JPH01209977A - Electric motor control device - Google Patents

Abstract

PURPOSE:To obtain a speed detecting means with the speed feedback information in a small ripple by calculating the speed information being based on the information, newly input, and the information input by the one-three preceding timing. CONSTITUTION:A signal, output from a sensor 1 detecting a rotating position of an electric motor, is stored in a present position register 2. A register 3 fetches a content of this present position register 2 in every fixed time, simultaneously transmitting data, stored existing up to now in the register 3, to a register 4. Next a differential amount of these registers is stored in a register 5. Here in registers 6, 7, 8, a value of the register 5 is stored respectively by the one, two and three preceding timing. A value of the register 5 multiplied by four, value of the register 6 multiplied by two and values of the registers 7, 8 are totalized, and multiplying this obtained value by an arbitrary constant N, thus obtained value is used serving as the speed feedback signal (b).

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a motor control device, and more particularly to an improvement in speed detection means for a motor.

2. Description of the Related Art In recent years, motor control devices have become increasingly digitalized due to advances in microcomputers and the like.

In general, a motor control device has a configuration as shown in FIG. 3, in which the rotation of the motor 15 is detected by a rotational position detector 11, and the detected signal is input to a speed detection device 12 to detect the speed. The speed error amplifier 13 calculates the detected speed feedback signal C and the speed command signal d from the outside.
The configuration is such that the electric motor 15 is driven and controlled via the current control device 14. Here, the speed feedback signal C plays a very important role.

When digitalizing a motor control device, an important point is how to obtain high-quality speed feedback information at a low cost, and conventional methods have had problems.

The speed detection means in a conventional motor control device will be explained below.

Figure 2 is a diagram showing the speed detection means of a conventional motor control device, in which a signal output from a sensor 1 that detects the rotational position of the motor is stored in a current position register 2 as a digital value (discrete value). .

The contents of the current position register 2 are taken into the register 3 at regular intervals (sampling period T), and at the same time, the data that has been in the register 3 is transferred to the register 4.

Through the above operations, the most recently input position information is stored in the register 3, and the position information input immediately before that is stored in the register 4. Next, the difference between these registers is stored in register 5, and as a result of integrating an arbitrary constant N, register 10
Obtain speed feedback information a.

The above is the principle of a conventional electric motor control device, and the concrete implementation means include 71-ware such as a digital LSI, microcomputer software, etc. .

Problems to be Solved by the Invention However, with the conventional configuration described above, there is no problem when the rotation speed of the electric motor is high, but when the rotation speed becomes low, the ripple of the speed feedback information a becomes thick. It is shown in Figure 4.

Especially when the change in the current position register 2 is slow with respect to the sampling timing t, the speed feedback information a is particularly large.
It can be seen that a ripple appears. This is due to the influence of quantization errors that occur because the rotational position information of the motor is input as digital values (discrete values). has poor controllability. Therefore, the resolution of the position detecting device 1 for detecting the rotational position of the electric motor is increased to minimize the quantization error, but this has the disadvantage of requiring an expensive position detecting device.

The present invention solves the above-mentioned conventional problems, and aims to provide a motor control device with good controllability and low cost by providing speed detection means with small ripples in speed feedback information.

Means for Solving the Problem To achieve this object, the motor control device according to the present invention uses, as a speed detection means, information VE4 inputted most recently from the arithmetic unit and information vE3 inputted at the previous timing.
For the information VE2 inputted at the timing before that, vEl inputted at the timing just before that, and an arbitrary constant N, N (4×VE4+2×VE3+VE2
+VE 1 ) is provided with a digital filter device that outputs speed information.

Effect: With the above configuration, speed feedback information of non-defective products can be obtained very easily and inexpensively, and the controllability of the motor control device can be improved.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows speed detection means of a motor control device in one embodiment of the present invention. In FIG. 1, 1 is a sensor for detecting the rotational position of the electric motor, 2 is a current position register 2.3, 4, 5, 6.7°, 8.9.10 is a register. Here, registers 5, 6, 7 and 8, 9 are registers for the digital filter device configuration according to the present invention, and the other registers have the same configuration as the conventional example.

The operation of the speed detection means of the motor control device of this embodiment configured as described above will be explained.

In FIG. 1, a signal output from a sensor l that detects the rotational position of the electric motor is stored in a current position register 2 as a digital value (discrete value). The contents of the current position register 2 are taken into the register 3 at fixed time intervals (sampling period T), and at the same time, the data previously stored in the register 3 is transferred to the register 4.

Through the above operations, the most recently input position information is stored in the register 3, and the position information input immediately before that is stored in the register 4. Next, the difference between these registers is stored in register 5. Here, register 6 stores the value of register 5 at one timing before, register 7 stores the value of register 5 at two timings before, and register 8 stores the value of register 5 at three timings before. has been done. Here, the sum of the value of register 5 multiplied by 4, the value of register 6 multiplied by 2, the value of register 7, and the value of register 8 is stored in register 9, and an arbitrary constant N is integrated. Speed feedback information was obtained in the register 10.

The above is an embodiment in which the speed detection means of the motor control device according to the present invention is configured by hardware.

FIG. 5 shows speed feedback information obtained from the speed detection means of the motor control device according to the present invention. It can be seen that the ripple is significantly reduced compared to the speed feedback information obtained from the speed detection means of the conventional motor control device shown in FIG.

The digital filter device used in the speed detecting means of the motor control device according to the present invention has the advantage that it has a very simple structure and can process at high speed, especially when it is processed by a microcomputer, because it can be processed by only a shift operation and an addition operation. Further, when comparing the motor control device according to the present invention with another motor control device equipped with a digital filter device having a complicated configuration, the controllability thereof is practically comparable.

Effects of the Invention As is clear from the above explanation, the present invention provides information on the information VE4 inputted most recently from the arithmetic unit in the speed detection means of the motor control device, the information VE3 inputted at the previous timing, and the information VE3 inputted one time before. Information V entered at the timing of
For VEI input at E2 and one timing before it, and an arbitrary constant N, N (4×VE4+2×VE3+
By providing a digital filter device that outputs speed information as VE2+VE1), good speed feedback information can be obtained, and this information can significantly improve the controllability of the motor control device at low speeds.

Furthermore, since the digital filter device having the above-mentioned specific characteristics is configured to be very easily processed by a microcomputer, the burden on the processing capacity of the microcomputer can be kept to a minimum. Of course, even when configured with hardware, it can be configured easily and inexpensively.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the speed detection means of a motor control device according to an embodiment of the present invention, FIG. 2 is a diagram showing the speed detection means of a conventional motor control device, and FIG. 3 is a diagram showing the speed detection means of a conventional motor control device. FIG. 4 is a diagram showing the speed feedback information of the conventional motor control means, and FIG. 5 is a diagram showing the speed feedback information of the motor control device according to the present invention. 1...Sensor that detects the rotational position of the electric motor, 2
...Current position register 2.3 to 10...
・Register, 11...Rotational position detector, 12.
...Speed detection device (speed detection means), 13...
... Speed error amplifier, 14 ... Current control device, 15 ... Parameter motor, 16 ... Arithmetic device, 17 ... Digital filter device, b. ...
...Speed feedback information, C...Speed foot check signal, d...Speed command signal. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2 Figure 3 Figure 4 Figure 6

Claims (1)

[Claims] A position detection device that detects the rotational position of the electric motor, and an operation that inputs the output of this position detection device at regular intervals and outputs the difference between the most recently input position information and the position information input immediately before. and a digital filter device that extracts and outputs speed information based on the output of this arithmetic device, and the digital filter device extracts and outputs speed information based on the output of the arithmetic device, and the digital filter device extracts and outputs speed information from the arithmetic device, and the digital filter device extracts and outputs speed information from the arithmetic device. Also, the information V entered at the previous timing
For E2, VE1 input at the previous timing, and an arbitrary constant N, N(4×VE4+2×VE3+V
An electric motor control device characterized in that it outputs speed information as E2+VE1) and uses this as speed feedback information.