KR102263027B1 - Control method in the critical sention for single shunt sensorless pmsm - Google Patents

Abstract

The critical section control method of a single decentralized sensorless PMSM according to an embodiment of the present invention uses a space vector modulation (SVPWM) control method for an AC motor, but uses a coordinate system expressed in U, V, and W phases as a dq-axis orthogonal coordinate system. As a critical section control method for a motor controller that performs instantaneous control by expressing the physical quantity of the motor through two variables by converting it to is preset, and when the motor enters the critical region, SVPWM control of the motor is stopped, and then, when the motor exits the critical region, SVPWM control of the motor is resumed.

Description

Critical section control method of single decentralized sensorless PMSM {CONTROL METHOD IN THE CRITICAL SENTION FOR SINGLE SHUNT SENSORLESS PMSM}

The present invention relates to a method for stopping motor driving in a critical section, and to a method for controlling a critical section of a single decentralized sensorless PMSM to prevent loss by stopping the driving of a motor in a critical operating section of the motor.

Permanent Magnet Synchronous Motor (PMSM) is a motor with high output and high efficiency, and is widely used not only for industry but also for electric vehicles such as hybrid vehicles and fuel cell vehicles.

Permanent Magnet Synchronous Motor (PMSM) Triangular wave PWM modulates each three-phase command voltage individually, whereas Space Vector PWM (SVPWM) converts the three-phase command voltage into a space vector in complex space. How to modulate it through In SVPWM, the phase voltage is expressed as a function of the switching state.

The AC motor instantaneously measures the position of the rotor using a resolver and instantaneously applies current to U, V and W phases to control the motor. The SVPWM controller of the motor can express the physical quantity of the motor through two variables by converting the coordinate system expressed in U, V, and W phases into a d-q-axis orthogonal coordinate system, and is configured to perform instantaneous control.

The d-axis is usually the axis where the motor flux is generated, and is selected as the direction of the magnetic flux generated in the U-phase winding of the stator. Therefore, the d-axis is a reference axis in vector control.

The q-axis is orthogonal to the d-axis and is the axis of current that generates torque in vector control. Therefore, in the case of current control, the q-axis is controlled.

The transformation of the d-q-axis Cartesian coordinate system is divided into a fixed coordinate system (Stationary Reference Frame) and a rotating coordinate system (Rotating Reference Frame).

In the conventional permanent magnet synchronous motor control method using the dq axis as described above, the current command generator receives the torque command (Te*) and the rotational speed (ω rpm) of the permanent magnet synchronous motor, and based on the current command map data, the d-axis current A command (q-axis current command, id*) and a q-axis current command (iq*) are generated.

If the current command generator generates and outputs the d-axis and q-axis current commands (id*, iq*), the current controller receives the d-axis and q-axis current commands from the d-axis and q-axis voltage commands (Vd*, Vq*). After generating the three-phase voltage command (Vu*, Vv*, Vw*), the pulse width modulation (PWM) of the inverter, and the control of the permanent magnet synchronous motor are performed through the three-phase current control process.

1 to 3 , in SVPWM control of PMSM, it is difficult to sense current in the section boundary (Δ) and the low modulation region during low-speed driving, so it is usually phase shift or double switching (double switching) technique is applied.

In the phase shift technique, harmonics may be generated due to distortion of the waveform, and the calculation becomes complicated. In the case of the double switching technique, although the harmonic characteristics are good, there are disadvantages in that switching loss and operation at high speed are difficult because double switching is required.

The present invention is to solve the problem of the critical section control method of the existing single decentralized sensorless PMSM. It is possible to increase the efficiency of the motor by reducing the loss during the critical section control, and to replace the complex algorithm, thereby reducing the complexity of the single decentralized operation. It is to provide a method for controlling the critical section of sensorless PMSM.

The critical section control method of a single decentralized sensorless PMSM according to the present invention for solving the above problems uses a space vector modulation (SVPWM) control method for an AC motor, but the coordinate system expressed in U, V, and W phases is set to the dq axis A critical section control method for a motor controller that performs instantaneous control by expressing a physical quantity of a motor through two variables by converting it into a Cartesian coordinate system. A critical area of ' is preset, and SVPWM control of the motor is stopped when the motor enters the critical area, and then SVPWM control of the motor is resumed when the motor exits the critical area.

The method for controlling the critical section of the PMSM includes: inputting a torque-RPM table to the controller in advance; stopping application of the SVPWM signal to the motor when the motor enters the preset threshold region; switching the control of the motor to a critical mode; estimating at least one of an angular velocity and an angular acceleration of the motor based on the pre-input torque-RPM table and a control equation of the motor in the critical mode; and estimating the rotational position of the motor by estimating the angular velocity of the motor, and resuming the SVPWM control when the motor has escaped the critical region.

In the critical section control method of the PMSM, it is checked whether the current position of the motor is in the critical region, and if the motor is in the critical region, estimating the angular velocity of the motor and estimating the position are repeatedly performed. It can be checked whether the motor has escaped the critical region.

In the critical section control method of a single decentralized sensorless PMSM according to another aspect of the present invention, when the motor enters the critical section, ADC sensing for an unmeasurable phase current is stopped, and for an unmeasurable phase current, a preset current estimation technique is used. The existing SVPWM control is continued by estimating the current, calculating the position and speed of the motor using the estimated current estimate, and then restarting the current sensing using the ADC when exiting the critical region after the SVPWM is continued.

When the SVPWM control is resumed, the controller may correct the position error of the motor with respect to the existing position.

The present invention according to the above solution is to solve the problem of the critical section control method of the existing single decentralized sensorless PMSM, without introducing a new modulation technique in the critical section, and supplying current in the critical section. By stopping and stopping the operation, it is possible to increase the efficiency of the motor by reducing the loss during critical section control, and to provide a critical section control method of a single decentralized sensorless PMSM with reduced computational complexity by substituting a complex algorithm.

1 is a conceptual diagram illustrating a change in an effective voltage vector in a complex space in SVPWM control of a PMSM.
FIG. 2 is a conceptual diagram illustrating a three-phase switching change according to a time change T of a section boundary of FIG. 1 .
3 is a circuit diagram showing a power bridge driver and AC motor of SVPWM control of PMSM.
4 is a flowchart of a method for controlling a critical section of a single decentralized sensorless PMSM according to an embodiment of the present invention.
5 is a schematic diagram of a system for performing a critical section control method of a single decentralized sensorless PMSM according to an embodiment of the present invention.
6 is a block diagram of a system for performing a critical section control method of a single decentralized sensorless PMSM according to an embodiment of the present invention.
7 is a schematic diagram of a system for performing a critical section control method of a single decentralized sensorless PMSM according to another embodiment of the present invention.
FIG. 8 is an exemplary view of estimating a current in a critical section according to the embodiment of FIG. 7;

Hereinafter, various embodiments of the present invention will be described with reference to specific embodiments shown in the accompanying drawings. The differences in the embodiments are not mutually exclusive and should be understood in a complex manner, and without departing from the spirit and scope of the present invention, specific shapes, structures and characteristics described in relation to the embodiments are implemented in other embodiments. can be

4 is an overall system block diagram including a method for controlling a critical section of a single decentralized sensorless PMSM according to an embodiment of the present invention, and FIG. 5 is a critical section control of a single decentralized sensorless PMSM according to an embodiment of the present invention. It is a schematic diagram of a system for performing the method, and FIG. 6 is a flowchart illustrating a method for controlling a critical section of a single decentralized sensorless PMSM according to an embodiment of the present invention.

Referring to FIG. 4 , the critical section control method of a single decentralized sensorless PMSM according to an embodiment of the present invention uses a space vector modulation (SVPWM) control method for an AC motor, but is expressed in U, V, and W phases. A critical section control method for a motor controller that performs instantaneous control by expressing the physical quantity of the motor through two variables by converting the coordinate system into a dq-axis Cartesian coordinate system. In the change, the critical area of the motor is preset, and when the motor enters the critical area, SVPWM control of the motor is stopped (S410), the angular velocity and/or angular acceleration of the rotor are estimated (S420), and from this, the rotor Estimate the position of ( S430 ), and when the motor escapes from the critical region ( S440 ), SVPWM control of the motor is resumed ( S450 ).

The critical section control method of PMSM according to an embodiment of the present invention includes the steps of pre-inputting the torque-rpm table 180 to the controller, and when the motor enters the preset critical range, stopping the SVPWM signal application to the motor estimating at least one of the angular velocity and angular acceleration of the motor rotor based on the torque-rpm table 180 and the control equation of the motor input in advance in the critical mode, converting the control of the motor to the critical mode; and estimating the position of the motor rotor by estimating the angular velocity of the motor, and resuming the SVPWM control when the motor has escaped the critical region.

In addition, in the critical section control method of PMSM according to an embodiment of the present invention, it is checked whether the current position of the motor is in the critical region, and if the motor is in the critical region, the step of estimating the angular velocity of the motor and the step of estimating the position are repeated It checks whether the motor has exited the critical region by performing

Next, when SVPWM control is resumed, the controller may correct the position error of the motor with respect to the existing position.

A controller applied to the present embodiment will be described as follows.

6 and 6 , the controller obtains an rpm setpoint (NREF), which in turn generates a dq (90 degree phase rotational coordinate system) current setpoint in the PI controller 100, and inverse in the Inverse Park converter 110 It is converted into a 90-degree fixed coordinate system voltage through Park transformation, then the voltage ripple is compensated by the DC bus ripple compensator 120, and then the gate driving signal for three phases is generated through space vector modulation in the SVM modulator 130. (SVM module). The gate driving signal is converted into three-phase power in the three-phase power bridge driver 140 through the gate driver unit 135 (GDU), and the three-phase power is supplied to the motor 150 to drive the motor 150 .

The PMSM controller senses the u, v, and w three phases from the PMSM's current sensor and first converts it to a stationary coordinate system with two axes, then converts it to a rotational coordinate system and converts it to a dq-axis current state. The controller generates a dq current output through the dq command and the sensed dq current, and since the current must be applied to the three-phase motor 150, the dq component is converted back to three-phase through dq inverse conversion.

At this time, the current flowing in the three phases of the motor 150 is sensed through the ADC 160, and the three phases are converted into the two-phase Cartesian coordinate system through Clerk transformation in the Fowrad Park converter, and the position connected to the torque-rpm table 180 and to the velocity estimation module. Then, by using the current and voltage information, position and speed estimation is performed (Position and Speed estimator module). The torque-RPM value is input to the position and speed estimation module and used together to estimate the rotational position and speed of the motor 150 . The position of the motor 150 is out of the critical region, and as the SVPWM control is resumed, the existing position of the motor 150 is corrected to the calculated current position. A process of calculating the position theta value of the motor according to the torque equation of the motor 150 is described below.

As described above, the current position of the motor can be calculated by referring to the torque equation of the motor and the torque-RPM table value. These calculations are entered into the position and velocity estimation module and performed automatically.

As another embodiment of the present invention, as shown in the flowchart shown in FIG. 7 , when the critical section is entered, the driving of the motor is continued. Since it is impossible to measure the current by ADC sensing, the current is estimated and the motor control is performed based on this estimate. When it continues and exits the critical section, current sensing and control using ADC can be performed again.

Referring to FIG. 7 , when the motor enters the critical section, ADC sensing is stopped for the unmeasurable phase current (S710), and for the unmeasurable phase current, the current is estimated by a preset current estimation technique (S720), and in the above Existing SVPWM control is continued by calculating the position and speed of the motor using the estimated current estimate (S740), and after SVPWM continues, current sensing using the ADC is resumed when exiting the critical region (S750).

In the present embodiment, if the driving speed of the motor is in continuity, BEMF (Back EMF: Back ElectroMotive Force) may be constant or may be corrected by multiplying a parameter value according to deceleration/acceleration.

If the current just before entering the critical section of the motor is iprev, the current after entering the critical section is iest.

On the other hand, the following describes a current estimation technique in the aspect of stopping the ADC trigger/conversion with respect to the unmeasurable phase current when entering the critical section. If the current just before entering the critical section of the motor is iprev, the current after entering the critical section is iest. The unmeasurable current in the critical section is estimated by the calculation of iest.

8 shows the measured current value before entering the critical section and the estimated current value in the critical section.

In the critical section control method of the single decentralized sensorless PMSM according to the embodiment of the present invention, it is assumed that the driving speed of the motor is in a continuity, and the BEMF is constant or corrected by multiplying the parameter value according to the deceleration/acceleration as follows. can do.

delete

Kbemf is a parameter for the amount of BEMF variation with respect to acceleration.

If the current just before entering the critical section is ib,prev, the current after entering the critical section is estimated.

Also in this embodiment, equations and ADC timings defined as critical sections of six sectors are similar to those described later.

In the critical section, the position is estimated through the existing BEMF observer based on the estimated current, the existing center aligned SVPWM control is continued by calculating the position/velocity using the current estimate, and current sensing is again using the ADC when exiting the critical section. By starting, it reverts to the old control method.

As such, in this embodiment, when the motor enters the critical section and an unmeasurable current is caught, the current sensing is stopped through the ADC, the motor control is continued by estimating the current from the previous current value, and the motor enters the critical section. In case of escape, loss due to excessive current consumption in the critical section can be prevented by detecting the current through the ADC and generating a signal to control the motor normally.

On the other hand, the controller applied to the present embodiment is different in that the current sensing processing unit (Current Sensing Processing) substantially the same as in FIG. 6 performs the above-described current estimation.

The critical section control method of PMSM according to each embodiment of the present invention reduces the loss during critical section control by stopping the driving by stopping the current supply in the critical section without introducing a new modulation technique in the critical section. It has the advantage of increasing the efficiency of , and reducing the complexity of computation by replacing complex algorithms.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations are possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains.

Accordingly, the embodiments expressed in the present invention are not intended to limit the technical spirit of the present invention, but to illustrate, and the scope of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas that are equivalent to or within the equivalent range should be construed as being included in the scope of the present invention.

100: PI controller 110: Inverse Park transducer
120: DC bus ripple compensator 130: SVM modulator
135: gate driver unit 140: power bridge driver
150: Motor 160: ADC
170: position and speed estimation module 180: torque-rpm table

Claims (8)

A space vector modulation (SVPWM) control method is used for AC motors, but by converting the coordinate system expressed in U, V, and W phases into a dq-axis orthogonal coordinate system, instantaneous control is performed by expressing the physical quantity of the motor through two variables. As a critical section control method for a motor controller,
(a) pre-inputting a torque-RPM table into the controller, and presetting a critical region of the motor in the change according to the angle of the effective voltage vector of the SVPWM control of the PMSM;
(b) entering the critical mode when the motor enters the critical region; and
(c) resuming SVPWM control of the motor when the motor exits the critical region;
The step (c) is,
In the critical mode, the angular velocity and angular acceleration of the motor are estimated based on the torque-RPM table and the control equation of the motor, and the rotational position of the motor is estimated according to the estimation result. If the motor is in the critical region, Confirming whether the motor has escaped the critical region by repeatedly performing estimation of the angular velocity and angular acceleration of the motor and the estimation of the rotational position according to the result
A critical section control method of in-single decentralized sensorless PMSM. According to claim 1, wherein the step (b),
(b-1) stopping application of the SVPWM signal to the motor when the motor enters the preset threshold region; and
(b-2) converting the control of the motor to a critical mode
A critical section control method of a single decentralized sensorless PMSM comprising a. delete delete According to claim 1,
When the SVPWM control is resumed, the method of controlling a critical section of a single decentralized sensorless PMSM further comprising the step of correcting a position error of the motor with respect to the existing position in the controller. delete delete delete

Images