JPH01126190A - Controller for dc brushless motor - Google Patents

Abstract

PURPOSE:To prevent rotational frequency from pulsating and operate at low noise, by generating pulse at every electrical angle of 60degrees from the output of a rotor position detecting circuit, and by measuring the intervals to estimate following rotational frequency. CONSTITUTION:A DC power source 1 is converted to three-phase AC voltage via an inverter 2, and current is fed to an armature winding 3. The controller of a DC brushless motor having a permanent magnet rotor 4 rotated by a magnetic field generated from the winding 3 is provided with a rotor position detecting circuit 5, a voltage setting circuit 6, the gate controlling circuit 7 of the inverter 2, a pulse generating circuit 9 for generating pulse at every electrical angle of 60degrees, a rotational frequency detecting circuit 10 having a timer 10a for measuring the pulse intervals and an arithmetic circuit 10b, and a rotational frequency estimating means 11 having memory 11b and a following rotational frequency estimating arithmetic means 11a. Then, according to a difference between estimated rotational frequency and command rotational- frequency, the output voltage of the inverter 2 is controlled so as to avoid the pulsating of rotational frequency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for a DC brushless motor,
In particular, the present invention relates to a control device for a DC brushless motor when driving a pulsating load such as a compressor.

[Conventional technology]

FIG. 4 is a block diagram showing a control device for a DC brushless motor disclosed in, for example, Japanese Unexamined Patent Publication No. 61-46193. In the figure, 1 is a DC power supply, 2 is an inverter, and the DC power supply It converts the DC voltage generated into any three-phase AC voltage and outputs it. 3 is an armature winding to which the output of the inverter 2 is supplied; 4 is a permanent magnet rotor that rotates by the magnetic field generated from the armature winding 3; 5 is a rotor that detects the rotational position of the permanent magnet rotor 4. Position detection circuit, 6
7 is a voltage setting circuit that sets the AC output voltage generated from the inverter 2, and 7 is a gate control circuit, which performs gate control of the inverter 2 based on the output of the rotor position detection circuit 5 and the output of the voltage setting circuit 6. do. 8 is a rotation speed detection circuit that detects the rotation speed of the permanent magnet rotor 4 based on the output of the rotor position detection circuit 5, and when the detected rotation speed reaches a set rotation speed, it generates an output signal and detects the voltage. Controls the setting circuit 6.

Next, the operation will be explained. When the output of the DC power supply 1 is supplied to the gate circuit 2, a plurality of gates provided in the gate circuit 2 are set to 0N-OF by the gate control circuit 7.
By being controlled by F, it is converted into a three-phase AC voltage and supplied to the armature winding 3. When a three-phase AC voltage is supplied to the armature winding 3, the generated magnetic field causes the permanent magnet rotor 4 to rotate, and the rotating shaft to which the permanent magnet rotor 4 is fixed rotates a load such as a compressor. Driven. and,
The rotation of this permanent magnet rotor 4 is controlled by a rotor position detection circuit 5.
detected by.

On the other hand, the gate control circuit 7 receives a voltage signal corresponding to the set rotation speed of the permanent magnet rotor 4 outputted from the voltage setting circuit 6 and a voltage signal corresponding to the set rotation speed of the permanent magnet rotor 4 outputted from the rotor position detection circuit 5.
The voltage signal corresponding to the rotation of the inverter 2 is compared with the voltage signal corresponding to the rotation of the inverter 2, and speed control corresponding to the difference value between the two is applied to the inverter 2.

Here, in a DC brushless motor having the rotation speed-load torque characteristic shown by line A in FIG. 5(A), if the load becomes large after time 70, the rotation speed will change to line As shown, it drops below the old level. Then, the rotation speed detection circuit 8 controls the set voltage of the voltage setting circuit 6 to be higher than the voltage V, as shown by the line in FIG. 5(B). As a result, the DC brushless motor is accelerated, and when the number of rotations reaches n1 or more, the increase in voltage is stopped. Here, in the related Japanese Patent Application Laid-Open No. 61-46193, it is described that the number of revolutions is controlled so as not to become less than n, but conversely, when the number of revolutions becomes more than n, the setting By lowering the voltage, it is possible to maintain the rotational speed at n.

[Problem that the invention seeks to solve]

The loads handled by conventional DC brushless motor control devices are:
This is a case where average rotation is performed, and it is not intended to control rotational pulsation during one rotation due to a pulsating load such as a compressor.

This rotational pulsation becomes an excitation force on the motor and its load, and its amplitude becomes large especially in the low rotation range, causing a problem of generation of vibration and noise.

This invention was made in order to solve the above-mentioned problems, and its purpose is to obtain a control device for a DC brushless motor that rotates smoothly even in a low rotation range and has low vibration and noise. .

[Problem that the invention seeks to solve]

The control device for a DC brushless motor according to this invention includes:
Means for obtaining a pulse of 60 electrical degrees from the magnetic pole position detection signal of the rotor, means for calculating the rotation speed of the rotor from the n pulse interval measurement results, and means for predicting the next rotation speed from the calculation result. and means for increasing or decreasing the output voltage of the inverter according to the difference between the predicted rotation speed and a target command rotation speed or command rotation speed range.

[Effect]

The DC brushless motor control device in this invention includes:
Pulses are generated every 60 electrical degrees from the magnetic pole position detection signal of the rotor, and n pulse intervals in these pulses are measured to predict the next rotation speed.

Since the inverter's output voltage is controlled to eliminate rotational speed pulsations according to the difference between the predicted rotational speed and the commanded rotational speed or commanded rotational speed range, it can be used in compressors, etc. Rotational pulsation is prevented, allowing motor drive with low vibration and low noise.

[Embodiments of the invention]

・Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. In FIG. 1, 1 is a DC power supply, and 2 is an inverter, which converts the DC voltage supplied from the DC power supply 1 into an arbitrary three-phase AC voltage and outputs it. 3 is an armature winding to which the output of the inverter 2 is supplied; 4 is a permanent magnet rotor rotated by the magnetic field generated from the armature winding 3; 5 is an armature winding 3
6 is a voltage setting circuit, and 7 is an output voltage of the rotor position detection circuit 5 and an output voltage of the voltage setting circuit 6. 9 is a pulse generation circuit that generates a pulse every 60 electrical degrees from the output of the rotor position detection circuit 5; 10 is a pulse generation circuit 9; A rotation speed detection means has a timer 10a that measures the interval between pulses generated in the rotation speed detection means 10, and a calculation means 10b that calculates the rotation speed from the measurement result.
A memory llb that stores m outputs, and a predictive calculation means 11a that predicts and calculates the next rotation speed from the stored m outputs.
It is a rotation speed prediction means including.

Next, the operation will be explained. The rotor position detection circuit 5 is
By detecting the signal induced in the armature winding 3 by the rotation of the rotor, the signal shown in FIG. 2(a) is generated. This signal is detected by the pulse generating circuit 8, thereby generating pulses every 60 electrical degrees as shown in FIG. 2(b). Such a pulse generating circuit 9 is constituted by a combination of a logic circuit and a differential circuit as shown in FIG. 3, for example. In FIG. 3, 29 to 31 are OR circuits, 32.33 are NAND circuits, 34 to 36 are diodes, 37.38 is a capacitor, and 39.40 is a resistor. In this pulse generating circuit 9,
The pulse interval is measured by starting and stopping the timer 10a of the rotation speed detection means 10 using the rising edge (falling edge if the pulse is generated in the negative direction) of the pulse shown in FIG. 2(a) as a trigger. . Here, the pulses for measuring the interval may be continuous or may be pulses spaced at n intervals. The pulse interval thus measured is subjected to the calculation process N=/T (k is a constant determined depending on the structure of the motor, etc.) in the calculation means 10b to calculate the rotation speed N. The rotational speed obtained in this way is stored in the memory llb of the rotational speed prediction means 11 for m times including this time. The prediction calculation means 10a calculates the next rotation speed from the rotation speed data stored in the memory llb. At this time, it is also possible to appropriately weight the m pieces of data.

Next, the voltage setting circuit 6 increases or decreases the output voltage according to the difference between the predicted rotation speed obtained in this manner and the command rotation speed or command rotation speed range. Here, if the predicted rotation speed exceeds the command rotation speed or command rotation speed range, the output voltage is lowered, and conversely, if the predicted rotation speed is lower than the command rotation speed or command rotation speed range, the output voltage is increased. . The gate control circuit 7 controls the switching element built in the inverter 2 according to the output of the rotor position detection circuit 5 and the output of the voltage setting circuit 6, and applies three-phase AC voltage to the motor. Prevents rotation speed pulsation.

In the above embodiment, the rotor position detection circuit 5 uses the induced voltage of the winding. However, if a sensor can be attached to the motor, the signal output from this sensor can be used as the rotor position detection circuit 5. A similar effect can be obtained by performing position detection using .

〔Effect of the invention〕

As described above, according to the present invention, pulses are generated every 60 electrical degrees from the output of the rotor position detection circuit, the rotation speed is determined by measuring the interval between the generated pulses, and the next rotation is determined based on the result. In order to prevent rotation speed pulsations due to pulsating loads such as compressors, it is possible to predict the number of rotations and change the output voltage of the inverter depending on the difference from the command rotation speed or command rotation speed range. It has the excellent effect of being able to drive a motor with low vibration and low noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control device for a DC brushless motor according to an embodiment of the present invention, and FIGS. 2(a) and (b)
1 is an operation waveform diagram of each part to explain the operation of the rotor position detection circuit and pulse generation path shown in FIG. 1, and FIG.
FIG. 4 is a circuit diagram showing a specific example of the pulse generation path shown in FIG. 4, and FIG. 4 is a circuit diagram showing a conventional DC brushless motor control device.
FIGS. 5A and 5B are characteristic diagrams used to explain the operation of FIG. 4. 1 is a DC power supply, 2 is an inverter, 3 is an armature winding, 4 is a permanent magnet rotor, 5 is a rotor position detection circuit, 6 is a voltage setting circuit, 7 is a gate control circuit, 9 is a pulse generation circuit, 1
0 is a rotation speed detection means, and 11 is a rotation speed prediction means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent: Masuo Oiwa (2 others) Figure 2 (b) - L-shi”■L1-stop”- Figure 3/8 Figure 4

Claims (1)

[Claims] Detecting a magnetic pole position in a rotor of a DC brushless motor having a permanent magnet rotor to generate a position detection signal,
In a control device for a DC brushless motor that controls an inverter according to the position detection signal to convert DC into three-phase AC and apply it to the DC brushless motor to drive the DC brushless motor, the DC brushless motor is driven by controlling an inverter according to the position detection signal.
means for generating pulses for each degree; means for measuring n pulse intervals in the pulses; and calculating the rotation speed from the measured pulse intervals; predicting the next rotation speed from the m calculation results; A control device for a DC brushless motor, comprising means for increasing or decreasing the output voltage of the inverter according to the difference between the predicted rotation speed and a target command rotation speed or command rotation speed range.