JP4999640B2 - Induction machine controller - Google Patents

Description

  The present invention relates to torque control accuracy and stability of an induction machine. In particular, the present invention maintains low-speed induction machine speed calculation accuracy and torque control accuracy while maintaining high-speed output power stability.

FIG. 3 is a block diagram showing a conventional example. 1 is an induction machine, 2 is a current detector, 3 is a power converter, 4 is torque control means, 5 is a magnetic flux calculator, and 6 is a speed calculator.
The current detector 2 detects a current i flowing through the induction machine 1.

  The magnetic flux calculator 5 calculates the induction machine magnetic flux φ by the equation (1) from the current i and the voltage command v input to the power converter.

ここで、Ｒ１は誘導機１の一次抵抗、Ｌ１は一次自己インダクタンス、Ｌ２は二次自己インダクタンス、Ｍは相互インダクタンスである。

Here, R1 is a primary resistance of the induction machine 1, L1 is a primary self-inductance, L2 is a secondary self-inductance, and M is a mutual inductance.

  The speed calculator 6 calculates the induction machine speed ωm from the current i and the induction machine magnetic flux φ using the equations (2) to (4).

ここで、Ｒ２は誘導機１の二次抵抗、ＦＡとＦＢは誘導機磁束φの成分である。

Here, R2 is a secondary resistance of the induction machine 1, and FA and FB are components of the induction machine magnetic flux φ.

Based on the induction machine speed ωm and the current i, the torque control means 4 outputs a voltage command v such that the magnetic flux and torque of the induction machine 1 become the magnetic flux command reference value φ * and the torque command τ *.
The power converter 3 amplifies the voltage command v and supplies power to the induction machine 1.

With the above configuration, the torque of the induction machine 1 can be controlled to the torque command τ *.
JP 11-066985 A

The prior art has the following problems.
When estimating the induction machine speed ωm using the formulas (1) to (4), the induction machine speed ωm is determined by the motor constant setting error of the induction machine 1, the detection error of the current detector 2, the quantization error at the time of calculation, etc. The calculation accuracy of ωm is slightly reduced.

If the speed calculation accuracy drops even slightly, there are the following problems.
On the high speed side, when the torque command τ * = 0 is controlled, a decrease in speed calculation accuracy may cause a decrease in output power stability, which may lead to generation of regenerative power. In the case of a vehicle control system, there is a zero torque control period at the end of torque control, and the generation of regenerative power with reduced speed calculation accuracy may boost the DC side voltage, leading to the destruction of the power element of the power converter 3, Furthermore, there is a risk of affecting the substation.

In order to alleviate the regenerative power due to speed calculation accuracy drop and to stabilize the output power, a measure to lower the magnetic flux command reference value φ * at the end of torque control can be considered.
However, on the low speed side, the voltage command v at the time of magnetic flux restriction is small, so the influence of the setting error of the primary resistance R1 is large, and the influence on the torque control of the induction machine 1 is great. Further, when the induction machine magnetic flux φ decreases, the calculation accuracy of the equation (2) deteriorates due to the quantization error, which leads to deterioration of the calculation accuracy of the induction machine speed ωm and affects the torque control of the induction machine 1.
The present invention has been made to solve the above problems.

  The limit amount calculator 8 that inputs the induction machine speed ωm and the magnetic flux command reference value φ * and outputs the lower limit magnetic flux command φL, and the magnetic flux that inputs the magnetic flux command reference value φ * and the lower limit magnetic flux command φL and outputs the control magnetic flux command φs A command limiter 7 is added, and a control magnetic flux command φs is used for torque control of the induction machine 1 instead of the magnetic flux command reference value φ *.

  By setting the magnetic flux command φ * as the control magnetic flux command φs, it is possible to maintain the low speed side induction machine speed calculation accuracy and the torque control accuracy while maintaining the high speed side output power stability.

  By manipulating the magnetic flux command, a mode capable of maintaining the low speed side induction machine speed calculation accuracy and the torque control accuracy while maintaining the high speed side output power stability is realized.

  FIG. 1 is a block diagram showing an embodiment of the present invention, where 7 is a magnetic flux command limiter and 8 is a limit amount calculator. Hereinafter, only the points of FIG. 1 different from FIG. 3 will be described.

  The limit amount calculator 8 inputs the induction machine speed ωm and the magnetic flux command reference value φ *, and outputs the lower limit magnetic flux command φL. FIG. 2 is a diagram showing one calculation example of the limit amount calculator 8 and shows the characteristic of the lower limit magnetic flux command φL with respect to the inductor speed ωm. Here, ωm1 is a high speed threshold value, ωm2 is a low speed threshold value, K1 is a high speed side limiting gain, and K2 is a low speed side limiting gain, and ωm2 ≦ ωm1, K1 ≦ K2, 0 ≦ K1 ≦ 1, 0 <K2 ≦ 1.

  The magnetic flux command limiter 7 inputs the magnetic flux command reference value φ * and the lower limit magnetic flux command φL, and outputs a control magnetic flux command φs. A control magnetic flux command φs that is an output of the magnetic flux command limiter 7 is input to the torque control means 4 instead of the magnetic flux command reference value φ *.

With the above configuration, the following effects can be obtained.
The lower limit value of the magnetic flux of the induction machine 1 can be changed by the induction machine speed ωm. In the high-speed side 0 torque control, the regenerative power can be reduced by reducing the speed calculation accuracy by greatly reducing the control magnetic flux command φs. The output power can be stabilized.

  On the low speed side, by reducing the aperture width of the control magnetic flux command φs, it is possible to prevent deterioration of the calculation accuracy of the induction machine speed ωm due to excessive reduction of the induction machine magnetic flux φ, and high-precision torque control of the induction machine 1 can be achieved. I can expect.

  In FIG. 3, if ωm1 = ωm2, a pattern in which the lower limit magnetic flux command φL changes stepwise at the induction machine speed ωm = ωm1 is obtained.

  By operating the magnetic flux command, it is possible to maintain the low speed side induction machine speed calculation accuracy and the torque control accuracy while maintaining the high speed side output power stability.

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a diagram showing one calculation example of the limit amount calculator of the present invention. FIG. 3 is a block diagram showing a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induction machine 2 Current detector 3 Power converter 4 Torque control means 5 Magnetic flux calculator 6 Speed calculator 7 Magnetic flux command limiter 8 Limit amount calculator

i ... current v ... voltage command τ * ... torque command φ * ... magnetic flux command reference value ωm ... induction machine speed φ ... induction machine magnetic flux φs ... ..Control magnetic flux command φL ... Lower limit magnetic flux command
K1 ・ ・ ・ ・ High-speed side limiting gain
K2 ・ ・ ・ ・ Low speed side limit gain ωm1 ・ ・ ・ High speed threshold ωm2 ・ ・ ・ Low speed threshold

Claims (1)

In an induction machine control device that calculates induction machine magnetic flux and induction machine speed from the current and voltage of the induction machine, and controls torque of the induction machine based on the current, induction machine speed, magnetic flux command reference value, and torque command,
A limit calculator that inputs the induction machine speed and the magnetic flux command reference value and outputs a lower limit magnetic flux command, and a magnetic flux command limiter that inputs the magnetic flux command reference value and the lower limit magnetic flux command and outputs a control magnetic flux command are added. An induction machine control device using the control magnetic flux command for torque control of the induction machine instead of the magnetic flux command reference value.

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