JPH0154959B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a secondary flux linkage calculation device necessary for vector control of an induction machine. First, let's talk about conventional technology. Magnetic field orientation vector control methods include embedding magnetic sensors in the stator magnetic poles to detect and control the gap magnetic flux (Japanese Patent Publication No. 50-34725), and controlling by integrating the motor induced voltage to determine the reference magnetic flux. The former method is impractical because it embeds a magnetic sensor, and the latter method is
It could not be used when the next frequency was zero or when rotating at ultra-fine low speeds. The principle of the latter integration method is explained as follows. The primary side voltage/current equation is E〓 ₁ = MpI〓 ₀ + (R ₁ + l ₁ p) I〓 ₁ ... (1 formula) However, E〓 ₁ is equal to E ₁ ε ^j( 〓 ^1t+ 〓 ⁾ and 1 Next terminal voltage (E〓 ₁ is the vector quantity, E ₁ is the scalar quantity), M is the primary and secondary mutual inductance, p is the differential operator in d/dt, I〓 ₀ is the exciting current (vector quantity) R ₁ is the primary resistance l ₁ is the primary leakage inductance I〓 ₁ is the primary current (vector quantity) ω ₁ is the primary angular frequency θ is the voltage phase angle t is the time. The secondary side voltage/current equation is 0 = MpI〓 ₀ − (R ₂ + l ₂ p) I〓 ₂ ... (2 formula) Here, R ₂ is the secondary resistance l ₂ is the secondary leakage inductance

[Formula] is the secondary current (I〓 ₂ is a vector quantity, I ₂ is a scalar quantity). Obtaining the secondary flux linkage vector φ〓 ₂ from (Equation 1) and (Equation 2), we get However, θ ₁ is the current phase angle. Since the secondary flux linkage vector φ〓 ₂ was calculated according to this (3), the integral calculation (1/p)
was inaccurate because the integrator error became large when the first-order angular frequency ω ₁ was zero or near zero. The present invention now aims to provide a new method and device that overcomes the above-mentioned drawbacks. That is, the present invention provides a method and apparatus that can accurately calculate the secondary flux linkage vector φ〓 ₂ of an induction machine even when the primary frequency ω ₁ is zero. Now, the principle of the present invention will be explained. The motor primary side or secondary side voltage/current equations are expressed by (Equation 4) and (Equation 5), respectively. E〓 ₁ = (R ₁ + L ₁ p) I〓 ₁ − MpI〓 ₂ = (R ₁ + L ₁ p) I〓 ₀ + (R ₁ + l ₁ p) I〓 ₂ ... (4 formula) 0 = MpI〓 ₁ − (R ₂ + L ₂ p) I〓 ₂ = MpI〓 ₀ − (R + l ₂ p) I〓 ₂ ... (5 formula) However, I〓 ₁ = I〓 ₀ + I〓 ₂ L ₁ = l ₁ + M L ₂ = l ₂ +M. FIG. 1 is an induction machine equivalent circuit corresponding to (4) and (5). The secondary flux linkage vector φ〓 ₂ is expressed as φ〓 ₂ = MI〓 ₀ −l ₂ I〓 ₂ ... (Formula 6), so from (Formula 4) and (Formula 6), φ〓 ₂ = M /R ₁ +L ₁ p{E〓 ₁ −(R ₁ +l ₁ p)I〓 ₂ }−l ₂ I〓
₂ ...(7 formula) becomes. When the transient characteristics of the induction machine are the same as the static characteristics and so-called proportional constant control is established, from the rotor side, the secondary flux linkage vector φ〓 ₂ = φ ₂ ε ^j 〓 ^2t is used as the reference vector. Then (φ ₂ is the scalar quantity of the secondary chain magnetic flux), the secondary current I〓 ₂ is The secondary current I〓 ₂ must be orthogonal to the secondary flux linkage vector φ〓 ₂ . Here, ω ₂ is a secondary angular frequency, and if the rotor rotational angular frequency is ω _N , then ω ₂ =ω ₁ −ω _N. Therefore, on the primary side, the instantaneous value of the secondary flux linkage vector is given by (Equation 7), (Equation 8), and the vector relationship shown in Figure 2. It is. Here, the primary voltage E〓 ₁ =E ₀ ε ^j( 〓 ^1t+ 〓 ⁾ is the detected primary terminal voltage,

[Equation] is a secondary current value and has an orthogonal relationship with the secondary interlinkage magnetic flux vector φ〓 ₂ , and is also made to correspond to the secondary current command value I _2S (described later) given by control. Of course, the secondary current I〓 ₂ is 1
It is also possible to use values obtained by calculation from detected values such as the secondary current I〓 ₁ and the primary voltage E〓 ₁ . FIG. 2 is a diagram for comparing the relationship between the secondary flux linkage vector φ〓 ₂ and other quantities according to the present invention. E〓 ₁₀ is the primary voltage under no load, E〓 ₀ is the internal induced voltage of the motor, and φ ₀ is the gap magnetic flux. In the present invention, this gap magnetic flux φ ₀ is φ〓 ₀ =M/R ₁ +jω ₁ L ₁ E〓 ₁₀ . For comparison, FIG. 3 shows an example of a block diagram for calculating the secondary flux linkage vector φ ₂ using the conventional integration method. 31 is an integrator, 32 is a primary impedance component factor, 33 is a secondary leakage/primary inductance component factor, and 34 and 35 are adders. Therefore, FIG. 4 is a block diagram representing one implementation of the secondary flux linkage vector φ〓 ₂ operation according to the present invention. 41 is the first primary delay filter, 44 is the first
, and 45 is a second subtractor. FIG. 5 is a block diagram showing another embodiment of the secondary flux linkage vector φ ₂ calculation according to the present invention. 51 is a second primary lag filter; 52 is a primary lag signal calculator for the primary impedance drop;
53 is a third subtractor, and 54 is a fourth multiplier. FIG. 6 is a diagram showing a specific circuit of the embodiment shown in FIG. 4. r ₁ to _{r 10} are resistors, C ₁ and C ₂ are capacitors, A ₁ to _{A 3}
is an operational amplifier, 61 constitutes a voltage divider, and 62 constitutes an inverter. Fig. 6 explains one phase, but when a signal corresponding to the secondary current I〓 ₂ is input to the parallel circuit of the capacitor C ₁ and the resistor r ₁ (primary impedance divider 32), 1 The signal corresponding to the voltage drop (R ₁ + pl ₁ ) I〓 ₂ due to the next impedance (R ₁ + pl ₁ ) is
The signal is input to a first primary delay filter 41 consisting of resistors r ₂ and r ₃ , a capacitor C ₂ , and an operational amplifier A ₂ . On the other hand, a voltage corresponding to the primary voltage E ₁ divided by the voltage divider 61 consisting of resistors r ₄ and r ₅ is input to the first primary delay filter 41, and from this voltage The signal obtained by subtracting the signal is inverted by the first primary delay filter 41, and the output signal corresponds to -φ ₀ . Further, a signal +I〓 ₂ obtained by inverting the secondary current −I〓 ₂ by the inverter 62 and a signal −φ ₀ corresponding to the gap magnetic flux φ〓 ₀ are added and inverted by the first subtractor 44 to form a secondary chain. The equivalent of the alternating magnetic flux vector φ〓 ₂ is output. FIG. 7 is a diagram showing a detailed circuit of another embodiment of FIG. 5. r ₁₁ to _{r 18} are resistors, C ₃ and C ₄ are capacitors, A ₄ to _{A 6}
is an operational amplifier. Although FIG. 7 explains one phase, when a signal corresponding to the secondary current I〓 ₂ is input to the operational amplifier 52, the primary impedance drop (R ₁ +pl ₁ )I〓 ₂
A signal corresponding to the above is generated by the capacitor C ₃ and the resistor C ₁₁ , and a first-order delay signal corresponding to the first-order impedance drop is output from the arithmetic unit 52 by the capacitor C ₄ , the resistor r ₁₂ , and the operational amplifier A ₄ . . On the other hand, the signal corresponding to the primary terminal voltage E = ₁ is the resistance
r ₁₃ , r ₁₄ and a capacitor C ₅ , and a primary terminal voltage E= ₁ is output from the primary delay filter 51 . Then, the output of the arithmetic unit 52 is subtracted from the output of the primary lag filter 51 in a third subtractor 53, and a signal corresponding to the gap magnetic flux φ ₀ is sent out. The signal corresponding to this gap magnetic flux φ〓 ₀ is counted in the fourth subtractor 54 as the secondary leakage magnetic flux equivalent to the secondary current I〓 ₂ multiplied by the secondary leakage inductance l ₂ , and the secondary chain A signal corresponding to the alternating magnetic flux φ〓 ₂ is sent out. Note that the equivalent of the secondary leakage flux is the resistance r ₁₇ ,
determined by the ratio of r ₁₈ . FIG. 8 shows an embodiment of a circuit for vector control of an induction machine using the present invention. 81 to 84 are subtractors, 85 and 86 are multipliers,
A _N is the speed amplifier, A _I is the current amplifier, A〓 is the integrating amplifier, IM is the induction machine, COM is the comparator, TG is the tachogenerator, CT is the current transformer, √ ² _d + ² _q is the square rooter, and SW is the square rooter. It's a switch. As soon as the power is turned on, the magnetic flux command value φ _S and the switch are turned on.
Initial excitation signal _I0 is input via SW. The output voltage of the current amplifier A _I is compared with the signal with carrier frequency f _H in the comparator COM, and the current amplifier
A frequency command according to the output of A _I is given to the PWM inverter. In this case, the output of the current amplifier A _I is a constant direct current, so the output frequency of the PWM inverter is also zero. PWM inverter output current I〓 ₁
is detected by the DC current transformer CT and becomes a negative feedback signal,
Primary current control is performed. On the other hand, from the output voltage of the PWM inverter or the primary terminal voltage E ₁ of the induction machine IM, the vector E〓 ₁₀ , which is equal to the vector E〓 ₁ , and the secondary magnetic flux linkage φ〓 ₂ , which is equal to the gap magnetic flux vector φ〓 ₀ , are derived, Excitation current command I〓 _0S is established. After the magnetic flux of the induction machine IM is established in this way, when a speed command value N _S is given, the speed amplifier A _N
A secondary current command value I〓 _2S is generated, which is the product of the output of and the secondary flux linkage φ ₂ . Then, as the vector sum of this secondary current command value I〓 _2S and exciting current command I〓 _0S , the primary current command value I〓 _1S
is sent. Note that the square root squarer √ ² _d + ² _q takes the square root of the sum of the squares of two orthogonal components of the secondary flux linkage vector φ〓 ₂ , and the absolute value of the secondary flux linkage vector φ〓 ₂ |φ ₂ ｜
In order to make the deviation between this |φ ₂ | and the command value φ _S zero, the proportional-integral amplifier A〓 and the multiplier 86
is provided. For example, when |φ ₂ | increases, the deviation φ _S −|φ ₂ | decreases, and the output of the proportional-integral amplifier A〓 decreases. Therefore, the excitation current command _I〓0S also decreases, and the primary voltage _E1 decreases. Therefore, the absolute value |φ ₂ | of the secondary flux linkage is controlled to be small. In this example, the primary impedance drop voltage (R ₁ + pl ₁ ) I ₂ and the secondary leakage magnetic flux l ₂ I ₂ are calculated using the secondary current command value I _2S , but Excitation current obtained by dividing voltage E ₁ by (R ₁ + pL ₁ )
It goes without saying that the secondary current value I〓 ₂ obtained by vectorially subtracting I〓 ₀ from the primary current I〓 ₁ may be used. Furthermore, if the present invention is to be implemented using a digital circuit, the result will be as shown in FIG. 9 is a microprocessor or signal processor, 91 is an A/D converter, 92 and 93 are 1
94 is a constant multiplier, 95 is an adder/subtractor, and 96 is a D/A converter. Primary voltage vector E〓 ₁ is E〓 ₁ = E ₁ 〓 + jE ₁ β Secondary current command value I〓 _2S is I〓 _2S = I _2S + jI _2S β Secondary flux linkage vector φ〓 ₂ is φ〓 ₂ = They are respectively expressed as φ ₂ 〓+jφ ₂ 〓. Therefore, the primary voltage vector E〓 ₁ is, for example, 3
In the case of a phase, take its real part E ₁ 〓 as the U-phase voltage E _U.
If E _V is the V-phase voltage, the imaginary part E ₁ 〓 is given by the following equation. The same applies to the secondary current command value (vector). The digitally converted quantities of E ₁ 〓, I _2S 〓, φ ₂ 〓 are
E ^D ₁ 〓, I ^D _2S 〓, φ ^D ₂ 〓, Z=R ₁ /L ₁ , T is the sampling period. Therefore, in FIG. 9, the real part φ ₂ 〓 of the secondary magnetic flux linkage is first calculated. That is, the primary voltage,
The real parts E ₁ 〓 and I _{2S 〓} of the secondary current command value are input into an A/D converter 91 and converted into E ^D ₁ 〓 and I ^D _2S 〓, respectively. E ^D ₁ 〓 is transmitted through the transfer function M/R ₁ (1-e ^-T/ 〓 ^Z-1 ) of the primary digital filter 92, and I ^D _2S 〓 is transmitted through the transfer function MR ₁ (1 −l ₁ /L ₁ )/R ₁ (1−e
^-T/ 〓 ^Z-1 ) and the multiplication constant of the constant multiplier 94 (Ml ₁ /L ₁ +l ₂ )
The first input is added, and the second and third inputs are subtracted. The output of the adder/subtractor 95 is φ ^D ₂ 〓, and by converting it into an analog quantity with an A/D converter, φ ₂ 〓=M/R ₁ +L ₁ S{E ₁ 〓−(R ₁ +l ₁ S) I _2S 〓｝ −l ₂ I _2S 〓 is obtained. Furthermore, the imaginary part (β component) of the secondary flux linkage vector φ〓 ₂ can also be calculated using E ₁ 〓 and I _2S 〓 in the same manner as in FIG. 9. This means that φ ₂ is expressed by orthogonal components of two axes. Therefore, both outputs φ ₂ 〓 and φ ₂ 〓 are √ ² ₂ 〓 + ² ₂ 〓
=｜
If we calculate the absolute value |φ ₂ | and the phase angle θ using φ ₂ | and θ=tan ^-1 φ ₂ 〓/φ ₂ 〓, we get 2
The next magnetic flux linkage vector φ〓 ₂ is now expressed in polar coordinate format. Although input and output are shown in the form of vectors in FIGS. 6 and 7, the actual calculations are performed in the same manner as in FIG. 9. As described above, according to the present invention, there is no need to integrate the motor terminal voltage when calculating the secondary flux linkage vector φ〓 ₂ , so even if the primary frequency is zero, the gap magnetic flux φ ₀ is reliably obtained. The accurate secondary magnetic flux linkage φ ₂ near the zero frequency is calculated. Therefore, although it is an AC machine, it can achieve controllability comparable to that of a DC machine. Further, according to the present invention, the motor 2
Since the secondary resistance R ₂ is not included in the calculation formula for the gap magnetic flux φ ₀ , the secondary resistance R ₂ has no effect on temperature changes. Therefore, the present invention, which completely eliminates the drawbacks of the conventional integral method, has made magnetic field orientation vector control practical.

[Brief explanation of drawings]

Fig. 1 is an induction machine equivalent circuit diagram corresponding to the motor primary and secondary side voltage/current equations, Fig. 2 is a comparison diagram of the secondary flux linkage vector and other quantities according to the present invention, and Fig. 3 The figure is a calculation block diagram of the secondary flux linkage vector using the conventional integration method.
The figure is a block diagram showing one embodiment of the secondary flux linkage vector calculation according to the present invention, FIG. 5 is a block diagram of another embodiment of the secondary flux linkage vector calculation according to the invention, and FIG. 7 is a diagram showing a detailed circuit of another embodiment of FIG. 5, and FIG. 8 is an example of vector control of an induction machine using the present invention. FIG. 9 is a circuit diagram showing the present invention digitally.
FIG. 3 is a block diagram for calculating the real part of the next-order magnetic flux linkage vector. 9...Microprocessor, 31...Integrator,
32...Primary impedance divider, 33...
Secondary leakage inductance coefficient factor, 34, 35,
81-84...Adder, 41...First primary delay filter, 44...First subtractor, 45...Second subtractor, 51...Second primary delay filter, 52... ...First-order delay signal calculator for the first-order impedance drop, 53...Third subtractor, 54...
... Fourth subtractor, 61 ... Voltage divider, 62 ... Inverter, 85, 86 ... Multiplier, 91 ... A/D converter, 92, 93 ... Primary digital filter,
94...constant multiplier, 95...addition/subtraction device, 96...
...D/A converter, _A1 to _A6 ...operational amplifier,
A _N ...Speed amplifier, A _I ...Current amplifier, A〓...
Proportional-integral amplifier, IM...induction machine, TG...tachogenerator, CT...current transformer, √ ² _d + ² _q ... square meter,
COM...Comparator, SW...Switch.

Claims (1)

[Claims] 1. Amplify the speed deviation obtained by negative feedback of the actual speed of the induction machine IM to the speed command N _S , and multiply it by the secondary linkage magnetic flux φ〓 ₂ of the induction machine IM to obtain the secondary current. The command I〓 _2S is calculated, and the excitation current command I〓 _0S is added to it to produce the primary current command I〓 _1S . At the beginning of startup, the initial excitation signal I〓 _O is added via the switch SW. In a device that amplifies the current deviation resulting from negative feedback of the inverter output current I〓 ₁ , controls the pulse width modulated inverter output current I〓 ₁ , and drives the induction machine IM, the primary resistance R ₁ of the induction machine IM and Primary impedance consisting of primary leakage inductance l ₁ (R ₁ + l ₁ P)
Secondary current command passed through the primary impedance factorizer 32 whose coefficient is
I〓 _2S is the primary terminal voltage E ₁ detected from the induction machine IM
A first subtracter 44 is provided to subtract from , and the primary voltage vector E 〓 ₁₀ of the output from this first subtractor 44 is the primary secondary mutual inductance M and the primary self-inductance L ₁ of the induction machine IM. The secondary current command I〓 _2S is converted to the induction motor IM from the signal which makes the gap magnetic flux vector φ〓 ₀ through the first primary delay filter 41 which has a constant of [M/(R ₁ +L ₁ P)].
A second subtracter 45 is provided for subtracting the signal passed through the secondary leakage inductance coefficient multiplier 33 with the secondary leakage inductance l ₂ as a coefficient, and the output derived from the second subtractor 45 is A secondary flux linkage vector calculation device for an induction machine, characterized in that the secondary flux linkage of the machine IM is φ= ₂ .