates the angular velocity 23 in the period E.

When the estimated angular acceleration 22 is acquired at each of the times t1 to t3, the angular velocity estimation unit 134 integrates the estimated angular acceleration 22 acquired at the time t1 in the time from the time t0 to the time t1. The angular velocity estimation unit 134 integrates the estimated angular acceleration 22 acquired at time t2 in the time from time t1 to time t2. The angular velocity estimation unit 134 integrates the estimated angular acceleration 22 acquired at time t3 in the time from time t2 to time t3. The angular velocity estimation unit 134 calculates the sum of the three integrated values as the estimated angular velocity 23 at time t3.

(Calculation of compensation rotation position θc)
With reference to FIG. 3, the position compensation unit 137 receives the initial rotation position or the rotation position θ from the rotation position acquisition unit 131. The position compensation unit 137 receives the estimated angular acceleration 22 acquired in step S22 from the angular acceleration estimation unit 133, and receives the calculated angular acceleration 32 calculated in step S19 from the angular acceleration calculation unit 136. The position compensation unit 137 receives the estimated angular velocity 23 acquired in step S24 from the angular velocity estimation unit 134, and receives the calculated angular velocity 33 acquired in step S17 from the angular velocity calculation unit 135. Steps S17 and S19 will be described later.

With reference to FIG. 4, the position compensation unit 137 receives one of the received initial rotation position and the received rotation position θ, and one of the received estimated angular acceleration 22 and the received calculated angular acceleration 32. The compensation rotation position θc is calculated using either the estimated angular velocity 23 or the calculated angular velocity 33 received (step S25). Specifically, the position compensation unit 137 calculates the compensation rotation position θc using the following equation (2).

In equation (2), θc is the compensation rotation position. θ is the rotation position or the initial rotation position. t _b is the acquisition time of the estimated angular acceleration 22 or the calculated time of the calculated angular acceleration 32. t _a, the rotation start time of the rotor, or a acquisition time of the rotational position. ω is the estimated angular velocity 23 or the calculated angular velocity 33. When the angular velocity 33 is calculated, the position compensation unit 137 applies the angular velocity 33 to the equation (2). α is the estimated angular acceleration 22 or the calculated angular acceleration 32. When the angular acceleration 32 is calculated, the position compensation unit 137 applies the angular acceleration 32 to the equation (2).

(Guard processing)
With reference to FIG. 4, the position compensation unit 137 executes a guard process for adjusting the compensation rotation position θc calculated in step S25 based on the position range 40 (step S26). Specifically, when the calculated compensation rotation position θc is larger than the upper limit value of the position range 40, the position compensation unit 137 matches the calculated compensation rotation position θc with the upper limit value of the position range 40. When the calculated compensation rotation position θc is smaller than the lower limit value of the position range 40, the position compensation unit 137 matches the calculated compensation rotation position θc with the lower limit value of the position range 40.

When the compensation rotation position θc is changed based on the upper limit value or the lower limit value of the position range 40, the position compensation unit 137 outputs the changed compensation rotation position θc to the vector conversion unit 112 and the vector inverse conversion unit 114. When the compensation rotation position θc is not changed, the position compensation unit 137 outputs the compensation rotation position θc calculated in step S25. As a result, the error of the compensation rotation position θc can be reduced.

For example, in the period from the time tp to the time t4 shown in FIG. 5, the position compensation unit 137 calculates the compensation rotation position θc larger than 60 degrees. This is because the initial rotation position is larger than the actual rotation position of the rotor 1R at time t0. In the period A, the position range 40 is 0 degrees or more and 60 degrees or less. In this case, the position compensation unit 137 changes the compensation rotation position θc to 60 degrees, which is the upper limit of the position range 40 in the period A, in the period from the time tp to the time t4. When the compensation rotation position θc calculated in the period A is smaller than 0 degrees, the compensation rotation position θc is changed to 0 degrees.

(Acquisition of rotation position θ)
With reference to FIG. 4, the process returns to the description of step S13. When the rotation position acquisition unit 131 acquires the rotation position θ (Yes in step S13), the rotation position acquisition unit 131 increments the number of acquisitions of the rotation position θ (step S14). The position compensation unit 137 outputs the rotation position θ received from the rotation position acquisition unit 131 to the vector conversion unit 112 and the vector inverse conversion unit 114 as the compensation rotation position θc (step S15). This is because the rotation position θ is more accurate than the compensation rotation position θc calculated based on the angular velocity and the angular acceleration.

For example, the rotation position acquisition unit 131 acquires the rotation position θ at the time t4 shown in FIG. The rotation position θ is 60 degrees at time t4. The position compensation unit 137 outputs the rotation position θ acquired at time t4 as the compensation rotation position θc. Similarly, the rotation position θ acquired at each of the times t5 and t6 is output from the position compensation unit 137 as the compensation rotation position θc.

(Calculation of angular velocity)
With reference to FIG. 4, the angular velocity calculation unit 135 determines whether or not the angular velocity 33 can be calculated (step S16). Specifically, the angular velocity calculation unit 135 determines whether or not the number of acquisitions is 2 or more.

If the number of acquisitions is less than 2, the rotation position acquisition unit 131 determines that the angular velocity cannot be calculated (No in step S16). The position specifying device 13 proceeds to step S18. On the other hand, when the number of acquisitions is 2 or more, the angular velocity calculation unit 135 determines that the angular velocity 33 can be calculated (Yes in step S16). The angular velocity calculation unit 135 calculates the angular velocity 33 using the two most recently acquired rotation positions θ (step S17). That is, when the number of acquisitions is 2 or more, the angular velocity calculation unit 135 calculates the angular velocity 33 each time the rotation position acquisition unit 131 acquires the rotation position θ.

In the example shown in FIG. 5, the angular velocity calculation unit 135 determines that the angular velocity 33 can be calculated at the time t5 when the second rotation position θ is acquired. The angular velocity calculation unit 135 calculates the angular velocity 33 by using the rotation position θ acquired at the times t4 and t5. Similarly, at the time t6 when the third rotation position θ is acquired, the angular velocity calculation unit 135 calculates the angular velocity 33 using the rotation positions θ acquired at the times t5 and t6.

(Calculation of angular acceleration)
With reference to FIG. 4, the angular acceleration calculation unit 136 determines whether or not the angular acceleration 32 can be calculated (step S18). Specifically, the angular acceleration calculation unit 136 determines whether or not the number of acquisitions is 3 or more.

If the number of acquisitions is less than 3, the angular acceleration calculation unit 136 determines that the angular acceleration 32 cannot be calculated (No in step S18). The position specifying device 13 proceeds to step S20. On the other hand, when the number of acquisitions is 3 or more, the angular acceleration calculation unit 136 determines that the angular acceleration 32 can be calculated (Yes in step S18). The angular acceleration calculation unit 136 calculates the angular acceleration 32 using the two angular velocities 33 most recently calculated by the angular velocity calculation unit 135 (step S19). That is, when the number of acquisitions is 3 or more, the angular acceleration calculation unit 136 calculates the angular acceleration 32 each time the rotation position acquisition unit 131 acquires the rotation position θ.

In the example shown in FIG. 5, the angular acceleration calculation unit 136 determines that the angular acceleration 32 can be calculated at the time t6 when the third rotation position θ is acquired. The angular acceleration calculation unit 136 calculates the angular acceleration 32 by using the calculated angular velocity 33 calculated at the times t5 and t6. In this case, the angular acceleration calculation unit 136 may acquire the rotation position θ acquired at each of the times t4 to t6 from the rotation position acquisition unit 131 to calculate the angular acceleration 32.

(End of position compensation)
After step S19 or S26, the positioning device 13 determines whether or not the rotor 1R has been instructed to stop (step S20). Specifically, when the torque command value 60 indicating that the torque is 0 is input to the inverter control device 10, the position specifying device 13 determines that the rotor 1R has been instructed to stop (Yes in step S20). , The process shown in FIG. 4 is terminated. When the current target value calculation unit 111 receives the torque command value 60 indicating a torque larger than 0 (No in step S20), the position specifying device 13 returns to step S14.

(Specific example of calculation of compensation rotation position θc)
With reference to FIG. 5, changes in parameters used for calculating the compensation rotation position θc will be described.

In the period A shown in FIG. 5, the rotation position acquisition unit 131 cannot acquire the rotation position θ, and acquires the position range 40 of 0 degrees or more and 60 degrees or less. In this case, the initial rotation position is determined to be 30 degrees. The determined initial rotation position is substituted into the first term on the left side of the equation (2).

In the period A, the calculated angular acceleration 32 and the calculated angular velocity 33 are not calculated. Therefore, the angular velocity 23 estimated by the angular velocity estimation unit 134 is substituted for the angular velocity ω in the second term on the left side of the equation (2). The angular acceleration 22 estimated by the angular acceleration estimation unit 133 is substituted for the angular acceleration α in the third term on the left side of the equation (2). Time _{t a} of the formula (2) is the time t0 at which the rotor 1R starts rotating. The time t _b is the calculated time of the estimated angular acceleration 22.

When the initial rotation position is substituted into the first term on the left side of the equation (2), the equation (2) indicates that the integrated values of the estimated angular acceleration 22 and the estimated angular velocity 23 are added to the initial rotation position. The rotor 1R rotates when the current is supplied to the motor 1 in a period after the time t0. It can be seen that the compensation rotation position θc continues to increase from the initial rotation position as shown in FIG. 5 in accordance with the rotation of the rotor.

From the time tp to the time t2, the compensation rotation position θc becomes larger than the upper limit value of the position range 40, which is 60 degrees. This is because the actual rotation position of the rotor 1R at time t0 is 15, whereas the initial rotation position is 30. The position compensation unit 137 changes the calculated compensation rotation position θc to the upper limit value of the position range 40 from the time tp to the time t2. As a result, the compensation rotation position θc becomes constant from the time tp to the time t2.

As the rotor 1R rotates in the period A, the rotation position acquisition unit 131 acquires 60 degrees as the rotation position θ at the time t4. The position compensation unit 137 outputs the rotation position θ acquired at time t4 as the compensation rotation position θc. The number of acquisitions increases to 1.

In the period B from the time t4 to the time t5, the estimated angular acceleration 22 and the estimated angular velocity 23 are acquired. This is because the angular acceleration 32 and the angular velocity 33 cannot be calculated when the number of acquisitions is less than 2. When the position compensation unit 137 calculates the compensation rotation position θc in the period B, the position compensation unit 137 substitutes the rotation position θ acquired at time t4 into the first term on the left side of the equation (2). The estimated angular acceleration 22 and the estimated angular velocity 23 are substituted into the equation (2) as in the period A. In the period B, the compensation rotation position θc deviates from the ideal curve L1 due to the estimation error of the estimated angular acceleration 22 and the estimated angular velocity 23.

As the rotor 1R rotates in the period B, the rotation position acquisition unit 131 acquires 120 degrees as the rotation position θ at the time t5. The compensation rotation position θc is set to 120 degrees at time t5. The position compensation unit 137 outputs the rotation position θ acquired at time t5 as the compensation rotation position θc. The number of acquisitions increases to 2.

Since the number of acquisitions is 2 or more, the angular velocity calculation unit 135 calculates the angular velocity 33 at time t5. Since the number of rotation positions θ required for calculating the angular acceleration 32 has not been acquired, the angular acceleration 32 is not calculated. When calculating the compensation rotation position θc in the period C from the time t5 to the time t6, the position compensation unit 137 substitutes the following parameters into the equation (2). That is, the position compensation unit 137 substitutes the rotation position θ acquired at time t5 into the first term on the left side of the equation (2). The angular velocity 33 calculated at time t5 is substituted as the angular velocity ω in the second term on the left side of the equation (2). The estimated angular acceleration 22 is substituted as the angular acceleration α in the third term on the left side of the equation (2). In the period C, the compensation rotation position θc deviates from the ideal curve L1 due to the estimation error of the estimated angular acceleration 22.

As the rotor 1R rotates in the period C, the rotation position acquisition unit 131 acquires 180 degrees as the rotation position θ at the time t6. The compensation rotation position θc is set to 180 degrees at time t6. The position compensation unit 17 outputs the rotation position θ acquired at time t6 as the compensation rotation position θc. The number of acquisitions increases to 3.

Since the number of acquisitions is 3 or more, the angular acceleration 32 and the angular velocity 33 are calculated at time t6. The position compensation unit 137 substitutes the following parameters into the equation (2) when calculating the compensation rotation position θc in the period D after the time t6. That is, the position compensation unit 137 substitutes the rotation position θ acquired at time t6 into the first term on the left side of the equation (2). The angular velocity 33 calculated at time t6 is substituted as the angular velocity ω in the second term on the left side of the equation (2). The angular acceleration 32 calculated at time t6 is substituted as the angular acceleration α in the third term on the left side of the equation (2).

In the period after the time t6, the angular velocity and the angular acceleration used for calculating the compensation rotation position θc are calculated based on the rotation position θ of the rotor 1R. The compensation rotation position θc does not include the estimation error of the angular velocity and the angular acceleration in the period after the time t6. In a period after time t6, the compensating rotation position θc can be made to substantially coincide with the ideal curve L1 indicating the actual rotation position of the rotor 1R.

In FIG. 5, when the rotation position acquisition unit 131 acquires the rotation position θ at time t0, the position identification device 13 can calculate the angular velocity 33 at time t4 and the angular acceleration 32 at time t5.

As described above, even if the positioning device 13 cannot calculate the angular velocity and angular acceleration of the rotor 1R based on the rotation position θ of the rotor 1R, the angular velocity and angular acceleration are based on the current supplied to the motor 1. Acceleration can be estimated. The inverter control device 10 can execute highly accurate vector control even when the rotation position cannot be acquired as in the case where the rotation of the rotor 1R is started. That is, the position specifying device 13 can start highly accurate vector control from the time when the rotor 1R starts rotating.

In the above embodiment, an example in which the rotation position acquisition unit 131 determines the median value of the position range 40 as the initial rotation position has been described (step S11 shown in FIG. 4), but the present invention is not limited to this. The rotation position acquisition unit 131 may determine the upper limit value or the lower limit value of the position range 40 as the initial rotation position. That is, the rotation position acquisition unit 131 may determine the initial rotation position based on the position range 40.

In the above embodiment, the inverter control device 10 has described an example of acquiring a current detection value Iu indicating a current detection result of the U phase 50U and a current detection value Iw indicating a current detection result of the W phase 50W. However, the combination of the acquired current detection values of the inverter control device 10 is not limited to the above embodiment. For example, the inverter control device 10 may acquire a current detection value Iu and a current detection value indicating a current detection result of the W phase 50W. Alternatively, the inverter control device 10 may acquire the detection results of the U-phase, V-phase, and W-phase currents.

Further, in the position specifying device 13 described in the above embodiment, each functional block may be individually integrated into one chip by a semiconductor device such as an LSI, or may be integrated into one chip so as to include a part or all of the functional blocks. Is also good. Although it is referred to as LSI here, it may be referred to as IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of making an integrated circuit is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and settings of the circuit cells inside the LSI may be used.

In addition, a part or all of the processing of each functional block of each of the above embodiments may be realized by a program. Then, a part or all of the processing of each functional block of each of the above embodiments is performed by the central processing unit (CPU) in the computer. Further, the program for performing each process is stored in a storage device such as a hard disk or a ROM, and is read and executed in the ROM or the RAM.

Further, each process of the above embodiment may be realized by hardware, or may be realized by software (including a case where it is realized together with an OS (operating system), middleware, or a predetermined library). .. Further, it may be realized by mixed processing of software and hardware.

For example, when each functional block of the above embodiment (including a modification) is realized by software, the hardware configuration (for example, CPU, ROM, RAM, input unit, output unit, etc.) shown in FIG. (Hardware configuration connected by) may be used to realize each functional unit by software processing.

Further, the execution order of the processing methods in the above-described embodiment is not necessarily limited to the description of the above-described embodiment, and the execution order can be changed without departing from the gist of the invention.

A computer program that causes a computer to perform the above-mentioned method and a computer-readable recording medium that records the program are included in the scope of the present invention. Here, examples of computer-readable recording media include flexible disks, hard disks, CD-ROMs, MOs, DVDs, DVD-ROMs, DVD-RAMs, large-capacity DVDs, next-generation DVDs, and semiconductor memories. ..

The computer program is not limited to the one recorded on the recording medium, and may be transmitted via a telecommunication line, a wireless or wired communication line, a network typified by the Internet, or the like.

Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

1 Motor 1R Rotor 2 Inverter 3, 4 Current sensor 5 Rotational position sensor 10 Inverter control device 11 Control unit 12 PWM signal generator 13 Position identification device 131 Rotational position acquisition unit 132 Torque estimation unit 133 Angular acceleration estimation unit 134 Angular velocity estimation unit 135 Angular velocity calculation unit 136 Angular acceleration calculation unit

Claims (4)

It is a position identification device that identifies the rotation position of the rotor included in the motor.
A rotation position acquisition unit that acquires the rotation position of the rotor,
A torque estimation unit that estimates the torque generated by the motor based on the current supplied to the motor, and
An angular acceleration estimation unit that estimates the angular acceleration of the rotor based on the torque estimated by the torque estimation unit, and
A position specifying device including a rotation position acquired by the rotation position acquisition unit and a position compensation unit that compensates for the acquired rotation position based on the angular acceleration estimated by the angular acceleration estimation unit. The position identifying device according to claim 1, further
An angular velocity estimation unit for estimating the angular velocity of the rotor using the estimated angular acceleration is provided.
The position compensation unit is a position specifying device that compensates for the acquired rotational position based on the angular velocity estimated by the angular velocity estimation unit. The position compensating device according to claim 1 or 2.
When the motor is driven, the rotation position acquisition unit acquires a range of rotation positions of the rotor, determines an initial rotation position of the rotor based on the acquired range, and determines the initial rotation position of the rotor.
The position compensating unit is a position specifying device that compensates for the rotation position after the rotor starts rotating based on the initial rotation position determined by the rotation position acquisition unit. It is a position identification method for specifying the rotation position of the rotor included in the motor.
A rotation position acquisition step for acquiring the rotation position of the rotor, and
A torque estimation step that estimates the torque generated by the motor based on the current supplied to the motor, and
An angular acceleration estimation step that estimates the angular acceleration of the rotor based on the torque estimated by the torque estimation step, and
A position specifying method including a rotation position acquired by the rotation position acquisition step and a position compensation step for compensating for the acquired rotation position based on the angular acceleration estimated by the angular acceleration estimation step.