JP2532373B2 - Rotating machine control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling the number of revolutions of a rotary cooker used in general households.

2. Description of the Related Art Conventionally, phase control has been often used for speed control of a rotary cooking machine. In this phase control, the amount of electricity supplied in one waveform of an AC power supply is controlled to control the rotation speed of an electric motor.

Hereinafter, a conventional controller for a rotary cooking machine as described above will be described with reference to the drawings.

FIG. 3 is a block diagram of a conventional control device for a rotary cooking machine. In FIG. 3, 101 is an AC power supply, and 102 is a full-wave rectifier, which is connected to both ends of the AC power supply 101 and converts AC to DC. The electric motor 103 and thyristor 104 are this full-wave rectifier.
The output terminal of 102 is connected in series to both ends. Reference numeral 105 designates a gate pulse generation circuit for generating a gate pulse of the thyristor 104, reference numeral 106 designates a gate pulse generation timing control circuit for controlling a timing for generating the gate pulse,
107 is a frequency discriminating circuit for discriminating the power supply frequency.

The following operation of the control device for a rotary cooking machine configured as above will be described.

First, the gate pulse generated by the gate pulse generation circuit 105 is generated by the gate pulse generation timing control circuit 106 at a timing such that the amount of electricity supplied to the electric motor 103 becomes a desired amount of electricity supplied. However, as shown in FIG. 4, when the gate pulse is generated at the same timing when the frequency is 50 Hz and 60 Hz, the amount of electricity supplied to the electric motor 103 is different, so that a large difference occurs in the rotational speed of the electric motor 103. Therefore, the frequency discrimination circuit 10 of FIG.
The frequency is discriminated in 7 and the generation timing of the gate pulse is changed according to each frequency so that the same energization amount is obtained.

Problems to be Solved by the Invention As shown in FIG. 5, a method of discriminating this frequency is to generate a pulse when the AC power source becomes 0 volt, and measure the number of pulses generated within a certain time. The power supply frequency can be determined. Further, the frequency can be similarly determined by measuring the pulse interval Δt. However, the above method requires a circuit that generates a pulse and a counter circuit that counts the pulse when the AC power supply becomes 0 V, and these circuits are very complicated and costly. There was a flaw.

Further, as another means for discriminating the frequency, Japanese Patent Laid-Open No. 60-
170497, the commercial power supply frequency detection unit for detecting the frequency of the commercial power supply, and a motor control circuit unit for controlling the energization time to the motor according to the power supply frequency by the detection output of the commercial power supply frequency detection unit. There was something that was done. However, since this commercial power supply frequency detection unit detects the power supply frequency every half cycle of the commercial power supply,
The motor control circuit unit needs to be configured to drive the thyristor via a flip-flop, an astable multivibrator, etc., which has a drawback that the energization rate of the motor can be changed only in a cycle longer than the cycle of the commercial power supply.

In view of the above drawbacks, the present invention provides a frequency discriminating circuit for keeping the number of revolutions of a motor constant irrespective of the power supply cycle, by counting the number of zero volt pulses within a certain period of time, and the pulse interval Δ.
To provide a control circuit that makes it possible to obtain a drive signal for a thyristor synchronized with a half cycle of an AC power source from the voltage across the thyristor without measuring the t response and to keep the rotation speed of the motor constant. To do.

Means for Solving the Problems In order to solve the above problems, a control device for a rotating machine according to the present invention includes a full-wave rectifier connected to both ends of an AC power source for converting AC into DC, and the full-wave rectifier. Of the rectifier output terminal connected in series to the thyristor, a first capacitor connected via a resistor and a diode between the anode and cathode of the thyristor, and the terminal voltage of the first capacitor First voltage comparator for comparing with the output voltage of the reference circuit, a pulse generation circuit for generating a pulse having a width proportional to the half-wave width of the AC power supply, and a CR integration connected to the output of the pulse generation circuit. A circuit and a second voltage comparator for comparing the output voltages of the CR integrator circuit and the second reference circuit, the thyristor being turned on in accordance with the output of the first voltage comparator. , The above The output of the voltage comparator differs depending on the power supply frequency of the AC power supply, and the output voltage of the first reference circuit is set in two ways according to the output of the second voltage comparator. There is.

Operation With this configuration, the capacitor of the CR integrator circuit is charged by the output of the pulse generation circuit during the period proportional to the half cycle of the AC power supply, and the output of the second voltage comparator can be changed according to the power supply frequency. From this result, the generation timing of the drive signal of the thyristor can be corrected by the power supply frequency, and the electric motor can be driven at a constant rotation speed regardless of the power supply frequency.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a controller for a rotating machine according to an embodiment of the present invention.

In FIG. 1, 1 is an AC power supply, 2 is a full-wave rectifier that converts AC into DC, and an electric motor 3 and a thyristor 4 are connected in series to the full-wave rectifier 2. 53 is a gate pulse generation timing control circuit, which connects the first capacitor 8 to the anode of the thyristor 4 via the resistor 6 and the diode 7, and connects the first capacitor 8 to the first voltage comparator 9. The terminal voltage of the first capacitor 8 is compared with the reference voltage of the first reference circuit 54. The gate pulse generation circuit 52 drives the thyristor 4 by the output of the first voltage comparator 9. Reference numeral 51 is a frequency discriminating circuit, which is a pulse generating circuit 55 for generating a pulse having a width proportional to the half-wave width of the AC power supply 1, a CR integrating circuit 56 connected to the output of the pulse generating circuit 55, and a CR integrating circuit. A second voltage comparator 24, which connects 56 and a second reference circuit 57, is provided, and the output of the second voltage comparator 24 is connected to a resistor 13 which is a part of the first reference circuit 54. It is connected via a resistor 28 to the base of a transistor 16 connected in parallel via 15.

 The operation based on the specific circuit configuration will be described below.

First, when one of the waveforms that is full-wave rectified by the full-wave rectifier 2 is applied, the first capacitor 8 of the gate pulse generation timing control circuit 53 passes through the motor 3, the resistor 6, and the diode 7.
Will be charged. When the voltage of the first capacitor 8 becomes higher than the voltage compared by the first voltage comparator 9, the output of the first voltage comparator 9 becomes "L" level, and the transistor 10 in the gate pulse generating circuit 52 When the transistor 10 is turned on, the electric charge of the first capacitor 8 is discharged to the gate terminal of the thyristor 4 via the transistor 10 and the resistor 12, and the thyristor 4 is turned on. The thyristor 4 turns on when the full-wave rectified waveform becomes 0 volt. After that, the above-described operation is repeated.

Here, the gate pulse is generated by delaying the constant time t created by the CR timer with the first capacitor 8 and the resistor 6, but if the power supply frequency changes to 50Hz or 60Hz, it may be delayed for the same time. Since the amount of electricity supplied to No. 3 changes and the rotation speed does not become constant, it is necessary to change the amount of electricity supplied according to the power supply frequency. Therefore, the reference voltage of the first reference circuit, which forms the reference voltage of the first voltage comparator 9, is changed according to the conduction state of the transistor 16 to change the level at which the voltage of the first capacitor 8 is detected to change the delay described above. The time t is changed so that the same amount of power is supplied when the power supply frequency is 50 Hz or 60 Hz.

 Next, the frequency discrimination circuit 51 will be described.

Reference numerals 17 and 18 are voltage dividing resistors for lowering the half-wave voltage level of the AC power supply 1. 19, 20 is an open collector output comparator 21
It is a voltage dividing resistor that makes the reference voltage of. When the half-wave of the AC power supply whose level is lowered by the resistors 17 and 18 becomes higher than the reference voltage created by the resistors 19 and 20, the output of the comparator 21 becomes open level and the capacitor is connected via the resistor 22 of the CR integration circuit 56. Charging is started in 23, and the voltage charged in the capacitor 23 is compared with the reference voltage of the second reference circuit 57 composed of the voltage dividing resistors 25 and 26 in the second voltage comparator 24 having an open collector output, When the voltage becomes higher than this reference voltage, the output of the second voltage comparator 24 becomes "L" level. As shown in FIG. 2, the reference voltage of the second voltage comparator 24 is set to the center voltage of the peak voltage V _P50 of the capacitor 23 at 50 Hz and the peak voltage V _P60 of the capacitor 23 at 60 Hz. In other words, when the output of the second voltage comparator 24 is 50 Hz, a negative pulse is output as shown in FIG. 2b, and when it is 60 Hz, the output is open. A capacitor 27 is provided at the output of the second voltage comparator 24.
Is connected, and while the output of the second voltage comparator 24 is at the open level, it is charged via the resistors 28 and 29 and the transistor 16 so that the capacitor 27 is used at 60 Hz.
The voltage of the
Is off. At 50 Hz, the output of the first voltage comparator 24 becomes "L" level at each power supply cycle, and therefore the voltage of the capacitor 27 does not exceed a certain level. If this voltage is set to a level at which the transistor 16 can be turned on sufficiently, the transistor 16 turns on at 50 Hz,
It seems to be off at Hz.

By doing so, the resistor 13 connected in parallel with the resistor 13 forming the reference voltage of the first voltage comparator 9 for changing the timing of generating the gate pulse described above.
15 can be connected or disconnected, the delay time t can be changed by changing the reference voltage, the amount of electricity to the electric motor 3 is the same at 50 Hz and 60 Hz, and the rotation speed of the electric motor 3 is constant. Of.

As described above, according to this embodiment, the terminal voltage of the first capacitor 8 charged by the voltage of the thyristor 4 connected in series to the electric motor 3 is compared with the reference voltage of the first reference circuit 54. The output of the CR comparator circuit 56 and the second reference circuit which are charged by the output of the voltage comparator 9 and the pulse generation circuit 55 which generates a pulse having a width proportional to the half-wave width of the AC power supply 1.
The second voltage comparator 24 for comparing with the reference voltage of 57 is provided, and the output of the second voltage comparator 24 is connected to the first reference circuit 54 so that the reference voltage can be changed according to the power supply frequency. The electric motor 3 can be driven at a constant rotation speed regardless of the power supply frequency.

Effects of the Invention As described above, the present invention provides a full-wave rectifier that is connected to both ends of an AC power source and converts AC into DC, and an electric motor and a thyristor that are connected in series to both ends of a rectification output terminal of the full-wave rectifier. , A first capacitor connected to the anode of the thyristor via a resistor and a diode, a first voltage comparator for comparing a terminal voltage of the first capacitor with a reference voltage of a first reference circuit, and an AC power supply Pulse generator circuit for generating a pulse having a width proportional to the half-wave width of the pulse generator, a CR integrator circuit connected to the output of the pulse generator circuit, and a second circuit connecting the CR integrator circuit and the reference circuit of FIG. And a voltage comparator for connecting the output of the first voltage comparator to the thyristor via a transistor, and
Since the output of the voltage comparator is connected to the first reference circuit so that the reference voltage can be changed according to the power supply frequency, the power supply frequency is discriminated every half cycle, and the thyristor drive signal is supplied every half cycle. Since the correction is performed, it is possible to always obtain a stable drive signal in synchronization with the half cycle of the AC power source, and it is possible to stably and constantly maintain the rotation speed of the electric motor.

Further, since no circuit element such as a flip-flop is used, the frequency of malfunctions is low, and the influence of impulse noise on the rotation speed of the electric motor can be suppressed.
Furthermore, the circuit configuration is simple, the reliability is high, and the cost is low.

[Brief description of drawings]

Circuit diagram of the control device of the rotary machine in an embodiment of Figure 1 the present invention, Figure 2 a, b is the voltage waveform and the second voltage comparator of the reference voltage of the capacitor of the CR integration circuit when the 50H _Z When,
Output waveform diagram of the second voltage comparator, the voltage waveform and the reference voltage diagram of the second voltage comparator of the capacitor of the CR integration circuit when the second FIG c is 60H _Z, Fig. 3 is of a conventional rotary machine 4 is a gate pulse waveform diagram and FIG. 5 is a pulse waveform diagram. 1 ... AC power supply, 2 ... Full-wave rectifier, 3 ... Electric motor, 4
...... Thyristor, 6 ... Resistance, 7 ... Diode, 8 ...
… First capacitor, 9 …… First voltage comparator, 10 ……
Transistor, 24 ... Second voltage comparator, 54 ... First reference circuit, 55 ... Pulse generation circuit, 56 ... CR integration circuit,
57 …… Second reference circuit.

Claims (1)

(57) [Claims] 1. A full-wave rectifier connected to both ends of an AC power source for converting AC into DC, and a motor and a thyristor connected in series to both ends of a rectified output terminal of the full-wave rectifier.
A first capacitor connected between the anode and cathode of the thyristor via a resistor and a diode; and a first voltage comparator for comparing the terminal voltage of the first capacitor with the output voltage of the first reference circuit, A pulse generation circuit for generating a pulse having a width proportional to the half-wave width of the AC power supply, a CR integration circuit connected to the output of the pulse generation circuit, and a CR integration circuit
The thyristor includes a second voltage comparator that compares the output voltage of the second reference circuit with the output voltage of the second reference circuit, and the thyristor is turned into a conductive state in accordance with the output of the first voltage comparator. The output of the voltage comparator differs depending on the power supply frequency of the AC power supply, and the output voltage of the first reference circuit is set in two ways according to the output of the second voltage comparator. Control device.