Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 shows a configuration example of a field weakening vector control device of a permanent magnet synchronous motor as an embodiment of the present invention. 1 is a permanent magnet synchronous motor; 2 is a voltage command value Vu for outputting an alternating current to three phases * 、Vv * 、Vw * A proportional voltage power converter; 21 is a direct current power supply; 3 is a current detector capable of detecting three-phase alternating currents Iu, iv and Iw; a magnetic pole position detector capable of detecting a position detection value θ i of the motor per 60 ° electrical angle; 5 calculating a frequency command value omega according to the position detection value theta i 1 * The frequency calculating section of (1); 6 is a value obtained from the position detection value thetai and the frequency command value omega 1 * Calculating a rotational phase command θ c of the motor * The phase operation unit of (1); reference numeral 7 denotes detected values Iuc, ivc, iwc of the three-phase alternating currents Iu, iv, iw and a rotation phase command θ c * A coordinate conversion unit for outputting the current detection values Idc, iqc of the d-axis and q-axis; 8 is based on the output voltage command value V in the weak magnetic region 1 * ref And an output voltage value V 1 * Calculating a first d-axis current command value Id * The field weakening instruction operation unit; reference numeral 9 denotes a d-axis current command value Id based on the first d-axis current command value Id output from the flux weakening command calculation unit * And a deviation from the d-axis current detection value Idc, and outputs a secondd-axis current fingerOrder value Id ** The d-axis current command calculation unit of (1); 10 is based on the first q-axis current command value Iq * And a deviation from the q-axis current detection value Iqc to output a second q-axis current command value Iq ** The q-axis current command operation unit of (1); reference numeral 11 denotes a 2 nd current command value Id according to an electric constant of the motor 1 ** 、Iq ** And the frequency command value omega 1 * Calculating a voltage command value Vd * 、Vq * A voltage vector operation unit of (2); 12 is based on the voltage command value Vd * 、Vq * Calculating the output voltage value V of the power converter 1 * An output voltage calculating section of (1); 13 is based on the voltage command value Vd * 、Vq * And a rotation phase command thetac * Outputting a voltage command value Vu of the three-phase alternating current * 、Vv * 、Vw * The coordinate transformation unit.
First, basic operations of voltage control and phase control in the vector control method when the field weakening command operation, which is a characteristic of the present invention, is used will be described.
For the voltage control, as shown in fig. 1, the output voltage calculation unit 12 in fig. 1 uses the voltage command values Vd on the d-axis and q-axis * 、Vq * To calculate the output voltage value V 1 * 。
[ number 1]
A weak magnetic command calculation part 8 for calculating a first d-axis current command value Id * To make the above-mentioned output voltage value V 1 * And the output voltage command value V in the weak magnetic region 1 * ref And (5) the consistency is achieved.
The voltage vector calculation unit 11 calculates the voltage command values Vd on the d-axis and q-axis in advance using the motor constants and the current command values on the second d-axis and q-axis shown by the number 2 * 、Vq * And controls the converter output voltage.
[ number 2]
Vd * =R 1 * Id ** -ω 1 * ·Lq * ·Iq **
Vq * =R 1 * ·Iq ** +ω 1 * ·Ld * ·Id ** +ω 1 * ·Ke * ...(2)
Here, R1 * Is a set value of resistance, ld * Is the set value of d-axis inductance, lq * Is the set value of the q-axis inductance, ke * Is the set value of the induced voltage constant.
On the other hand, for the phase control, the magnetic pole position can be grasped every 60 degrees of electrical angle in the magnetic pole position detector 4. In the present embodiment, the position detection value θ i at this time is
[ number 3]
θi=60i+30...(3)
Wherein i =0, 1,2, 3, 4, 5.
The frequency calculation unit 5 calculates an average rotational frequency ω within the shortest 60-degree interval from the position detection value θ i 1 * (hereinafter referred to as a frequency command value).
[ number 4]
ω 1 * =Δθ/Δt...(4)
Here, Δ θ = θ i- θ (i-1), and Δ t is a time until the position detection signal of the 60-degree section is detected.
The phase calculation unit 6 uses the position detection value θ i and the frequency command ω 1 * Calculating the rotation phase command θ c as in FIG. 5 * The reference phase of the motor 1 is controlled.
[ number 5]
θ * =θi+ω 1 * ·Δt ...(5)
The above is the basic operation of the voltage control and the phase control.
Next, the field weakening command operation unit 8 in the feedback control method, which is a feature of the present invention, will be described with reference to fig. 2.
In the weak magnetic instruction operation part 8, the output voltage instruction value V in the weak magnetic region 1 * ref And an output voltage value V 1 * The deviation (2) is inputted to an integration operation unit 81 having an integration gain of a constant K, and integrated. The calculated value is input to the limiter calculation unit 82 whose positive side is limited to zero, and the output value thereof is the first d-axis current command Id * 。
Next, the operation and effects of the present invention will be described with reference to the present example.
The control device of FIG. 1 considers the first d-axis current command value Id * The control is "zero" (the weak magnetic instruction operation is not performed).
V output from the voltage vector operation unit 11 1 * Substituting the number 2 into the number 1 yields:
[ number 6]
In addition, if V is set 1 * Has a saturation value of V 1 * max The voltage saturation region forms a relationship of a number 7.
[ number 7]
V 1 * max 2 =(R1 * Id ** -ω 1 * ·Lq * ·Iq ** ) 2 +(R1 * ·Iq ** +ω 1 * ·Ld * ·Id ** +ω 1 * ·Ke * ) 2 ...(7)
Here, by sorting the number 7, the frequency command ω can be obtained 1 * The second order equation of (a) is,
[ number 8]
A·ω 1 *2 +B·ω 1 * +C=0...(8)
Wherein, the first and the second end of the pipe are connected with each other,
A=(Ld * ·Id ** ) 2 +(Lq * ·Iq ** ) 2 +(Ke * +2·Ld * ·Id ** )
B=2·R1 * ·Iq ** ·(Ke * +(Ld * -Iq ** )·Id ** )
C=R1 *2 ·(Id **2 +Iq **2 )-V 1 * max 2
from the number 8, V can be obtained 1 * Omega at saturation 1 * 。
[ number 9]
Here, when Id is set ** =Id * =0、Iq ** Motor torque tau and frequency command omega when t/KT 1 * The relationship of (c) is shown in fig. 3.
Here, τ is a motor torque, and KT is a torque coefficient.
The solid line shown in FIG. 3 is V 1 * The boundary of saturation is a region in which the upper side is saturated and the lower side is unsaturated, and is a range in which the operation can be performed practically.
Therefore, the d-axis current command value Id is set * The vector control set to "zero" has a problem that the operating range in the high speed region is limited to be low.
Therefore, in this embodiment, the output voltage value V is 1 * With the output voltage command value V in the weak magnetic region 1 * ref In a consistent manner, a first d-axis current command value Id is calculated * And using the Id * Generating a second d-axis current command value Id ** The voltage vector is calculated.
In this case, the weak magnetic regionOutput voltage command value V 1 * ref And is set as 10.
[ number 10]
V 1 * ref <V 1 * max ...(10)
As a result, the voltage vector operation part 11 outputs the voltage value V 1 * Unsaturated (to less than V) 1 * max Value (d) of the voltage command value Vd is calculated * 、Vq * Therefore, the operating range in the high speed region can be expanded.
Since the present invention can generate a current in accordance with a current command value, it is possible to realize a high-precision torque control and to expand an operation range as shown in fig. 4.
In addition, when a high torque is required during the torque control operation, a large current corresponding to the torque needs to be applied. If high torque is required for a continuous period of time, heat is generated by the motor current, causing the resistance R of the windings inside the motor to increase with time. In this way, the resistance set value calculated by the voltage vector calculation unit does not match the actual resistance value, and thus a necessary voltage cannot be supplied to the motor.
Therefore, by providing the current command calculation unit in the upstream portion of the vector calculation unit and controlling the output voltage so that the motor current matches the current command value as in fig. 1 of the present embodiment, it is possible to provide a control device for an alternating current motor in which torque shortage does not occur from a low speed region without being affected by a change in the motor constant or an attachment error of a hall element or the like.
[ example 2]
Fig. 5 shows another embodiment of the present invention.
In this embodiment, the frequency command ω is used 1 * Method for changing integral gain of weak magnetic instruction operation part in feedback control modeAnd a control device for a permanent magnet synchronous motor.
In FIG. 5, 1 to 7,9 to 13, and 21 are the same as those in FIG. 1. 8a is a weak magnetic instruction arithmetic unit based on the frequency instruction omega 1 * Automatically correct for V 1 * ref And V 1 * The deviation of (2) is an integral gain in the integral operation.
Next, the field weakening command calculation unit 8a, which is a feature of the present invention, will be described with reference to fig. 6.
In the weak magnetic command operation part 8a, the output voltage command value V in the weak magnetic region 1 * ref And an output voltage value V 1 * The deviation (b) is input to the integration operation unit 8a1 having an integration gain of constant K, and is integrated. At this time, the integral gain K is derived from the frequency ω 1 Is automatically corrected. The output value of the integration operation unit ga1 is input to the limiter operation unit 82a that limits the positive side to zero, and is the first d-axis current command Id * 。
Using the current command value Id * Generating a second current command value Id ** Calculating a voltage command value Vd * 、Vq * And controlling the output voltage of the converter.
The present embodiment is described with reference to the effects of the present invention.
When the integral gain K used by the weak magnetic instruction operation is a certain time, the time is from no load (Iq) * V of = 0) 1 * ref To Id * Closed loop transfer function G Φ (s) is
[ number 11]
Here, s is the laplace operator. According to the number 11,Id * Generated by a delay, the response time constant T of which Ф Number 12, known as T Φ According to the frequency command omega 1 * And (3) varied.
[ number 12]
Therefore, the integral gain K of 8a1 is calculated as shown in fig. 13.
[ number 13]
K=1/ω 1 * ·ω c /Ld * ...(13)
Wherein, ω is c Is the control response angular frequency (rad/s) of the flux weakening command operation. Thus, the new transfer function G Φ '(s) become
[ number 14]
Wherein the new response time constant T Φ ' is
[ number 15]
T Φ ′=1/ω c ...(15)
Thus, T Φ ' can be associated with the frequency command omega 1 * Independently set, a higher response effect can be obtained.
In addition, the frequency command ω 1 * The control device of the permanent magnet synchronous motor of the method of changing the integral gain of the field weakening command calculation unit in the feedback control method according to the present embodiment can be applied to a control system other than the control system having the current command calculation unit in the upstream portion of the voltage vector calculation unit shown in fig. 5.
[ example 3]
Fig. 7 shows another embodiment of the present invention. The present embodiment is a field weakening vector control device for a permanent magnet synchronous motor in which a feed-forward method is used in a field weakening command calculation unit.
In fig. 7, the constituent elements 1 to 7,9 to 13, and 21 are the same as those in fig. 1.
The field weakening command calculation unit 8b in the feedforward control system, which is a characteristic of the present invention, will be described with reference to fig. 8.
In addition to the present example, the d-axis current command generated in the no-load state is obtained by performing calculation in advance.
In the weak magnetic command calculation unit 8b, the calculation unit 8b1 outputs the voltage command value V from the weak magnetic region 1 * ref Minus the induction voltage command value (= ω) 1 * Ke * ) And dividing the subtracted value by ω 1 * And Ld * The product of (a) and (b). The output value of the computing unit 8b1 is input to the first-order delay filter8b2. The output value of 8b2 is input to the limiter arithmetic unit 8b3 that limits the positive side to zero, and the output value thereof is the first d-axis current command Id * 。
Using the current command value Id * Generating a second current command value Id ** And calculates a voltage command value Vd * 、Vq * To control the converter output voltage.
In the high speed region, even if the torque is "zero", only the torque is limited by Vq * Induced voltage command value (= ω) 1 * Ke * ),V 1 * It will also saturate.
Id is a d-axis current command value necessary for the operation out of the voltage saturation region * ff0 Then, then
[ number 16]
Id * ff0 =(V 1 * max -ω 1 * ·Ke * )/(ω 1 * ·Ld * ) ...(16)
In this way, by setting the time constant T of the primary delay filter of 8b2 as in numerical value (17), the same effect as in example 2 can be obtained even in the feedforward control method.
[ number 17]
T=1/ω c ...(17)
In the case where the feedforward method is used for the field weakening command calculation unit of the present embodiment, the field weakening torque control device of the permanent magnet synchronous motor can be applied to a control system other than the control system having the current command calculation unit in the upstream portion of the voltage vector calculation unit shown in fig. 7.
[ example 4]
Fig. 9 shows another embodiment of the present invention. In the present embodiment, the present invention is a control device for a permanent magnet synchronous motor in a case where a feedforward control method and a feedback control method are used for a field weakening command calculation unit.
In fig. 9, components 1 to 7,9 to 13, and 21 are the same as those in fig. 1. The field weakening command calculation unit 8c in the feedforward control method and the feedback control method, which are the features of the present invention, will be described with reference to fig. 10.
In the weak magnetic command calculation unit 8c, the calculation unit 8c1 outputs the voltage command value V from the weak magnetic region 1 * ref Subtracting the induction voltage command value (= ω) from the induction voltage command value 1 * Ke * ) And dividing the subtracted value by ω 1 * And Ld * The product of (a) and (b).
The output value of the arithmetic unit 8c1 is input to the first-order delay filter 8c2. The output value of 8c2 is input to the limiter calculation part 8c3 for limiting the positive side to zero, and the output value is Id * ff 。
Further, a voltage command value V is outputted 1 * ref And an output voltage value V 1 The signals are simultaneously input to the integral calculation unit 8c4 having an integral gain of constant K, and are subjected to integral calculation. At this time, the integral gain K is controlled by the frequency ω 1 And (6) automatically correcting.
The output value of the integral operation unit 8c4 is input to the limiter operation unit 8c5 that limits the positive side to zero, and the output value is Id * fb 。
Thus, by the following equation (18)Shows the output value Id of the feedforward control * ff And the output value Id of the feedback control * fb Adding the first d-axis current command Id to calculate a first d-axis current command Id * 。
[ number 18]
Id * =Id * ff +Id * fb ...(18)
In this embodiment, the same operation as in the above embodiment can be performed, and the effect of higher response can be obtained.
Similarly, the control device of the permanent magnet synchronous motor in the case where the feedforward control method and the feedback control method are used for the field weakening command calculation unit according to the present embodiment can be applied to a control system other than the control system having the current command calculation unit in the upstream portion of the voltage vector calculation unit as shown in fig. 9.
[ example 5]
Although embodiments 1 to 4 are a system in which the 3-phase alternating currents Iu to Iw detected by the expensive current detector 3 are detected, they can be applied to a control device that detects inexpensive currents.
Fig. 11 shows this embodiment. In FIG. 11, the constituent elements 1,2,4 to 7,8a,9 to 13, and 21 are the same as those shown in FIG. 5.
Reference numeral 14 denotes a current estimation unit which estimates three-phase ac currents Iu, iv, and Iw in the motor 1 from a dc current IDC on the power converter input bus.
Using the estimated current values Iu, iv, iw, the coordinate conversion unit 7 calculates current detection values Idc, iqc for the d-axis and q-axis.
In this current-less sensor control method, id is also individually commanded * And Idc, iq * Since the measured value is equal to Iqc, the same operation and the same effect as those of the above-described embodiment can be obtained.
Although the embodiment of fig. 6 is used in the field weakening command calculation unit in the present embodiment, similar effects can be obtained by using the embodiments of fig. 2, 8, and 10.
[ example 6]
Fig. 12 shows another embodiment of the present invention.
This embodiment is suitable for a control device that performs inexpensive current detection and omits a magnetic pole position detector.
In FIG. 12, the constituent elements 1,2,7,8a,9 to 13, and 21 are the same as those shown in FIG. 5.
6' is a phase operation part for instructing the frequency ω 1 * Integral to calculate the rotation phase command thetac * 。
Reference numeral 14 denotes a current estimating unit which estimates three-phase ac currents Iu, iv, and Iw in the synchronous motor from a dc current IDC on an input bus of the power converter.
Using the estimated current values Iu, iv, iw, the current detection values Idc, iqc of the d-axis and q-axis are calculated in the coordinate conversion unit 7.
Reference numeral 15 denotes a phase error calculation unit which calculates a phase error from the voltage command value Vd * 、Vq * And current detection values Idc and Iqc are added to estimate the rotation phase command θ c * Phase error Δ θ c (= θ c) of deviation from rotational phase θ of motor 1 * -θ)。
Reference numeral 16 denotes a frequency estimation unit which calculates ω so that the phase error Δ θ c becomes zero 1 ** . The same operation as in the above-described embodiment can be performed in the position-less and current-sensor control method, and the same effects can be obtained.
Although the embodiment of fig. 6 is used in the field weakening command calculation unit in the present embodiment, similar effects can be obtained by using the embodiments of fig. 2, 8, and 10.
[ example 7]
An example in which the present invention is applied to a module will be described with reference to fig. 13. This example shows an embodiment of example 1. Here, the frequency calculation unit 5, the phase calculation unit 6, the coordinate conversion unit 7, the field weakening instruction calculation unit 8, the d-axis current instruction calculation unit 9, the q-axis current instruction calculation unit 10, the voltage vector calculation unit 11, the output voltage calculation unit 12, and the coordinate conversion unit 13 are configured by a single chip microcomputer. The single chip and the power converter are housed in a single module formed on the same substrate. Here, the module means a "normalized unit of construction" and is composed of separable hardware/software components. Although it is preferable to form the substrate on the same substrate in terms of manufacturing, the substrate is not limited to the same substrate. Therefore, the present invention can be configured to a plurality of circuit boards incorporated in the same housing. In other embodiments, the same configuration may be adopted.
As described above, the present invention can provide a field weakening vector control device for a permanent magnet synchronous motor, which can realize a high-precision and high-response motor torque even in a field weakening region; further, the present invention can be used in a system for detecting a current at low cost and a system for omitting a magnetic pole position detector.