JPS60109785A - Speed control circuit of ac motor - Google Patents

Abstract

PURPOSE:To enable to select to arbitrarily switch a full-speed mode, a deceleration mode and stop mode by selecting a combination of the outputs of speed timings to output a plurality of speed mode voltages. CONSTITUTION:An AC motor 15 is driven through a switching element 13 from an AC power source 1. A zero crossing detector 2, a 1/3 deceleration synchronous timing forming circuit 4, a 1/2 deceleration synchronous timing forming circuit 5 and a selector 8 are provided in a drive circuit. The mode is switched by a level input signal for selecting a level input signal 9 for selecting 1/2 or 1/3 speed rotation mode, a selection level input signal 10 of full speed or non-full speed motor, and a level input signal 11 for selecting the rotation or stop mode, thereby operating the stop, full speed, 1/2 deceleration or 1/3 deceleration of the motor.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a speed control circuit for an AC motor, and particularly to a speed control circuit for an AC motor that can be switched between full speed, several deceleration modes, and stop modes, and that does not require a constant speed. sink.

The present invention relates to a speed control circuit for an AC motor suitable for controlling the speed of a Ronas motor or the like.

[Background of the invention]

Conventionally, a mechanism for controlling the speed of an AC motor such as a synchronous motor has been known to have a monitor equipped with a reducer such as a gear head, but this requires a lever or other device to change the speed. Since it requires manual operation, it has disadvantages such as poor operability and increased weight and capacity. On the other hand, electric motors are equipped with a tacho generator, which detects a voltage proportional to the number of rotations, and performs phase control using Cyrisk etc. according to the detected voltage amount to maintain a constant speed. However, a speed control circuit must be added in addition, which has the disadvantage of complicating the circuit configuration and increasing the price.

[Purpose of the invention]

The purpose of the present invention is to eliminate such conventional drawbacks, and to provide an AC motor that is small, lightweight, easy to operate, has a simple circuit, and is low in price, which can switch between full speed mode, deceleration mode, and stop mode at will. The object of the present invention is to provide a speed control circuit.

[Summary of the invention]

In order to achieve the above object, the AC type 11+ according to the present invention
The speed control circuit of the machine includes means for creating a plurality of speed timings from a waveform of an input AC power source, and selecting a combination of outputs of the speed timings in a speed control circuit that controls the rotational speed of an AC motor. The present invention is characterized in that it includes means for outputting a speed mode voltage of , and means for supplying driving power to the AC motor using the speed mode voltage.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a speed control circuit for an AC motor showing an embodiment of the present invention, and FIG. 2 is a waveform diagram of each part in FIG. 1.

In FIG. 1, 1 is an AC power supply, for example, 5Q
H or 60H2 commercial AC power supply, or an inverter output AC power supply that generates AC voltage may be used, but a constant frequency AC power supply is most desirable. 2 is a zero-cross detection circuit, for example, one composed of a step-down transformer for isolation, a diode full-wave co-current bridge, and a transistor switching circuit, or a step-down center tap output cadence for isolation, and an aftereffect rectifier diode. Instead of an isolation transformer, a zero-cross detection circuit that combines an isolation element such as a photocoupler or phototransistor with a thyristor or the like may be used. 3 is the output signal of 2.

ヰ is a 1/3 deceleration synchronization timing creation circuit, and the convex part is a 1/2 deceleration synchronization timing creation circuit. Both circuits are composed of, for example, a logic synchronous counter IC or a synchronous shift register IC. Anything you like is fine. 6 is a dedicated output signal, and 7 is a convex output signal, and output signals 6 and 7 are synchronized with output signal 3. 8 is a selector circuit, for example, it is implemented by an inverter IC for logic, an OR IC, an AND IC, etc., and the selector circuit is controlled by mode switching determined by the combination of level input signals 9, 10, and Output 12 of circuit 8 is switched and selected.

Here, 9 is for selection of 1/2 speed rotation mode or 1/3 speed rotation mode, 10 is for selection of full speed mode or non-full speed mode, and 11 is rotation mode These are level signals with respective meanings for selecting the mode or stop mode. 12 is an output signal of the selector circuit 8. 13
is a switching element, and may be, for example, a semiconductor switching element such as an SSR, or a switching element having a mechanical contact with an N magnetic switch or a relay. Reference numeral 14 denotes a drive circuit for the switching element 13, which may be, for example, a transistor, an IC for logic owned by the oven collector, or the like. 15 is an AC electric power country, for example, there is a synchronous motor, etc. 16 is 15
This is a phase advance capacitor.

Next, the operation will be explained with reference to FIG.

When AC power supply 1 is turned on, the voltage waveform of AC power supply 1 is indicated by A in the second section, and after full-wave rectification in zero-cross detection circuit 2 (the full-wave rectified voltage waveform is indicated by B in Fig. 2). ), the inverter waveform is shaped by transistor switching, and C in Figure 2 is obtained.C has just detected the phase of A, that is, the zep cross point. uses zero cross detection output 3 as the trigger input,
They output frequency-divided output signals 6 and 7, respectively.

The output waveforms of the frequency-divided output signals 6 and 7 are D and E in FIG. Here, the frequency-divided output signals 6 and 7 are synchronized with the zero-cross detection output 5. That is, the minute signal 6 is a signal synchronized with a cycle twice that of A, and the signal 7 is synchronized with a cycle three times that of A.

8 is a selector circuit which receives signals 6, 7, 9° 10.11 as input, and internally has a three-stage configuration.
That is, the F1 stage is an AND stage for outputs 6 and 7 using the level input signal 9, the second stage is an OR stage for each output of the first stage using the level input signal IO, and the third stage is as follows: This is an AND stage formed by each output of the second stage and the level input signal 11. The input signal 90 level is '11' level and 'l,
There is a case of two levels with I+ level, and 1/2 deceleration rotation mode selection and 1. /3X Compatible with cross-section rotation mode selection. That is, it is F in FIG.

Now, if the input signal 90 level is "L" level, only the logical product output with output cuff, and if the input signal 90 level is °'L'' level, only the logical product output with output O. , the first stage of the selector circuit 8 outputs the signal. The second stage output is the binary level of the input signal 10, that is, if it is "H" level, full speed mode is selected, and if it is "L" level, it is non-full speed mode selection. When is at the +Ll+ level, the first stage output of the selector circuit 8 is output as is, and when the input signal 10 is at the 'H' level, the output is 'H' regardless of the first stage output of the selector circuit 8.
”° level is output.The third stage output also receives the input signal 11.
That is, if the level is ++H++, the rotation mode is selected, and if it is 1 level, the stop mode is selected.Since it is H in FIG.
When it is at the ° level, the second stage output of the input signal 8 is output as it is, and when it is at the I+ level, the "L" level is output, which is related to the second stage output of the selector circuit 8. Ru.

That is, I in FIG. 2 expresses all of the above cases.

This is the output signal 12 of the selector circuit 8. .

The signal 12 opens and closes the switching element 13 via the drive circuit 14. That is, when the signal 12 is...F(...-, the switching element 13 is closed, and when the signal 12 is °°L'', Switching element 1
3 is open, the voltage waveform input to the AC motor 15 is as follows.
It becomes J. In this embodiment, it has been explained that the input level signals of the selector circuit 8 are 9, 10, and 11, but if the timing generation circuit in the previous stage is changed to the circuit configuration in which 5 is used as the input signal, the selector circuit 8 can be simplified. It is easily obvious that this will be the case. Further, in this embodiment, the mode is full speed rotation mode.

An example of four motor rotation modes, 1/2 speed rotation mode, 1/3 speed rotation mode, and stop mode, has been explained, but in the case of a small number of modes, it is recommended to reduce the number of circuit blocks in one of them. , or 9, 10, and 11 depending on the selection of the mode generated by the combination of input levels. In the case of a large number of modes, the deceleration synchronization timing generation circuits 4 and 5 can be used in the same manner.
It can be easily inferred that it is only necessary to increase the select signals 9 to 11 for selecting the output, and in either case, it can be realized. According to this embodiment, by using 4.5.8.degree. 14 circuit blocks (logic ICs), the packaging density can be improved.

In addition, 50H2 commercial AC power supply is applied to this implementation circuit, and 50H2 commercial AC power is applied.
H,, 3000 rpm with a commercial AC power supply [When the rotation speed was measured by rotating the motor under load, it was 3000 rms in full speed rotation mode, 1500 rms in 1/'2 deceleration rotation mode, 1010 in 1/3 deceleration rotation mode.
0Or, it has been confirmed that C stops reliably in stop mode. Furthermore, it is also evident that the voltage waveforms at various parts of this embodiment of the circuit are as shown in FIG.

In Figure 1, all of the circuit block sections 2 to 14, or all the circuits except for sections 15 and 16, can be mounted on the board for high-density mounting, resulting in lighter weight and smaller volume. , can bring about lower prices. Also,
Further developing the unique effects of Honji 1, part 3 of 2...
8.12.1 Focusing on the fact that all of the circuit block parts of the cow are semiconductor elements, ICs, and element configurations, it can be made into hybrids, highly integrated hybrids, highly integrated ICs, etc., resulting in a lightweight single circuit configuration. simplification, smaller size, power saving,
This can further reduce prices. .

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to switch to a plurality of speed modes, and this is done automatically, so the operability is good, the circuit is simple, and the circuit blocks are integrated into ICs, so that the 4-type It is possible to realize a more beautiful house and lower prices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a speed control circuit for an AC motor showing an embodiment of the present invention, and FIG. 1 is a waveform diagram of each part of the r1 diagram. l Two-current source, 2: Zero cross detection circuit, 4 = 1/3 deceleration synchronization timing creation circuit 5.5: 1/2i; Speed synchronization timing creation circuit, 8: Selector circuit, 9! 1/
Level human power signal for selection of 2 or 1/3 continuous transmission mode,
lO: Level input signal for selection of full speed or non-full speed rotation mode, 11: Level human power for selection of rotation or stop mode [O, 13: Switching element, 14: Drive circuit, 15: AC motor, 16:. Phase advance capacitor. Representative Patent Attorney Akio Takahashi

Claims (1)

[Claims] (1) A speed control circuit that controls the rotational speed of an AC motor. means for outputting a mode voltage;
A speed control circuit for an AC motor, comprising means for supplying driving power to the AC motor using the speed mode voltage.