JPH0355379A - Circuit for brushless motor for automatic door - Google Patents

Abstract

PURPOSE:To make smooth speed control feasible in PWM inverter chopping method by preventing hunting from occurring in low-speed range with output voltage from a chopper circuit switched in stages respectively in high-speed and in low-speed modes, CONSTITUTION:As a high-speed command signal Sw is given to a switching circuit 40 for a switching regulator 55, switching output voltage Vu is given to a differential amplifier 33, and a regulator 25 operates, allowing a chopper circuit 20 to output DC high voltage. As a ramp input is given as a speed command voltage VS from a DC voltage-setting circuit 98, the speed of a brushless motor 70 varies within the scope of high-speed mode. When a low-speed command signal SW is given to the circuit 40, the regulator 55 operates on switching output voltage VU, making it a reference voltage, and DC output voltage from the circuit 20 declines thereby. When a voltage VS is given to the circuit 40 from the circuit 98, the speed of the motor 70 varies within the scope of low- speed mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a brushless motor circuit for automatic doors.

[Prior Art] FIG. 3 is a block diagram of a conventional automatic door brush 17 smoker circuit, which employs a so-called PWM inverter chopping method.

The a current/smoothing circuit 10 converts an AC input of, for example, IOOV into a DC input, and provides a DC high voltage to the chopper circuit 20 . The chopper circuit 20 includes an on/off circuit (switching element such as a transistor) for chopping and a smoothing circuit, and converts a DC high voltage input into a DC low voltage and outputs the same. The differential amplifier 33 calculates the deviation of the output voltage VM of the chopper circuit 20 with respect to the DC setting voltage of +33V, for example, and outputs the deviation. The pulse width modulation circuit 50 proportionally converts the output voltage φ8 of the differential amplifier 33 into a pulse width, and sets the output voltage VM of the chopper circuit 20. At this time, the pulse width of the chopper signal P given from the pulse width modulation circuit 50 to the chopper circuit 20 is determined by comparing the voltage φM with a triangular wave signal of, for example, 2C10 kHz. The above rectifier/smoothing circuit 10, chopper circuit 20, differential amplifier 33, and pulse width modulation circuit 50 constitute a switching regulator 55.

A constant DC voltage vM is obtained from the chopper circuit 20 by the switching regulator 55.

This constant voltage (8) is applied to the stator winding of the brushless motor 70 via the inverter circuit 60 to create a rotating magnetic field. When using a three-phase brushless motor, the inverter circuit 60 includes, for example, three transistors forming an upper arm and three transistors forming a lower arm.

However, each transistor constituting the lower arm is subjected to pulse width modulation via a Darlint connection transistor.

A position detector made of a Hall element is arranged near the rotor made of a permanent magnet of the brushless motor 70, and a rotor position detection circuit 80 is constituted by a logic circuit including this detector.
detects the position of the rotor of the brushless motor 70 and issues on/off commands to the inverter circuit 60 to sequentially supply current to specified stator windings, and also generates speed pulses with a repetition frequency corresponding to the motor speed. Output PR. When using Hall elements for rotor position sensing, it is difficult to obtain speed pulses of more than 12 pulses per motor revolution. Thus, the number of speed pulses PR is, for example, 1 to 12 pulses per motor rotation.

The F/V conversion circuit 90 proportionally converts the repetition frequency of this speed pulse PR into a DC voltage and outputs it. This F
As the /V conversion circuit 90, a circuit in which a differentiating circuit 91, a one-shot multivibrator 92, and a smoothing circuit 93 are successively connected in cascade is used. The differential amplifier 95 has F/V
A deviation R of the output voltage V of the conversion circuit 90 with respect to the speed command voltage V8 is calculated. The pulse width modulation circuit 100 includes a differential intensifier 9
The lower arm transistor of the inverter circuit 60 applies pulse width modulation by proportionally converting the output voltage φR of No. 5 into a pulse width. The pulse width of the chopper signal P given from the pulse width modulation circuit l00 to the inverter circuit 60 is determined by comparing the voltage φR with a triangular wave signal of, for example, C2, 20 kHz.

In the conventional automatic door brushless motor circuit described above, the direct a voltage VM, that is, the motor voltage, applied from the switching regulator i-noter 55 to the brushless motor 70 via the inverter circuit 60 is constant. However, since the on-time of each transistor constituting the lower arm of the inverter circuit 80 is pulse width modulated by speed feedback, the brushless motor 70 is controlled to a constant speed according to the magnitude of the speed command voltage V8, and at low speeds. Torque can be increased. At this time, in the F/V conversion circuit 90,
A differentiating circuit 9l detects each edge of the speed pulse PR, a one-shot multivibrator 92 generates a pulse with a constant width starting from each edge, and a smoothing circuit 93 smoothes this pulse into a DC voltage. The output pulse width of the one-shot multivibrator 92 is set by a time constant circuit connected thereto.

[Problem to be solved by the invention] Normally, in a brushless motor that drives the opening and closing of an automatic door, for example, 1000 to 3000 rplI
high speed mode in the range of e.g. 250-500 rp
Only two modes are required: a low speed mode in the w range.

However, in the conventional automatic door brushless motor circuit, although the number of speed pulses PR output from the rotor position detection circuit 80 is as small as 1 to 12 pulses per motor rotation, it is 250 to 250 pulses including an unnecessary range. 3 0 0
The following problem occurred because the speed range of 0 rpm was attempted to be covered by one speed feedback control.

That is, the output of the one-shot multivibrator 92 is adjusted so that the output pulses of the one-shot multivibrator 92 are not connected to each other at the maximum motor speed of 3000 rpm, where the period of the speed pulse PR is the shortest. If the pulse width setting is made small, narrow pulses will be given to the smoothing circuit 93 at long intervals during low speed rotation. Therefore, during low-speed rotation, the ripple included in the output voltage of the smoothing circuit 93, that is, the output voltage VR of the F/V conversion circuit 90 becomes very large. This pulsation also appears in the output voltage φR of the differential amplifier 95, causing the pulse width of the chopper signal PC2 output from the pulse width modulation circuit 100 to fluctuate irregularly, causing the on-time of the lower arm transistor of the inverter circuit 60 to fluctuate. . Therefore, in the past, when the motor speed was less than about 300 rpm, the brushless motor 70 was prone to hunting, which caused problems such as vibration and torque unevenness, especially in the case of lightweight doors.

To solve this hunting problem at low speeds, for example,
It is conceivable to connect a rotary encoder that outputs 100 pulses per rotation to the rotating shaft of the brushless motor 70 to detect the position of the rotor, but the problem is that the rotary encoder is expensive.

The present invention was made in view of the special circumstances in the case of brushless motor circuits for automatic doors in which only two-stage modes of high speed and low speed are required. The object of the present invention is to realize smooth speed control in both modes even when the number of speed pulses per rotation of the motor is small.

[Means for Solving the Problems] A brushless motor circuit for an automatic door according to the present invention is a motor circuit that supplies the output of a chopper circuit to a stator winding of a brushless motor via an inverter circuit, and is capable of high-speed rotation. High DC setting voltage when receiving a command to
a switching circuit that respectively switches and outputs a low DC set voltage when receiving a command to rotate at a low speed; a first differential amplifier that calculates the deviation of the chopper circuit output voltage with respect to the switching output voltage of the switching circuit; A first pulse width modulation circuit that proportionally converts the output voltage of the first differential amplifier into a pulse width to set the output voltage of the chopper circuit, and a first pulse width modulation circuit that detects the position of the rotor of the brushless motor and controls the inverter circuit. - A rotor position detection circuit that issues an off command and outputs speed pulses with a repetition frequency that corresponds to the motor speed;
An F/V conversion circuit is purchased with a cascade connection of a differentiating circuit, a one-shot multivibrator, and a smoothing circuit, and proportionally converts the repetition frequency of speed pulses into a DC voltage and outputs it, and the output of this F/V conversion circuit. A second differential amplifier that calculates the deviation of the voltage from the speed command voltage, and a proportional conversion of the output voltage of this second differential amplifier to a pulse width to set the on-time of the switching elements that constitute the inverter circuit. and a second pulse width modulation circuit.

[Function] The switching circuit, the first differential amplifier, the first pulse width modulation circuit, and the chopper circuit use a switching regulator that can obtain a plurality of different constant voltage outputs. That is, when a command for high speed rotation is given to the switching circuit, a DC high voltage output is obtained from the chopper circuit, and when a command for low speed rotation is given to the switching circuit, a DC low voltage output is obtained from the chopper circuit.

This one. The variable output of the bar circuit is supplied to the stator winding of the brushless motor via the inverter circuit to generate a rotating magnetic field. The speed of the rotor of this brushless motor is fed back to the inverter circuit through a rotor position detection circuit, an F/V conversion circuit, a second differential amplifier, and a second pulse amplitude modulation circuit. That is, the on-time of the switching elements constituting the inverter circuit is pulse width modulated according to the magnitude of the speed command voltage, and constant speed control is executed. However, if a command for high-speed rotation is given to the switching circuit and a high DC voltage is applied from the chopper circuit to the inverter circuit, the speed command voltage may be as low as, for example, 1000 to 3000 rpm. A fast mode of range is realized. On the other hand, if a command for low-speed rotation is given to the switching circuit and a low DC voltage is applied from the chopper circuit to the inverter circuit, the second speed command voltage is in the same range as the high-speed mode. A low speed mode in the range of 250 to 50 O rpm, for example, can be realized even if the current is applied to a differential amplifier of 250 to 50 O rpm. In other words, the low-speed mode can be realized without extremely narrowing the pulse width of the chopper signal applied from the pulse width modulation circuit to the inverter circuit.

In other words, since the output pulse width of the one-shot multivibrator in the F/V conversion circuit for speed feedback can be set within each range of high speed mode or low speed mode, it is possible to increase this output pulse width setting. can. Therefore, even if the number of speed pulses output from the rotor position detection circuit is as small as 1 to 12 pulses per revolution of the motor, the output ripple of the smoothing circuit connected to this Funshot multivibrator will be small. , smooth speed control is achieved in both modes.

[Embodiment] FIG. 1 is a circuit diagram of a brushless motor circuit for an automatic door according to an embodiment of the present invention.

For example, an IOOV AC power source 2 is connected to a rectifier/smoothing circuit 10 . This rectifier/smoothing circuit 10 converts an AC input into a DC input and provides a DC high voltage to a chopper circuit 20 . In this chopper circuit 20, the output voltage of the rectifier/smoothing circuit 1O is applied to a series circuit of the primary winding of the pulse transformer 2l and the NPN transistor 22, which is the main switching element.

The base circuit of this main transistor 22 is connected to another NPN transistor 24 insulated by another pulse transformer 23.
(subtransistor) collector circuit. The secondary side of the pulse transformer 2l, to which the main transistor 22 is connected to the primary winding, is connected to the inverter circuit 6 via a smoothing circuit 25 composed of a diode, a coil, and an output capacitor.
Connected to 0.

The voltage across the output capacitor of the chopper circuit 20 is applied not only to the inverter circuit 60 but also to the two resistors 31 and 32.
It can also be applied to a voltage divider circuit formed by connecting in series. The connection point voltage VM of both resistors 31 and 32 is used to monitor the output voltage of the chopper circuit 20. That is, this voltage VM is applied as an inverting input to the differential amplifier 33, and the voltage feedback circuit 30 is implemented here.

Reference numeral 40 indicates a switching circuit for switching the magnitude of the DC setting voltage applied to the non-inverting input terminal of the differential amplifier 33. In this switching circuit 40, +10 VDC is applied to an analog switch 41, and +33 VDC is applied to another analog switch 42. One analog switch 4
1 is given the speed switching signal Sv via the NOT circuit 43, and the other analog switch 42 is given the speed switching signal Sv. d is given directly. When the H level speed cut signal Sv, that is, the high speed command is given to the switching circuit 40,
The analog switch 42 turns on and the DC high voltage +33V
is applied to the differential amplifier 33 as the switching output voltage V. On the other hand, when an L level speed switching signal Sv, that is, a low speed command is given to the switching circuit 4o, the analog switch 41
Then, the DC low voltage +IOV is applied as the switching output voltage V, to the differential amplifier 'J533.

The output voltage φ8 of the differential intensifier 33 has a variable pulse width, M times m
50, the comparator 51 connects the triangular wave oscillation circuit 52.
It is compared in magnitude with the output signal T1 of the output signal T1 to obtain a chopper signal PCI. This chopper rK number F'C1 is applied to the base of the sub-transistor 24 of the chopper circuit 20, and turns on/off the main transistor 22 via the pulse transformer 23. That is, the pulse width modulation circuit 50 proportionally converts the output voltage φH of the differential amplifier 33 into a pulse width, and sets the output voltage VM of the chopper circuit 20. Note that the frequency of the triangular wave signal T1 is, for example, 20 kHz.

The above rectifier/smoothing circuit IO, chopper circuit 20, voltage feedback circuit 30, switching circuit 40, and pulse width modulation circuit 50 constitute a switching regulator 55 whose output voltage can be switched in two stages.

The output voltage of the chopper circuit 20 is applied to the stator winding of the brushless motor 70 via the inverter circuit 60 to create a rotating magnetic field. When using a three-phase brushless motor, the inverter circuit BO includes three PNP transistors (upper arm) 81a. 6lb. 61c and three NPNs
Transistor (lower arm) 62a, 82b. 62c. A flywheel diode is connected to each transistor. However, each transistor Ha, 82b. 62c is connected to another PNP transistor 63a. The collectors of transistors 63b and 63c are connected to each other, and these transistors 63a
．． 63b. The emitter of 63c is connected to DC power supply VBB through one common PNP transistor 64 for applying pulse width modulation.

The brushless motor 70 has a rotor made of, for example, two-pole permanent magnets, around which Mikawa stator windings are equally spaced at 120 degrees. Furthermore, three position detectors 81 made of Hall elements are equally distributed near the rotor at 12011ffi.
These detectors output speed signals A, B, and C corresponding to the rotor position of the brushless motor 70, respectively. These speed signals A, B, and C are input to the drive logic circuit 82, and output the on/off commands U, V, and W for the upper arm of the inverter circuit 60, and the on/off command X for the lower arm. , Y, and Z. However, the on/off command UVW for the upper arm is a PNP transistor 61a,
8lb. The base of 61c is directly driven, but is it for the lower arm? On/off commands X, Y, Z are PNP }
Transistors 63a, 63b. N through the base of 63c
Drives PN transistors 82a, 82b, and 82c, respectively. The drive logic circuit 82 also outputs speed signals A,
A speed pulse PR is generated by combining B and C. The rate of this speed pulse PR is, for example, 12 pulses per rotation of the brushless motor To. However, since the circuit structure of the drive logic circuit 82 is well known, detailed explanation thereof will be omitted. Note that the position detector 81 and the drive logic circuit 82 constitute the rotor position detection circuit 80.

The speed pulse PR is input to the F/V conversion circuit 90.

The F/V conversion circuit 90 includes a differentiating circuit 91, a one-shot multi-bicycle rate 92, and a smoothing circuit 93 connected in series, and converts the repetition frequency of the speed pulse PR into a DC voltage VR proportional to the repetition frequency. The output voltage ■■ of this F/V conversion circuit 9o is input to the inverting input terminal of the differential amplifier 95. This Q differential amplifier 95 receives a speed command voltage 8 from a DC voltage setting circuit 98 which is a resistor voltage divider circuit.
is manually input to the non-inverting input terminal to calculate the deviation of the output voltage VR of the F/V conversion circuit 90 with respect to the speed command voltage 8. In addition, the F/V conversion circuit 90 and the differential amplifier 95, etc.
Purchase speed feedback circuit 9B.

The output voltage φR of the differential amplifier 95 is the pulse width modulation circuit 1
00, the triangular wave oscillation circuit 1 is activated by the converter 101.
The chopper signal Pc is compared in magnitude with the output signal T2 of 02.
It becomes 2. This chopper fi No. PC2 drives the base of the common PNP transistor 64 in the inverter circuit 60, and lower arm transistors 132a. 62b. [Apply pulse width modulation to i2c. That is, this pulse width modulation circuit 100 proportionally converts the output voltage φR of the differential amplifier 95 into a pulse width, and converts the output voltage φR of the differential amplifier 95 into a pulse width, and converts the output voltage φR of the differential amplifier 95 into a pulse width, 82b. Set the on time of 82c.

Note that the frequency of the triangular wave signal T2 is, for example, 2 kHz.

FIG. 2 is a timing chart showing the operation of the automatic door brushless motor circuit described above.

The rectifier/smoothing circuit to converts an AC input of, for example, 100V supplied from the AC power supply 2 into DC, and provides a DC high voltage to the chopper circuit 20. The chopper circuit 20 converts this direct current high voltage human power into direct current low voltage and supplies it to the inverter circuit 80.

On the other hand, in the position detection circuit 80, the position detector 81 is
Speed signals A, B, and C corresponding to changes in the rotor position of the brushless motor 70 are output, respectively.

These speed signals A, B, and C are sent to the inverter circuit 60 by the drive logic circuit 82 to provide on/off commands U, V.
, W, X, Y, Z.

At this time, the upper arm transistor 8 of the inverter circuit 80
1a. 6lb. 81c and lower arm transistor 62a,
One each of 62b and 62c is selected, and a current flows through a specified stator winding according to the rotor position of the brushless motor 70, a rotating magnetic field is generated, and the rotor rotates. However, since the current supply to the stator winding is limited to the ON time of the common PNP transistor 64, the brushless motor 70 responds to the magnitude of the speed command voltage v8 by the chopper signal PC2 output from the pulse width control circuit 100. constant speed control is executed.

At this time, as shown in the left half of FIG. 2, when an H-level speed switching signal S1, that is, a high speed command is applied to the switching circuit 40, a DC high voltage of +33V is applied to the differential amplifier 33 as the switching output voltage Vu. The switching regulator 55 operates using this voltage as a reference voltage. Therefore, a DC high voltage is output from the chopper circuit 20. At this time, if a ramp input as shown in the figure is given as the speed command voltage V8, the speed of the brushless motor 70 will be increased to 1, for example.
It changes in the high speed mode range of 000 to 3000 rpm.

On the other hand, as shown in the right half of the figure, when an L-level speed switching signal S1, that is, a low speed command is applied to the switching circuit 40, the switching regulator 55 operates using the switching output voltage Vu of +10V as a reference voltage. , chopper circuit 2
0 DC output voltage decreases. At this time, speed command voltage■
Even if a ramp input S in the same range as in the high-speed mode shown in the figure is applied, the speed of the brushless motor 70 changes in the low-speed mode range of, for example, 250 to 500 rpm. In other words, the low speed mode can be realized without extremely narrowing the pulse width of the chopper signal Pc2 provided from the pulse width modulation circuit IQQ to the inverter circuit 60.

In other words, since the output pulse width of the one-shot multivibrator 92 in the F/V conversion circuit 90 for speed feedback can be set within each range of high speed mode or low speed mode, this output pulse width setting should be increased. I can do it. Therefore, if the number of speed pulses PR output from the rotor position detection circuit 80 is small, the output ripple of the smoothing circuit 93 becomes small, and smooth speed control is realized in both modes.

[Effects of the Invention] As explained above, the brushless motor circuit for automatic doors according to the present invention uses a so-called PWM inverter chopping method to switch the output voltage of the chopping circuit in stages between high-speed mode and low-speed mode. According to the present invention, smooth speed control can be achieved in both modes even when the number of speed pulses per rotation of the motor is small. In other words, not only can speed control be executed smoothly during high-speed rotation, but unlike conventional systems, notching can be prevented at low speeds.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a brushless motor circuit for an automatic door according to an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of the brushless motor circuit for an automatic door shown in the previous figure, and FIG. 3 is a conventional one. FIG. 2 is a block diagram of a brushless motor circuit for an automatic door. Description of symbols IO... Rectifier/smoothing circuit, 20... Chiyo-Sova circuit, 30... Voltage feedback circuit, 33... Differential amplifier, 4
0...Switching circuit, 50...Pulse width modulation circuit, 55
...Switching regulator, 60...Inverter circuit, 70...Brushless motor, 80...Rotor position detection circuit, 8l...Position detector, 82...Drive logic circuit, 90... F/V conversion circuit, 91... Differential circuit, 92... One shot multi-vibrator,
93... Smoothing circuit, 95... Differential amplifier, 96...
・Speed feedback circuit, 9B...DC voltage setting circuit, 100
... Pulse width modulation circuit, P , P ... Chotu CI
C2 signal, P...speed pulse, S. d...Speed switching signal R No., V8...Speed command voltage. Ichiginma t Figure 2

Claims (1)

[Claims] 1. A motor circuit that supplies the output of the chopper circuit to the stator winding of a brushless motor via an inverter circuit, and when it receives a command to rotate at high speed, it applies a high DC setting voltage to the motor that should rotate at low speed. A switching circuit that switches and outputs a low DC set voltage when receiving a command, a first differential amplifier that calculates the deviation of the chopper circuit output voltage with respect to the switching output voltage of this switching circuit, and this first differential amplifier. A first pulse width modulation circuit that proportionally converts the output voltage of the amplifier into a pulse width to set the output voltage of the chopper circuit, and a first pulse width modulation circuit that detects the position of the rotor of the brushless motor and issues on/off commands to the inverter circuit. It also consists of a rotor position detection circuit that outputs speed pulses with a repetition frequency that corresponds to the motor speed, and a cascade connection of a differentiator circuit, a one-shot multivibrator, and a smoothing circuit, and proportionally converts the repetition frequency of speed pulses into DC voltage. F/V to output this
a conversion circuit, a second differential amplifier that calculates the deviation of the output voltage of the F/V conversion circuit from the speed command voltage, and an inverter circuit that proportionally converts the output voltage of the second differential amplifier into a pulse width. A brushless motor circuit for an automatic door, comprising: a second pulse width modulation circuit that sets the on time of a switching element constituting the brushless motor circuit.