JPH07170782A - Method and apparatus for controlling commutatorless motor - Google Patents

Abstract

PURPOSE:To protect the transistors of an inverter section from damage and breakdown by keeping a position detecting circuit operating for a specified time by the use of a backup power source, and preventing its position detection signal from being abnormal during the stop control of a commutatorless motor. CONSTITUTION:When power supply stops instantaneously, the voltage of the input DC power source of an inverter section 2 begins to lower. Switching over to the side of a backup circuit 6 is made by switching means 7, and the backup voltage is supplied to a position detecting circuit 4 in place of the output voltage of a DC/DC converter 5. As a result, the voltage of the power source of the position detection circuit 4 does not lower even at the instantaneously cut-off time of the power source, the position detecting circuit 4 outputs a normal position detection signal. This normal position detection signal is inputted to a control circuit 3, and the control circuit 3 outputs to the inverter section a control signal for exciting and stopping the rotor of a commutatorless motor 1 at a correct position. Since the control signal is prevented from being abnormal, it becomes possible to protect the group of transistors of the inverter section 2 from damage and breakdown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-commutator motor control method and apparatus for protecting a control device for controlling rotation of a non-commutator motor (sensorless DC brushless motor) used in a compressor of an air conditioner. It is about.

[0002]

2. Description of the Related Art In order to control the rotation of this non-commutator motor, for example, a control device shown in FIG. 2 is required. In FIG. 2, this control device sequentially excites the armature windings U, V, W of the non-rectifier motor 1, so that the DC power source obtained by AC / DC converting the commercial power source is switched to switch the armature winding U,
Inverter section 2 applied to V and W, and a plurality of transistors Ua, Va, Wa, Xa, Y of this inverter section 2
and a control circuit (microcomputer) 3 for outputting a control signal for turning on and off a and Za.

Further, since the commutatorless motor 1 is a sensorless DC brushless motor, the control device rotates the commutatorless motor 1 by the terminal voltages of the armature windings U, V, W of the commutatorless motor 1. A position detection circuit 4 that outputs a position detection signal for detecting the position of the child to the control circuit 3, and a DC / DC converter (DC / DC converter) that supplies the position detection circuit 4 with a voltage Vcc obtained by DC / DC converting a DC power supply. DC converter) 5.

The control device having the above-mentioned configuration switches the DC power supply and applies it to the armature winding of the non-rectifier motor 1, while the transistors Ua, Va, W of the inverter section 2 are applied.
A, Xa, Ya, and Za are turned on and off in a predetermined manner to adjust the voltage applied to the armature winding, and the rotation speed of the non-rectifier motor 1 is controlled. Moreover, the timing of the control signal of the inverter unit 2 is determined based on the output position detection signal from the position detection circuit 4, and the armature windings U, V, W are appropriately sequentially excited by this control signal, Rotation of the commutator motor 1 is efficiently controlled.

Further, in the above control device, a change in the input DC power source of the inverter section 2 is detected, and when the detected voltage becomes a predetermined value or less, the control circuit 3 stops the non-rectifier motor 1. However, overcurrent to the inverter unit 2 is prevented. For this reason, the power supply of the control circuit 3 is designed to fall after the DC power supply.

[0006]

By the way, for example, AC
When the outlet is disconnected (the power supply of the control device is cut off momentarily) and the DC power supply of the inverter unit 2 drops sharply, DC / D
The output voltage of the C converter 5 (power supply of the position detection circuit 4) may also drop, and when the AC outlet is disconnected, the output position detection signal of the position detection circuit 4 may become abnormal.

When such an abnormal position detection signal is input to the control circuit 3, the control circuit 3 outputs an abnormal control signal, that is, a control signal that simultaneously turns on the transistor groups of the upper and lower arms of the inverter unit 2. May be output, which may damage or damage the transistor.

The present invention has been made in view of the above problems, and an object thereof is to prevent damage or breakage of a transistor group in an inverter section when power is cut off, and to improve reliability of a control device. It is an object of the present invention to provide a method of controlling a commutatorless motor and a device therefor.

[0009]

In order to achieve the above object, the present invention switches a DC power supply by inverter means and applies it to an armature winding of a non-commutator motor to control the rotation of the same commutator motor. At the time of detecting the position of the rotor of the non-commutator electric motor by the position detecting means, in the control method of the non-commutator electric motor controlling the inverter means at the timing of the position detection signal from the position detecting means,
It has a backup power source for the position detecting means, converts the DC power source into a power source for the position detecting means by converting the DC power source into a power source for the position detecting means, and the power source for the position detecting means is kept for a predetermined time when the power source of the control device is interrupted. The gist is to switch to the backup power source.

[0010]

With the above-mentioned means, when the AC outlet is disconnected and the input DC power source of the position detecting means is lowered, the power source of the position detecting means is switched to the backup power source. Does not become abnormal, but becomes normal. Therefore, when the power supply is interrupted, a control signal for controlling the inverter means for stopping the non-rectifier motor is obtained based on the normal position detection signal.

Therefore, the switch means of the upper and lower arms constituting the inverter means are not turned on at the same time, and the switch means is damaged by the voltage (back electromotive force etc.) generated in the armature winding of the non-rectifier motor. It will not be damaged.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention switches a direct current power source with inverter means and applies it to the armature winding of a non-rectifier motor,
Further, in the control method and apparatus for a non-rectifying motor, the position of the rotor of the same commutator motor is detected by the position detecting means, and the inverter means is controlled at the timing of the position detection signal from the position detecting means. When a power supply is provided, for example, the AC outlet is disconnected and the power supply of the control device is momentarily cut off, the position detection means is maintained by the backup power supply for a predetermined time, and at least during the stop control of the non-rectifier motor, the position detection means is provided. Make sure that the output position detection signal of does not become abnormal.

Thus, even when the power supply is interrupted, the non-commutator motor can be stopped and controlled based on the normal position detection signal, and the switching elements of the upper and lower arms of the inverter means are turned on at the same time. Nor.

Therefore, the control device for the non-commutator motor of the present invention has the configuration shown in FIG. In the figure, the same parts as those in FIG.

In FIG. 1, this control device is, for example, A
C outlet comes off (power supply of the control device is momentarily cut off),
Alternatively, a backup circuit 6 and a switch (switching means) 7 that operate when the input DC power supply of the inverter unit 2 is lowered are provided, and the power supply of the position detection circuit 4 can be switched to the power supply by the backup circuit 6. The backup circuit 6 and the switch 7 may be known ones.

In the controller for a commutatorless motor having the above-described structure, the control circuit (microcomputer) 3 first outputs a predetermined control signal (for example, a PWM signal) to bring the commutatorless motor 1 to a predetermined rotation speed, It is assumed that the commutatorless electric motor 1 is rotationally controlled.

At this time, for example, the AC outlet is disconnected,
That is, when the power supply is momentarily cut off, the DC power supply of the inverter unit 2 drops and then the power supply of the control circuit 3 drops. That is, the control circuit 3 needs to excite the rotor of the non-commutator motor 1 at the correct position and stop it.

By the way, when the AC outlet is disconnected, that is, when the power supply is momentarily cut off, the input DC power supply of the inverter section 2 starts to decrease, but the switch means 7 is used as the backup circuit 6.
The voltage Vcc of the backup power supply by the backup circuit 6 is supplied to the position detection circuit 4 instead of the output voltage Vcc of the DC / DC converter 5.

From the above, even if there is a momentary power failure, the power of the position detection circuit 4 does not drop, and the position detection circuit 4 is not affected by the momentary power failure. 4 outputs a normal position detection signal. This normal position detection signal is input to the control circuit 3, and the control circuit 3 outputs to the inverter unit 2 a control signal for exciting and stopping the rotor of the non-rectifier motor 1 at the correct position.

As a result, the transistors in the upper and lower arms of the inverter unit 2 are normally driven, and, for example, the transistors Ua and Xa in the upper and lower arms are not turned on at the same time, resulting in the armature winding of the commutatorless motor 1. The transistors Ua and Va are not damaged or damaged by the back electromotive force generated in the lines.

Further, after a lapse of a predetermined time from the momentary interruption of the power supply, for example, after the control circuit 3 stops the commutatorless motor 1, the power supply to the position detection circuit 4 is stopped and the switch 7 is set to DC / DC. It is switched to the converter 5. Therefore, the AC outlet is attached again,
When the power is turned on, the rotation of the commutatorless motor 1 can be controlled as usual.

In this way, when switching the DC power supply and applying it to the armature winding of the non-rectifier motor 1, for example, A
When the C outlet is disconnected and the power supply is momentarily cut off, the position detection circuit 4 of the rotor of the non-rectifier motor 1 is switched to the backup power supply, and the voltage from the backup power supply is maintained for a predetermined time. Supply to 4.

Therefore, even if the AC outlet is disconnected, the position detection circuit 4 is not affected, and the position detection circuit 4 outputs a normal position detection signal.
Since this normal position detection signal is input to the control circuit 3, the control signal for stopping and controlling the rotor of the non-commutator motor 1 at a correct position becomes normal, that is, the control circuit 3 constitutes the inverter unit 2. There is no output of a control signal to turn on the transistors of the upper and lower arms at the same time, the transistors constituting the inverter unit 2 are not damaged or damaged, and the reliability of the control device is improved. You can

[0024]

As described above, according to the present invention, the DC power source is switched in the inverter unit and applied to the armature winding of the non-rectifier motor, and the position of the rotor of the non-rectifier motor is adjusted. And a device for controlling the non-rectifier motor that controls the inverter unit at the timing of the position detection signal from the position detection circuit, and a device therefor have a backup power supply for the position detection circuit, For example, if the AC outlet is disconnected (power is cut off momentarily) or the DC power supply of the inverter unit drops, the position detection circuit is maintained by the backup power supply for a predetermined time, and the position detection circuit of the same position detection circuit is maintained during the stop control of the non-rectifier motor. The output position detection signal has been set so that it does not become abnormal, so when the power is interrupted, the control circuit controls the non-commutator motor to stop. The control signal for control does not become abnormal, and, for example, the upper and lower arm transistors that make up the inverter are not turned on at the same time, and the transistor group in the inverter can be prevented from being damaged or damaged. There is a useful effect that the reliability of the device can be improved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a control device to which an embodiment of the present invention is applied and which applies a control method for a non-rectifier motor.

FIG. 2 is a schematic block diagram of a conventional controller for a commutatorless motor.

[Explanation of symbols]

1 Non-commutator motor (sensorless DC brushless motor) 2 Inverter unit (inverter means) 3 Control circuit (microcomputer) 4 Position detection circuit 5 DC / DC converter 6 Backup circuit 7 Switch (switching means) U, V, W armature Winding (of non-rectifier motor 1) Ua, Va, Wa Transistor (upper arm of inverter section 2) Xa, Ya, Za Transistor (lower arm of inverter section 2)

Claims (2)

[Claims] 1. When the DC power source is switched by an inverter means and applied to the armature winding of the non-commutator motor to control the rotation of the non-rectifier motor, the position of the rotor of the non-rectifier motor is set to the position. A control method of a non-rectifier motor, which detects the position by a detecting unit and controls the inverter unit at the timing of a position detecting signal from the position detecting unit, comprising a backup power supply for the position detecting unit, DC / DC is converted to a power source for the position detecting means, and the power source of the position detecting means is switched to the backup power source for a predetermined time when the power source of the control device is momentarily cut off. Control method of slave motor. 2. The position of the rotor of the non-commutator motor is controlled when the DC power is switched by the inverter means and applied to the armature winding of the non-commutator motor to control the rotation of the non-rectifier motor. A controller for a non-commutator motor, which detects the position with a detection unit and controls the inverter unit at the timing of a position detection signal from the position detection unit, wherein the DC power supply is converted into a DC / DC power supply to the position detection unit. DC / DC converter, backup means for outputting the backup power source of the position detecting means, and switching means for switching the power source of the position detecting means to the output backup power source of the backup means for a predetermined time when the control device is momentarily cut off. A control device for a non-commutator motor, comprising: