JP2577036Y2 - Self-diagnosis device for brushless motor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-diagnosis device for a brushless motor such as a fan motor used together with a temperature sensor in an automobile.

[0002]

2. Description of the Related Art An automatic air conditioner mounted in a vehicle is provided with a temperature sensor for detecting the temperature inside the vehicle. A fan is provided to increase the accuracy of detecting the temperature inside the vehicle. Thus, the air in the vehicle is blown to the temperature sensor. Conventionally, DC motors have been used as fan motors, but brushless motors have come to be used because of low noise and low power consumption.

In the meantime, while the brushless motor is being used, failures such as short-circuit and open of the brushless motor coil and the drive line of the brushless motor (hereinafter, collectively referred to as motor line) may occur. In some cases, when such a failure occurs, the detection accuracy of the temperature sensor decreases and the automatic air conditioner cannot operate properly. Since the brushless motor generates little noise, even if the above-described failure occurs and the fan stops, it cannot be known especially during operation. For this purpose, a self-diagnosis device for a brushless motor is further provided to automatically detect and display such a failure as described above.

FIG. 5 is a block diagram showing an example of a conventional brushless motor self-diagnosis device, wherein 1 is a brushless motor, 2 is a drive circuit, 3 is a current detection unit, and 4 is a voltage detection circuit.

In FIG. 1, a brushless motor 1 is driven by a drive current supplied from a drive circuit 2. The current detection unit 3 detects the drive current, the voltage detection circuit 4 determines the state of the motor line from the detection result of the current detection unit 3, and outputs a detection voltage signal A indicating the result. The detection voltage signal A is “H” (high level) when the motor line is short-circuited, and is “L” (low level) when the motor line is open. , "L".

When the voltage detection circuit 4 determines that the motor line is short-circuited, the voltage detection circuit 4 controls the drive circuit 2 to perform short-circuit protection control for preventing a current from flowing through the motor line.

FIG. 6 is a circuit diagram showing a specific configuration of such a conventional example, wherein R1 to R10 are resistors, TR1, TR2
Is a transistor, D1 to D4 are diodes, CP is a comparator, ML is a motor line, and portions corresponding to FIG.

In FIG. 1, during a steady operation of the brushless motor, the transistor TR2 is turned on and the resistor R
8 and R9, a predetermined bias voltage is applied to the base of the transistor TR1, and the transistor TR1
And a current IM is supplied to the brushless motor via a resistor R1 forming a current detection unit 3.

At this time, a voltage VRS of VRS = R1 × IM (1) is generated in the resistor R1 and supplied to the voltage detection circuit 4. In the voltage detection circuit 4, the resistors R2 to R5 determine the output voltage VSD ′ of the comparator CP as VSD ′ = k × VRS / (1−k) (2) where R2 = R3 and R4 = R5. , K = R4 / (R2 + R4), R6≪R7, and the voltage of the diode is VD
Then, the next voltage VSD is obtained from the voltage detection circuit 4 (this is the detection voltage signal A in FIG. 5).

VSD = VSD′−VD (3) At this time, the diode D1 is forward-biased and turned on, whereby the diode D3 is reverse-biased and turned off. The diode D4 is also reverse-biased and turned off.

When the motor line ML is opened, the current IM hardly flows through the resistor R1 of the current detector 3, and VRS = 0 according to the above equation (1). Therefore, according to the above equations (2) and (3), VSD ≒ 0, and
This is "L" described above.

When the motor line ML is short-circuited, the diode D4 turns on, and the potential at the point P becomes equal to the voltage VD of the diode D4. As a result, the transistor TR2 is turned off, and the transistor TR1 is also turned off because its base bias voltage increases. For this reason, the current IM flowing through the motor line ML becomes zero. This is the short-circuit protection control described above.

On the other hand, when the transistor TR2 is turned off,
The diode D1 is also turned off by applying a reverse bias. For this reason, the power supply voltage E3 is supplied to the output resistor R7 via the resistor R10 and the diode D3. By setting R10７R7, the output voltage VSD of the voltage detection circuit 4 becomes VSD = E3-VD. (4) This is "H" described above. However, VD in the equation (4) is the voltage of the diode D3, and the diode D2 is reverse-biased and off.

In the above operation, by making the output voltage VSD of the equation (3) lower than the output voltage VSD of the equation (4), the brushless motor operates steadily from the magnitude of the output voltage VSD. Or motor line ML
Is open or short-circuited. An example of this case will be described below.

In this example, E1 = E3 = + 5 (V), E
2 = + 12 (V), R8 = 470 (Ω), R9 = 1.8
(KΩ) and R1 = 15 (Ω), IM =
30 (mA). In the voltage detection circuit 4, R2 = R3 = 10 (kΩ), R4 = R5 = R7 =
47 (kΩ), R6 = 1 (kΩ), and R10 = 820
(Ω). Note that the voltage VD of the diode is 0.
6 (V).

Based on the above settings, equations (1), (2),
According to (3), the voltage V during the steady operation of the brushless motor is obtained.
When SD is obtained, VRS = 30 (mA) × 15 (Ω) =
Since it is 450 (mA), VSD = 450 (mA) × (47/10) −0.6 (V) = 1.5 (V). On the other hand, according to the above equation (4), the motor line ML
Is short-circuited, VSD = 5 (V) -0.6 (V) = 4.4 (V), and the voltage VSD is significantly different from that when the brushless motor is operating normally.

Therefore, the output voltage VS of the voltage detection circuit 4 is determined by using a determination circuit having a voltage range as shown in FIG.
By judging which of these D is included, it is possible to judge whether the brushless motor is performing a steady operation and whether the motor line ML is short-circuited or opened.

[0018]

However, in the above-described conventional self-diagnosis apparatus, when the brushless motor cannot rotate due to foreign matter entering the brushless motor and the so-called motor locked state is determined, this is determined. Could not. This means that even when the motor is locked, the current I as large as when the motor line ML is short-circuited.
This is because M does not flow and the output voltage VSD of the voltage detection circuit 4 falls within the same voltage range as when the brushless motor shown in FIG.

An object of the present invention is to provide a self-diagnosis device for a brushless motor which solves such a problem and can determine a motor lock state in addition to a determination of a steady operation, a short circuit, and an open state of the brushless motor. It is in.

[0020]

In order to achieve the above object, the present invention detects a drive current of a brushless motor as a voltage, and the detected voltage level indicates a short-circuit state.
In this case, the voltage of the first level is
When indicating the state of the open, the first level lower than the first level
2, the detection voltage level is short-circuited or
The first and second levels when indicating a state other than open
A self-diagnosis device for a brushless motor including voltage detection means for outputting a voltage at a third intermediate level between
The detection voltage is replaced with a DC voltage having a constant level lower than a reference voltage, and a waveform shaping means for comparing a level with the reference voltage, and an output voltage of the waveform shaping means.
Smooth, short, open and motor locked
The fourth level voltage during normal operation
A smoothing means for outputting a voltage other than the level , and the smoothing means when the output voltage of the voltage detecting means is at the first level.
Judgment of short-circuit condition regardless of output voltage
And the output voltage of the voltage detecting means is at the second level.
Irrespective of the output voltage of the smoothing means,
And the output voltage of the voltage detecting means is
And the output voltage of the smoothing means is the fourth level.
When it is at the level, it is determined that the motor is locked,
The output voltage of the detection means is at the third level and
Steady state when the output voltage of the sliding means is other than the fourth level
Determining means for determining the operating state ;

[0021]

When the brushless motor rotates, the drive current pulsates in a cycle corresponding to the magnetic number and the rotation speed of the rotor, and when the motor is locked, the drive current remains at the amplitude immediately before the occurrence of the motor lock state. Is held.
For this reason, the output voltage of the voltage detecting means pulsates at a constant cycle when the brushless motor is operating steadily, but becomes a constant DC voltage when the motor is locked. Therefore, the detection voltage of the voltage detection means is
While the brushless motor is pulsating when operating steadily, the voltage is a DC voltage in other states including the motor lock state.

In the waveform shaping means, the DC component of the detected voltage is combined with a constant level DC voltage lower than the reference voltage.
After that , the detected voltage is compared with the reference voltage. Therefore, when the supplied detected voltage is a DC voltage, the output voltage of the waveform shaping unit becomes 0 (V), and therefore, the output of the smoothing unit is changed. The voltage is also 0 (V). In contrast, if there is a ripple component in the detection voltage supplied, the waveform shaping
The output voltage of the means is rectangular, and the output voltage of the smoothing means is other than 0 (V). That is, the output voltage of the smoothing means is 0 at the time of short, open, and motor lock.
(V), when the brushless motor is in a steady state, 0
(V).

As described above, since the output voltage of the voltage detecting means is different in the level range between short and open, and other than that, the discriminating means is determined from the output voltage of the smoothing means and short circuit, open and motor lock. , The steady operation state of the brushless motor can be determined.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a self-diagnosis device for a brushless motor according to the present invention, wherein 5 is a waveform shaping circuit, 6 is a smoothing circuit, 7 is a discriminating circuit, 8 to 11 are output terminals, and R11 to R17. Is a resistor, C1 and C2 are capacitors,
CP1 is a comparator, and portions corresponding to those in FIG. 6 are denoted by the same reference numerals, and redundant description is omitted.

In this figure, this embodiment adds a waveform shaping circuit 5, a smoothing circuit 6 and a discriminating circuit 7 to the prior art shown in FIG. 6, and the discriminating circuit 7 compares the output voltage VSD of the voltage detecting circuit 4 with the output voltage VSD. From the voltage VDC obtained by the waveform shaping circuit 5 and the smoothing circuit 6 in addition to the respective states of short-circuiting and opening of the motor line ML and steady-state operation of the brushless motor 1,
The motor lock state can also be determined.

The output voltage VSD 'of the comparator CP is also supplied to the waveform shaping circuit 5. In the waveform shaping circuit 5, first, the DC component of the voltage VSD ′ is removed by the capacitor C1, and then the DC voltage V1 (= E4 × R12 / (R11 + R) obtained by dividing the power supply voltage E4 by the resistors R11 and R12.
12)) are superimposed and compared with the reference voltage V2 (= E5 × R14 / (R13 + R14)) obtained by dividing the power supply voltage E5 by the resistors R13 and R14 in the comparator CP1 as the voltage to be compared. Here, as shown in FIG. 2B, V2> V1 is set, and the comparator CP1 is “H” when the compared voltage ≧ V2 and “L” when the compared voltage <V2, ie, , 0
(V) voltage VC is output. This voltage VC is equal to the resistance R1
5, and is smoothed by a smoothing circuit 6 including a resistor 16 and a capacitor C2.

When the motor line ML is open or short-circuited, similar to the prior art described above,
The output voltage VSD 'of the comparator CP is a DC voltage. Further, when the brushless motor 1 is performing a steady operation, the drive current IM pulsates at a cycle corresponding to the magnetic number and the number of rotations of the rotor, and as a result, as shown in FIG.
The voltage VRS occurring at 1 and therefore the output voltage VSD 'of the comparator CP also pulsates. However, if the motor lock occurs while the brushless motor 1 is operating in a steady state, the drive current IM becomes a DC current of the magnitude at the time of the occurrence from the occurrence of the motor lock, and therefore, the output voltage VS of the comparator CP.
As shown in FIG. 3, D 'is also a DC voltage of a magnitude immediately before the motor lock occurrence time t.

When the open / short or motor lock of the motor line ML occurs, when the DC voltage VSD 'is supplied to the waveform shaping circuit 5, the DC voltage VSD' is supplied to the capacitor C.
1, the DC voltage V1 from the resistors R11 and R12 is compared with the reference voltage V2 by the comparator CP1. Here, since V1 <V2, this comparator C
The output voltage VC of P1 is 0 (V), and therefore the output voltage VDC of the smoothing circuit 6 is also 0 (V).

On the other hand, during the steady operation of the brushless motor 1, the output voltage VSD 'of the comparator CP is
As shown in (b), the pulsating voltage is converted into a pulsating voltage of V1 by the capacitor C1 and the DC voltage V1 in the waveform shaping circuit 5 and compared with the reference voltage V2 by the comparator CP1. Is done. As a result, the output voltage VC of the comparator CP1 becomes a rectangular voltage having the same cycle as the pulsation, as shown in FIG. 2C, and is not 0 (V) by being smoothed by the smoothing circuit 6. DC voltage VDC is obtained.

As described above, the output voltage VD of the smoothing circuit 6
C is when the brushless motor 1 is operating normally,
The voltage will be different for short, open and motor lock. Also, as in the prior art shown in FIG. 6, the output voltage VSD obtained from the resistor R7 has a range of different values for short-circuit, steady-state operation, and open as shown in FIG. It is within the operating voltage range. FIG. 4 summarizes the relationship between the voltages VSD and VCD and each state.

The discriminating circuit 7 detects these voltages VSD, VDC
The state is determined from the relationship shown in FIG. 4, and when the brushless motor 1 is determined to be in the steady state, it is connected to the output terminal 8; when the motor is locked, to the output terminal 9; In some cases, for example, a signal of “H” is output to each of the output terminals 11 to display, for example, a display element (not shown).

As described above, in this embodiment, it is possible to distinguish between the normal operation of the brushless motor 1 and the motor lock state, and it is possible to determine and indicate the open / short state of the motor line ML.

Note that a microcomputer can be used as the determination circuit 7. Further, the above numerical values are shown as an example for convenience of explanation, and the present invention is not limited by these numerical values.

Further, in the above embodiment, the judgment results of the short circuit, open circuit, motor lock state, and steady operation state of the brushless motor are represented by outputting an "H" signal to separate output terminals. May be represented by signals of different levels, and may be obtained at one output terminal. Further, the voltage detection circuit 4 may output a voltage of “L” when short-circuited and output a voltage of “H” when open.

[0035]

[Effects of the Invention] As described above, according to the present invention,
It is possible to distinguish between a steady operation state of the brushless motor and a motor lock state, and it is possible to determine an abnormal state such as a motor lock in addition to a short circuit or open motor line.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a self-diagnosis device for a brushless motor according to the present invention.

FIG. 2 is a diagram showing voltage waveforms at various parts during a steady operation of the brushless motor of FIG. 1;

FIG. 3 is a diagram showing a voltage waveform when the motor lock state of FIG. 1 occurs.

FIG. 4 is a diagram showing a specific example of a state determination criterion of a determination circuit in FIG. 1;

FIG. 5 is a block diagram showing an example of a conventional brushless motor self-diagnosis device.

FIG. 6 is a circuit diagram showing a specific configuration of the conventional example shown in FIG.

FIG. 7 is a diagram showing criteria in the specific example shown in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brushless motor 2 Drive circuit 3 Current detection part 4 Voltage detection circuit 5 Waveform shaping circuit 6 Smoothing circuit 7 Discrimination circuit 8-11 Output terminal

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02P 6/12 H02P 7/06-7/34 H02P 5/00

Claims (1)

(57) [Scope of request for utility model registration] 1. A driving current of a brushless motor is detected as a voltage , and the level of the detected voltage indicates a short-circuit state.
In this case, the voltage of the first level is
When indicating the state of the open, the first level lower than the first level
2, the detection voltage level is short-circuited or
The first and second levels when indicating a state other than open
A self-diagnosis device for a brushless motor provided with voltage detection means for respectively outputting a voltage at a third intermediate level, wherein the detected voltage is replaced by a DC voltage having a constant level lower than a reference voltage. a waveform shaping means for comparing the reference voltage and the level, the output voltage of the waveform shaping means to smooth, short and open
When the motor is locked, the fourth level voltage is
A smoothing means for outputting a voltage other than the fourth level in the steady operation state , and a smoothing means for outputting the voltage when the output voltage of the voltage detecting means is the first level.
Regardless of the output voltage of the smoothing means,
State, and the output voltage of the voltage detection means is set to the second level.
, Regardless of the output voltage of the smoothing means,
When the output voltage of the voltage detecting means is determined to be in the open state,
The third level and the output voltage of the smoothing means is
When the level is the fourth level, it is determined that the motor is locked,
Whether the output voltage of the voltage detecting means is at the third level
When the output voltage of the smoothing means is other than the fourth level
A self-diagnosis device for a brushless motor, comprising: a determination unit configured to determine a normal operation state .