JPH0216672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brushless motor drive device,
A position detection means that detects the rotational position of the rotor and generates a position detection signal, a distribution circuit that distributes the position detection signal to a switching element (often a switching transistor) for energizing the drive coil, and a rotation command. In a drive device equipped with a comparator that compares a voltage (speed command voltage or rotational torque command voltage) with a reference voltage and controls the conduction hole of the switching element based on the comparison output, high frequency coloring is caused in the loop of the drive circuit. The present invention is intended to reduce power consumption with an extremely simple configuration in which high-frequency switching power is supplied to the drive coil.

Incidentally, a brushless motor drive device equipped with the position detection means, the switching element, the distribution circuit, and the comparator (more precisely, a comparison transistor) is disclosed in USP No. 3662238 or Japanese Patent Application Publication No. 1973. 47802, and the idea of generating a switching carrier for high frequency switching within the loop of the drive circuit is known from USP No. 4153864 or Japanese Patent Application Publication No. 47911 of 1973. .

The purpose of this invention is to provide a specific construction method when applying the switching carrier generation method proposed by the latter document of the present invention to a widely known brushless motor drive device.

In addition, in this type of brushless motor, the rotational speed of the brushless motor is controlled by causing the transistors that switch and supply power to the plurality of drive coils based on the position detection signal to perform on/off operations at a cycle shorter than the cycle of the position detection signal. The idea of controlling was first introduced in the Japanese Patent Publication No. 1963
No. 20396, and this document generates on/off signals using a mechanical centrifugal force governor. However, as an example where this centrifugal force governor is replaced with a semiconductor oscillator, USP No. 4051417 or Japanese patent Publication No. 28610 of 1978 is known.

However, the devices disclosed in these documents all attempt to control or vary the rotational speed of a brushless motor by causing the transistor that performs position detection switching to perform on/off operations at a higher frequency than the position detection signal. For this purpose, a configuration is adopted in which an intermittent current is passed directly through the drive coil.

In such a configuration, if the intermittent frequency to the drive coil is too high, interference radio waves will be generated from the motor part, so it is necessary to electromagnetically shield not only the drive circuit part but also the motor part. If the current flowing through the coil is interrupted, the drive coil will generate a whirring sound.

As can be seen from the example of the switching regulator, in order to perform switching power supply to the load and reduce power consumption, it is necessary to use a relatively high frequency (30 to
It is preferable to switch at a frequency of 100 KHz), but the device shown in the above document originally had the purpose of reducing power consumption as much as possible, in other words.
Since it is not designed to perform high frequency switching of 30 to 100 KHz, various problems will occur if the switching frequency is increased.

Additionally, these devices require a mechanical switch or an independent oscillator to generate the switching signal, making the device complex.

In order to solve these problems, the present invention simplifies the configuration of the device by generating a switching carrier within the loop of the brushless motor drive circuit (therefore, no special oscillator is required). By converting an intermittent high-frequency current into a direct current using a chiyoke coil and supplying it to a drive coil, a device is realized in which the generation of interference radio waves from the motor part is eliminated, and the present invention Various other derivative effects of the configuration will be explained in order.

The configuration of the present invention will be explained below based on the drawings.
FIG. 1 is a circuit diagram of a brushless motor drive device according to an embodiment of the present invention. In FIG. 1, the outputs of Hall elements 1, 2, and 3 for detecting the rotational position of a rotor (not shown) of a brushless motor are applied to a position detection signal amplifier 100. The phase outputs are applied to the distribution circuit 200.

On the other hand, the plus side feed line P and the minus side feed line N (grounding point)
Switching transistors 5 and 6 are connected in series between them, and similarly switching transistors 8 and 9 are connected with a choke coil 7 in between.
Switching transistors 11 and 12 are connected with a switch coil 10 in between, and a first switch circuit 300 is configured by the switch coil 4 and the transistors 5 and 6, and a first switch circuit 300 is configured by the switch coil 7 and the transistors 8 and 9. A second switch circuit 400 is constituted by the above-mentioned switch coil 10 and a third switch circuit 500 is constituted by the above-mentioned transistors 11 and 12.

Further, the drive coil 13 and the drive coil 14 are connected to bridge the switch circuit 300 and the switch circuit 400, and the drive coil 14 is connected to bridge the switch circuit 400 and the switch circuit 500. Drive coil 14 and drive coil 1
5 is connected. That is, the drive 13 and the drive coil 14 are connected in series between the collector of the transistor 6 and the collector of the transistor 9, and the drive coil 1 is connected between the connection midpoint of both drive coils and the collector of the transistor 12.
5 are connected, and the drive coils 13, 14, 1
5 has a so-called star connection.

Note that flywheel diodes 16, 17, and 18 are connected between the collectors of the transistors 5, 8, and 11, and the negative power supply line N, respectively, and the collectors of the transistors 6, 9, and 12, and the negative power supply line N are connected to each other. Smoothing capacitors 19, 20, and 21 are connected between them, respectively.

Further, the upper three-phase outputs of the distribution circuit 200 are applied to a combining circuit 600, and the combining circuit 600
The three-phase outputs of the transistors 5, 8,
11 bases. The distribution circuit 200
The lower three phase outputs of the transistors 6 and
It is applied to the bases of 9 and 12. Further, the bases of transistors 22, 23, and 24 are connected to the bases of transistors 6, 9, and 12, respectively, and the emitters of transistors 22, 23, and 24 are connected to the negative side feed line N via resistors 25, 26, and 27, respectively. and their collectors are commonly connected to the inverting input terminal 7 of the comparator 700.
00a, and is also connected to the plus side feed line P via the resistor 28. Further, a reference voltage source 29 for current limiting is connected between the non-inverting input terminal 700b of the comparator 700 and the positive feed line P.

An inverting input terminal 800a of a comparator 800 is connected to the rotation speed command voltage input terminal S via a resistor 30.
is connected, a reference voltage source 31 for setting the rotational speed is connected between the non-inverting input terminal 800b of the comparator 800 and the negative feed line N, and the output of the comparator 800 is applied to the combining circuit 600. ing.

Further, diodes 32, 3 are connected to the switch circuit sides of the drive coils 13, 14, 15, respectively.
The anodes of the diodes 32, 33, and 34 are connected in common, and a resistor 35 is connected between these cathodes and the negative feed line N. A voltage is applied to the inverting input terminal 800a of the comparator 800 via a phase shift circuit 900,
The output of the comparator 700 and the pulse width correction output appearing at the output terminal 200p of the distribution circuit 200 are also configured to be applied to the inverting input terminal 800a of the comparator 800.

The phase shift circuit 900 includes a series circuit of a capacitor 36 and a resistor 37, a capacitor 38 connected in parallel to the series circuit, and the comparator 8.
It is constituted by a capacitor 39 connected between the inverting input terminal 800a of 00 and the negative feed line N.

A transistor 4 is connected between the output terminal 200r of the distribution circuit 200 and the base of the transistor 6.
A first current booster composed of 0, 41 and a resistor 42 is inserted, and a second current booster composed of transistors 43, 44 and a resistor 45 is inserted between the output terminal 200s and the base of the transistor 9.
A current booster is inserted, and the same output terminal 200
A third current booster composed of transistors 46, 47 and a resistor 48 is inserted between T and the base of the transistor 12, and these current boosters keep the output current of the distribution circuit 200 constant. It is amplified by magnification.

Furthermore, an output terminal 200 of the distribution circuit 200
r, 200s, 200t and the transistor 6,
Diodes 49, 50, and 51 are connected between the collectors of transistors 9 and 12, respectively, and these diodes have a function of preventing saturation of the transistors 6, 9, and 12 in the small current region. Therefore, the operation of the diode 49 will be explained as an example. The collector-emitter voltage of the transistor 6 is the sum of the base-emitter voltage and the base-emitter voltage of the transistor 41, plus the knee voltage of the diode 49.
Voltage), the distribution circuit 200
Since the current from the output terminal 200r of the transistor 6 is bypassed between the collector and emitter of the transistor 6, the base current of the transistor 6 decreases and complete saturation is prevented.

When the transistor 6 operates with a relatively small current (about 1/10 of the allowable current), the base-emitter voltage and the collector-emitter saturation voltage of the transistor 6 increase as the collector current increases. However, as the collector current increases, the collector resistance will greatly contribute to the collector-emitter saturation voltage. block) action is not performed. That is, during steady rotation of the brushless motor, saturation of the transistor 6 is prevented by the diode 49, so that the distribution circuit 200
Smooth switching is performed depending on the command current from the motor (not affected by variations in the DC current amplification factor, etc.), and the diode 49 does not operate when starting the brushless motor, which requires the largest rotational torque. Therefore, the transistor 6 can be completely saturated, which is very convenient.

Now, in FIG. 1, the position detection signal amplifier 100 and the distribution circuit 20 are represented by blocks.
Examples of the synthesis circuit 600 and the comparator 700 are shown in FIGS. 2, 4, 6, and 7, respectively, and the outline of their operation will be briefly explained. Note that it is assumed that comparator 800 has the same configuration as comparator 700.

First, FIG. 2 shows a specific circuit connection diagram of the position detection signal amplifier 100, in which terminal B is a positive power supply terminal and terminal G is a negative power supply terminal. Transistors 101, 102, 103,
104, 105, 106, 107, 108 and a resistor 109 constitute an emitter follower type constant voltage circuit, and the constant voltage output is also supplied to the outside via the terminal 100a. Transistors 110, 11
1, 112 and a resistor 113 constitute a starting circuit for the constant voltage circuit, and once a constant voltage output appears, the transistor 110 is turned off.

On the other hand, transistors 114, 115, 116,
A first differential amplifier circuit is configured by resistors 117, 118, 119, 120, 121, transistors 122, 123, 124, resistors 125, 12
6, 127, 128, 129 constitute a second differential amplifier circuit, and transistors 130, 13
1,132, resistance 133, 134, 135, 13
6, 137 constitute a third differential amplifier circuit, and the first differential amplifier circuit has an input terminal 100.
The output of the Hall element 1 is applied to the second differential amplifier circuit through input terminals 100d and 100e, and the output of the Hall element 2 is applied to the second differential amplifier circuit through the input terminals 100d and 100e. The output of the Hall element 3 is applied through input terminals 100f and 100g. Further, the collectors of the transistors 115 and 124 are both connected to the first transistor.
The collectors of the transistors 123 and 132 are both connected to the second output terminal 100i, and the transistor 1
Collectors 31 and 116 are both connected to the third output terminal 100j. Note that the transistors 106, 108, 114, 122, and 130 constitute a current mirror circuit, and their common base is connected to a constant current reference terminal at 100k, and is configured to supply base current to an external constant current transistor. There is.

Now, the Hall elements 1, 2, and 3 are 1A and 1A in FIG. 3, respectively, depending on the rotational position φ of the rotor magnet.
Output voltage waveforms as shown in 2A and 3A are generated, but along with this, transistors 115 and 12
The collector currents of 3 and 131 are respectively 1 in Fig. 3.
It changes like 15A, 123A, 131A. Further, the changes in the collector currents of the transistors 116, 124, and 132 are
The resistors 121, 129,
121A and 1 in Fig. 3 are attached to both ends of 137, respectively.
Signal waveforms as shown at 29A and 137A appear.

Note that the voltage amplification gains of the first, second, and third differential amplifier circuits in FIG. 2 depend on the resistance ratio of the resistor inserted on the emitter side of each differential transistor and the load resistor on the collector side. However, the Hall element 1,
When the output amplitudes of transistors 2 and 3 increase, the collector current waveforms of the transistors 115, 123, and 131 and the voltage shapes across the resistors 121, 129, and 137 become as shown by the dotted lines in FIG. 3, respectively.

Next, FIG. 4 shows a specific circuit connection diagram of the distribution circuit 200, in which the input terminals 200a, 20
0h, 200i, 200j, 200k are the output terminals 100a, 100h, 100i, 100 of the position detection signal amplifier 100 shown in FIG.
j, 100k are connected. In FIG. 4, transistors 201, 202, 203, resistor 20
4,205,206, transistor 207,20
8, 209, 210 constitute a 3-differential switch circuit, and transistors 211, 212, 213
constitute a three-differential amplifier circuit. Therefore,
Voltage waveforms as shown by 200H, 200I, and 200J in FIG. 5 (these voltage waveforms are the same as voltage waveforms 121A, 129A, and 137A in FIG. 3) were applied to input terminals 200h, 200i, and 200j, respectively. When, output terminal 200l, 20
0m, 200n, 200r, 200s, 200t
The current waveforms flowing out from each are shown in 2 in Figure 5.
00L, 200M, 200N, 200R, 200
S,200T. It is assumed that appropriate loads are connected to these output terminals.

In addition, transistors 227, 228, 229,
230, 231, 232, 233, 234, resistors 235, 236, and diode 237 are input terminal 2
It constitutes a ripple generation circuit that generates a ripple voltage having a level gradient that depends on the gradient of change when the level of the position detection signal applied to 00h, 200i, and 200j changes, and an appropriate load is connected to the output terminal 200P. When the diode 2
The current waveform flowing through 37 is 200P in Figure 5.
It becomes as shown in.

That is, input terminals 200h, 200i, 20
The level of the signal applied to 0j is the reference voltage terminal 2.
If it is the same level as 00a, transistor 2
27, 228, and 229 (these transistors have a double emitter structure), an emitter current having a value twice that of the transistor 230 flows through the input terminal 200.
If the level of the signal applied to the transistors 227, 200i, and 200j becomes lower than the level of the reference voltage terminal 200a, the emitter current of the transistor 230 increases.
The combined collector current of 28,229 is a maximum of two-thirds of the emitter current of the transistor 210,
It changes to a minimum value depending on the amplitude width of the voltage waveform applied to the input terminals 200h, 200i, and 200j.

Therefore, the resistance value of the resistor 235 can be changed to the resistance value of the resistor 236.
By selecting 1.5 times the resistance value of
The current flowing through the diode 237 has a minimum value of zero and a maximum value that depends on the amplitudes of the voltage waveforms 200H, 200I, and 200J, as shown at 200P in FIG. Dependent.

Next, FIG. 6 shows a specific circuit connection diagram of the synthesis circuit 600, in which input terminals 600l, 6
Output terminals 200l, 200m, 200n of the distribution circuit 200 in FIG. 4 are connected to 00m and 600n, respectively.
is connected, the output of the comparator 800 is applied to the input terminal 600y, and the output terminals 600u, 6
00v and 600w are connected to the bases of the switching transistors 5, 8, and 11 shown in FIG. 1, respectively, and the input terminal 600k is connected to the output terminal 100k of the circuit shown in FIG.

Now, the function of the synthesis circuit 600 shown in FIG.
1,602,603 or the resistance value of the resistor 604), input terminals 600l, 60
Output current according to the distributed current supplied to the output terminals 600u, 600v, 600w
The transistor 605,
Reference numerals 606 and 607 constitute drive transistors for driving the switching transistors 5, 8, and 11, respectively, and the emitter areas of these drive transistors are set larger than those of the other NDN transistors.
In the individual circuits described so far, including FIG. 6, it is assumed that the emitter areas of all the small current NPN transistors are equal, except for the Zener diode-connected transistors 103 and 112.

In the circuit of FIG. 6, transistor 608,
609, 610 are input terminals 600l, 600m,
This is provided to prevent the drive transistors 605, 606, and 607 from becoming conductive only by the distributed current supplied to the transistor 600n. That is, the maximum value of the distributed current is equal to the collector current of constant current transistor 238 in FIG. Since it is equal to the collector current of the transistor 223, all of the supply current is absorbed by the transistors 608, 609, 610.

FIG. 7 shows a specific circuit wiring diagram of the comparator 700 or 800, and shows an inverting input terminal 700a and a non-inverting input terminal 7.
00b output terminal 700y, and input terminal 700q is connected to output terminal 200q of the circuit of FIG. Note that the configuration and operation of the circuit shown in FIG. 7 are well known, so a description thereof will be omitted.

Now, in the device shown in FIG.
17, 18, diodes 32, 33, 34, and resistor 35, and the phase shift circuit 900, its operation is similar to that of a conventionally well-known brushless motor drive device. There is no difference. Note that the flywheel diodes 16, 17, and 18 have conventionally been used to prevent the switching transistors 6, 9, and 12 from being destroyed by a surge voltage at the time of switching off due to the inductance of the drive coils 13, 14, and 15. It has been used for many purposes.

However, the upper switching transistor 5,
The switch coils 4, 7, 10 are inserted between the collectors of the transistors 8, 11 and the collectors of the lower switching transistors 6, 9, 12. , 10, the phase shift circuit 90
Comparator 800 for rotational control via 0
By feeding back the output signal of the drive circuit to the input side of the comparator 800 and the combining circuit 6,
00, the upper switching transistor 5,
A drive circuit constituted by 8 and 11 operates as a kind of phase-shifted oscillator, and a switching carrier is generated within the loop of the drive circuit.

That is, the phase shift circuit 900 negatively feeds back the output of the drive circuit in an extremely low frequency region to stabilize the system, and also
3, 14, and 15 are fed back to the input side of the comparator through the shortest loop (outputs from the rotation speed detector and rotation phase detector are applied to the rotation command voltage input terminal S, but these As shown in the above-mentioned USP No. 4153864 or Japanese Patent Application Publication No. 47911 of 1973, it includes a relatively large time constant circuit, and therefore the command voltage appearing at the input terminal 7 is generally large. However, the voltage phase on the drive coil side of the chiyoke coils 4, 7, and 10 is delayed (the phase of the current flowing through the chiyoke coil is delayed). ), capacitor 3
At high frequencies where the voltage phase at both ends of transistor 9 is delayed by 180 degrees, a 360 degree phase difference occurs between the output side of the drive circuit (collector side of upper switching transistors 5, 8, and 11) and the input side (originally due to a negative feedback loop). The above-mentioned 180-degree phase delay is added to the 180-degree phase difference due to the 180-degree phase difference, resulting in a 360-degree phase difference as a whole), resulting in high-frequency oscillation.

Conveniently, this high-frequency oscillation will continue gradually if the loop gain is high enough, but
The rotational speed or rotational phase of the rotor changes significantly due to an increase in the load on the brushless motor, etc.
The level of the input terminal S decreases and the comparator 80
When the transistors of the drive circuit starting from 0 become saturated, the loop gain of one round decreases and the generation of high frequency carriers is stopped, and as a result, the upper switching transistors 5, 8, 10 become the lower switching transistor 6. , 9 and 12, the switching operation is performed by the position detection signal supplied from the distribution circuit 200.

When the load on the brushless motor becomes lighter, the rotor's rotational speed increases and returns to its original state, but if the load becomes even lighter, the rotor's rotational speed will rise above the standard value. The output transistor of the comparator 800 operates at an operating point close to the cut-off state, but in this case as well, the loop gain for one round is sufficient, so a high frequency carrier is generated, and the upper transistors 5, 8, 11
performs high frequency switching while having an extremely short conduction period.

As a result, the upper switching transistor 5,
8 and 11 perform a low-speed switching operation with a conduction period or a cut-off period depending on the increase or decrease of the load until the brushless motor reaches its generation limit torque, while also performing a high-speed switching operation using high-frequency oscillation. Thus, the sinking current waveform of comparator 800 under a constant load is:
The collector current waveforms of switching transistors 5, 8, and 11 are shown in Figure 5 at 800Y and 600Y, respectively.
It becomes as shown in U, 600V, 600W.

By the way, the output terminal 200p of the distribution circuit 200
Since a current as shown at 200P in FIG. 5 is sucked in from 200P in FIG. As shown at 19A, 20A, and 21A in the figure, the level change gradient is smooth, and smooth rotation of the rotor can be expected.

In addition, in FIG. 5, the waveforms indicated by broken lines are the same as in FIG.
This is the signal waveform when the output amplitude becomes large.

In this manner, the brushless motor drive circuit of the present invention is configured to generate a high frequency carrier for switching within the drive circuit loop including the upper switching transistor for distributing the position detection signal to the drive coil. Therefore, it is possible to save power consumption extremely easily without the need for a special oscillator or switching regulator.Furthermore, with the configuration shown in Figure 1, the following can be achieved. You can expect many effects as listed below.

First of all, by disposing the switch coils 4, 7, and 10 between the first, second, and third switch circuits, the switch can be prevented from momentary short-circuiting of the drive coil and destruction of the Hall element. This can prevent current damage to the switching transistor.

That is, in the embodiment shown in FIG. 1, the brushless motor has three-phase windings and uses a single energization method, so the upper switching transistor 5 and the lower switching transistor 6 are connected to each other. Although there is almost no risk of simultaneous conduction, the Hall element may fail or the insulating film may be torn due to heat generated by the drive coil, causing an excessive current to momentarily flow through the switching transistors 5 and 6 at the same time. is possible.

For continuous overcurrent, current detection transistors 22, 23, 24 and resistors 25, 2
6, 27, 28, the reference voltage source 29, and the comparator 700, there is no problem because the current limiting mechanism operates, but there is a delay in circuit operation in response to instantaneous overcurrent. The current limiting mechanism cannot fully operate, and the current limiting mechanism does not react at all to an accident such as a short circuit between the collector and emitter of the lower transistor due to a foreign object. In such a case, the chiyoke coil 4,
7 and 10 can reduce the risk of destruction of the switching transistor due to excessive inrush current.

Furthermore, as mentioned above, the phase shift circuit 900 can contribute not only to generating a high frequency carrier for switching, but also to improving the stability of the drive circuit and, ultimately, the control characteristics. In this case, relatively low frequency components are fed back via a capacitor 36 and a resistor 37, and high frequency components are fed back via a capacitor 38 with the capacitor 36 and the resistor 37 short-circuited. The optimum value varies considerably depending on the AC characteristics of the drive circuit and the detector connected to the input terminal S, so it cannot be said with certainty, but in reality, the capacitors 36, 38,
39 capacitances are 0.02μF, 2000PE, and 0.47μF, respectively.
Very good results were obtained when By the way, the Chi York coils at that time were 4, 7, 10.
The inductance of the capacitor 1 is 100μH, and the inductance of the capacitor 1
The capacitance of Nos. 9, 20, and 21 was 4.7 μF.

By the way, in the embodiment shown in FIG. 1, the voltage across the phase shift circuit 900 is configured to be unrelated to fluctuations in the power supply voltage, so even if the power supply includes ripple, the capacitor 36, 38,
39 does not change and does not adversely affect the smooth rotation of the rotor. That is, as can be seen from FIG. 1, the reference potential point of the comparator 800 (the reference potential point of the reference voltage source 31) is provided on the negative power supply line, and the upper switching transistors 5, 8, and 11 are connected to high-frequency switching transistors. and switching based on the position detection signal, and the lower switching transistors 6, 9, 1
2 is made to perform switching only based on the position detection signal, so that the voltages across the capacitors 19, 20, and 21 during normal rotation remain constant unless the load of the brushless motor changes, while Input terminal 80
Since the potential from the negative power supply line 0a is also kept constant, the voltage across the phase shift circuit 900 remains constant regardless of fluctuations in the power supply voltage.

Incidentally, when the reference potential point of the comparator 800 is provided on the plus side feed line (when the reference voltage source 31 is connected between the plus side feed line P and the non-inverting input terminal 800b of the comparator 800), the above Since the voltage across the phase shift circuit 900 changes according to changes in the power supply voltage, the capacitors 36, 38, and 39 are repeatedly charged and discharged due to power supply ripples, which impairs the stability of the operation of the drive circuit. It will be done.

Furthermore, as already explained with reference to FIG. 1, a ripple voltage having a level gradient depending on the gradient of change when the level of the position detection signal changes is generated inside the distribution circuit 200 and applied to the input side of the comparator 800. In particular, the signals applied to the bases of switching transistors 5, 8, 11 can be
Since modulation is applied, it is possible to smoothly switch the current to the drive coil, and smooth rotation of the rotor can be expected.

Furthermore, in the embodiment shown in FIG. 1, the upper switching transistor is configured with a PNP type bipolar transistor, and this upper switching transistor is made to perform high frequency switching, so that the upper switching transistor is configured with an NPN type bipolar transistor. The lower switching transistors 6, 9, and 12 are made to perform switching only in response to position detection signals, and there is a major reason for this.

In other words, as can be seen from the explanation of each block so far, this type of system is monolithic.
By using IC, the number of parts will be reduced dramatically,
Since circuit characteristics can be easily matched, operation stability and reliability are improved, and production costs are also reduced. However, with current technology, it is quite difficult to form a PNP bipolar transistor and an NPN bipolar transistor, which can carry large currents, on the same chip, and this results in a significant increase in chip size. Moreover, when high-frequency switching is performed, switching loss increases, and power loss becomes larger than when low-frequency switching is performed using a position detection signal.

In the device shown in Figure 1, taking these things into consideration,
Semiconductor parts except the upper transistors 5, 8, 11 and flywheel diodes 16, 17, 18 and most of the resistance parts are designed to be monolithic ICs. That is, even if the lower transistors 6, 9, and 12 through which the largest amount of current flows are formed on an IC chip, these transistors perform on/off operations at a relatively low frequency.
The power dissipation in these transistors is very low since they only operate in the active region for a short period of time when switching on and off (to smooth the current switching). For example, it is easy to set the collector-emitter on voltage to about 0.6V when the collector current is 0.5A, so
Even if the lower switching transistors 6, 9, and 12 are formed on one chip, the chip can be housed in an IC package with relatively high thermal resistance (for example, a dual in-line plastic package with 16 to 22 pins). Therefore, PNP type large current transistors (upper switching transistor 5,
8, 11) and flywheel diodes 16, 1, which require low operating resistance and low knee voltage for efficient power regeneration.
7 and 18 are made up of discrete components or separate chip ICs, and the system design becomes more rational if the parts other than these are made into monolithic ICs.

By the way, in the embodiment shown in FIG. 1, the brushless motor has a three-phase winding, and the phase shift circuit 900 is connected to the star-connected drive coil through diodes 32, 33, and 34. The connection may be a delta connection, or the drive coil 1 may be star connected as shown in FIG.
It is also possible to connect one end of the phase shift circuit 900 to the midpoint of connections between nodes 3, 14, and 15, and the present invention can be applied in exactly the same way to a brushless motor having two-phase windings as shown in FIG.

Furthermore, the output side of the switching transistor that supplies switching power to the drive coil based on the position detection signal, which is the basic idea of the present invention, and the input side of the comparator (both of which constitute the drive circuit of the brushless motor) By inserting a choke coil and a phase shift circuit, a switching carrier is generated within the loop of the drive circuit, and the switching transistor is capable of performing low frequency switching based on the phase detection signal and high frequency switching using the switching carrier. The idea of causing this to occur can also be applied to a half-wave drive type brushless motor, as shown in FIG.

In FIG. 10, a first switching transistor 5, a first chain coil 4, and a first drive coil 13 connect a first transistor connected between a plastic side feed line P and a negative side feed line N. The second series circuit 350 is constructed by the second switching transistor 8, the second choke coil 7, and the second drive coil 14.
50 are configured. It also includes a distribution circuit 250 that detects the rotational position of the rotor (not shown) using the Hall element 1 and distributes the position detection signal to the first and second switching transistors, and a rotation command voltage and a reference voltage. Comparator 800 to compare
and a combining circuit 600 that combines the output of the comparator and the output of the distribution circuit and applies the result to the first and second switching transistors. Furthermore, diodes 32, 33, resistor 35
A combining circuit 1000 that combines the voltages appearing in the first and second drive coils is configured, and the output voltage of the combining circuit 1000 is fed back to the input side of the comparator 800 via a phase shift circuit 900. In particular, the first and second switching transistors are caused to perform a relatively low frequency switching operation based on the position detection signal and a high frequency switching operation using the phase shift circuit 900.

In addition, in FIG. 10, the drive coils 13, 1
Capacitors 19 and 20 connected in parallel to 4 are used together with the yoke coil 4 and the yoke coil 7 to smooth the high frequency carrier.

In addition, in FIG. 10, the function of the distribution circuit 250 is to amplify the output of the Hall element 1 by a differential amplifier in the same way as the position detection signal amplifier 100 in FIG. 5 and 8, and since there is no lower switching transistor due to the half-wave drive method, the function of the distribution circuit 200 used in FIGS. 1, 8, and 9 is not necessary. Not fried.

Furthermore, in the embodiment shown in Fig. 1, bipolar transistors are used for each transistor including the switching transistor;
They may be unipolar transistors such as FETs, or switching transistors 5, 8, 11, 6, etc. may be used for high power switching.
Other switching elements such as high speed thyristors can also be used in place of 9 and 12.

As described above, in the brushless motor drive device of the present invention, the switching coil is connected between the output side of the switching element that switches and supplies power to the drive coil based on the position detection signal and the input side of the comparator that constitutes the drive circuit. By connecting the voltage synthesizing means and the transfer circuit, a switching carrier is generated in the loop of the drive circuit, and the switching element performs low-speed switching based on the position detection signal and high-speed switching by the switching carrier. Since this is done, the power consumption can be reduced with an extremely simple configuration, resulting in a great effect.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of a brushless motor drive device according to an embodiment of the present invention, FIG. 2 is a circuit connection diagram showing an example of a position detection signal amplifier, FIG. 3 is a signal waveform diagram of each part, and FIG. The figure is a circuit wiring diagram showing an example of a distribution circuit, Figure 5 is a signal waveform diagram of each part of Figures 1 and 4, and Figures 6 and 7 are circuit wiring diagrams showing an example of a synthesis circuit and a comparator, respectively. 8, 9, and 10 are circuit configuration diagrams showing other embodiments of the present invention. 4, 7, 10... Chi York coil, 5, 8, 1
1...Switching transistor (upper side), 6,
9, 12...Switching transistor (lower side),
200...Distribution circuit, 300, 400, 500...
...Switch circuit, 600...Synthesis circuit, 800...
... Comparator, 900 ... Phase shift circuit, 1000
...Synthetic circuit.

Claims (1)

[Claims] 1. A first switching circuit having first and second switching elements connected in series to a power supply with a first switch coil interposed therebetween;
a second switch circuit having third and fourth switching elements connected in series to a power supply with a switch coil interposed therebetween; a connection point between the first switch coil and the second switching element; a drive coil connected to bridge a connection point between the second York coil and the fourth switching element; first and second smoothing capacitors respectively connected to these connection points;
a voltage synthesizing means for synthesizing the voltages across the first and second smoothing capacitors; a position detecting means for detecting the rotational position of the rotor and generating a position detection signal;
The position detection signal is transmitted to the first, second, third, and fourth
a distribution circuit that distributes the voltage to the switching elements, a comparator that compares the rotation command voltage and the reference voltage,
a combining circuit that combines the output of the comparator and the output of the distribution circuit and applies the result to the first and third switching elements; and a combining circuit connected between the output side of the voltage combining means and the input side of the comparator. , comprising a phase shift circuit that generates high frequency oscillation in a loop from the comparator to the voltage synthesizing means, the first and third switching elements having a low speed switching operation depending on the position detection signal and the high frequency A brushless motor drive device configured to perform high-speed switching operation using oscillation. 2. A first series circuit consisting of a first switching element, a first switch coil, and a first drive coil connected between the power supplies, a second switching element and a second switch coil connected between the power supplies,
a second series circuit including a second drive coil; a connection point between the first drive coil and the first drive coil; a connection point between the second drive coil and the second drive coil;
the first one connected to the connection point of the drive coil, respectively;
and a second smoothing capacitor, and the first and second smoothing capacitors.
a voltage synthesizing means for synthesizing the voltages across the smoothing capacitor; a distribution circuit for detecting the rotational position of the rotor and distributing the position detection signal to the first and second switching elements; and a rotation command voltage and a reference voltage. a comparator for comparing the outputs of the comparator and the output of the distribution circuit, a synthesis circuit for synthesizing the output of the comparator and the output of the distribution circuit and applying it to the first and second switching elements, and an output side of the voltage synthesis means and an input side of the comparator. a phase shift circuit connected between the comparator and the voltage synthesizing means to generate high frequency oscillation in a loop from the comparator to the voltage synthesizing means; A brushless motor drive device configured to perform a switching operation and a high-speed switching operation using the high frequency oscillation.