JPS6152194A - Speed controller of synchronous motor - Google Patents

Abstract

PURPOSE:To reduce the size and to enhance the efficiency of a synchronous motor without containing a position detector in a motor body by detecting the induced voltage of a stator coil to control the conduction of an inverter. CONSTITUTION:An induced voltage generated in a stator coil is detected from the neutral point voltage of stator coils Su, Sv, Sw coupled in a star-connection of a synchronous motor 4, a pulse signal synchronized with the rotation of the motor is generated from a synchronizing pulse generator 6, a drive circuit 9 is controlled by the pulse signal to drive the motor by controlling to conduct an inverter 3. When the motor is starting, a firing pulse signal is forcibly generated from a firing pulse generator 8 instead of the pulse signal, thereby controlling to conduct the inverter to start the motor and automatically switching to the drive by the induced voltage after staring.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a speed control device for a synchronous wall heater used in an air conditioner or the like.

<Technical background of the present invention and its problems> Conventionally, synchronous motors using permanent magnets as rotors were driven by being directly connected to a commercial frequency power source, but the speed could not be varied and the rotational speed of the rotor If the rotor is not synchronized with the power supply frequency, effective torque will not occur, making starting difficult. However, there were problems in that the configuration was complicated, expensive, and efficiency deteriorated.

However, with the recent development of inverters, a motor is connected to a commercially available frequency power source via an inverter, and the frequency of the power source is variably controlled by the inverter, thereby controlling the rotation speed of the motor at variable speed. This has come to be commonly used.

This inverter drive system is effective for three-phase induction motors, but for synchronous motors, sudden fluctuations in the number of cycles such as overload, start-stop, etc. will cause a synchronization error, resulting in so-called failure. There is a problem in that there is a risk of harm.

In addition, the so-called brushless motor, which is configured to detect the rotor position of a permanent magnet using a rotor position detector such as a H/L/element and is controlled by this detection signal, has excellent controllability and high efficiency. Since then, it has come to be frequently used as a drive source for office automation equipment, audio equipment, etc.

This bookless motor uses electronic circuits such as Hall elements to
It is a very effective means for small motors of @W or less that are integrated with the drive circuit for positioning at night, but it is not suitable for motors used in night air conditioners etc. that require more than 10 W. Since the drive circuit becomes large, it is difficult to integrate the motor with the force, especially the heat generated by these motors. In this case, there are problems in that the device becomes large in size, malfunctions occur due to thermal stress, and reliability decreases.

This is because the method used is to connect the main circuit of the main unit and the lead wire of the position detector.

However, when configured in this way, (a) the mounting member for the position detector is incorporated, which requires space in the motor body, making it large and expensive.

(b) When a Hall lv element is used as a position detector, the hole μ
Since the elements are sensitive to heat, the heat generation of the motor must be suppressed to maintain reliability, and the motor must be made larger to improve heat dissipation, or the motor output must be lowered.

(c) The number of lead wires is large (for example, 8 to 11), which requires a lot of effort and becomes a factor in high costs.

(2) The output signal of the position detector is weak (for example, 5Qmv to 100mV in the case of a Ho/l/element), and the longer the lead wire is, the more likely it is to pick up noise, lowering reliability and causing malfunction.

There is a problem.

On the other hand, recent air conditioners are required to have very fine electronic controllability, and along with this, motors are also required to have fine variable speed control, higher efficiency, smaller size, and lower cost. Even brushless motors equipped with position detectors cannot sufficiently meet the above requirements.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to incorporate a position detector such as a V element into the motor body without adding a squirrel cage coil or a hysteresis ring. To provide a device that is compact and highly efficient, and can be driven with precise variable speed control.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention aims to provide an induced voltage generated in the stator coil μ from the neutral point voltage of the star-connected stator coil μ of a synchronous motor connected to a DC voltage via an inverter circuit. is detected, thereby generating a pulse signal synchronized with the motor slip, and the pulse signal is used to control conduction of the inverter circuit to drive the motor, and when the motor is started, the pulse signal is activated. Instead, an ignition pass μ signal is forcibly generated, which controls the conduction of the imperter to start the motor, and after starting, the motor is automatically switched to drive using the induced voltage described above. .

Embodiments of the Present Invention First, in order to facilitate understanding of the present invention, the voltage generated at the neutral point of the stator coil μ will be explained.

For the DC power supply, transistors Qu, Qv, Qpw, %-Q
y (via an inverter circuit connected in a bridge shape,
Stator coil of star-connected synchronous motor p%ms,
, S meter is connected to sequentially conduct the transistor cages of the inverter circuit to drive the permanent magnet rotor, the stator coil/L/5u-8v,
Each phase of Sψ has an induced voltage ~* as shown in Figure 2 (→)
As can be seen from this voltage waveform, the energization timing of the transistor (9) is 60 degrees (electrical angle) before and after the maximum value of the induced (back emf) voltage.
The ideal energization is to energize at ° (Fig. 2 (→
, (Tri). When ideal energization is performed in this way, the neutral point voltage vN generated at the neutral point N0 of the stator coil ξ* Sv, ~.

is, stator carp/I/Su, Sv, SWl! The voltages measured from the neutral point Np of the r-phase induced voltage are F, , , respectively.
11. , F.

Assuming that the resistance valve of the stator coil μ is R, and the voltage applied to the inverter circuit is v8, in the period (1) shown in Fig. 2 (/), the transistor (and writing force;
Since the other transistors Q, ..., Qw, Q, and QJz# are off, the equivalent circuit at this time is shown as shown in Figure 3, and the neutral point voltage vNo at this time is calculated by first taking the current In addition, the above vN0 can be shown as vN0=R'FJv (and α) above, and by eliminating i from equation (2), it can be shown as follows. Therefore, the neutral point voltage vNo has a value that is independent of the resistance and current of the stator coil μ. The other periods (1) to (to) can be shown in the same way, and if only the results are shown, it will be the next energization. .

That is, at the neutral point N0 of the stator coil N Su, sv, 5Vf), a voltage that is the sum of 1/2 of the applied voltage (vf) and 1/2 of the induced voltage (for example,
It is shown as a figure (/u).

For the reason mentioned above, the neutral point N is reached from the point of 1/2 of the applied voltage vs. If the configuration is configured to measure the voltage vNo of (However, E: E, Majesty, general term for E shell), and the present invention is capable of detecting the induced voltage E regardless of the applied voltage v8, as is clear from the above (4) This was done with a focus on the ability to

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a DC power supply, and 2 is a path μ width modulation type chopper power supply circuit connected to the DC power supply 1 through connection terminals P and N, and configured to output a variable output voltage. be. This is inserted between the connection terminals P and N above, through the collector and emitter of the control transistor Q, and in series with the choke coil μL and the capacitor C, y2, and the resistor R between the collector and the paste of the transistor Q. The anode of the diode wire whose cathode is connected to the emitter of the transistor Q is connected to the connection terminal N, and resistors R3 and R4 are inserted in series between the terminals of the capacitor C. The connection point between resistors R3 and R4 is connected to the inverting input terminal of a voltage error detector EEA consisting of an operational amplifier, and the non-inverting input terminal of this n-voltage difference detector EA is connected to the
The output voltage corresponding to the rotation speed of the motor is set, and this is sent as a speed command.The output terminal of the speed setting circuit (not shown) is connected to the output terminal of the error detector EA. It is connected to the inverting input terminal of a comparator CP consisting of an operational amplifier whose output end is an open collector via a diode D2 with an i-sode connected to the end. The output terminal of a current error detector EA2 consisting of an amplifier is connected via a diode D3 whose cathode is connected to the output terminal as described above, and a constant voltage power supply V is connected to the non-inverting input terminal of this error detector ERA2. The inverting input terminal of the error detector EA2 is connected to a current detector consisting of a resistor inserted in series between the circuit 2 and the circuit ground, and the connection point of resistors R5 and R6 is connected. The inverting input terminal of the comparator CP is connected to the constant voltage power supply V via the constant current source CI. , and the output terminal of a pass generator O8C that oscillates a saw-wave pulse signal at a constant frequency (for example, 30KH2) is connected to the non-inverting input terminal of the comparator CP. The output terminal of the CP device is connected to the base of the transistor Q2 whose emitter circuit is grounded, and the constant voltage power supply V is connected through the resistor R7.

and connect the collector of the transistor Q2 to the resistor R2.
t'' to the base of the transistor Q, and sends out the voltage between the terminals of the capacitor C as the output voltage vs, and detects an error in this output voltage vs via a voltage divider consisting of resistors R3 and R4. The error with the speed command is detected by inputting it to the equipment EA engineer, and the comparator CP
The bus width modulation signal (hereinafter referred to as PW) sent from the output terminal of the
The on-period of the transistor Q is controlled via the transistor Q2 by varying the M signal (referred to as the M signal), and an output voltage (8) corresponding to the speed command is sent out. Furthermore, when the output voltage from the current detector is about to exceed a predetermined value (that is, the value corresponding to the overcurrent set in advance by resistors R5 and R6), the circuit 2 controls the output voltage of the error detector EA2. The output voltage vKA of the error detector mA is determined by vEA2.
Similarly to the above, the on-period of the transistor Q can be controlled to lower the output voltage v8 and suppress the current by setting the relationship vEA2 < vEA. If this happens, it will function as an overcurrent limiter. 3 is a so-called 120 which is connected to the output end of the chopper power supply circuit 2 and supplies power to a three-phase synchronous motor (hereinafter simply referred to as motor) 4.
'It is a current-carrying type inverter circuit. This means that three PNP transistors are connected to the positive output terminal of the chopper power supply circuit 2.
e Qv-ψ emitter is connected and this transistor (,
Connect the collectors of three transistors %-Qy-%, whose emitters are grounded to the circuit ground, to the collectors of
The above transistor (and Q engineering, ctV and QA, Q, 7
The above transistor (
DC input voltage v8 is converted into a three-phase AC voltage and supplied to the motor 4 by energizing the transistor 120" at appropriate times. Furthermore, a flywheel is connected between the collector and emitter of the transistor %. Diode D, 7
D, 7% each inserted. As is well known, the motor 4 is composed of a rotor 4a permanently magnetized with a plurality of magnetic poles, and a stator (not shown) disposed opposite to the rotor 4a and wrapped with a Nuteta carp/l/Su, Sv, S shell. Shi, the above stator carp/1/Su, Sv, 5vp
One end is commonly connected to form a star connection, and this stator coil i
v Su, S,, SρThe other end is connected to the above inverter circuit 3
are connected to each output terminal of the 5 inserts resistors R8 and R9 in series between the input y5i of the inverter circuit 3, and the voltage dividing point (R8 and R).

This is a voltage dividing circuit that outputs an output voltage v5 obtained by dividing the input voltage v8 by half from the connection point of the input voltage v8.

6 is a synchronization circuit which is set to detect an induced voltage by comparing the voltage vNo in the stator coils Su, Sv, and Sρ of the motor 4 with the output voltage v5 of the voltage dividing circuit 5, and to generate a pulse signal synchronized with this. This pulse generation circuit connects the non-inverting input terminal of comparator 'a OP 2, which is an operational amplifier, to the neutral point N0, and connects the inverting input terminal of comparator CP2O to the output terminal of voltage dividing circuit 5. The output terminal of this comparator CP2 is connected to a first bus generator MB consisting of a monostable multi-pie break which sends out a one-shot pulse signal at the rising edge of the input signal. It is connected to both input terminals of a second bus generator MB2, which is a monostable multi-receiver circuit configured to send out a one-shot pulse signal at the same time. Connect the output terminal Q to the input terminal of the OR circuit OR circuit, and connect the above transistor (
"When switching the gain ρ, a synchronous pulse signal is sent out that is synchronized with the rising and falling zero points of the neutral point voltage vNo, preventing malfunctions due to spike voltages generated in the induced voltage.7 is a DC blocking circuit in which a capacitor C is inserted between the non-reflective input terminal of the comparator CP2 of the synchronous pulse generating circuit 6 and the neutral point N0 of the motor 4, and a bias resistor is inserted between the input terminal of the comparator CP2. R is inserted to cut and send the DC component included in the neutral point voltage vNo to the non-reverse input terminal of the ratio gearbox CP2 of the synchronous PA/I/7° generating circuit 6, and The output voltage v5 of the voltage dividing circuit 5 is sent out via the bias resistor R1o, and only the induced voltage is detected and outputted by the comparator CP2. 8 is connected to the output terminal of the synchronization pulse generation circuit 6. The transistor of the inverter circuit 3 (drive circuit 9 is connected to the base of the inverter circuit 3)
This is a ps generation circuit which sends out a pulse signal at the time of starting the motor 4, etc. through the ignition. This is done by connecting the input end of the tour circuit NOR circuit to the output end of the OR circuit OR circuit of the synchronous pulse generation circuit 6, and
Connect the cathode of a diode D4 to the output terminal of 0R1, and connect the constant voltage power supply ■ to the anode of this diode D4. and the resistor R inserted in series between the circuit ground and the capacitor C3.
This connection point (point b) is connected to the set input terminal S of the RS flip-flop circuit FF formed by the NAND circuit NA and NA2 via the knot circuit N. Connect the output terminal Q of this 7 lip-flop circuit FF circuit (the output terminal of the NA circuit) to the input terminal of the tour circuit NOR circuit, and connect the output terminal Q of the above-mentioned tour circuit NOR circuit to the circuit ground. is connected to the resistor R via the knot circuit N2. and capacitor C4 in series, connect the connection point (point e) of the resistor R and capacitor C4 to the reset input terminal R (input terminal of NA2) of the above free lag flop circuit FF circuit, and turn on the power. When the special motor 4 is in a stopped state, a pulse signal for starting the motor 4t is sent to the output terminal Q of the free lag flop circuit FF.
An OR circuit OR2 is connected to the high output terminal from 0 to 0.
゜Sends out the output signal of ゜75 island raゞH rubeμ, and thereafter, every time the input signal rises to count, the output terminal 0-> has the same number of OR circuits oRu to OR2 as the above transistors, The output terminal O of the counter CU is connected to the input terminal of the OR circuit ORu.
0 and O□, output terminals 02 and 03 to the input terminal of ORV, O
Output terminals 04 and 05 are connected to the input terminal of Rw, output terminals 03 and 04 are connected to the input terminal of ORx, and output terminals 0. and O
8, the input terminal of OR2 is formed from the output terminal O and the distribution 33 DE V connected to 02, respectively, and the transistor %-Q is connected from the output terminal of the OR circuit ORu to OR2.
, 10 is connected to the above-mentioned DC α source 1, and a constant voltage power supply is provided to each circuit. This is a constant voltage power supply circuit that sends out as a control power supply.

Next, its operation will be explained with reference to FIGS. 4 to 6.

(2) Starting when the power is turned on When the power switch (not shown) is turned on with all the transistors (~~μ) off and no speed command given, the DC power 1 is supplied and the constant A constant voltage power supply V is supplied from the voltage power supply circuit 10 to each circuit as a control power supply.As a result, in the chopper power supply circuit 2, the output of the comparator CP becomes 'H' Vbe, so that the transistor Q2 is The transistor Q is turned on, and the output voltage V8 is not sent out until it is turned off.-By supplying the force control power,
The drive circuit 9 has an output terminal of the counter CU, for example, 0.2
＞, 1H level output signals are sent out, so the OR circuit of the distributor DE■, for example, the output signal of 'H level μ from ORu and ORy is used as a base drive signal to drive the transistors Q, , Qf of the inverter circuit 3. However, since the inverter circuit 3 does not receive the input voltage v8, it does not turn on, and the motor 4 remains stopped.

In this state, when an output voltage corresponding to a predetermined rotational speed is given as a speed command from a speed setting circuit (not shown), the error detector EA receives this and outputs a voltage that has detected an error with the other input (OV). Output EAI. At this time, the output voltage vEA of the error detector EA and the output voltage vEA2 of the error detector EA2 have a relationship of vEA x vEA2, so the diode D2 is conductive (diode D3 is non-conductive). The comparator CP compares the levels of the above-mentioned EA and the saw-wave output signal of the bus generator O3C, and determines the period during which the output signal of the bus generator oSC is at a higher level than the vEA. Transistor Q2 by 1H Lebel! The transistor Q is turned on during this off period while receiving the input signal of the L level, and the capacitor C is charged via the choke coil L, and the charged voltage is applied to the inverter circuit 3 as the output voltage v6. Send to. On the other hand, the above control "m'. iF+:r
By supplying i, the ignition pulse generating circuit 8 receives an output signal of 'L level from the synchronizing valve generating circuit 6, and the output signal of the NOT circuit N2 becomes 'IH level', and the capacitor C4 is connected to the resistor R. , is charged in a time period determined by the OR time constant, the potential at point e rises to 'H lupéμ, and the output signal of the tour circuit NOR becomes 'H lupéμ, and diode D4 becomes non-conducting. The capacitor C3 is charged through the resistor R in a time period determined by the OR time constant, and the potential at point b rises, and this potential at point b becomes the threshold hold level of the knot circuit N. Figure 4 b)
When the output signal of the not circuit N is inverted to L level (Fig. 4C), the flip-flop circuit FF is set due to this inversion, and the output signal of the output terminal Q is set to 1H.
(output of FIG. 4, 8). The counter CU, which receives this through the OR circuit OR2 of the drive circuit 9, counts at the rising edge of the input signal and inverts the output signal of the output terminal, for example, O, to 1H level μ.At this time, the output terminal o0 outputs The signal is inverted to "L rube μ" (Fig. 4 00, o),
The distributor DEV receiving this is connected to its OR circuit, for example, OR
u and OR2 send out the transistor QIu(!:Q4I/'C) using the output signal of ``HH'' as the base drive signal, turning it on and driving the stator coils lvSu and S of the motor 4.
Turn on WK. At this time, the ignition pulse generating circuit 8 outputs an output signal from the output terminal Q of the flip-flop circuit FF.
By rotating the ``HH'' level, the output signal of the tour circuit NOR is inverted to ``LL'', the diode D4 passes through, and the electric charge of the capacitor Ci is discharged through the diode D4, thereby increasing the potential at point 5b. Threshold Hold
Since the level goes down, the output signal of the knot circuit N is '
Flip to H level (Figure 4C). Also, knot circuit N
The output signal 2 discharges the charge of L level through the low resistance R circuit, so that the potential at point e drops, and this dropping potential at point e becomes the threshold of tour circuit NA2 of flip-flop circuit FF□. When the level /I/vth2 is reached (Fig. 4e), the flip-flop circuit FF is reset, the output signal at its output terminal Q is inverted to 'L level μ, and the OR circuit oR2
The output signal of the circuit 8 becomes 1L μ (4th
Figure 8 output). When the output signal of the flip-flop circuit FF is inverted to 'L level', the ignition pulse generating circuit 8 operates in the same manner as described above and sends out a pulse signal (output shown in FIG. 4, 8). , the drive circuit 9 receiving this is oR
From the output terminal of u~OR2, at the rising edge of the input signal, the transistor Qu of the 1H level circuit 3 is connected to, for example, Qu-Qy.
-Qr''%-Qw-Qy!' A base drive signal is sent out to control on/off in the order.

In this manner, when the motor 4 is started, the transistors of the inverter circuit 3 are forcibly switched and energized by the bus lv signal of the ignition pulse generation circuit 8. At this time, since the induced voltage is zero or very small, the current flowing through the stator coil/L/Su, SvlSwK of the motor 4 tends to become very large, but this current is detected by the current detector and the output voltage is chopped. When this input voltage is about to become larger than the other input voltage, the error detector EA2 erroneously sets the output voltage EA2 to the output voltage VEA of the image detector EA. Since the relationship is vEA > vEA2, diode D3 becomes conductive and D2 becomes non-conductive), error detector EA
The output of 2 is sent to the comparator CP 19 times before the other one,
In response to this, the comparator CP compares the level with the other input signal and outputs the output signal of ``H Lupe μ'' so that the bus width is widened to lengthen the on period of transistor Q2. , shorten the ON period of the transistor Q to enable output, lower the voltage v8, and prevent current exceeding a certain level from flowing (
suppress. That is, it functions as an overcurrent limiter. Then, friction occurs due to the relationship between the current flowing through the stator coils Su, SV, S, and the permanent magnet of the rotor 4a, and the rotor 4-; moves to a predetermined position, generating an induced voltage and neutralizing it. The comparator CP2 of the synchronous pulse generation circuit 6, which receives the neutral point voltage vNo at point N0 via the DC blocking circuit 7, compares the level with the output voltage 5 (VS/2) of the voltage dividing circuit 5, and determines that vNO>■ 5 relationship ``IHf
The output signal having the level μ is the first. Second pulse generator MB
□, send to MB2. In response to this, the pulse generator MB2 is input to the pulse generator MB2.
generates a one-shot pulse signal having a constant width T of 3177 at each falling edge of the input, and sends this to the OR circuit O.
The OR circuit O of the drive circuit 9 uses the output signal obtained by taking the logical sum of both pulse signals from the output terminal of the R circuit as a synchronous pulse signal.
Output of Fig. 4 (6) sent to counter CU via R8)
, enters so-called synchronous operation. When synchronous operation starts, the induced voltage also increases, so the current decreases and the function as an overcurrent limiter is canceled, and the output voltage v8 corresponding to the speed command is sent to the inverter circuit 3, and the output voltage V8 corresponding to the above output voltage VS is sent out. At the speed the motor 4 rotates 4 times.

In this way, the ignition pulse generation circuit 8 forcibly generates a pulse signal, which switches the transistor QQr of the inverter circuit 3 and energizes it, making it easy to start the motor. The circuit 8 has the following characteristics by selecting the OR time constant of the resistor P□ and the capacitor C3.
The buffless signal can be generated at a frequency (hereinafter referred to as starting frequency) corresponding to the speed at the time of starting the motor 4 that is suitable for the load.

Then, when the motor 4 enters synchronous operation, the synchronous pulse generation circuit 6 sets the stator coil /L/Su, Sv, Sρ to the neutral point N. Since the induced voltage generated by lc is detected and a synchronizing pulse signal is sent to the drive circuit 9 (output in Fig. 4, 6),
The charge voltage of 3) discharges without reaching the threshold μ level /L/v of the knot circuit N The generation of forced pulse signals is prevented. In other words, when the motor 4 enters synchronous operation, the synchronizing pulse signal of the synchronizing pulse generating circuit 6 is transferred from the transistor (ρ switching is the bus forcibly sending out the ignition pulse generating circuit 80) of the inverter circuit 3. This is done by dynamically switching to 1.

(6) Steady operation By applying the output voltage vS corresponding to the speed command mentioned above from the chopper power supply circuit 2 via the inverter circuit 3 to the stator coil /l/Su, Sv, 5vTK of the motor 4, the output voltage vS corresponding to this voltage vS is applied. The motor 4 is driven at this speed and enters a so-called steady operation.

To further explain the operation during this steady state axis, the transistor commutation noise of the inverter circuit 3 is sequentially switched by %-'W'' by the base figure signal of the drive circuit 9, and the commutation noise of the transistor is generated at the neutral point '1 section voltage vNo. Due to the weight, this conductive noise causes the synchronous bias iL/,
The comparator CP2 of the x generation circuit 6 operates and sends out an output signal. That is, as shown by the input CP2 in FIG. 5, the neutral point voltage vNO is affected by the spike voltage vsP due to the switching of the transistor %-%, and this crosses the level of the output voltage V5 of the voltage dividing circuit 5. Therefore, the pulses that are generated during the entire period WK after detecting the necessary detection points g and h points are unnecessary, and it is necessary to so-called mask them to prevent malfunctions. Therefore, in the present invention, a one-shot pulse signal is sent to the output terminal of the comparator CP2 at a constant value of 1 at the rising edge and falling edge of the input signal. Second pulse generators MB□ and MB2 are provided, and the first pulse generator MB is used for the W period of the positive half wave of the neutral point voltage v1, and the pulse generator MB is used for the W period of the positive half wave of the neutral point voltage v1. For the W period, a one-shot pulse signal is generated by the second pulse generator MB, respectively, and the MB1 and MB
By making the signal the logical sum of the pulse signals of 2 and 9.
165 As shown in the output of Fig. 6, the rise timing of the output signal is at the same time as the zero point of the neutral point voltage vNO, which prevents malfunctions due to the shar voltage that occurs when the transistor ζ is switched. Therefore, the synchronous pulse generation circuit 6 sends out a pulse signal synchronized with the induced voltage (fifth pulse signal).
and the output of 6 in Fig. 6). I received this j[j3!
Each time the counter CU of the +/re circuit 9 counts at the rising edge of the input, it sequentially sends out an output signal of hH rube ρ from its output M Oo~05. The device DEFY sequentially sends out pace drive signals from the output terminal of the OR circuit 0Ru-OR2 according to the combination of input signals. %-Qw
→The motors are turned on for a 120° current-carrying period at appropriate times in the order of Qρ (see FIG. 6), and the input voltage V8 is supplied to the motor 4 as three-phase AC power to drive it.

◎ Variable speed control Next, when changing the speed of the motor 4 in the above steady operating state, the speed command (not shown) of the speed setting circuit (
This is done by changing the output voltage). That is, by changing the speed command to a voltage corresponding to the speed desired to be decelerated or accelerated, the PWM signal sent from the collector of transistor Q2 is changed.
The output voltage v8 of the chopper power supply circuit 2 is increased (accelerated) or decreased (decelerated) by controlling the on-period of the motor 4, and the stator coil A/Sv, Sρ of the motor 4 is adjusted to the neutral point N. The induced voltage generated in the comparator CP2 of the synchronous pulse generation circuit 6
The first . When the second bar/l' signal is generated i43?4Bx, the pulse signal of MB2 is sent to the drive circuit 9 as a synchronous pulse signal via the OR circuit OR1, and the pace drive signal of this causes the transistor % of the impark circuit 3 to be -Q'z is made conductive in a timely manner, and the impark circuit 3 converts the input voltage vs into a 3-phase AC voltage and supplies it to the motor 4, so it follows the rotation speed of the motor 4 to the same "IJ". The speed of the motor 4 is controlled again.Moreover, since the induced voltage is detected at 1/6 cycle/L/(60°)@, the rotation speed of the motor 4 is adjusted without causing step-out. The motor 4f is controlled by the output voltage v8 of the chopper power supply circuit 2 and the number of word of mouth commensurate with the load torque μ:
It is important to rotate it.

At this time, even if the speed command is suddenly changed and the output voltage vs of the chopper power supply circuit 2 is suddenly changed, the synchronous pulse generation circuit 6 detects only the induced voltage.
There is no possibility that the above-mentioned output "[i°C voltage dD opening] is erroneously detected as a change in the induced voltage, and the speed of the motor 4 can be variably controlled without causing step-out.

q When a load torque that locks the rotation of the motor 4 is applied during overload, when the current tries to increase, the output voltage vEA2 of the error detector EA2 of the chopper power supply circuit 2 becomes the output of the error detector EA. Voltage ``EA engineering is small'' (vE
A2 EAI 〈V ), the output voltage V of the error detector EA2 is sent to the comparator CP, and the output voltage V of the error detector EA2 is sent to the collector of transistor Q2 to narrow the bus width.
The WM signal is sent out at the same pace as the transistor, so that the output voltage v8 of the chopper power supply circuit 2 is lowered with priority over the speed command, and the current is suppressed.

If the synchronization of the synchronization pulse signal of the synchronization pulse generation circuit 6 becomes longer than the period of the pulse signal of the firing pulse generation circuit 8 due to the drop in the output voltage v8, then ) Since the transistors Qu-Q2 of the inverter circuit 3 are sequentially switched via the drive circuit 9, the stator coil p of a specific phase is switched without being continuously energized, and the motor 4 is switched under load P. Even if the stator coil μ of a particular phase is locked and stopped, there is no inconvenience such as overheating the stator coil μ of a particular phase.
Further, the inconvenience of overheating only a specific transistor may/may occur.

Moreover, if the load that causes the lock is removed, the same thing as at the time of startup mentioned above will occur! Create an i/I and automatically enter synchronous operation.

Effects of the present invention> According to the present invention, the following effects are achieved.

(a) Since the HN pressure generated by the motor itself switches the transistors in the inverter circuit, it is possible to ensure that the motors rotate in synchronization.
Synchronous interlocking can be performed without step-out even at low speeds where the induced voltage is undetectable, and the speed can be freely controlled over a wide range from low to high speeds without using a synchronous motor. .

(In addition, with variable speed, simply by changing the voltage applied to the inverter circuit, the motor can be automatically driven at a drive frequency that matches the motor load conditions.)

(c) Also, even if the motor rotation speed increases rapidly due to the load, the induced voltage should be reduced by 1/6 cycle (60°).
Since the system detects and tracks each time, it is possible to further improve the tracking ability and synchronize without losing synchronization even in response to sudden changes in load.

In addition, even if a condition such as the motor locking occurs, the transistors in the inverter circuit are switched on and off in sequence, so current continues to be applied to the coil μ of a specific phase or to a specific transistor. There is no such thing at all, and there is no such thing as overheating the carp μ or causing thermal damage to the transistor, and it also prevents the motor from being made larger for heat dissipation, and from using the motor at a lower output. I can do it.

(E) Moreover, unlike brushless motors equipped with position sensing elements, there is no need to house a printed circuit board for the position sensing element in the motor body, and there is no need to suppress heat generation from semiconductor components used in the device. Also, a heat dissipation means is not required, so the motor can be made smaller, its reliability can be further improved, and it can be made cheaper.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams of position detection using induced voltage in FIG.
Figure 2 is a time chart diagram, Figure 3 is a motor U-
FIG. 3 is an equivalent circuit diagram when the V phase is energized. Fig. 4 is a time chart diagram explaining the #J operation at startup in Fig. 1, fg Fig. 5 is a time chart diagram explaining the operation of the synchronizing pulse generation circuit in Fig. FIG. 3 is a time chart diagram illustrating operations during steady state. 1: DC power supply, 2: Chopper power supply circuit, 3: Inverter circuit, 4: Synchronous motor, 5: Voltage divider circuit, 6: Synchronous pulse generation circuit, 8: Firing pulse generation circuit, 9: Drive circuit, MB engineering: First pulse generator, MB2: Second pulse generator, Fig. 4 Fig. 6 Fig. 5

Claims (1)

[Claims] A chopper power supply circuit that is connected to a DC power supply and sends out a variable output voltage according to the speed command, an inverter circuit that has multiple transistors connected in a three-phase bridge shape at the output end of this, and a star-shaped power supply circuit. A synchronous motor to which connected stator coils are respectively connected, and the transistor is made conductive in a timely manner by a paste drive signal of a drive circuit to drive the synchronous motor,
A voltage divider circuit is provided between the input terminals of the inverter circuit, which divides the input voltage into half and outputs the divided voltage, and the output terminal of the comparator is connected between these output terminals and the neutral point of the stator coil. Connect the input terminals of the first and second pulse generators, each of which sends out a one-shot pulse signal at the rising edge and falling edge of the input signal, and connect the output signals of the first and second pulse generators to the OR. The input terminal of the comparator of the synchronous pulse generation circuit is connected to the input terminal of the comparator, and the synchronous pulse signal of the synchronous pulse generation circuit is used to control the conduction of the transistor via the drive circuit. Characteristic synchronous motor speed control device.