JPH0239197B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor, and particularly to a DC motor that efficiently utilizes electric power supplied from a power source.

Conventionally, when controlling the speed of a DC motor, for example, a transistor or the like is used to reduce and control the DC current with a constant output voltage, and a drive voltage corresponding to the speed of the motor is supplied to the coil.
In such a configuration, the power supplied by the DC power supply is the sum of the effective power consumption in the coil and the collector loss of the transistor. In normal DC motors, the ratio of effective power consumption to power supplied by the power source (power efficiency) is small, about 10 to 80%. In particular, DC motors with a wide variable speed range and multi-speed switching, and DC motors for take-up with a wide variable range of driving force, have significantly poor efficiency during low speed or low driving force operations.

In order to solve such drawbacks, the present applicant has proposed in Japanese Patent Application No. 17375/1983 a power-efficient DC motor using a switching type voltage converter capable of extracting a variable output DC voltage. The explanation is given using an electronic commutator type (brushless type) DC motor as an example. Incidentally, in a DC motor having such a configuration, current is supplied to the coil through a switching transistor of a voltage converter. Now, if we consider the case of speed control, during the startup and acceleration stages of the motor, the output voltage of the voltage converter increases and it is necessary to supply a large current to the coil, and the switching transistor coil of the voltage converter also needs to be supplied with a large current. In order to supply a large current, the base current when turned on must be increased.
On the other hand, in a state where the speed is controlled at a predetermined speed (constant speed rotation control state), the output voltage of the voltage converter becomes the required value in response to the load torque and the back electromotive force (proportional to the rotational speed of the motor). The current supplied to the motor is quite small compared to that during startup and acceleration (for example, approximately 2A during startup and 250mA during constant speed control). Therefore, the base current (when on) required during constant speed control is significantly smaller than the base current (when on) of the switching transistor that is required at the time of large current at startup. As a result, if the switching transistor is provided with a base current that enables large current conduction (required to increase the starting torque) at startup, it is possible to This is undesirable as it causes significant power loss.

Taking these points into consideration, the present invention detects the speed of the motor and responds to the detected value by increasing or decreasing the base current when the switching transistor is turned on (the switching transistor is turned on and off). The purpose of the present invention is to provide a DC motor that can reduce base current loss during constant speed rotation control, and includes a field means, a multi-phase coil, and a DC motor inserted between the coil and a DC power source. , a voltage conversion means for obtaining an output voltage proportional or substantially proportional to the duty of a switching transistor that operates on and off; a distribution means for switching and controlling a current path from an output terminal of the voltage conversion means to the coil; A DC motor is provided with a speed detection means for obtaining a speed voltage signal of a DC voltage corresponding to the speed of a motor, the voltage conversion means includes a triangular wave generating means for obtaining a triangular wave signal of a predetermined frequency, and a a comparator means which compares the signal and the speed voltage signal and obtains a duty pulse signal corresponding to the voltage value of the speed voltage signal; and a comparator means which receives an added current of a current corresponding to the speed voltage signal and a predetermined current, and calculates the added current. current mirror means for outputting a current proportional or substantially proportional to , and pulsing the output of the current mirror means into a pulse current by turning on and off the input side of the current mirror means according to the pulse signal of the comparator means. supply means for supplying the pulse current to the base terminal of the switching transistor; and smoothing means for smoothing the pulse voltage caused by the on/off operation of the switching transistor using an inductance element, a capacitor, and a diode. Through this, the intended purpose was achieved.

The present invention will be explained below based on illustrated embodiments. FIG. 1 is an electrical circuit representing one embodiment of the present invention. In Fig. 1, 1 is a direct current, 2 is a field magnet, and 3, 4, and 5 are magnets 2.
6 is a distributor that switches the current path to the coils 3, 4, and 5 according to the position of the motor moving part (rotor), and 7 is a speed that detects the speed of the motor moving part. The detector 8 is a switching type voltage converter that obtains a variable output DC voltage _VM from the DC current 1.

If the distributor 6 is constituted by a brush commutator, for example, the motor movable parts will be the coils 3, 4, and 5, and the speed detector 7 will detect the rotational speed of the coils. Further, if the distributor 6 is constructed of, for example, a Hall element and a group of transistors, the magnet 2 becomes a movable part of the motor, and the speed detection part 7 detects the rotational speed of the magnet 2.

The speed detection unit 7 is composed of, for example, a frequency generator and a period/voltage converter, and when the speed of the motor moving part is slow, the detection voltage Vd is large, and when the speed is near or above a predetermined speed, the detection voltage Vd is high.
Vd changes in response to speed, and becomes smaller as speed increases.

The output voltage Vd of the speed detector 7 is input to the voltage converter 8, and the output voltage Vd of the speed detector 7 is inputted to the voltage converter 8, and the output voltage Vd of the speed detector 7 is inputted to the voltage converter 8.
A comparator 12 compares the signal with a triangular wave signal (approximately Hz), and turns the transistor 13 on and off at a duty corresponding to the speed detection signal Vd. When transistor 13 is on, transistor 17
is turned off, the base current of the switching transistor 20 becomes zero, and the switching transistor 20 is turned off. When the transistor 13 is off, the current i ₁ of the constant current source 15 and the current i ₂ corresponding to the speed detection voltage Vd are supplied to the current mirror consisting of the diode 16, the transistor 17, and the resistors 18 and 19, and the current i ₁ +i ₂ is A corresponding (proportional) current is drawn from the collector side of the transistor 17. The collector current of transistor 17 becomes the base current of switching transistor 20, turning switching transistor 20 on. That is, the switching transistor 20 operates on and off at an on-time ratio (duty) corresponding to the speed detection signal Vd, and the base current when it is on changes in response to the signal Vd of the speed detector 7.

When the switching transistor 20 is turned on, the voltage Vs (20V) of the DC power supply 1 is output (Vi
Vs) is supplied to the capacitor 23 and the distributor 6 via the inductance element 22. When the switching transistor 20 is turned off, the flywheel diode 21 becomes conductive and supplies the energy stored in the inductance element 22 to the load side. As a result, the output voltage V _M of the voltage converter 8 is smoothed by the diode 21, the inductance element 22, and the capacitor 23, and becomes a value corresponding to the on-time ratio of the switching transistor 20 (a value corresponding to the speed detection signal Vd). Become.

The output voltage V _M of the voltage converter 8 is supplied to the coils 3, 4, and 5 via the distributor 6 to control the power supplied to the coils and, therefore, the power generated by the motor. Therefore, a speed control loop is constituted by the speed detector 7, the voltage converter 8, and the coils 3, 4, and 5.
The motor movable part is rotationally controlled at a predetermined speed.

In the embodiment shown in FIG. 1, since the base current of the switching transistor 20 of the voltage converter 8 is changed in response to the output Vd of the speed detector 7, the base current loss in the constant speed control state is reduced. It's getting smaller. To explain this, the output of the speed detector 7 during the motor startup/acceleration stage is
Vd increases and switching transistor 2
0 becomes larger, the output voltage V _M of the voltage converter 8 becomes larger, and the current supplied to the coils 3, 4, and 5 becomes larger. In order to increase the current to the coil, it is necessary to increase the current flowing through the switching transistor 20 when it is on (collector current), and therefore, it is necessary to increase its base current. Now, the current supplied to the coil is 2A.
Assuming that the current amplification h _FE when the switching transistor is on is 30, it is necessary to supply 2A/3067mA as its base current.

Here, assuming that the current supplied to the coil in the constant speed control state is 250 mA (corresponding to the load torque), only 250/308.3 mA is required as the base current when the switching transistor 20 is turned on. . At this time, if the base current (67 mA or more) required during startup and acceleration is allowed to flow as is, a loss of 67 mA - 8.3 mA = 58.7 mA (58.7 mA × 20 V = about 1.17 W) will always occur. .

In this embodiment, the base current of the switching transistor 20 is changed according to the output Vd of the speed detector 7, and a sufficient base current (67 mA or more) is supplied during startup and acceleration, and in the constant speed control state. The base current is made small. Now, if we reduce it to half of 67mA, the loss will be 33.5mA (33.5mA x 20V =
670mW), which is one third of 67mA.
If it were to be made as small as 67×2/344.7m
The loss of A (44.7mA x 20V = about 893mW) is reduced.

FIG. 2 is an electrical circuit diagram representing another embodiment of the invention. In this embodiment, the constant current source 15 of the voltage converter 8 in the embodiment of FIG. 1 is replaced with a resistor 31,
In addition, the input terminals of the comparator 12 are replaced, and a current mirror (diode 16, transistor 17, resistors 18, 19) is connected to the collector side of the transistor 32 which responds to the comparator 12.

FIG. 3 shows an electric circuit diagram representing still another embodiment of the present invention. In this embodiment, the distributor 6 in the embodiment shown in FIG. 1 has an electronic configuration (using a transistor), and the magnet 2 is configured to rotate. To explain this, a position detector 41 consisting of a Hall element that detects the magnetic flux of the magnet 2 and a circuit that shapes its output, a coil 3,
Drive transistor 4 that switches the current path to 4 and 5
2, 43, 44, and drive transistors 42, 43, 4 that are turned on in response to the output of the position detector 41.
The distributor 6 is constituted by a selector 45 that selects 4, and a current supply 46 that supplies current to the selector 45.

The selector 45 is composed of transistors 59, 60, and 61 whose emitters are connected in common, and the output of the position detector 41 is applied to the base side of each transistor 59, 60, and 61, and the highest of the base voltages is applied to the base side of each transistor. The low transistor becomes active and distributes the emitter current to the collector side. transistor 59,
The collector currents 60 and 61 become the base currents of the drive transistors 42, 43, and 44, respectively, so that the drive transistor selected by the selector 45 (therefore corresponding to the output of the position detector 41) is turned on, and the other drive transistors are turned on. The drive transistor is turned off. As the magnet 2 rotates, the drive transistors that are turned on are switched, and the current paths to the coils 3, 4, and 5 change.

In the current supply device 46, the current i ₃ of the constant current source 52 and the current i ₄ responsive to the output Vd of the speed detector 7 are combined and input to a current mirror (diode 53, transistor 54, resistors 55, 56). The signal is inverted and amplified and output via a current mirror of transistors 57 and 58. The output current of the current supply device 46 is passed through the selector 45 to the drive transistors 42 and 4.
The base current becomes 3.44, and the selected drive transistor is turned on (saturated). The output current of the current supply device 46 changes in response to the output Vd of the speed detector 7, increasing the output current during startup/acceleration (when Vd is large), and increasing the output current during constant speed rotation (when Vd is small). reduces the output current. As a result, sufficient base current is supplied to turn on the drive transistors 42, 43, 44 even during large current operation during startup and acceleration, and the base current of the drive transistors 42, 43, 44 is reduced during constant speed rotation ( (1/2 to 1/4 at startup) to reduce loss due to base current (drive transistors 42, 4
3 and 44 operate on and off).

In addition, resistors 62', 64', 66' and capacitors 63', 6 are connected in parallel to the coils 3, 4, 5.
The series circuit of 5' and 67' reduces the spike voltage caused by switching the current path. Furthermore, the configuration and operation of the speed detector 7 and the voltage converter 8 are the same as those in the embodiment shown in FIG. 1, and their explanation will be omitted.

FIG. 4 shows an electric circuit diagram representing still another embodiment of the present invention. In Fig. 4, 1 is a DC power supply, 2 is a field magnet, 3, 4, and 5 are three-phase coils, 6 is a distributor, 7 is a speed detector, 8 is a voltage converter, and 9 is an operation detector. It is a controller. In this example, a current corresponding to the output voltage Vd of the speed detector 7 is supplied to the coils 3, 4, 5 by the drive transistors 78, 79, 80, and the operation of the drive transistors 78, 79, 80 when energized is performed. The voltage is detected by the operation detection controller 9, and the output voltage _VM of the voltage converter 8 is changed so that the operation voltage becomes a predetermined value within the active region.

To explain this, the speed of the magnet 2 (motor movable part) is detected by the speed detector 7, and the detected signal Vd is inputted to the distributor 6. detection signal
Vd increases when the motor speed is slow and decreases when the motor speed is fast. The distributor 6 includes a level converter 62, a current controller 67, a position detector 69, and a selector 74.
, drive transistors 78 , 79 , and 80 , and a current detector 81 .

The level converter 62 compares the voltage of the DC voltage source 63 and the output voltage Vd of the speed detector 7, and the current converter 64 outputs a current according to the difference, and the voltage V ₁ according to the output current. resulting diode 65
and a resistor 66 in series. FIG. 5 shows a specific example of the configuration of the current converter 64.
The detection voltage Vd and the voltage of the DC power supply 63 are applied to the bases of the transistors 111 and 112, respectively,
The current of the constant current source 115 is distributed to the collector side according to the voltage difference. Transistor 111,1
The collector current of transistors 116 and 11
The signal is inverted and compared by a current mirror No. 7, and output via a transistor 118 and a current mirror (transistors 121 and 122).

The current detector 81 is composed of a resistor 82 inserted in series in the current path to the coils 3, 4, and 5.
A voltage drop signal is generated according to the combined supply current to the coils 3, 4, and 5.

Output V ₁ of level converter 62 and current detector 81
The output is input to a current controller 67, which outputs a current according to the difference. FIG. 6 shows a specific example of the configuration of the current controller 67. The output V ₁ of the level converter 62 is applied to the base side of the transistor 131, and the output signal of the current detector 81 is applied to the emitter side. The collector current of the transistor 131 changes depending on the voltage between the base and emitter, and is outputted via a current mirror (transistors 132 and 133).

The output current of the current controller 67 becomes the common emitter current of the differential transistors 75, 76, and 77 of the selector 74. The output voltages (outputs of the position detector 69) of the Hall elements 70, 71, 72 that sense the magnetic flux of the magnet 2 are applied to the base sides of the transistors 75, 76, 77, and the transistors 75, 76, and 77 distribute the common emitter current to the collector side. transistor 7
The collector currents 5, 76, and 77 become base currents of drive transistors 78, 79, and 80, and the currents are amplified and supplied to the corresponding coils 3, 4, and 5.

Current detector 8 supplies current to coils 3, 4, and 5.
1 and input to the current controller 67.
Therefore, current controller 67, selector 74, drive transistors 78, 79, 80 and current detector 81
A first feedback loop (current feedback loop) is constituted by the current coil 3, which corresponds to the output V ₁ of the level converter 62, and therefore the output Vd of the speed detector 7.
4 and 5. This reduces the influence of variations in the current amplification _hFE of the drive transistors 78, 79, and 80, and facilitates switching of the current path in response to the output of the position detector 69. Note that the capacitor 68 is provided for phase compensation (to prevent oscillation) of the first feedback loop.

Next, the operations of the motion detection controller 9 and the voltage converter 8 will be explained. The operation detection controller 9 generates a reference voltage of a predetermined voltage V ₂ from the common connection point (emitter side) of the drive transistors 78, 79, 80 by a constant current source 91, a resistor 92, and diodes 93, 94, and the reference voltage point Detection transistors 95 and 9 have one end (emitter side) connected in a DC manner to
The respective output currents of 6 and 97 are combined (collector sides are commonly connected), input to a current mirror consisting of a diode 98, a transistor 99, and resistors 100 and 101, inverted and amplified, and output (current sucked). That is, the detection transistor 95,
96, 97 are drive transistors 78, 79, 80
By comparing each operating voltage (collector-emitter voltage) with a predetermined voltage V ₂ −V _D (where V _D is the forward voltage drop between the emitter and base of the transistor), the drive transistor 78 when energized is determined. ,7
When the operating voltages of transistors 9 and 80 become lower than a predetermined voltage V ₂ -V _D , detection transistors 95, 96 and 97 output current to the collector side. Therefore, a current corresponding to the operating voltage when the drive transistors 78, 79, and 80 are energized is drawn into the operation detection controller 9.

The output current of the operation detection controller 9 is converted into a voltage by the resistor 102 of the voltage converter 8, and compared with the triangular wave signal of the triangular wave generator 11 by the comparator 12. on/off control. Therefore, the switching transistor 20 is controlled on and off, smoothed by the flywheel diode 21, the inductance element 22, and the capacitor 23, and the output voltage V _M of the voltage converter 8 depends on the output of the operation detection controller 9. will be the value. Note that the base current of the switching transistor 20 when it is on is the sum of the current i ₁ through the resistor 31 and the current i ₂ corresponding to the output Vd of the speed detector 7, which is inverted and amplified, and the output voltage of the voltage converter 8 is Coils 3, 4, 5 from V _M
Current is supplied to

Therefore, a second feedback loop is constituted by the operation detection controller 9, the voltage converter 8, and the coils 3, 4, and 5, and the operating voltage when the drive transistors 78, 79, and 80 are energized is within the active region. The output voltage _VM of the voltage converter 8 is controlled to a predetermined small value (about 1V to 2V).

To explain this, the output of the speed detector 7 is
When Vd becomes slightly larger, the output V ₁ of the level converter 62 of the distributor 6 becomes larger, and the operation of the first feedback loop increases the current supplied to the coil. Now, consider the case where the drive transistor 78 is selected and supplies current to the coil 3. An increase in the current supplied to the coil 3 increases its voltage drop and reduces the operating voltage of the drive transistor 78. A decrease in the operating voltage increases the output current of the detection transistor 95 of the operation detection controller 9 and increases the collector current of the transistor 99. This increases the voltage drop across the resistor 102 of the voltage converter 8, reduces the on duty of the transistor 13, and increases the on duty (on time ratio) of the switching transistor 20. As a result, the output voltage V _M of the voltage converter 8 increases,
The operating voltage of the drive transistor 78 increases (the current supplied to the coil 3 is constant due to the first feedback loop, and its voltage drop also does not vary with V _M ). As a result, regardless of the current supplied to the coils, the operating voltages of drive transistors 78, 79, and 80 when energized are controlled to a predetermined small value within the active region.

Therefore, the current flowing to the coils 3, 4, 5 can be controlled finely and accurately by the drive transistors 78, 79, 80, and the collector loss thereof is also reduced. Furthermore, the base current when the switching transistor 20 of the voltage converter 8 is turned on is reduced during constant speed rotation, and base current loss is also reduced.

In addition, although the above-mentioned example showed the example which used the three-phase coil, this invention is not limited to such a case, and can generally configure a DC motor having a plurality of phase coils. Furthermore, various known configurations can be adopted for the speed detector 7, distributor 6, etc. Furthermore, not only a rotary type DC motor but also a linear type DC motor in which the motor movable part moves in a straight line can be configured. In addition, various modifications are possible without changing the gist of the present invention.

As is clear from the above description, the DC motor of the present invention can be configured with high power efficiency. Therefore, if a DC motor for audio/visual equipment using a dry battery as a power source is constructed based on the present invention, equipment with low power consumption and long battery life can be realized.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram representing one embodiment of the present invention, FIGS. 2, 3, and 4 are electric circuit diagrams representing other embodiments of the present invention, and FIG. 5 is an electrical circuit diagram of a current converter. FIG. 6 is a diagram showing a specific example configuration of a current controller. 1...DC power supply, 2...Magnet, 3, 4,
5... Coil, 6... Distributor, 7... Speed detector, 8... Voltage converter, 9... Operation detection controller,
11... Triangular wave generator, 12... Comparator,
41, 69...Position detector, 42, 43, 44,
78, 79, 80...drive transistor, 45,
74...Selector, 46...Current supply device, 62...
Level converter, 64...Current converter, 67...Current controller, 70, 71, 72...Hall element, 9
5, 96, 97...detection transistor.

Claims (1)

[Claims] 1. A field means, a plurality of phase coils, and a voltage conversion means inserted between the coil and a DC power source to obtain an output voltage proportional or approximately proportional to the duty of a switching transistor that operates on and off; A DC motor comprising: a distribution means for switching and controlling a current path from an output terminal of a voltage conversion means to the coil; and a speed detection means for obtaining a speed voltage signal of a DC-like voltage corresponding to the speed of a movable part of the motor. , the voltage conversion means includes a triangular wave generating means for obtaining a triangular wave signal of a predetermined frequency, and a comparator means for comparing the triangular wave signal and the speed voltage signal to obtain a pulse signal with a duty corresponding to the voltage value of the speed voltage signal. and current mirror means for inputting a summed current of the current corresponding to the speed voltage signal and a predetermined current and outputting a current proportional or approximately proportional to the summed current; pulsing means that turns the output of the current mirror into a pulse current by turning it on and off in response to a pulse signal; supply means that supplies the pulse current to the base terminal of the switching transistor; - A DC motor characterized by having a smoothing means for smoothing a pulse voltage caused by an OFF operation using an inductance element, a capacitor, and a diode.