JPH11235078A - Operating method for dc sensorless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable simultaneous control of a plurality of motors by the use of a single inverter circuit by switching output modes in order, on the basis of the change of the resultant voltage of induced voltages produced in stator windings not in continuity by the rotation of the rotors of a plurality of DC sensorless motors. SOLUTION: Two DC sensorless motors 1a, 1b have the same specifications, and are connected to terminals 3u, 3v, 3w in parallel. And if the load of the motor 1a is lighter than that of the motor 1b, the time in which mode 2 is maintained becomes shorter for the motor 1a than for the motor 1b when the same voltage is applied to the stator windings, and their rotational speeds become to differ. Accordingly, induced voltages generated in stator windings to be in noncontinuity are compounded and it appears on a connecting terminal in noncontinuity, since the motors 1a, 1b have been connected to the same connecting terminals, though the induced voltages differ. And a signal generating part 8 switches a conduction node from mode 2 to mode 3 on the basis of this compounded induced voltage. Consequently, it becomes possible to control the motors to the same rotational speed by the use of a single controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation method for simultaneously controlling the operation of a plurality of DC sensorless motors based on a change in an induced voltage generated in each non-energized stator winding.

[0002]

2. Description of the Related Art As an operation method for simultaneously controlling a plurality of motors, there is an operation method described in Japanese Patent Application Laid-Open No. 4-465589. This is configured as shown in FIG. 7, in which induction motors 101 and 102 used for a compressor and a blower for an air conditioner are connected to a single microcomputer 110.
A predetermined DC voltage obtained from an AC power supply via a power supply circuit is supplied to the first inverter circuit 111 and the second
A signal from the microcomputer 110 is supplied to each of the inverter circuits 111 and 112 via the first drive circuit 121 and the second drive circuit 122 as an input voltage of the inverter circuit 112.
And the voltage of the AC power supplied to the second induction motor 102,
It controls the frequency.

An operation method for controlling a plurality of motors with a single inverter circuit is disclosed in Japanese Patent Application Laid-Open No. Hei 9-13559.
No. 4 discloses this. This is configured as shown in FIG. 8, in which a plurality of AC motors a to f are connected to an inverter circuit 210 via electromagnetic contactors 211a to 211f, respectively, and motor select keys 212a to 212f are connected.
Any one of the electromagnetic contactors 211a to 211 selected in
f is closed, and the three-phase AC based on the PWM generated by the inverter circuit 210 is supplied to the selected AC motors a to f to operate.

[0004]

The former technique controls the operation of two motors at the same time, but the microcomputer 110 is shared, but the inverter circuits 111 and 112 and the drive circuits 121 and 12
2 must be provided independently for each motor, which makes it impossible to reduce the size of the circuit and simplify the circuit design. In addition, since the microcomputer 110 must substantially process control signals for two motors, it is extremely difficult to design an algorithm with a microcomputer that does not have sufficient processing capability.

In the latter technique, one motor is selected from a plurality of motors to operate, and a plurality of motors cannot be operated at the same time.

[0006] When these two technologies are combined, it is conceivable to connect a plurality of induction motors to a single inverter circuit. However, the induction motor rotates with a different slip amount depending on the magnitude of each load. Therefore, the rotation speeds of all the induction motors cannot be the same at the frequency of the AC power output from the inverter circuit.

An object of the present invention is to solve such a problem, and provides an operation method that enables simultaneous control of a plurality of motors by a single inverter circuit by using a DC sensorless motor. It is.

[0008]

According to the present invention, there is provided a magnetic field generated from a stator winding of a DC sensorless motor connected to a plurality of connection terminals for outputting DC power in accordance with a preset output mode. In the method of operating a DC sensorless motor configured to maintain the rotation of a rotor having a permanent magnet, a plurality of DC sensorless motors having substantially the same characteristics are connected in parallel to the plurality of connection terminals, and the plurality of connection terminals are connected in parallel. The output mode is sequentially switched based on a change in a composite voltage of an induced voltage generated in a non-energized stator winding of each DC sensorless motor by rotation of a rotor of the DC sensorless motor. Is what you do.

According to a second aspect of the present invention, two or three DC sensorless motors are connected in parallel,
This makes it possible to optimize the follow-up performance with respect to the fluctuation of the rotation speed. According to a third aspect of the present invention, abnormal rotation due to a difference in characteristics is prevented by using a DC sensorless motor having the same standard in design. Claim 4
The described invention suppresses a failure at the time of starting by limiting the DC power supplied to the stator winding until the rotation speed of the DC sensorless motor becomes the same at the time of starting. Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an electric circuit diagram showing a specific embodiment of the present invention, in which three-phase stator windings U, V, W and four poles are connected in a star shape. This is applied to the operation control of two DC sensorless motors 1a and 1b each including a rotor having a magnetized permanent magnet. In addition,
The number of poles of the rotor can be arbitrarily selected in multiples of two, and the number of teeth winding the stator windings U, V, W can be arbitrarily selected in multiples of three. Absent.

The two DC sensorless motors 1a,
1b is the same standard in design, and the connection terminals 3u, 3v,
3w is connected in parallel. These connection terminals 3u, 3
As described later, DC power is output to v and 3w according to an output mode in which a combination is set in advance. If the motors have substantially the same characteristics, not only two motors but also three or more motors are connected in parallel. It is possible to Here, the ranges of the same characteristics are required to be at least stators and rotors having substantially the same shape and the same characteristics, impedance characteristics of substantially the same stator windings, and substantially the same output. preferable.

Reference numeral 5 denotes six power switching elements (M
OS-type FET) connected in a three-phase bridge, and a P-channel FET
h, vh, and uh, and N-channel FETs wl, vl, and ul on the low side.
, A flywheel diode is provided between the drain and the source. The source of the high side FET is +
The low-side FET is connected to the high potential terminal of the DC power of 36 V, and the source of the low-side FET is connected to the ground potential via the resistor 6. As an inverter semiconductor having an equivalent circuit having such a configuration, Toshiba MP6403 can be used. The power switching element is not limited to an FET, but a bipolar power transistor can be used. For example, six power transistors (three P-channels and three N-channels) are connected in a three-phase bridge. An inverter semiconductor MP6301 manufactured by Toshiba or the like having such an equivalent circuit may be used.

8 is a mode from mode 1 to mode 6 shown in FIG.
A signal generation unit that generates an ON / OFF signal in the output mode, sets a combination of ON / OFF states of the six power switching elements from mode 1 to mode 6 in advance,
Each time the rotor rotates 60 electrical degrees, the output mode is sequentially switched and the cycle of modes 1 to 6 is repeated. Here, the ON duty (Ton) of the chopping cycle T of the low-side FET is changed to change the connection terminal 3.
The DC power output from u, 3v, and 3w can be controlled to control the rotation speed of the rotor.

Referring to FIG. 2, in mode 1, a current is output from the connection terminal 3u and the stator windings U,
V and returns to the connection terminal 3v. In mode 2, the stator windings U and W flow from the connection terminal 3u to the connection terminal 3w. In mode 3, the stator windings V and W flow from the connection terminal 3v.
And in mode 4, the stator windings V and U flow from the connection terminal 3v to the connection terminal 3u in mode 4, and in mode 5, the stator windings W and U flow from the connection terminal 3w.
And returns to the connection terminal 3u. In mode 6, the stator windings W and V flow from the connection terminal 3w and return to the connection terminal 3v. Also, referring to the explanatory diagram showing the generation of the induced voltage at each of the connection terminals 3u, 3v, and 3w shown in FIG. Appear in the connection terminal 3w, the connection terminal 3v in mode 2, the connection terminal 3u in mode 3, the connection terminal 3w in mode 4, the connection terminal 3v in mode 5, and the connection terminal 3 in mode 6.
The induced voltage appears at u. The signal generator 8 that sequentially switches the output mode based on the induced voltage includes, for example, M
Micro Linear Semiconductor (BLDC PW
MMotor Controller) ML4433
(Or ML4425) can be used.

The internal configuration of the signal generator 8 is configured as shown in the block diagram of FIG. 3, and detects a change in the induced voltage generated in the stator windings U, V, and W applied to the 14th to 16th pins. And outputs a signal corresponding to the change.
ON duty (Ton) based on this signal and the speed (rotational speed) signal given to the fifth pin, and based on PWM (pulse width modulation).
"PWM SPE" that outputs a chopping signal with different
ED CONTROL ”section and“ BACK EMF S
The output mode is sequentially switched in accordance with the signal from the “AMPLER” section, and the low side is turned ON by the chopping signal.
"COMMUTION & CONTROL L" which corrects the / OFF signal to determine ON / OFF of the six power switching elements constituting the inverter, and outputs the signal to "HIGH SIDE GATE DRIVE" and "LOW SIDE GATE DRIVE".
OGIC ”etc. and“ HIGH SIDE GATE ”
DRIVE "and" LOWSIDE GATE DRI "
VE ”via the 7th to 9th pins and the 11th to 13th pins, an ON / OFF signal (HIGH / LOW potential or LOW)
/ HIGH potential).

Reference numeral 9 denotes a detection circuit for detecting a voltage applied to the first pin of the signal generating unit 8, which is composed of a resistor and a capacitor. The voltage generated at the resistor 6 (the current flowing through the resistor 6, that is, the current flowing through the motor) Is applied. The signal generator 8 controls the ON duty (Ton) of the switching element so that the voltage does not exceed the set value, and controls the current flowing through the motor. Reference numeral 7 denotes a capacitor connected between the 19th and 20th pins of the signal generator 8, which is a reference voltage to which the output voltage of the voltage detection circuit 9 is compared. , And sets the time of a function commonly called soft start. FIG. 4 is an equivalent circuit of the soft start function.
The voltage applied to the terminal increases from 0 to a reference voltage set by the resistors 31 and 32 at a speed corresponding to the capacity of the capacitor 7. Therefore, the voltage applied to the + terminal of the comparator 30 gradually increases. During this time, the increase in the number of revolutions of the motor is limited to a low level, and a DC voltage corresponding to the set number of revolutions is immediately supplied at startup. Is prevented.

Reference numeral 10 denotes a circuit for operating the signal generation unit 8, which is composed of an electrolytic capacitor and a capacitor,
V DC voltage is stabilized. Reference numeral 11 denotes a circuit connected to the 17th and 18th pins, which is composed of an electrolytic capacitor, two capacitors, and two resistors, and sets a frequency of the VCO and a rising speed of the rotation speed. Reference numeral 12 denotes a circuit connected to the third and fourth pins, which is composed of an electrolytic capacitor, two capacitors, and a resistor, and sets a stop level and a rotation direction of the motor. Reference numeral 13 denotes a circuit constituted by a variable resistor, which is connected to the fifth pin and sets a target rotation speed of the motor. A resistor for setting the frequency of the chopping signal to 25 kHz is connected to the sixth pin. I have.

Reference numeral 14 denotes a circuit connected to the 7th to 9th pins and the 11th to 16th pins, and resistors for interface with the signal generator 8 are connected to the respective terminals. 1
The 4th to 16th pins are respectively connected to the respective phases of the stator windings U, V, and W of the motor via resistors, and are connected to the U, V, and W outputs of the inverter 5, and ,
An induced voltage generated in V and W is detected. The 11th to 13th pins are connected to the respective gates of the low-side FET via respective resistors, and are connected to a “LOW SIDE GATEdri”.
VE / ON / O output from 11th to 13th pins
With the FF signal (HIGH / LOW voltage), the low side F
Controls ON / OFF of ET.

15, 16 and 17 are high-side FETs
The emitter is connected to the 7th to 9th pins via respective resistors,
7 by "HIGHSIDE GATE DRIVE"
ON / OFF signal (LOW /
HIGH voltage), ON / O of transistors 15-17
Controls FF. The collectors of the transistors 15 to 17 are connected to the high side F via resistors 18 and 19, resistors 20 and 21, and resistors 22 and 23, which are connected in series.
Like the ET source, it is connected to the high potential end of +36 V DC power. 24, 25, and 26 are resistors 19, 2
These capacitors are connected in parallel with the resistors 1 and 23, and have a capacity of 0.0
1 μF. Each base of the transistors 15 to 17 is
+ 12V DC power and the potential is always +12
It is kept at V. High-side FET of inverter 5
Are connected to the connection points of the resistors 18 and 19, the resistors 20 and 21, and the resistors 22 and 23 corresponding to each phase.

In this circuit, when the ninth pin of the signal generator 8 outputs an ON signal (LOW level voltage), the transistor 17 is turned ON, and the divided voltage (36-12) by the resistor 23 is applied to the gate of the FETuh of the inverter 5. = 24
V is divided by the resistor 22 and the resistor 23, and a voltage equivalent to the resistor 23 is applied, and the FETuh is turned on. When the output of the ninth pin becomes an OFF signal (high level voltage), the transistor 17 is turned off, the voltage divided by the resistor 23 becomes 0 V, and the FETuh is turned off. Similarly, the other high-side FETs vh and wh are turned on / off by the output signals of the 7th and 8th pins of the signal generation unit 8.
Is controlled.

High side FETuh, low side F
When both ETul are OFF, the current flow is FE
When Tul is turned OFF following FETuh (mode 6 in FIG. 2), the stator winding U enters an open state (a state in which no voltage is applied), and changes in the induced voltage caused by the rotation of the rotor. Only current flows. The current due to the induced voltage mainly flows from the stator winding U to the forward direction of the flywheel diode of the FETuh, to the high potential end of the DC power of +36 V, and partly flows from the drain-gate of the FETuh in the reverse direction. The charge flows to the capacitor 26 whose potential has been lowered, and is stored in the capacitor 26. As described above, during the operation delay of the flywheel diode of the FETuh, the current due to the induced voltage generated in the stator winding U is accumulated in the capacitor 26 via the drain-gate of the FETuh. Since the OFF resistance between the drain and the source of the FETul is large, the current due to the induced voltage does not substantially flow between the drain and the source of the FETul.

Next, such FETuh, FETul
When the ON signal is supplied to the FETuh from the OFF state (mode 1 in FIG. 2), first, the transistor 1
7 is turned on. At this time, the potential of the collector of the transistor 17 is changed to a voltage of +36 V DC power by the capacitor 2.
Since the potential to which the voltage of 6 is applied is applied, the switching speed of the transistor 17 is increased by that amount, and the ON speed of the FETuh is also accelerated. After the transistor 17 is turned on, the capacitor 26 is set at +36 V
Is charged in the opposite direction to the induced voltage. Since the charging of the capacitor 26 reverse-biases the source and the gate of the FETuh, the FETuh is prevented from malfunctioning due to noise despite the OFF signal during the modes 3 to 5 in FIG.

The above operation is performed by the other high-side FET v
h and FET wh. The same operation is obtained when a bipolar power transistor is used for the inverter instead of the FET.

FIG. 5 is a time chart showing the generation of an induced voltage when one motor is connected to this circuit. The operation principle (the operation principle of the signal generation unit 8) will be described by taking the switching from the mode 2 to the mode 3 as an example. Then, the mode is switched to mode 3 after T1 (k × T0 (k: coefficient)) time from the point in time when the polarity of the induced voltage changes. By adjusting the coefficient k, the phase of energization of the stator with respect to the rotational position of the rotor can be adjusted, and efficiency can be adjusted during acceleration / deceleration of the rotor or at a constant speed. Also,
From the point in time when the polarity of the induced voltage changes in Mode 1, Mode 2
, The time T3 up to the point in time when the polarity of the induced voltage changes may be measured, and the mode may be switched to mode 3 with T0 = T3 / 2. The same applies to the switching to another mode. Thereafter, the mode is sequentially switched based on the time at which the polarity of the induced voltage changes. The mode switching method is not limited to these means, and may be any method based on a change in the induced voltage, such as a method of shaping the induced voltage waveform.

FIG. 6 shows the state of the induced voltage when two motors 1a and 1b are connected to the connection terminals 3u, 3v and 3w, and is an explanatory diagram of switching from mode 2 to mode 3. Here, the load of the motor 1a is lighter than the load of the motor 1b, or even if the load is the same, due to a manufacturing error, the motor 1a
Assuming that b is heavier, the time during which mode 2 is maintained when the same voltage is applied to the stator winding,
“a” is shorter than the motor 1b, and there is a difference in the number of rotations (T1 = k × T0 and k is the same). Therefore, the induced voltage generated in the non-energized stator winding is different from 1a and 1b shown in FIG. 6, and there is a difference between the time points Ta and Tb at which the polarity of the induced voltage changes. However, since the motors 1a and 1b are connected to the same connection terminal, the connection terminals that are not energized are the same, the connection terminals that generate induced voltages are the same, and the induced voltages of the motors 1a and 1b are combined. Appears at the non-energized connection terminal (broken line in FIG. 6).

The signal generator 8 switches the conduction mode from mode 2 to mode 3 based on the combined induced voltage as described above, and switches the output mode based on the time Tc at which the polarity of the induced voltage changes. Switch. Therefore, for the motor 1a, the mode maintenance time is longer than the actual rotation, and the brake is applied to reduce the rotation speed. For the motor 1b, the mode maintenance time is shorter than the actual rotation of the rotor. The motor 1a is accelerated to increase the rotation speed.
1b converges to have the same rotation speed. At this time, power corresponding to the load is distributed to each stator winding. Even when the rotation speed of any of the motors changes due to some load fluctuation, the rotation speed is similarly adjusted.

Since the signal generator 8 performs the rotation speed control (ON duty control) on the converged rotation speed, the rotation speeds of the two motors 1a and 1b are finally controlled to be the same. You.

As described above, since the operating method of the present invention is used by synthesizing the induced voltages from the respective motors, a large distortion of the synthesized waveform is likely to cause a malfunction. However, it is preferable that about two or three motors be connected because it is easy to suppress distortion and the time required for convergence of the number of rotations is shortened. When connecting four or more motors, there was no problem unless motors of the same standard were used in the design and rapid acceleration / deceleration was not performed. Also, at startup, the rotation speeds of multiple motors converge to the same low rotation speed while the soft start function is operating. Step-out and locking can be suppressed.

[0029]

As described above, according to the operation method of the DC sensorless motor of the present invention, the rotation speeds of a plurality of motors connected in parallel to the connection terminals are controlled to the same rotation speed by a single control device. Thus, the circuit can be downsized and the circuit design can be simplified.

The DC sensorless motor to be connected is 2
By adopting three or three units, the follow-up performance to fluctuations in the number of rotations can be optimized, and by using a DC sensorless motor of the same standard in design, abnormal rotation due to differences in characteristics can be prevented. You can do it. Then, by restricting the DC power supplied to the stator winding until the rotation speed of the DC sensorless motor becomes the same at the time of startup, it is possible to suppress a failure at the time of startup.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a time chart of a preset output mode.

FIG. 3 is a block diagram of a signal generation unit.

FIG. 4 is an equivalent circuit diagram showing a soft start function.

FIG. 5 is a time chart illustrating generation of an induced voltage in the case of one motor.

FIG. 6 is an explanatory diagram showing a state of an induced voltage in the case of two motors.

FIG. 7 is a circuit diagram of a conventional motor operating method.

FIG. 8 is a circuit diagram of a conventional motor operating method.

[Explanation of symbols]

 1a, 1b DC sensorless motor U, V, W Stator winding

Claims (4)

[Claims] 1. A magnetic field generated from a stator winding of a DC sensorless motor connected to a plurality of connection terminals from which DC power is output in accordance with a preset output mode, to maintain rotation of a rotor having a permanent magnet. In the method for operating a DC sensorless motor configured as described above, a plurality of DC sensorless motors having substantially the same characteristics are connected in parallel to the plurality of connection terminals, and each of the DC A method for operating a DC sensorless motor, wherein the output modes are sequentially switched based on a change in a combined voltage of induced voltages generated in a stator winding that is not energized of the sensorless motor. 2. The method for operating a DC sensorless motor according to claim 1, wherein two or three DC sensorless motors are connected to the connection terminals in parallel. 3. The method for operating a DC sensorless motor according to claim 1, wherein the DC sensorless motor has the same standard in design. 4. The DC sensorless motor according to claim 1, wherein at startup, DC power supplied to the stator winding is limited until the rotation speed of the DC sensorless motor becomes the same. how to drive.