JPH02250694A - Brushless motor protector - Google Patents

Abstract

PURPOSE:To protect semiconductors from breakdown due to excessive current by turning an open/close means OFF for a predetermined time when the wind speed is higher than a predetermined value or when the wind speed is lower than the predetermined value and DC current exceeds over a predetermined value during operation. CONSTITUTION:Intensity of outer wind force is detected through an outer wind speed detecting means 7, and when the detected intensity exceeds over a predetermined level an open/close means 9 is turned OFF for a predetermined time. When the outer wind speed is lower than a predetermined level and the outer wind force increases during operation of a brushless motor 16 thus increasing load on the brushless motor 16, load condition is detected through a DC current detecting means 10 and when DC current exceeds over a predetermined level all elements in a semiconductor switching group 2 are turned OFF for a predetermined time thus preventing excessive current flow through the winding 3 of the brushless motor 16 and the semiconductor switch group 2.

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 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 applied as a motor for driving an outdoor fan of a separate type air conditioner, if the fan is forcibly driven from outside by abnormal wind force such as during a typhoon. However, this has the disadvantage that an excessively large induced voltage is generated within the brushless motor, causing a short-circuit current to flow within the motor windings and destroying the semiconductors.

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 a fan from the outside, and an output of the wind speed detection means that has a constant value. a direct current detecting means for detecting the direct current flowing through the semiconductor switching group; and a direct current discriminating means for determining whether the output of the direct current detecting means exceeds a certain value. , an opening/closing means inserted between the motor winding and the semiconductor switching group, and a timer means for holding the switch for a certain period of time when the opening/closing means is turned off. If the DC current value exceeds a certain value during operation, the opening/closing means is turned off for a certain period of time.

According to the brushless motor protection device of the present invention, even if the fan is forcibly driven from the outside due to abnormal wind power such as during a typhoon, no short-circuit current will flow through the motor windings, and the semiconductors will be protected against excessive current. It is possible to prevent damage due to

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 detection means for detecting the magnetic pole position of the rotor 4; 6 is a phase detection means for generating a signal necessary for rotating the rotor 4 in a certain direction based on the output signal of the phase detection means 5, and outputting it to the semiconductor switching group 2; Driving means, 7 external wind speed detection means, 8
is a determination means for determining whether the outside wind speed value detected by the outside wind speed detection means 7 exceeds a certain value. Reference numeral 9 denotes an opening/closing means inserted between the semiconductor switching group 2 and the motor winding 3.

Further, reference numeral 10 indicates a DC current detection means for detecting the value of the DC current flowing through the semiconductor switching group 2, 11 indicates a DC current determination means for determining whether the DC current value detected by the DC current detection means 10 exceeds a certain value, and 12 is a timer means that holds the time for a certain period of time when the opening/closing means 9 is turned off.

FIG. 2 is a configuration diagram of an outdoor unit of an air conditioner. In the figure, 15 is a propeller fan, 16 is a brushless motor, and 17 is a propeller fan.
is a heat exchanger. Now, in order to cool the heat exchanger 17,
The ON and OFF states of the semiconductor switching group when the brushless motor 16 is rotated in a fixed direction will be explained with reference to FIGS. 4 and 5. FIG.

FIG. 4 shows the state when the brushless motor 16 is rotated in the forward direction by external wind power. In this state, no current flows through the motor winding 3, and only a direct current flows between the upper and lower arms of the semiconductor switching group 2. Only the voltage (1) increases. On the other hand, in Figure 5, the brushless motor 1 is
6 represents the state when it is rotated in the opposite direction, and in this state, a short circuit current (solid line and broken line arrow) flows in 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 16 increases, eventually leading to destruction of the semiconductor switching group. , all elements of semiconductor switching group 2 are O
This means that you should keep it in the FF state and never turn it 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 rotational speed of the brushless motor 12 with respect to the wind power and the DC voltage v appearing between the upper and lower arms of the semiconductor switching group 2! It represents the relationship between lc.

In the present invention, the strength of the external wind force is detected by the external wind speed detection means, and when it exceeds a certain value, the opening/closing means 9 is turned off for a certain period of time. Further, if the external wind speed increases while the brushless motor 16 is being operated with the external wind speed below a certain value, and the load on the brushless motor 16 increases, the DC current detection means 10
detects the load condition, and if the DC current value exceeds a certain value, all elements of the semiconductor switching group 2 are turned off for a certain period of time to prevent excessive current flowing through the brushless motor 160 winding 3 and the semiconductor switching group 2. In addition to preventing this, it also prevents hunting.

FIG. 6 shows a 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 self-heating thermistor has a difference in the amount of heat radiated 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 resistors 23 and 24. It is determined whether the external wind power has exceeded a certain value. Thermistor 21
is installed in a place where the external wind is applied, so when the external wind speed exceeds a certain level, when comparing the voltage division points V, Vt, the resistance value of thermistor 21 becomes larger than the resistance value of thermistor 22. vl becomes larger than V2, and the output of the comparator 25 becomes "L". Also, resistance 31.3
2.33 detects the DC current, compares it with the reference voltage 34 and the comparator 35, and when the DC current value exceeds a certain value, the monostable multivibrator 26 sets the output signal to "L" for a certain period of time. , the relay 30 is turned off for a certain period of time via the monostable multivibrator 26.
F.

Note that 28 is a transistor that drives the relay 30, 27 is a base resistance of the transistor 28, and 29 is a flywheel diode.

As described in detail, the brushless motor protection device of the present invention is applicable to a system in which a brushless motor is applied to drive an outdoor fan of an air conditioner. an open/close means inserted between the semiconductor switching group and the motor winding; a DC current detection means for detecting the DC current flowing through the switching element group; DC current determining means for determining whether the current exceeds the
A timer means is provided to hold the opening/closing means for a certain period of time when the opening/closing means is turned off, and the opening/closing means is turned off when the external wind force value is above a certain level.
In other words, if the outside wind speed value is below a certain value, this is the condition for starting brushless motor operation, and if the load increases during operation, the load condition is detected by DC current, and the DC current value exceeds a certain value. This system turns off the opening/closing means for a certain period of time when the brushless motor is forced to rotate due to abnormal external wind force, such as a typhoon, due to its simple configuration.
This has the effect of preventing excessive current from flowing through the windings of the brushless motor, thereby preventing damage to the semiconductor switching group due to excessive current.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing the basic configuration of the brushless motor protection device of the present invention, Figure 2 is a configuration diagram of an outdoor unit of an air conditioner, and Figure 3 is a circuit diagram showing the basic configuration of the brushless motor protection device of the present invention. Figure 4 is a characteristic diagram of the external wind force, DC voltage, and motor rotation speed in the OFF state. Figure 4 is a circuit diagram showing the state of the same brushless motor protection device during forward rotation. Figure 5
FIG. 6 is a circuit diagram showing the state of the brushless motor protection device during reverse rotation, FIG. 6 is a flowchart of the brushless motor protection device, and FIG. 7 is a circuit diagram showing an embodiment of the brushless motor protection device. 2... Semiconductor switching group, 5...
Phase detection means, 6... Drive means, 7...
・Outside wind speed detection means, 8... Outside wind connection judgment means, 9
...Opening/closing means, 10... Direct current detection means, 11... Direct current judgment means, 12...
...Timer means. Agent's name: Patent attorney Shigetaka Awano 1 person 2 - Semiconductor Switching S-a Fukukyoya α child role 6 - driver's hand role 7 - - Dato Kazesoku Kashiguchi hand role 8 - 1 person)! E14 Shin I Ri 1 hand role 9 - Intermediate role tO- & 5 power 5 Qi Chite role 11.- Directly looking at the 9th period "means OF1"? wind liao

Claims (1)

[Claims] a semiconductor switching group that controls motor winding current;
A signal necessary for rotating the rotor in a certain direction is generated based on an output signal of a phase detection means for detecting the magnetic pole position of the rotor, which is composed of a permanent magnet, and a signal is generated between the motor winding and the semiconductor switching group. an opening/closing means to be inserted, a drive means for outputting to the semiconductor switching group, a wind speed detection means, a wind speed determination means for determining whether a wind speed value detected by the wind speed detection means exceeds a certain value, and the semiconductor Consisting of a DC current detection means for detecting the DC current flowing through the switching group, a DC current judgment means for determining whether the DC current value exceeds a certain value, and a timer means for holding the switch for a certain period of time when the opening/closing means is turned off. and when the wind speed value is above a certain value, the opening/closing means is turned off to prevent short-circuit current from flowing through the motor windings, and the DC current value is kept at a constant value during operation when the wind speed value is below a certain value. A brushless motor protection device configured to turn off the opening/closing means for a certain period of time when the voltage exceeds the limit.