JPS6395883A - Vacuum cleaner - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric vacuum cleaner, and particularly to a speed control device for an electric motor that is a II drive source thereof.

[Conventional technology]

An electric blower consisting of a fan and an AC commutator is used as the drive source for a vacuum cleaner. However, it involves mechanical sliding between a brush and a commutator, and with the recent trend toward smaller size and lighter weight due to higher speeds, commutation conditions have become stricter, causing sparks to be generated from the brushes and resulting in a shortened brush life.

As a countermeasure to this problem, an electric blower using a brushless DC motor has been proposed as described in Japanese Patent Laid-Open No. 60-242827. However, no consideration has been given to a speed control method for brushless DC motors suitable for vacuum cleaners.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not consider the speed control method of a brushless DC motor suitable for a vacuum cleaner, and has the problem of not being able to respond to changes in the load condition of the vacuum cleaner.

An object of the present invention is to control the speed of a brushless DC motor depending on the load condition of a vacuum cleaner.

[Means for solving problems]

The above object is achieved by performing open-loop voltage control on the brushless DC motor using an inverter control device based on a speed command, and further correcting the speed command in accordance with the load current of the motor.

[Effect]

A brushless DC motor is a synchronous motor that uses a permanent magnet for the field, but since the motor is controlled by an inverter control device in open-loop voltage control based on a speed command, the drooping characteristics of the motor cause the motor to rotate according to load changes. The number changes. Furthermore, by correcting the speed command according to the load current of the electric motor, the range of change in the rotational speed in response to load changes is increased, and a series characteristic is obtained. This allows for optimal motor control in response to vacuum cleaner load changes.
A vacuum cleaner with improved suction performance can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 shows the overall configuration of a speed control device comprising a brushless DC motor and an inverter control device according to the present invention.

The inverter control device 10 connects an AC power source 14 to a rectifier circuit,
15 and the smoothing capacitor 16, the illustrated DC voltage Ed
is obtained and supplied to the inverter 20.

This inverter 20 includes transistors T r x~T
12 composed of Re and freewheeling diodes D1 to DB.
It is a 0 degree conduction type inverter, and its AC output voltage is controlled by chopper operation by pulse width modulation of the conduction period (120 degrees electrical angle) of the positive potential side transistors TRx to TRs of the DC voltage Ed. It is assumed that

Furthermore, a low resistance R1 is connected between the common emitter terminals of the transistors TR4 to TRe and the common anode terminals of the freewheeling diodes D4 to DB.

The brushless DC motor 9 consists of a rotor 9-2 whose field is a two-pole permanent magnet and a stator into which an armature winding 9-1 is inserted, and the winding current flowing through the armature winding 9-1 is as follows. Since the voltage also flows through the low resistance R1, the load current Io of the motor 9 can be detected by the voltage drop across the low resistance Rz.

The control circuit that controls the speed of the brushless DC motor 9 is
A microcomputer 13, a magnetic pole position detection circuit 12 that detects the magnetic pole position of the rotor 9-2 upon receiving the output from the Hall element 11, a current detection circuit 17 that detects the value of the load current Io from the voltage drop across the low resistance R1, Transistor T R1
” It consists of a pace driver 19 that drives the T Re and a speed command circuit 18 that transmits a reference speed to the microcomputer 13.

The magnetic pole detection circuit 12 is a circuit that receives the output from the Hall element 11 and forms a position detection signal 12S corresponding to the rotor position. Then, using this position detection signal 128, the rotational speed of the brushless DC motor 9 is calculated and determined by the microcomputer 13.

The current detection circuit 17 is a circuit that detects the load current Io in response to a voltage drop across the low resistance R1, and forms a current detection signal 17S using an A/D converter (not shown) or the like.

Further, the microcomputer 13 includes a CPU, R
It is composed of OM, RAM, etc., and is connected to each other by an address bus, a data bus, and a control path (not shown).

The ROM stores various processing programs necessary to drive the brushless DC motor 9, such as speed calculation processing, command acquisition processing, speed control processing, and the like.

On the other hand, the above-mentioned RAM is made up of a storage section for reading and writing various data necessary for executing the above-mentioned various processing programs.

The transistors TR1 to TRe are configured by the pace driver 19 in response to the firing signal 13S from the microcomputer 13. Note that the voltage command circuit 21 forms a chopper signal as described later. In other words, in a brushless DC motor, the winding current flowing through the armature winding corresponds to the output torque of the motor, and by controlling the single winding current for each magnetic pole position, continuous control of the output torque is possible. It is.

FIG. 1 is a schematic block diagram showing the control circuit of the present invention. In the figure, when a command is input from the speed command circuit 18 to the microcomputer 13, the microcomputer 13 performs command acquisition processing, determines the speed command N, and outputs the voltage command V with a gain of 1. This voltage command V- is input to the D/A converter of the voltage command circuit 21, this output is compared with the output of the triangular wave generation circuit by a comparator, and the output is input to the pace driver 19, and the output is input to the brushless DC motor 9. The applied voltage is determined.

As a result, the brushless DC motor 9 is operated under open-loop voltage control based on the speed command N*, so the rotation speed may change due to the drooping characteristics of the motor due to changes in the load on the vacuum cleaner (for example, due to clogging of the filter in the main body of the vacuum cleaner). When the load is light, the number of revolutions increases, and when the load becomes heavy, the number of revolutions decreases.

That is, the same characteristics as AC commutator motors used in current vacuum cleaners can be obtained, and the motor can be controlled appropriately for vacuum cleaners.

Furthermore, the output of the current detection circuit 17 is input to the microcomputer 13, and the microcomputer 13 calculates the load current In and calculates the difference (rot-It) from the reference value Ior.
, calculates ΔV with a gain of 2, and adds it to the voltage command Vl. As a result, the voltage command v- of the brushless DC motor 9 is corrected by the value of the load current In corresponding to the load change (in other words, the speed command N is corrected), and the brushless DC motor 9 is opened based on this new voltage command V+oV. Since it is operated using loop voltage control (this control is called series control), the variable range of rotation speed is widened and series winding characteristics can be achieved, which has the effect of providing a vacuum cleaner with improved suction performance. .

FIG. 3 shows a performance curve of a vacuum cleaner in which a brushless DC motor is driven by the speed control device of the present invention.

The horizontal axis represents the air volume Q passing through the vacuum cleaner, and the vertical axis represents the suction power Poutyl, which represents the suction performance of the vacuum cleaner.It represents the rotation speed N and load current IO of the motor, from the maximum operating point to the minimum. The range of operating points is the operating range of the vacuum cleaner. The chain line shows the case when the motor is operated under normal closed-loop speed control, and since the rotation speed N is constant with respect to changes in air volume Q, the suction work: rate Pout is small, which is necessary as a vacuum cleaner. On the other hand, the solid line shows the case where the motor is operated under the open-loop voltage control according to the fourth invention, and since the rotational speed increases as the air volume Q decreases, the suction ratio Pout is large, The required performance as a vacuum cleaner can be obtained.Furthermore, the dash-dotted line shows the case where the motor is operated with series winding control according to the present invention, and the load current is .

Since the voltage correction amount Δv1 is determined from the amount by which the load current Io decreases with respect to the change in the air volume Q (Ioz Io) based on ID1, the rotation speed increases to the 12th power as the air flow fQ decreases. As a result, the suction power Pout
' is further increased, which has the effect of providing a vacuum cleaner with improved suction performance.

〔Effect of the invention〕

According to the present invention, an inverter-controlled brushless DC DC machine is used as the drive source of the vacuum cleaner, open-loop voltage control is performed based on the speed command, and the speed command is further corrected according to the load current. The electric motor can be controlled optimally in response to changes in the machine's load, and the vacuum cleaner with improved suction performance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing in block form a control circuit of a speed control device according to an embodiment of the present invention, FIG. 2 is an overall configuration diagram of a speed control device consisting of a brushless DC motor and an inverter control device, FIG. 3 is a performance curve diagram of the vacuum cleaner according to the present invention. 9... Brushless DC motor, 10... Inverter control device, 11... Hall element, 12... Magnetic pole position detection Im, 13... Microcomputer, 17...
Current detection circuit, 18... Speed command circuit, 19... Pace driver, 20... Inverter, 21... Voltage command circuit.

Claims (1)

[Claims] 1. In a vacuum cleaner using a speed control device consisting of a brushless DC motor and an inverter control device as a drive source, the control circuit of the inverter control device is a microcomputer, a current detection circuit, and a magnetic pole position detection circuit. and a speed command circuit, and the electric motor is subjected to open-loop voltage control based on the speed command of the speed command circuit. 2. The vacuum cleaner according to claim 1, wherein the speed command is corrected according to the load current of the electric motor.