JP5074318B2 - Rotor position estimation device for synchronous motor - Google Patents

Description

  The present invention relates to a rotor position estimation device for a synchronous motor that estimates a rotor position without using a position sensor.

  In a synchronous motor such as a permanent magnet synchronous motor (PMSM) using a permanent magnet as a rotor, the energization of the stator is controlled based on the position information of the rotor. The position sensor for detecting the magnetic pole position) is used.

  However, in order to detect the rotor position using a position sensor such as a resolver, a processing circuit for the detection signal is required in addition to the position sensor, and furthermore, the position sensor must be attached and adjusted. There is a disadvantage that the cost of the electric motor becomes high.

  Therefore, a so-called position sensorless control method has been proposed in which the energization control is performed by estimating the rotor position without using a position sensor (see, for example, Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2).

In the position sensorless control method described in Patent Document 1, a position estimation error Δθ _e that is a difference between an actual value of a rotor position and an estimated value is obtained based on a motor voltage equation including an induced voltage term, and the position estimation is performed. updating the estimate of the rotor position so as to eliminate the error [Delta] [theta] _e. However, in the position sensorless control method described in Patent Document 1, since the approximation that ignores the differential term is performed when the position deviation Δθ is obtained, the control may become unstable when performing a rapid acceleration / deceleration operation. is there.

  In the position sensorless control method described in Non-Patent Document 1, the rotor position is estimated from the phase of the expansion induced voltage. However, in the position sensorless control method described in Non-Patent Document 1, the extended induced voltage is estimated using an observer, and the pole position of the observer must be designed.

Since the obtained position estimation error Δθ _e includes the influence of noise or the like, generally, the estimated value of the angular velocity and the rotor position are determined by a PLL (Phase Locked Loop) using the position estimation error Δθ _e as an input. The estimated value is obtained. At that time, it is also necessary to set the gain of the PLL. Therefore, matching the observer pole setting and the PLL gain setting becomes an issue. Further, since the observer pole changes depending on the rotation speed of the electric motor, the gain of the PLL needs to be set according to the rotation speed of the electric motor. Therefore, the setting process for estimating the rotor position becomes complicated.

In the position sensorless control method described in Non-Patent Document 2, the speed electromotive force is estimated from the error between the estimated current calculated by the voltage equation of the motor and the actual current, and the rotor position is estimated from the estimated speed electromotive force. ing. However, since the approximation that the position estimation error Δθ _e between the actual value and the estimated value of the rotor position is approximately 0 is performed in the voltage equation of the motor, the estimation accuracy of the rotor position may be deteriorated.
JP 2001-251889 A Shinji Ichikawa and 4 others, “Sensorless control of salient-pole permanent magnet synchronous motor based on extended induced voltage model”, The Institute of Electrical Engineers of Japan, 2002, Electrical Theory D, Vol. 122, No. 12, p. 1088-1096 Takaharu Takeshita and three others, “Sensorless salient pole type brushless DC motor control based on speed electromotive force estimation”, The Institute of Electrical Engineers of Japan, 1997, Electrical Theory D, Vol. 117, No. 1, p. 98-104

  The present invention has been made in view of the above background, and provides a rotor position estimation device for a synchronous motor that can accurately estimate a rotor position by a relatively simple calculation process without using a position sensor. Objective.

  The present invention has been made to achieve the above object, and is a rotor position estimation device for estimating the rotor position of a synchronous motor, the voltage applying means for applying a voltage to a stator coil of the motor, Using a position estimation error that is a difference between the actual value and the estimated value of the rotor position, the current detection means for detecting the current flowing through the stator coil and the relationship between the command voltage of the stator coil of the motor and the current flowing through the stator coil are used. Calculated by applying a predetermined voltage based on the estimated value of the rotor position to the command voltage to the simplified model formula of the motor excluding the term including the position estimation error and the term including the rotor angular velocity from the voltage equation expressed as The second current detected by the current detection means when a driving voltage corresponding to the predetermined voltage is applied to the stator coil of the motor and the stator coil of the motor. Current estimation deviation calculation means for calculating a current estimation deviation that is a difference from the value, position estimation error calculation means for calculating the position estimation error based on the current estimation deviation, and position estimation error calculation means. Rotor position estimating means for updating the estimated value of the rotor position of the electric motor so as to eliminate the position estimation error.

  According to the present invention, the simple model formula of the electric motor excludes a term including a position estimation error that is a difference between an actual value and an estimated value of the rotor position of the electric motor and a term including a rotor angular velocity. . Therefore, when the first current value calculated by applying the predetermined voltage to the simplified model formula and a voltage corresponding to the predetermined voltage are applied to the stator coil of the electric motor, the current detection means detects the current value. The current estimation deviation which is the difference from the second current value includes information on the position estimation error.

  Therefore, the position estimation error calculation means can calculate the position estimation error based on the current estimation deviation calculated by the current estimation deviation calculation means. In this case, although details will be described later, the position estimation error can be directly calculated from the current estimation deviation without performing an approximation process by a simple calculation process. Therefore, the rotor position estimation means can accurately estimate the rotor position by updating the estimated value of the rotor position so as to eliminate the position estimation error.

  Further, the rotor position estimating means updates the estimated value of the rotor position of the electric motor by reducing the position estimation error calculated by the position estimation error calculating means by a PLL (Phase Locked Loop). To do.

  According to the present invention, by reducing the position estimation error by the PLL, it is possible to reduce the influence of noise and estimate the rotor position.

  Further, the motor is converted into an equivalent circuit having a d-axis that is a magnetic flux direction of the field of the motor and a q-axis that is orthogonal to the d-axis, and a γ-axis and a γ-phase that are out of phase with respect to the d-axis The current estimated deviation calculating means uses the following equation (2) as a simple model equation of the electric motor, which is handled by an estimated rotational coordinate system consisting of a δ axis orthogonal to the axis.

_However, i γδ _M [n]: current vector of the simplified model in the control cycle n (estimated gamma-axis current i _γ _M [n], the estimated [delta] -axis current _{i δ _M [n]),} R: resistance, Ld: d-axis Inductance, Ts: Control period, I: Unit matrix of 2 rows and 2 columns, i _γδ [n−1]: Current vector (actual γ-axis current i _γ [n−1], actual in the control cycle n−1 δ-axis current i _δ [n-1]), v _γδ [n-1]: voltage vector of the motor in the control cycle n-1 (γ-axis voltage v _γ [n-1], δ-axis voltage v _δ [n- 1]).

  According to the present invention, the electric motor is converted into an equivalent circuit having a d-axis and a q-axis, and is handled by an estimated rotational coordinate system including a γ-axis that is out of phase with the d-axis and a δ-axis that is orthogonal to the γ-axis. In some cases, the current estimated deviation calculating means can calculate the current estimated deviation using the equation (2) as a simple model of the electric motor.

  Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a synchronous motor control device 1 (hereinafter referred to as a control device 1) including the configuration of a synchronous motor rotor position estimation device of the present invention. The control device 1 is an electronic unit configured by a microcomputer or the like. It is.

  Referring to FIG. 1, control device 1 performs speed control of an IPMSM (Interior Permanent Magnet Synchronous Motor) type motor 40 (corresponding to the synchronous motor of the present invention). The controller 1 estimates the rotor position and controls the speed of the motor 40 without providing a position sensor (such as a resolver) that detects the rotor position of the motor 40.

  Note that the information on the rotational speed of the motor 40 may be information obtained from a position signal of a load driven by the motor 40 (a detection signal from the machine end detector), instead of an estimated value of the rotor position. Moreover, it is good also as a structure which adds position controller and performs position control, or the structure which performs torque control which deleted the speed controller.

The control device 1 converts the motor 40 into an equivalent circuit based on a dq coordinate system having a d-axis which is a magnetic flux direction of a field pole of a rotor (not shown) and a q-axis orthogonal to the d-axis. As shown in FIG. 5, the motor 40 is handled by a γδ coordinate system having a position estimation error Δθ _e that is a difference between an actual value and an estimated value of the rotor position with respect to the dq coordinate system.

Then, the control device 1 performs energization control on the motor 40 so as to reduce a deviation between an angular velocity command value ω _{r —} c given from the outside and an estimated angular velocity value ω _{r —} e calculated by processing to be described later.

Further, current detection signals i _u (detection signals of current flowing in the U-phase stator coil) and i of current sensors 31 and 32 (corresponding to current detection means of the present invention) that detect current flowing in the stator coil of the motor 40 and i. _v (a detection signal of the current flowing through the V-phase stator coil) is input to the control device 1. Of the three phases, current detection for at least two phases may be performed.

Further, the control device 1 supplies three-phase (u, v, w phase) voltage command values v _{u —} c, v _{v —} c, to a PDU (Power Drive Unit) 30 (corresponding to the voltage applying means of the present invention). v _w _c is input. The PDU 30 generates a three-phase drive voltage corresponding to the three-phase voltage command values v _{u —} c, v _{v —} c, and v _{w —} c and applies it to the stator coil of the motor 40.

  By causing the microcomputer provided in the control device 1 to execute a predetermined control program, the microcomputer has a speed control unit 10, a command current generation unit 11, a current control unit 12, a γδ / uvw conversion unit 13, It functions as a position estimation error acquisition unit 14, rotor position estimation unit 15, divider 16, and uvw / γδ conversion unit 17.

The speed control unit 10 determines a torque command value T _r _c for reducing a deviation between the angular velocity command value ω _r _c and the estimated value ω _r _e. Command current generating unit 11 determines the command gamma-axis current i _gamma _c the command [delta] -axis current i _[delta] _c for generating a torque command value T _r _c.

The current control unit 12, a deviation between the command gamma-axis current i _gamma _c and actual gamma-axis current i _gamma (calculated by uvw / the ?? converting section 17), the command [delta] -axis current i _[delta] _c and the actual [delta] -axis current i _[delta] The command γ-axis voltage v _{γ —} c and the command δ-axis voltage v _{δ —} c are determined so as to reduce the deviation (calculated by the uvw / γδ converter 17).

the ?? / uvw converting section 13, a command [delta] -axis voltage v _[delta] _c and command gamma-axis voltage v _gamma _c, using the estimated value theta _e _e rotor position of the motor 40 (electric angle of the rotor), 3-phase (u , V, w phase) voltage command values v _{u —} c, v _{v —} c, v _{w —} c.

The position estimation error acquisition unit 14 determines the actual rotor position of the motor 40 based on the command γ-axis voltage v _{γ —} c, the command δ-axis voltage v _{δ —} c, the actual γ-axis current i _γ, and the actual δ-axis current i _δ. A position estimation error Δθ _e that is a difference between the value and the estimated value is obtained.

The rotor position estimation unit 15 updates the estimated value θ _e _e of the rotor position and the estimated value ω _e _e of the angular velocity (electric angular velocity) so as to eliminate the position estimation error Δθ _e of the motor 40. Further, the divider 16 divides the estimated electrical angular velocity value ω _{e —} e by the number of pole pairs q to calculate the estimated mechanical angular velocity value ω _{r —} e of the motor 40.

uvw / the ?? converter 17, a current detection signal i _u and i _v are output from the current sensors 31 and 32, based on an estimate theta _e _e rotor position, the actual gamma-axis current i _gamma and actual δ-axis current i Convert to _δ .

The control device 1 includes a position estimation error acquisition unit 14 and a rotor position estimation unit 15, and obtains an estimated value θ _{e — e} of the rotor position and an estimated value ω _{e — e of the} electrical angular velocity. Therefore, there is no need to provide a sensor for detecting the position of the rotor such as a resolver.

A procedure for calculating the position estimation error Δθ _e by the position estimation error acquisition unit 14 and a procedure for calculating the rotor position estimation value θ _e _e and the angular velocity estimation value ω _e _e by the rotor position estimation unit 15 will be described below.

First, a procedure for calculating the position estimation error Δθ _e by the position estimation error acquisition unit 14 will be described with reference to FIGS. With reference to FIG. 2B, the position estimation error acquisition unit 14 calculates a position estimation error Δθ _e using the simplified model 20 of the motor 40.

  Here, the voltage equation of the motor in the γδ coordinate system can be expressed by the following equations (3) and (4).

Where v _γ : γ-axis voltage, v _δ : δ-axis voltage, R: resistance, p: differential operator by time, L _d : d-axis inductance, Δθ _e : position estimation error (actual value and estimated value of rotor position) ), Ω _e : electrical angular velocity, L _q : q-axis inductance, i _γ : γ-axis current, i _δ : δ-axis current, i _d : d-axis current, i _q : q-axis current, φ: induced voltage constant.

  When the above equations (3) and (4) are expressed in a vector format, the following equations (5) to (8) are obtained.

However, v _γδ = (v _γ , v _δ ) ^T , i _γδ = (i _γ , i _δ ) ^T.

In the normal operation of the motor, the following equations (9) and (10) are assumed on the assumption that the time derivative of the position estimation error Δθ _e is smaller than the rotational speed of the motor.

θ _e _r: actual value of rotor position (electrical angle of rotor), θ _e _e: estimated value of rotor position (electrical angle of rotor), ω _e _r: actual value of angular velocity (electrical angular velocity) of rotor, ω _e _e : Estimated value of rotor angular velocity (electrical angular velocity).

  By applying the above formulas (9) and (10) to the above formula (5), the following formula (11) is obtained. When the formula (11) is expressed by a state equation, the form of the following formula (12) is obtained. become.

  When the above equation (12) is discretized, the following equation (13) is obtained, and the following equation (14) which is a current equation of the motor is obtained from the equation (13).

  Where Ts: control cycle. n, n-1: The cycle number of the control cycle.

On the right side of the above equation (14), the following equation (15) in which terms including angular velocities ω _{e —} e and e _γδ , which are terms relating to the rotor position and angular velocity, are regarded as disturbances and deleted is defined as a simple model equation of the motor.

_{However, i γδ _M = (i γ} _M, i δ _M) T: Equation (15) gamma-axis current in the simple model of a motor by and [delta] -axis current.

Here, from the equation current vector i _γδ [n] by (14), by subtracting the current vector i _γδ _M [n] according to the equation (15), the current estimated differential .DELTA.i _{the ??} of the formula (16) Can be calculated.

The current estimation deviation Δi _γδ according to the equation (16) reflects the disturbance information deleted in the equation (14).

  When the above equation (16) is modified into the following equations (17) and (18), and further modified using the above equation (6), the following equations (19) and (20) are obtained.

Accordingly, the position estimation miscalculation Δθ _e can be directly obtained based on the current estimation deviation Δi _γδ without estimating the induced voltage by the following equations (21) and (22).

Referring now to FIG. 2 (b), the position estimation error acquisition unit 14, a voltage corresponding to a predetermined voltage v _{the ??} _c when applied to the motor 40, the uvw / the ?? converter 17 (see FIG. 1) The calculated actual current i _γδ (i _γ , i _δ ) of the γ-axis and δ-axis (corresponding to the second current value of the present invention) and the predetermined voltage v _γδ are calculated by the above formula (15). The difference between the γ-axis and δ-axis current values i _γδ —M (i _γ —M, i _δ —M) (corresponding to the first current value of the present invention) calculated by inputting to the model 20 is the current estimated deviation Δi _γδ. Is calculated by the subtractor 21. The configuration for calculating the current estimated deviation Δi _γδ in this way corresponds to the current estimated deviation calculating means of the present invention.

The position estimation error acquisition unit 14, the position estimation error calculating unit 22, as shown in FIG. 3, the actual current of _{i γδ (i γ, i δ} ) in gamma-axis and [delta] axis of the formula (22) Substituting i _γδ (i _γ , i _δ ) and substituting the current estimation deviation Δi _γδ (Δi _γ , Δi _δ ), the position estimation error Δθ _e is calculated. The configuration for calculating the position estimation error Δθ _e based on the current estimation deviation Δi _γδ in this way corresponds to the position estimation error calculating means of the present invention.

Next, with reference to FIG. 4A and FIG. 4B, the calculation process of the estimated value θ _e _e of the rotor position and the estimated value ω _e _e of the angular velocity by the rotor position estimating unit 15 will be described.

  FIG. 4A shows an example in which the rotor position estimation unit 15 is configured using a phase synchronization unit 50 using a PLL. In the present embodiment, the estimated responsivity is determined with the phase synchronization unit 50 having the same configuration as the simplest PI (proportional integration) controller according to the following equation (23). However, the configuration of the phase synchronization unit is not limited to the PI controller according to the following equation (23).

  However, Kp: proportional gain, Ki: integral gain.

Here, in order to make the position estimation error Δθ _e zero, when the closed loop transfer function from the rotor position θ _e to the position estimation error Δθ _e is calculated, the following equation (24) is obtained.

In the above equation (24), the convergence speed (natural angular frequency of the control system) ω _n and the damping factor (attenuation coefficient) ζ of the position estimation error Δθ _e are determined by the PI control gains Kp and Ki. When the motor 40 is operating at a constant speed (the angular speed ω _e is constant), the input θ _e becomes a ramp input. Therefore, in order to converge the rotor phase difference Δθ _e to zero, the phase synchronization unit 50 is set to 2 Must be a type controller.

  Next, FIG. 4B shows an example in which the rotor position estimation unit 15 is configured using the same-dimensional observer 60. In this case, for example, a one-dimensional observer according to the following equation (25) may be used.

  However, Ts: Control cycle, K1, K2: Calculation gain.

Incidentally, so as to eliminate such a position estimation error [Delta] [theta] _e, configured to update the estimate theta _e _e rotor position corresponds to the rotor position estimation means of the present invention.

  In the present embodiment, the IPMSM 40 is shown as the synchronous motor of the present invention. The invention can be applied.

  Further, in the present embodiment, the control device 1 treats the motor 40 by the model of the γδ coordinate system and defines the simple model of the present invention by the above equation (15), but the terms relating to the rotor position and the rotor angular velocity are deleted. If it is a thing, you may use the simple model by another coordinate system and form.

The block diagram of the control apparatus of the synchronous motor containing the structure of the rotor position estimation apparatus of this invention. Explanatory drawing of (gamma) delta coordinate system, and a block diagram of a position estimation error calculation part and a rotor position estimation part. Explanatory drawing of a position estimation error calculation part. Explanatory drawing of a rotor position estimation part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Control apparatus of synchronous motor, 14 ... Position estimation error acquisition part, 15 ... Rotor position estimation part, 20 ... Simple model of motor, 22 ... Position estimation error calculation part, 50 ... PLL (PI controller), 60 ... PLL (Same dimension observer)

Claims (3)

A rotor position estimation device for estimating a rotor position of a synchronous motor,
Voltage applying means for applying a voltage to the stator coil of the motor;
Current detection means for detecting a current flowing in the stator coil of the motor;
The position estimation error is included from a voltage equation that expresses the relationship between the command voltage of the stator coil of the motor and the current flowing through the stator coil using a position estimation error that is the difference between the actual value and the estimated value of the rotor position. A first current value calculated by applying a predetermined voltage based on an estimated value of the rotor position to the command voltage, and a simple model formula of the motor excluding the term and a term including the rotor angular velocity, and a stator coil of the motor Current estimation deviation calculation means for calculating a current estimation deviation that is a difference from the second current value detected by the current detection means when a driving voltage corresponding to the predetermined voltage is applied to
Position estimation error calculation means for calculating the position estimation error based on the current estimation deviation;
A rotor position estimating device for a synchronous motor, comprising: rotor position estimating means for updating an estimated value of the rotor position of the electric motor so as to eliminate the position estimation error obtained by the position estimation error calculating means. . The rotor position estimation device for a synchronous motor according to claim 1,
The rotor position estimation means updates the estimated value of the rotor position of the motor by reducing the position estimation error calculated by the position estimation error calculation means by a PLL (Phase Locked Loop). An apparatus for estimating the rotor position of an electric motor. In the synchronous motor rotor position estimating apparatus according to claim 1 or 2,
The electric motor is converted into an equivalent circuit having a d-axis that is a magnetic flux direction of the field of the electric motor and a q-axis that is orthogonal to the d-axis, and is orthogonal to the γ-axis and the γ-axis that are out of phase with the d-axis. Treated as a model of an estimated rotational coordinate system consisting of
The current estimation deviation calculating means uses the following formula (1) as a simple model formula of the electric motor, the rotor position estimating device for a synchronous motor:

_However, i γδ _M [n]: current vector of the simplified model in the control cycle n (estimated gamma-axis current i _γ _M [n], the estimated [delta] -axis current _{i δ _M [n]),} R: resistance, Ld: d-axis Inductance, Ts: Control period, I: 2 × 2 unit matrix, i _γδ [n−1]: Current vector of motor in control cycle n−1 (real γ-axis current i _γ [n−1], real δ Shaft current i _δ [n-1]), v _γδ [n-1]: voltage vector of the motor in the control cycle n-1 (γ-axis voltage v _γ [n-1], δ-axis voltage v _δ [n-1] ]).

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