JPH0731187A - Drive controller for dc brushless motor - Google Patents

Abstract

PURPOSE:To provide a power supply circuit for control components having circuitry as simple as possible and the heat generation is decreased. CONSTITUTION:A power supply circuit 22 for a comparator 10, which decides the rotor position based on the electromotive force induced cyclically in one nonconducting phase winding among three phase windings of a stator, is connected between P and N terminals of a DC power supply. Operating current for a photocoupler 14 connected between a comparator 10 and an inverter control circuit 6 is drained from a power supply circuit 20 different from the power supply circuit 22 for comparator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive controller for a DC brushless motor.

[0002]

2. Description of the Related Art A brushless motor including a stator in which three-phase windings are connected in a star shape and a rotor including permanent magnets,
An apparatus for driving and controlling a DC brushless motor, comprising: an inverter connected to the input terminal of the brushless motor; and an induction generator that is generated in a non-energized phase that cyclically occurs in one phase of three-phase windings. The determination means for determining the position and rotation speed of the rotor based on the change in the polarity and magnitude of the electric power, the photocoupler connected to the output end of the determination means, and the determination means transmitted through this photocoupler. According to the judgment result, the two energized phases of the three-phase winding are sequentially determined, and the energization control of the inverter is performed so as to supply the alternating current with the adjustable energization time ratio from the DC power supply in order to generate the desired rotation speed and torque. A drive control device for a DC brushless motor including a control means for controlling the drive is known.

The rotor position determination based on the back electromotive force is compared with the induced voltage of the non-energized phase winding and the neutral point of the star-connected winding as a reference, and the comparison result is compared with the filter circuit. There is a well-known method for making a determination through the method, and a method for making a comparison by comparing the induced voltage in the non-energized phase winding with the midpoint (1/2 voltage point) of the inverter DC voltage as a reference voltage.

One of the major problems in this type of drive control device is the comparison between the induced electromotive voltage generated in the winding of the non-energized phase and the other reference voltage. Conventionally, an analog voltage comparator is used for this comparison. This voltage comparator is made into an IC (aggregation circuit) module, and the rated value of the power supply voltage for operating this is generally a low voltage such as 36 V or less, and the input voltage range is a lower value. Therefore, when the input voltage of the inverter is as high as 280V like the inverter for driving the compressor of the air conditioner,
It is not possible to directly input the induced voltage of the winding in the non-energized phase to the voltage comparator, and it is necessary to divide both the induced voltage of the winding and the reference voltage at the same ratio to obtain the comparison voltage or reference voltage of the voltage comparator. I am trying.

On the other hand, since the magnitude of the induced voltage in the motor winding is proportional to the motor speed, when the motor is driven at a variable speed by an inverter, high comparison accuracy is required especially in voltage comparison in the low speed region. To meet this requirement,
It is necessary to set the power supply of the voltage comparator, the comparison voltage, and the reference voltage as high as possible within the rated range.

Therefore, as the power source for this voltage comparator, for example, a transformer interposition type D connected to the main circuit DC voltage circuit is used.
Although it is conceivable to use a power supply circuit using a C-DC converter, the use of a DC-DC converter has a drawback that a new complicated and expensive circuit device is required only for this voltage comparator.

Therefore, as a relatively simple method, it can be considered to obtain from the Zener diode and the series resistance based on the DC voltage of the main circuit.

A power supply circuit using this Zener diode has a circuit configuration as shown in FIG. Referring to FIG. 3, first, referring to the main circuit, the brushless motor 2 has a star-shaped three-phase winding represented by R, S, and T phase windings and a series of symbols representing internal electromotive force. Shown by a stator with lines. Illustration of the rotor is omitted here. The inverter 4 is interposed between the winding end of the motor 2 and the DC power supply. The inverter 4 is a three-phase bridge connection of six arms U, V, W, X, Y and Z each of which is composed of a controllable rectifying element such as a transistor and a diode connected in antiparallel thereto. The inverter 4 basically converts the DC power input from the DC power supply terminals P and N into AC power having an arbitrary frequency and supplies the AC power to the brushless motor 2. Arm U,
V and W are arranged on the DC plus side, and the arms X, Y, and Z are arranged on the DC minus side. The controllable rectifying element of each of these arms is controlled by the control circuit 6 via the driver D so as to sequentially and cyclically energize every two phases of the three-phase winding of the motor 2. The rotational position and rotational speed of the rotor are determined by using the induced electromotive force of another non-energized one-phase winding. For this determination, a voltage dividing circuit 8 composed of a pair of voltage dividing resistors respectively connected between the terminals of the phase windings R, S, T of the motor 2 and the negative terminal N of the DC power source.
Comparator 10 provided with the voltage obtained by each phase
Is introduced as a comparison voltage. An intermediate potential between the DC power supplies P and N obtained from an intermediate connection point of a pair of series resistors 11 and 12 of equal value connected between the DC power supply terminals P and N is input to the reference terminal of each comparator 10. is doing.
The output signal of each comparator 10 is input to the control circuit 6 via the photocoupler 14 for electrical insulation. As well known, the photocoupler 14 is a light emitting element (for example, LED).
= Light emitting diode) and a light receiving element (for example, a phototransistor).

Each comparator 10 and each photocoupler 14
A power supply circuit 16 is connected between the DC power supply terminals P and N in order to obtain the operation power supply of (the light emitting element of), and the output thereof is supplied to the comparator 10 and each photocoupler 14. The operating power supply for the driver D provided in the plus side arms U, V, W of the inverter 4 is obtained from the inverter output terminals R, S, T for each phase via the power supply circuit 18, and the minus side arms X, Y are provided. , Z, the operating power source of each driver D is obtained from the DC power source negative terminal N via the power source circuit 20.

[0010]

In the circuit using the Zener diode as described above, the power source of the voltage comparator and the power source of the photocoupler are shared, and the Zener diode is also used for the light emitting element forming the photocoupler. The current is now supplied from the power supply circuit.

However, since the light emitting element (LED) which constitutes this photocoupler is a current source element which consumes a relatively large current, the power loss in the resistor in series with the Zener diode is large and the resistor element having a large rating is large. Was needed. Further, this causes a problem that the amount of heat generated by the resistor also increases, so that it is necessary to take heat dissipation measures.

Therefore, an object of the present invention is to provide a drive control device for a DC brushless motor which has a structure as simple as possible and requires a small amount of heat generation.

[0013]

In order to achieve the above object, the present invention provides a brushless motor comprising a stator in which three-phase windings are connected in a star shape and a rotor composed of a permanent magnet, and an input end of the brushless motor. A device for driving and controlling a DC brushless motor including a connected inverter, wherein a rotor position is determined based on an induced electromotive force generated in a non-energized phase that cyclically occurs in one phase of a three-phase winding. Of the three-phase windings according to the comparison result of the comparator that outputs the signal that represents, the photocoupler connected to the output terminal of this comparator, and the comparator that is transmitted through this photocoupler.
In a drive controller for a DC brushless motor having a control means for sequentially determining one energizing phase and controlling energization of an inverter, a comparator power supply circuit for supplying operating power to a comparator is connected between terminals of a DC power supply, The operating current of the light emitting element of the photocoupler is obtained from a power supply circuit different from the power supply circuit for the comparator.

[0014]

By taking the operating power source of the comparator from the DC power source and the operating power source of the photocoupler from a power source different from the power source circuit for the comparator, all the problems described in the above-mentioned prior art can be solved. .

In the present invention, the comparator requires a sufficient power supply voltage and a comparison input voltage to stabilize the determination of the magnitude of a minute voltage, but the current consumption is small, whereas the power supply of the photocoupler is high speed. This is because the relatively high current is required to cover the low conversion efficiency that is likely to occur in the photocoupler, but the accuracy and the stability are not required so much. This is a skillful application.

[0016]

FIG. 1 shows an embodiment of the present invention.
In FIG. 1, the same circuit elements as those in FIG. 3 are designated by the same reference numerals. One of the features of the device of FIG.
Is taken from between the DC power supply terminals P and N via the power supply circuit 22, and the other is a power supply circuit in which the operating power supply of the light emitting element of the photocoupler 14 is connected to the DC power supply terminal N. It is starting from 20. Power supply circuit 2
2 includes a series circuit of a resistor 23 and a Zener diode 24 connected between the DC power supply terminals P and N, and a capacitor 25 connected in parallel to the Zener diode 24. The other circuit parts are the same as the circuit of FIG. Although the capacitor 25 may be omitted in some cases, if it is connected, it is possible to suppress an instantaneous voltage fluctuation.

Now, the operation of the comparator 10 and the photocoupler 14 will be described by focusing on the winding voltage of a specific phase, for example, the S phase.

The S-phase comparator 10 has series resistors 11, 12
The voltage at the connection point of is input as the reference voltage B, and the voltage divider 8
Therefore, the S-phase voltage is input as the comparison voltage C. The S-phase comparator 10 compares the voltages B and C, and as shown in FIG.
If C> B, an H signal is output to the output terminal D, and the photocoupler 14 connected to the output side is inoperative (LED current is zero). When C ≦ B at time Q, the comparator 10
Outputs an L signal, an LED current E flows from the power supply circuit 20 to the LED of the photocoupler 14 connected to the output side of the photocoupler 14, emits light correspondingly, and the phototransistor conducts to control circuit 6 from point F. The L level signal is transmitted.

In any of the above cases, the comparator power supply circuit 22
Does not supply a current to the light emitting element of the photocoupler 14, and by appropriately selecting the resistance value of the resistor 23, an element current sufficient for signal transmission by the photocoupler 14 even if this voltage is low. Can be supplied.

According to the present invention, the comparator 10 takes a sufficient power supply voltage and a comparison input voltage from the DC power supply circuit through the Zener diode 24 to stabilize the determination of the magnitude of the minute voltage, and uses the series resistor 23. However, the current consumption of the comparator 10 is small and the power loss does not become a problem. On the other hand, the power supply of the photocoupler 14 requires a relatively large current required to cover the low conversion efficiency, but accuracy and stability are not required so much.
The power is obtained from the minus side driver power supply circuit 20.

[0021]

As described above, according to the present invention, it is possible to provide a drive control device for a DC brushless motor which avoids the problems existing in the prior art and has a high reliability and a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a circuit connection diagram showing an embodiment of a drive control device according to the present invention.

FIG. 2 is a time chart for explaining an operating state of the device shown in FIG.

FIG. 3 is a circuit connection diagram showing an example of a conventional drive control device.

[Explanation of symbols]

 2 Brushless motor 4 Inverter 6 Control circuit 8 Voltage dividing circuit 10 Comparator 14 Photocoupler 18 Power supply circuit 20 Power supply circuit 22 Power supply circuit 23 Resistor 24 Zener diode 25 Capacitor P, N DC power supply terminal D driver

Claims (3)

[Claims] 1. A DC brushless motor having a brushless motor comprising a stator having three-phase windings connected in a star shape and a rotor having a permanent magnet, and an inverter connected to an input end of the brushless motor. And a comparator that outputs a signal representing a rotor position based on an induced electromotive force generated in a non-energized phase that cyclically occurs in one phase of the three-phase winding, and a comparator of the comparator. Control means for sequentially determining the energization of the inverter by sequentially determining two energized phases of the three-phase winding according to the comparison result of the photocoupler connected to the output end and the comparator transmitted through the photocoupler. In a drive control device for a DC brushless motor comprising: a comparator power supply circuit for supplying operating power to the comparator, connected between terminals of the DC power supply; It said comparison dexterity drive control device of a DC brushless motor, characterized in that it has to take from another power supply circuit and power supply circuit the operating current of the light emitting element. 2. The drive control device according to claim 1, wherein
The comparator power supply circuit comprises a series circuit of a resistor and a Zener diode connected between DC power supply terminals, and both ends of the Zener diode constitute output terminals, and drive control of a DC brushless motor is performed. apparatus. 3. The drive control device according to claim 1, wherein the operating current of the light emitting element of the photocoupler is obtained from a driver operating power supply circuit for driving the negative side arm of the inverter. A drive control device for a DC brushless motor characterized by: