JPS60204286A - Drive device of dc brushless motor - Google Patents

Abstract

PURPOSE:To suppress the heating of transistors of output stages of a drive circuit by converting an oscillating frequency proportional to the rotating speed into a voltage, modulating to a pulse width, and inputting it to a control voltage input terminal of a drive circuit. CONSTITUTION:A Hall element 29 sequentially detects a drive permanent magnet of a rotor by the rotation of a rotor, controls to sequentially turn ON and OFF the output transistors 25, 26 of a drive circuit 23, and sequentially flows currents to drive coils 28U-28W. An oscillator 10 generates an oscillating pulse of the frequency matched to the rotating speed of a rotor by the rotation of the rotor, a frequency/voltage converter 14 generates an output control voltage in response to the oscillated frequency, the output control voltage is pulse-modulated by a pulse width modulator 24 having a triangular wave oscillator 19, a comparator 17 and a transistor 21, and supplied to the drive circuit 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a DC brushless motor drive device that suppresses heat generation of transistors.

[Technical background of the invention and its problems]

Generally, this type of DC brushless motor drive device includes an oscillator 1 that oscillates a frequency proportional to the rotational speed of the rotor as shown in FIG. A voltage converter 2, a rotation speed adjustment volume 3 connected to this converter 2, and this converter 2
a drive circuit 4 whose on state is changed depending on the magnitude of the rotation speed control voltage output from the drive circuit 4; a stator coil 51.5V star-connected to the output part of the drive circuit 4;
5W, and a magnetic sensor Hall element 6.6.6 which inputs into the drive circuit 4 an output signal that detects the position of the permanent magnet of the rotor.

The oscillator 1 has a permanent magnet arranged on the rotor in which N poles and S poles are arranged alternately in an annular shape, and a circuit board facing the magnet is arranged in a manner corresponding to the number of N poles and S poles. When the magnet is rotated by the rotation of the rotor, a current is induced in the pattern, and an oscillation pulse with a frequency matching the number of pattern intervals is generated.

Further, the frequency-voltage converter 2 generates a voltage according to the oscillation frequency of the oscillator 1, and depending on the magnitude of the control voltage of this converter 2, it is incorporated into the bridge circuit of the drive circuit 4 and is controlled by the Hall element 6.6.6. Transistor 7.8 turned on
The on state is changed, and this transistor 7.8 becomes class A operation, controls the current flowing to the coils 5U, 5V, and 5W, and when the motor is started or a large load is applied to the motor, the number of revolutions is reduced to the specified revolution. Since the converter 2 outputs the maximum control voltage to the drive circuit 4, the transistor 7.8 of the drive circuit 4 becomes fully on class B operation, and the coil 5U, 5V.

The maximum current flows through 5u, and the rotational speed becomes the specified rotational speed.

In such a conventional device, the final stage transistor 7.8 is normally operated in class A mode.
Since the on-voltage of the transistor 7.8 is considerably higher than that during the switching operation that switches the energization of the coil 50.5V, 5W, the power consumption of the transistor 7.8 is large, and a large amount of heat is generated.
It has the disadvantage that it cannot be used with large capacity motors.

Therefore, a method of discretely incorporating transistors in the drive circuit could be considered, but since the output control voltage of the frequency-voltage converter changes analogously, the final stage will inevitably operate in class A, and the heat generation will not be eliminated. In addition, there was nothing that was satisfactory in terms of size and cost, such as complex transistor drive logic.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a drive device for a DC brushless motor that generates little heat, is small, inexpensive, and has a large capacity.

(Summary of the Invention) The present invention provides an oscillator that generates an oscillation pulse with an oscillation frequency proportional to the rotational speed, a frequency-voltage converter that converts the frequency of the oscillation pulse generated by the oscillator into a voltage, and a a pulse width modulation circuit that pulse width modulates the control voltage frequency-voltage converted by the pulse width modulation circuit; and a drive circuit that inputs the control voltage pulse width modulated by the pulse width modulation circuit to control the power to the stator coil. It is equipped with the following.

Further, in the second invention, in the above configuration, each output terminal corresponding to each coil of the drive circuit is connected to a connection point between an anode of one Zener diode and a cathode of the other Zener diode, and The base of a PNP transistor is connected to the cathode of the diode through a resistor, and the base of the NPN transistor is connected to the anode of the other Zener diode through a resistor, and the collectors of both transistors are connected to each other. A stator coil is connected to the connection point of the collector of the transistor, a resistor is inserted between the emitter base of both transistors, and the emitter of one transistor is connected to the voltage mt voltage, and the emitter of the other transistor is connected to the power supply ground. It is what it is.

[Embodiments of the invention]

The configuration of an embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

Reference numeral 10 denotes an oscillator, and a pattern 12 formed in an annular shape by alternately bending in the shape of an opening is formed on a wiring board 11 fixed to a stator.
A permanent magnet 1 having S and N poles arranged alternately and annularly around the rotor periphery facing this pattern 12.
When the permanent magnet 13 rotates with the rotation of the rotor, a current is induced in the pattern 12, and an oscillation pulse with a frequency equal to the number of intervals of the pattern 12 is generated. For example, if the number of intervals in the pattern 12 is 34 and the number of rotations of the rotor is 300+'pm, the frequency will be 17011z as 34x300ppm/60sec=17011z.

Further, 14 is a frequency-voltage converter, and this converter 514 generates a voltage according to the oscillation frequency from the oscillator 10, and this converter 14 outputs a rotation speed control voltage.
As the rotation speed decreases, it increases, and as the rotation speed increases, it decreases.

Furthermore, 15 is a rotation speed adjusting volume connected to the converter 14.

Further, an amplifier 16 for amplifying the output control voltage of the converter 14 is connected to the output terminal of the converter 14.
is connected to one input terminal 18 of the comparator 17.

Zarano 19 is a triangular wave oscillator, for example, the frequency is about 20
It is set to K11z. This oscillator 19 is connected to the other input terminal 20 of the comparator 17.

The output end of the comparator 17 is connected to the base of a transistor 21 , the collector of which is connected to the power supply voltage Vcc through a resistor 22 , the collector is connected to the control voltage input end of the drive circuit 23 , and the triangular wave oscillator 19 , the comparator 17 and the i-transistor 21 constitute a pulse width modulation circuit 24.

The drive circuit 23 has a three-phase specification, and the output stage is NPN.
type power transistor25. ! 6, a bridge circuit 21 is assembled, and a stator coil 280.28V, 28W is connected to one output part of this bridge circuit 27 in a star connection, and the drive circuit 23 is connected to the position of the rotor driving permanent magnet. Hall element of magnetic sensor to detect 29.29
．． 29 is connected, and the output signal of the ball element 29, 29°29 is input to the drive circuit 23, and the output signal of the Hall element 29, 29, 29 turns on the output transistor 25, 26 of the bridge circuit 27. , OFF is determined, and the drive coils 28U, 28V, and 2H are energized at the appropriate timing.

Furthermore, a forward/reverse rotation changeover switch 30 is connected to the drive circuit 23.

Next, the operation of this embodiment will be explained.

As the rotor rotates, the Hall elements 29, 29, 29 sequentially detect the permanent magnets for driving the rotor, and sequentially turn on and off the output transistors 25, 26 of the drive circuit 23,
The drive coils 281J, 28V, and 28W are energized in sequence with good timing.

Further, as the rotor rotates, the oscillator 10 generates an oscillation pulse with a frequency matching the rotation speed of the rotor, and a frequency-voltage converter 14 generates an output control voltage according to the oscillation frequency, and this output control Voltage is triangular wave oscillator 19 comparator 1
Pulse width modulation circuit 2 consisting of 7 and transistor 21
The signal is pulse width modulated at step 4 and supplied to the drive circuit 23. This pulse width modulated output control voltage is not an analog quantity but a digital ω, so the final stage transistor 2
5.26 is a switching operation of the B drive operation, and the on-voltage of the transistors 25.26 becomes 1V or less, and the heat generation of the transistors 25.26 is suppressed.

Next, the configuration of another embodiment will be explained with reference to FIG.

In the configuration of the embodiment, the drive circuit 23 rotates in the normal direction;
The output end of the comparator 11 is connected to the reverse rotation switching input terminal 31, and a pulse width modulated pulse is supplied to the forward rotation/reverse rotation switching input terminal 31 of the drive circuit 23.

Further, the control voltage input section 32 of the drive circuit 23 is connected to the power supply voltage Vcc through a resistor 33.

The control input to the forward rotation/reverse rotation input terminal 31 is an L signal, a forward rotation -1H signal causes a reverse rotation, and an intermediate state M signal causes a stop.

By connecting the pulse width modulated pulse to the drive circuit 23 through the collector of the transistor 21 in this manner, the final stage transistors 25 and 26 are repeatedly turned on and off to perform the operation of the embodiment described above.

Further, the operation of another embodiment will be explained with reference to FIG.

In the configuration of the embodiment shown in FIG. 1, the final output horn for driving the coils 28U, 28V, 28- of the drive circuit 23 has two Zener diodes 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 35, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 34, 42, 34, 42, 34, 42, 34, 42, 34, 34, 34, 42, 34, 34, 34, 34, 32, 32, 32, 34 be connected to each other, respectively. 35 are connected in series, and the cathode of one Zener diode 34 and the other Zener diode 35 are connected in series.
The anodes are connected to the bases of the PNP power transistor 38 and the NPN power transistor 39 through resistors 36 and 37, respectively, and the collectors of the transistors 1 to 38 and 39 are connected to each other, and a resistor is connected between the emitter and base. 36 and 37 are inserted, the emitter of one transistor 38 is connected to the power supply voltage Vcc, the emitter of the other transistor 39 is connected to the power supply anode, and the filter of the drive circuit 23 is connected to the connection point of the Zener diode 34 and 35. The output end of the drive signal is connected, and the coils 2811.28V and 28W are connected to the connection points of the collectors of both transistors 38 and 38, respectively. Then, if the total Zener voltage Vcc of the Zener diodes 34.35 is greater than the total Zener voltage Vcc, and one Zener voltage Vz has a relationship of Vc>Vz>Vc/2, the driving signal LU for each coil is 281.28V, 211W. , LV, and L- are three-phase waveforms as shown in FIG. Note that the M level is the level when both the transistors 38 and 39 in the output stage are in off-operation.

The operation of this embodiment will be explained.

Final stage Zener diode 34.3 of drive circuit 23
When the output at the connection point 40 between the Zener diodes 34 and 35 is trubel, the Zener diode 35 is turned on, transistor Mi9 is turned on, and at this time the Zener diode 34 and the transistor 38 are turned off, and the When the level is at Trubel, the Zener diode 34 is turned on, transistors 1 to 38 are turned on, Zener diode 35 is turned off, and transistors 1 to 39 are also turned off. Furthermore, when the connection point 40 between the Zener diodes 34 and 35 is at the intermediate M level, both Zener diodes 3
4.35 cannot be turned on, both transistors 38.3
9 is also in the off state.

In the configuration of the embodiment shown in FIG. 1, when used for a large current driving function, one of the transistors in the final stage of the drive circuit 23 generates a large amount of heat, and the operational limit is also determined.
The collectors of both transistors 38 and 39 must be followed by a parallel circuit. In this case, a circuit as shown in FIG. 7 can be considered, but if this circuit is used as the final stage of a pulse width modulation system, a power 1 transistor 38. Since the transistor 39 performs a switching operation, the transistors 41 and 42 in the input section are unnecessary. However, the transistor in the input part 41.4
2 is removed, one transistor 38 is always on, and when the other transistor 39 is turned on, a short circuit current flows through both transistors 38, 39, transistors 38 and 39 are destroyed, and this transistor 41. 4
2 cannot be removed and is expensive.

Therefore, the configuration of the embodiment shown in FIG. 4 can solve the above problem, and the final stage drive circuit of the pulse width modulation type is collector-followed, so that the heat generation of the transistors 38 and 39 is reduced.

〔Effect of the invention〕

According to the present invention, since the oscillation frequency proportional to the rotational speed is converted into a voltage and the pulse width is modulated and inputted to the control voltage input terminal of the drive circuit, heat generation of the transistor in the output stage of the drive circuit is achieved. Therefore, a transistor-controlled motor that can be driven with a large current and can be driven with a large current can be obtained using a simple drive circuit.

In addition, in the second invention, a Zener diode is connected in series to the final stage of the drive circuit, and a coil drive signal is input to this connection point, so that the 1 to 1 transistors in the final stage are made into cholera tough 40- has less fever,
A transistor-controlled motor with a simple circuit configuration and a large current drive can be obtained at low cost.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a DC brushless motor drive device showing one embodiment of the present invention, Fig. 2 is an explanatory diagram of a part of the same oscillator, and Fig. 3 is a DC brushless motor drive showing another embodiment. A circuit diagram of a part of the device, Fig. 4 is a circuit diagram of a part of a DC brushless motor drive device showing an embodiment of Haku, Fig. 5 is a waveform diagram of the same as above, and Fig. 6 is a drive of a conventional DC brushless motor. The circuit diagram of the device, FIG. 7, is a circuit diagram of the output section of the drive circuit which is the premise of the present invention. 10. Oscillator, 14. Frequency-voltage converter, 23.
・Drive circuit, 24...Pulse modulation circuit, 28u12
8V, 2811...Coil, 36.37...Resistance,
38.39...Transistor.

Claims (3)

[Claims] (1) An oscillator that generates an oscillation pulse with an oscillation frequency proportional to the rotation speed, a frequency-voltage converter that converts the frequency of the oscillation pulse generated by this oscillator into voltage, and a frequency-voltage conversion using this converter. and a drive circuit that inputs the control voltage pulse width modulated by the pulse width modulation circuit and controls the power to the stator coil. DC brushless motor drive device. (2) The DC brushless motor drive device according to claim 1, wherein the output end of the pulse width modulation circuit is connected to the forward/reverse rotation switching input end of the drive circuit. (3) An oscillator that generates an oscillation pulse with an oscillation frequency proportional to the rotation speed, a frequency-voltage converter that converts the frequency of the oscillation pulse generated by this oscillator into voltage, and a frequency-voltage conversion using this converter. The drive circuit includes a pulse width modulation circuit that pulse width modulates the control voltage, and a drive circuit that inputs the control voltage pulse width modulated by the pulse width modulation circuit to control power to the stator coil. Each output terminal corresponding to each coil of the circuit is connected to the connection point between the anode of one Zener diode and the cathode of the other Zener diode, and a PNP transistor is connected to the cathode of one Zener diode via a resistor. At the same time, connect the base of the NPN transistor to the anode of the other Zener diode via a resistor, connect the collectors of both transistors to each other, and connect the stator coil to the connection point of the collectors of both transistors. , a DC brushless Tanabata drive characterized in that resistors are inserted between the emitter bases of the transistors, the emitter of one transistor is connected to the power supply voltage, and the emitter of the other transistor is connected to the power supply ground. Device.