KR910008827B1 - Revolution detecting circuit of electric motor - Google Patents

Abstract

The detector detects the magnetic field varied according to the rotation of a rotator and converts the magnetic field variation into corresponding voltage level using a F/V modulator. The detector includes a magnetic field detector (81,82,83) for generating pulse signals according to the magnetic field created between a stator and a rotor, and a F/V modulator (101) for converting the frequency of the pulse into the voltage level. The magnetic field sensors (81,82,83) detects the magnetic field generated by (A),(B), and (C) stator coil and rotator respectively to decrease the input period of pulse signals.

Description

Speed Detection Circuit of Motor

1 is a circuit diagram showing a fan circuit of this embodiment.

2 is a schematic configuration diagram showing a gas combustion hot water heater of this embodiment.

3 is a block diagram showing a control device of a gas combustion hot water heater.

4 is a schematic diagram showing a brushless DC motor of this embodiment.

5 is a time chart of output voltages of the F / V conversion circuit according to the present embodiment and the prior art.

6 is a waveform diagram showing an output state of a three-phase hall IC.

* Explanation of symbols for main parts of the drawings

80: brushless motor (motor)

81, 82, 83: Hall IC (magnetic field detection means)

87: rotor 100: rotation speed detection circuit

101: F / V conversion circuit (F / V conversion means) A, B, C, a, b, c: stator

84, 85, 86: stator winding

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation speed detection circuit for detecting rotation speed of an electric motor, and in particular, a rotation detection circuit that detects a magnetic field generated by rotation of a rotor and converts the voltage to a voltage corresponding to the rotation speed of the rotor. It is about.

In the case where there is a device to be driven in synchronization with the rotational speed of the motor by using an electric motor whose rotational speed changes in response to the control state, especially when the motor is used for driving such as a blower, the rotational speed of the motor is controlled. It is difficult to follow and may be delayed, so it is necessary to detect the rotation speed frequently.

For this reason, a method of detecting a magnetic field generated by the rotor of the rotor by magnetic field detecting means such as a hole element and detecting the number of revolutions based on the detected pulse signal is performed.

In this method, a single magnetic field detecting means detects the magnetic field by the rotor to generate a pulse signal. Then, the voltage value is changed to a predetermined voltage in the F / V conversion circuit 101 as shown in FIG. It is being read by the signal indicating the rotation speed.

However, in order to read as a signal indicating the number of rotations of the output voltage value in the F / V conversion circuit, the output voltage of the F / V conversion circuit must be as stable as possible.

Since this output voltage is shown as the output voltage of the smoothing circuit by the capacitor | condenser 102 connected to the output terminal of an F / V conversion circuit in FIG. 1, in order to stabilize an output signal, it is good enough to enlarge this capacitor capacity | capacitance. However, when the capacity of the condenser is large, the reaction when the rotation speed is changed tends to be slow, and as in the present state, in the F / V conversion by the pulse signal in one magnetic field detection means, the accuracy of the reaction speed and output voltage is There is a problem that it is difficult to improve the degree of synchronization with the electric motor to be opposed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotation speed detection circuit having a good detection accuracy while increasing the harvesting speed of a rotation speed change in a rotation speed detection circuit of an electric motor.

The present invention provides a magnetic field detecting means for generating a pulse signal by detecting a magnetic field generated between the rotor and the stator by means of a rotor provided in the stator, and based on the pulse signal from the magnetic field detecting means. In a rotation speed detection circuit of an electric motor comprising an F / V conversion means for generating a voltage corresponding to the rotation speed of an electron, a plurality of magnetic field detection means are provided in response to a constant of a winding of the stator, and the F / V conversion is performed. The technical means is to generate a voltage corresponding to the rotational speed of the rotor based on the pulse signal from the magnetic field detecting means.

In the rotation speed detection circuit of the present invention, magnetic field detection means are provided in accordance with the constants of the windings of the stator of the motor, and the F / V converting means has a rotation speed of the rotor due to the pulse signal in each of the magnetic field detection means. Output the voltage corresponding to

In the present invention, the F / V conversion means receives pulse signals from the magnetic field detection means corresponding to the number of stators. Therefore, since the input period is shortened in the pulse signal as compared with the conventional rotational speed detection circuit, the number of input pulses at the same rotational speed becomes large.

As a result, the output voltage generated by the F / V converting means is stabilized. In addition, when the rotation speed of the motor changes, it is possible to quickly harvest only the minute in which the pulse signal input cycle is short and to output a voltage corresponding to the rotation speed.

Next, the rotation speed detection circuit of the electric motor of this invention is demonstrated based on the Example shown in drawing.

2 shows a gas-fired hot water heater 1, in which a combustor case 10 is installed in the hot water heater case 2, and therein, a fuel gas supplied by the gas supply pipe 20 is combusted. Two burners 11 are provided.

Moreover, the combustor case 10 is equipped with the combustion fan 12 using the brushless direct current (DC) motor of a 3-phase Y connection line, and the burner 11 is the combustion supplied by this combustion fan 12. It is a forced-air combustor combusted by the use air, and combustion exhaust gas is exhausted from the exhaust port 3 to the outside.

And the heat exchanger 13 connected with the water supply pipe 30 is installed above the combustor case 10, and the water which passes inside is heated by the heat which the burner 11 generate | occur | produces.

In the vicinity of the burner 11 in the combustor case 10, a sparker 14 as an ignition device and a flame rod 15 as flame detection means are provided.

Furthermore, a temperature fuse 16 for stopping the operation of the gas-fired hot water heater is provided on the upper outer portion of the combustor case 10 that is melted and broken when the combustor case 10 becomes hot due to abnormal combustion.

The gas supply pipe 20 has a constant pressure regulator which controls the supply pressure of the primary solenoid valve 21, the kettle valve 22, and the fuel gas to be supplied with a supply pressure, through which the fuel gas passes through the upstream. Replacement solenoid valves 24 for blocking the fuel gas to one of the proportional valve 23 and the double burner 11 in accordance with the use state are provided, respectively, to supply the fuel gas to the burner 11 described above.

In addition, a water discharge pipe 32 having a water filter 31 is installed at the uppermost part of the water supply pipe 30, and downstream of the water supply pipe 30, a water quantity control is performed by a geared motor for adjusting the inflow of water into the heat exchanger 13. A valve 33 is provided, and the water quantity control valve 33 is provided with a potentiometer 34 for detecting the opening degree.

Then, the water in which the flow rate is adjusted in the water flow control valve 33 is immediately detected the temperature by the water inlet temperature thermistor 35 installed downstream, the flow rate is detected again by the water flow sensor 36 downstream, the water supply pipe Passed through (30) is sent to the heat exchanger (13).

In addition, the heat exchanger 13 is provided with a safety switch 37, and the timing of the fire extinguishing of the burner 11 and the control of water in the water supply pipe 30 is poor, and the heat exchanger 13 is operated by the remaining fire. The operation stops when the temperature in the water rises abnormally. A tapping temperature thermistor 38 is provided, and a boiling preventing switch 39 is provided downstream.

In addition, in the vicinity of the water supply pipe 30 in the water heater case 2, a freeze prevention heater 40 is provided at several places, and when the low temperature is sensed by the low temperature detection switch 41 in the water heater case 2, it is energized and cold Seven segments are displayed which are indicated by the number of devices due to freezing of the city. In this seven segment, an error message specified in advance when the control circuit 60 is abnormal can be displayed.

The control circuit 60 includes a sparker circuit 61, a fan circuit 62, a proportional valve circuit 63, a geared motor circuit 64, centering on a microcomputer 70 (hereinafter referred to as a CPU). There are a position detecting circuit 65 and a quantity detecting circuit 66, and these circuits are subjected to predetermined control by the CPU 70.

In addition, the sparker circuit 61 causes a flame discharge on the discharge cap of the sparker 14, detects the flame discharge on the discharge cap, and sends a detection signal to the CPU 70.

The fan circuit 62 is formed like the circuit shown in FIG. 1, and the three-phase Y connection shown in FIG. 4 for rotating the combustion fan 12 in response to a combustion demand such as a set water temperature. The rotation speed is detected by a motor driving circuit 90 for energizing the brushless DC motor 8 and hall ICs 81, 82, 83 provided in the brushless DC motor 80. It is comprised by the rotation speed detection circuit 100 which sends a detection signal to CPU70.

In addition, the brushless DC motor 80 has stator windings 84, 85, and 86 respectively provided in the stator A, (a), (B), (b), (c), and (c) facing each other. Hall ICs 81, 82, and 83 are provided to provide terminals 91, 92, and 93 of the motor drive circuit 90, respectively, in order to energize the circuits.

The hall ICs 81, 82, 83 and the rotation speed detection circuit 100 are the magnetic field detection means and the rotation speed detection circuit of the present invention, respectively. The detection cycle is shortened by detecting rotation signals from the hall ICs 81, 82 and 83 provided in all three-phase stators.

The output terminals 94, 95 and 96 of the motor drive circuit 90 are connected to the winding terminals 84a, 85a and 86a of the brushless DC motor 80, respectively. The common terminal 80a of the 80 is connected to the earth terminal 97 of the motor drive circuit 90.

The hole ICs 81, 82, and 83 in the brushless DC motor 80 have their respective projection ends when the projection ends of the rotor 87 are attracted to each stator (A), (B) and (C). The switching signal is generated by the magnetic field generated between and, and the polarity of the stator A, a, B, b, C, c is changed according to the switching signal, and this is repeated, thereby rotating the rotor 87. Continues.

In addition, the input terminals 91, 92 and 93 of the motor driving circuit 90 are terminals to which predetermined signals output from the hall ICs 81, 82 and 83 are input. The outputs of (82) and (83) are input to the logic circuit and at the same time as the input terminal of the F / V conversion circuit 101.

Accordingly, as a combination of logic circuits, the winding terminals 84a (of the motor) at the output terminals (94: U phase windings of the motor), (95: V phase windings), (96: W phase windings) of the motor driving circuit 90 ( 85a) (86a) is inputted to flow current in the order of U → V → W → U winding.

In other words, when a current is first flowed from the U-phase winding to the W-phase winding, the magnetic pole is formed in the U-phase winding to the N pole, and the magnetic pole is formed in the S-phase winding.

After a predetermined current flows from the V-phase winding to the W-phase winding, the V-phase winding forms an N-pole magnetic field, and the W-phase winding forms an S-pole magnetic field, and a rotor magnetic field is formed by the sequential current. As the rotor 87 rotates, a predetermined frequency is generated in the hall ICs 81, 82 and 83.

In addition, the output of the Hall IC is input through the input terminals 91, 92 and 93 of the motor drive circuit 90 to be fed back.

The feedback signal is again formed through the logic circuit which is the motor driving circuit 90 to form the driving signal of the motor and outputs it through the output terminals 94, 95 and 96. It is formed as shown in FIG.

In addition, the magnetic field signals Hu, Hv, and Hw are inverted through respective inverters 97, 98, and 99, and then the digital transistors 104, 105 in the rotation speed detection circuit 100 are respectively inverted. ) And 106 are added to the F / V conversion circuit 101, wherein the input signal is a combination of the rotor magnetic signals (Hu, Hv, Hw), the number of pulses are Hu, Hv, Hw It has three times as many pulses as each pulse number.

On the other hand, the F / V conversion circuit 101 having received the above signal counts the number of pulses, generates a predetermined voltage proportional to the count value, and applies the predetermined voltage to the predetermined system. It is controlled to a predetermined voltage proportional to the rotation speed.

Since the rotor 87 is quadrupole, four switching signals are generated in each of the hall ICs 81, 82, and 83 while the rotor 87 is rotated once.

In addition, although the rotation speed detection circuit 100 inputs only four switching signals from one Hall IC in the related art, in this embodiment, the switching signals are input from all of the Hall ICs 81, 82, and 83. Therefore, the switching signal 100 is input three times the switching signal in accordance with the constant of the winding of the stator.

When the switching signals are input from all of the Hall ICs 81, 82, and 83, the period of the signal input to the rotation speed detection circuit 100 is shortened, and the F / V conversion circuit of the rotation speed detection circuit 100 is reduced. The variation in the output voltage at 101 is small compared to the broken line E showing the conventional output voltage as indicated by the solid line D in FIG.

Therefore, since the voltage range when smoothed by the condenser 102 and read in at the rotational speed from the output terminal 103 can be narrowed, the change is quickly expressed as a change in the rotational speed of the combustion fan 12 and the harvestability is increased. This is good.

And the proportional valve circuit 63 is a circuit which controls the energization amount to the constant pressure proportional valve 23 in order to adjust the supply amount of fuel gas so that combustion in the burner 11 may be performed by a desired air-fuel ratio, and a constant pressure proportional valve The amount of energization to 23 is controlled based on the rotational speed of the combustion fan except at the time of ignition.

In this embodiment, since the harvestability of the combustion fan 12 of the rotation speed detection circuit 100 described above is good, the desired air-fuel ratio can be reliably obtained even when the set temperature is changed.

The geared motor circuit 64 is a circuit for driving the geared motor of the water quality control valve 33 for adjusting the water flow in the heat exchanger 13, and the water quality control valve 33 responds to the control signal. Open road.

In addition, the position detection circuit 65 is a circuit for analyzing a signal from the potentiometer 34 provided for detecting the opening degree in the water quantity control valve 33.

Then, the quantity detecting circuit 66 detects the quantity of water obtained by the rotation speed of the quantity sensor 36 provided with the vane in the water supply pipe 30.

In addition, the CPU 70 performs control in accordance with the setting state of each of the main controller 54 and the sub-controller 54a. The CPU 70 operates the operation sequence and timing of the respective circuits in a predetermined sequence, and obtains an acquisition temperature and an input. Calculate the most efficient combustion method based on water quantity, set water temperature and tapping temperature to control the amount of combustion and the amount of water obtained.

In the gas combustion hot water heater 1 having the above configuration, the rotation speed detection circuit 100 of the present invention operates as follows.

When a tap (not shown) is opened to start hot water supply, operation starts according to a predetermined sequence, and the amount of combustion is calculated so as to reach a set water temperature, and the fuel is burned at a desired air-fuel ratio.

When the set water temperature is changed by the controller during combustion, the rotation speed of the combustion fan 12 changes with the change in the combustion amount. At this time, the rotation speed change of the combustion fan 12 appears as a change in the output voltage of the F / V conversion circuit 101 in the rotation speed detection circuit 100. In the F / V conversion circuit 101, pulse signals from the hall ICs 81, 82, and 83 provided in the stators A, B, and C of the brushless DC motor 80 Since all of them are input and the input period of the pulse signal is short, the fluctuation of the output voltage is small.

As a result, the reading accuracy of the output voltage of the F / V conversion circuit 101 is improved, and the harvesting ability is improved, so that the current value of the constant pressure proportional valve 23 is increased by rapidly harvesting the change in the rotational speed of the combustion fan 12. Is changed.

Therefore, in the burner 11, since the constant pressure proportional valve 23 is supplied with the fuel gas of the desired air-fuel ratio corresponding to the rotation speed of the combustion fan 12 and the supply amount of the combustion air which changed with the change, Stable combustion can be continued.

As described above, the accuracy of the rotation speed detection circuit is improved by the rotation speed detection circuit of the present invention, and with this, the harvestability to the change of the rotation speed of the electric motor is improved.

Therefore, in the case of a device that is harvested and driven by the rotation of the electric motor can improve the harvestability.

Claims (2)

Magnetic field detecting means (81) (82) (83) provided in the stator for detecting a magnetic field generated between the rotor and the stator by the rotation of the rotor and generating a pulse signal; The magnetic field detection means (81) (82) in the rotation speed detection circuit (100) of the electric motor comprising the F / V converting means (101) for generating a voltage corresponding to the rotation speed of the rotor based on a pulse signal of? A plurality of 83 are provided in response to the constants of the windings of the stator A, B, and C, and the F / V conversion means 101 is provided by the magnetic field detection means 81, 82, 83. And a voltage corresponding to the rotational speed of the rotor (87) based on the pulse signal of the motor. 2. The rotation speed detection circuit according to claim 1, wherein the motor (80) is a direct current motor having the stator windings (84) (85) (86) of three phases.

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