JPS63140688A - Protective device for brushless motor - Google Patents

Abstract

PURPOSE:To prevent the breakage of semiconductors, by a method wherein a means is provided for detecting speed of a wind driving a fan forcibly from outside, and the output thereof is decided whether it has exceeded a given value. CONSTITUTION:A brushless motor, equipped with a coil 3, a rotor 4 and a phase detecting means 5, detecting the position of a magnetic pole, is driven by controlling a semiconductor switching group 2, which conducts current from a DC power source 1 through said coil 3. Further, the switching group 2 is controlled by a driving means 6. In this case, an outer air speed detection means 7 and a decision means 8, which decides whether an outer air speed value, detected by the outer air speed detection means 7, has exceeded a given value or not, are provided. When the outer air speed becomes the given value or higher, all elements of the semiconductor switching group 2 are put OFF. According to this method, overcurrent, conducted through the coil 3 and the semiconductor switching group 2 of the brushless motor, may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brushless motor protection device when the brushless motor is applied to drive an outdoor fan of an air conditioner, for example.

BACKGROUND OF THE INVENTION In recent years, efforts have been made to improve the operating efficiency of fan drive motors with the aim of operating air conditioners more efficiently. Therefore, the conventionally used induction motors are being replaced with brushless motors, which have higher operating efficiency.

Particularly in separate air conditioners, many of the indoor fan motors are now brushless motors, and brushless motors for the outdoor side will continue to be considered in the future.

Problems to be Solved by the Invention When a brushless motor is used as a motor for driving an outdoor fan of a separate air conditioner, the fan is forcibly driven from outside by abnormal wind force such as during a typhoon. However, there is a problem in that an excessive induced voltage is generated within the brushless motor, causing a short-circuit current to flow within the motor windings and destroying the semiconductor components.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to prevent destruction of semiconductors caused by induced voltage generated when a fan is driven by an external force.

Means for Solving the Problems In order to solve the above problems, the brushless motor protection device of the present invention includes a wind speed detection means for detecting the wind speed for forcibly driving the fan from the outside, and an output of the wind speed detection means. The wind speed determining means is configured to determine whether or not the wind speed exceeds a certain value, and when the wind speed value exceeds a certain value, all the elements of the semiconductor switching group are configured to be set to ON-J.

Function: Due to the above configuration, the brushless motor protection device of the present invention prevents short-circuit current from flowing in the motor windings and prevents semiconductors from flowing even if the fan is forcibly driven from the outside due to abnormal wind power such as when a typhoon occurs. Destruction due to excessive current can be prevented.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a basic configuration diagram of the present invention, and in the figure, 1
2 is a semiconductor switching group for controlling the current flowing through the winding 3 of the brushless motor, and 4 is the rotor of the brushless motor, which is composed of a permanent magnet. 5 is a phase detecting means for detecting the magnetic pole position of the rotor 4; 6 is a phase detecting means for generating a signal necessary for rotating the rotor 4 in a certain direction based on the output signal of the phase detecting means 5; 7 is an outside wind force detection means, and 8 is a determination means for determining whether the outside wind coupled force value detected by the outside wind force detection means 7 exceeds a certain value.

FIG. 2 is a configuration diagram of an outdoor unit of an air conditioner. In the figure, 11 is a propeller fan, 12 is a brushless motor, and 13 is a propeller fan.
is a heat exchanger. Now, the ON and FF states of the semiconductor switching group when the brushless motor 12 is rotated in a fixed direction to cool the heat exchanger 13 will be explained with reference to FIGS. 4 and 5.

FIG. 4 shows the state when the brushless motor 12 is rotated in the forward direction by external wind power. In this state, no current flows through the motor winding 3, and only between the upper and lower arms of the semiconductor switching group 2. Only the DC voltage VDC increases. - Figure 5 of the power cylinder shows the state when the brushless motor 12 is rotated in the opposite direction by external wind force,
In this state, a short circuit current (solid line and broken line arrow) flows through the motor winding 3 through the elements of the semiconductor switching group 2. Naturally, this current increases as the number of rotations of the brushless motor 12 increases, eventually leading to destruction of the semiconductor switching group. Therefore,
When the outside wind speed exceeds a certain level or the rotation speed of the brushless motor exceeds a certain level, all elements of the semiconductor switching group 2 must be kept in the OFF state and must never be turned ON.

FIG. 3 shows that all elements of semiconductor switching group 2 are OF.
In the F state, when the brushless motor 12 is rotated by external wind power, the number of rotations of the brushless motor 12 relative to the wind power and the DC voltage VDC appearing between the upper and lower arms of the semiconductor switching group 2 are detected by the means, and the DC voltage VDC is detected to be higher than a certain value. When this happens, turn off all elements of semiconductor switching group 2.
By maintaining the F state, the winding 3 of the brushless motor 2
This also prevents excessive current from flowing through the semiconductor switching group 2.

FIG. 6 shows the flowchart at this time.

FIG. 7 shows one specific embodiment of the thermistor 21.
22, the thermistor 21 is installed in a place where the external wind force is applied, and the thermistor 22 is installed in a place where the external wind force is not applied. A thermistor that generates heat by itself has a difference in the amount of heat released depending on the presence or absence of external wind, and the temperature of the thermistor changes, which appears as a difference in resistance value, and the comparator 25 compares the voltage divided by the resistor 23 and 24. By this, it is determined whether the external wind power has exceeded a certain value. Thermistor 21
is installed in a place where external wind power is applied, so the voltage division point V1. Comparing V2, the resistance value of thermistor 21 is larger than the resistance value of thermistor 22, so vl is equal to v2
becomes larger, the output of the comparator 25 becomes open, and the I
The power supply of C29 is kept at 0FFL by the transistor 28, and all the elements of the semiconductor switching group 2 are kept at FF state.

As described in detail, the brushless motor protection device of the present invention has the following features:
In a system in which brushless morph is applied to the outdoor fan drive of an air conditioner, an external wind force detection means for detecting the external wind power and an external wind power judgment means for determining whether the external wind power has exceeded a certain value and have deviated are provided. If the value exceeds the value, all elements of the semiconductor switching group are kept in the FF state.In other words, the brushless morph starts operation only when the external wind force is below a certain value.With a simple configuration, it is possible to prevent abnormal external wind conditions such as typhoons. Even when the brushless morph is forcibly rotated by wind, no excessive current flows through the windings of the brushless morph, which has the effect of preventing damage to the semiconductor switching group due to excessive current.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of a brushless morph protection device according to an embodiment of the present invention, Fig. 2 is a configuration diagram of an outdoor unit of an air conditioner equipped with the device, and Fig. 3 is a complete diagram of a group of semiconductor switches in the device. A characteristic diagram showing the relationship between the external wind force, DC voltage, and motor rotation speed when the element is in the FF state, Figure 4 is a circuit diagram showing the state of the same device when it rotates in the forward direction, and Figure 5 is the reverse view of the same device. FIG. 6 is a circuit diagram showing the state during rotation, FIG. 6 is a flowchart of the device, and FIG. 7 is a circuit diagram of the main part of the device. Name of agent: Patent attorney Toshio Nakao 1 person 2-
Semiconductor switching group 5-4 stand 8 + detection 4-#Jt 6- production + stage 7- outside jL4 office knowledge hand 8- outside OFI'' ON OFFFigure 5Figure 6Figure 7

Claims (1)

[Claims] A semiconductor switching group for controlling the motor winding current, a phase detection means for detecting the magnetic pole position of the rotor composed of permanent magnets, and a phase detection means necessary for rotating the rotor in a fixed direction based on the output signal of the phase detection means. generate a signal,
It is comprised of a driving means for outputting to the semiconductor switching group, a wind speed detecting means, and a wind speed determining means for determining whether the wind speed value detected by the wind speed detecting means exceeds a certain value, and the wind speed value is a certain value. A protection device for a brushless motor configured to prevent all elements of the semiconductor switching group from being turned on in the above case.