JP3815812B2 - Fan motor drive unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fan motor drive device, and more particularly to a fan drive device that variably controls the rotational speed.
[0002]
[Prior art]
The circuit configuration diagram shown in FIG. 7 is a fan motor driving device that controls the rotational speed of the fan motor in accordance with, for example, a temperature change. In the figure, the rotor R of the fan is driven by two-phase drive coils L1, L2. The rotation detector 1 using a Hall element or the like is provided in the vicinity of the rotor R, and a detection signal is output from the rotation detector 1 according to the rotational position of the rotor R. The detection signal is input to the drive circuit 2, whereby the drive coils L1 and L2 are alternately excited. On the other hand, the ambient temperature of the fan motor is detected by the heat detection circuit 12, and a (detection output) voltage corresponding to this temperature is sent to the variable voltage circuit 11. The variable voltage circuit 11 changes the voltage applied to the drive coils L1 and L2 in accordance with the voltage from the heat detection circuit 12. The rotation speed of the fan motor is changed by this applied voltage.
[0003]
[Problems to be solved by the invention]
In the fan motor drive circuit configured as described above, when the voltage applied to the drive coils L1 and L2 decreases, the excitation current supplied to the drive coils L1 and L2 also decreases accordingly. For this reason, for example, even if the fan motor stops once due to a predetermined temperature condition and the power is turned on again when the fan motor tries to restart because the condition is removed, the applied voltage remains low. There is a problem that the starting torque is insufficient, and as a result, the fan motor does not restart or it takes time to reach a predetermined rotation.
[0004]
The present invention has been made to solve the above-mentioned problems existing in the prior art, and the problem is that when the rotational speed of the fan motor is variably controlled, the fan motor is restarted. It is an object of the present invention to provide a highly reliable fan motor drive device that can be reliably executed and can be driven smoothly.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a fan motor drive device according to the present invention comprises a drive means for sequentially exciting the drive coil in accordance with the rotational position of the rotor and a reverse of the drive coil in order to rotationally drive the rotor. Kickback voltage detection means for detecting an electromotive voltage and outputting a signal; and charge / discharge signal output means for outputting a signal at a predetermined cycle by charge / discharge based on the detection signal output from the kickback voltage detection means; A comparison means for comparing the output signal output from the charge / discharge signal output means with a rotation control signal for changing the rotor rotational speed to output an on / off signal; and excitation to the drive coil by the on / off signal. And a control means for controlling the current.
[0006]
According to the fan motor driving device of the present invention, it is desirable that the signal output from the charge / discharge signal output means has a cycle of an electrical angle of 180 degrees. The control means is provided between the drive coil and a positive voltage power source. The control means further includes a bypass circuit that bypasses the drive coil and the on / off signal. And a switching circuit for intermittently energizing the coil.
[0007]
According to the fan motor drive device of the present invention, the detection signal is output by the kickback voltage detection means using the back electromotive voltage generated in the drive coil by the rotation of the rotor, and this detection signal is the charge / discharge signal of the next stage. For example, the output unit outputs the signal as a predetermined signal having an electrical angle of 180 degrees. Then, the rotation control signal for changing the rotor rotational speed from the temperature detection means and the output signal from the charge / discharge output means are compared by the comparison means, and an on-off signal is thereby output. The excitation current of the drive coil is controlled by the control means based on this on / off signal, and thereby the rotor rotational speed of the fan motor is varied.
[0008]
In order to vary the rotor speed, the excitation to the drive coil is not due to a change in the voltage applied to the drive coil as in the prior art, but the time during which the excitation current flows to the drive coil, that is, the energization at an electrical angle of 180 degrees. The ratio is changed. This is because the energization ratio is changed by the control means being controlled by the on-off signal. Thereby, the starting failure at the time of restarting due to the drop of the starting torque is improved, the starting characteristics are improved, and the time for reaching the predetermined rotational speed is shortened.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A fan motor drive device according to the present invention will be described with reference to the accompanying drawings. 1 is a fan drive apparatus according to the first embodiment of the present invention, and FIG. 2 shows a specific circuit diagram of FIG. FIG. 5 is a timing chart showing the state of signal waveforms in each part of FIGS. In these drawings, the rotation detection circuit 1 (for example, the Hall element HE) provided in the vicinity of the rotor R has its output terminal connected to the drive circuit 2 (for example, the input side of the drive integrated circuit IC1). The output side of the drive circuit IC1 is connected to one end of each of the drive coils L1 and L2 for driving the rotor R to rotate.
[0010]
At the other end of each of the drive coils L1 and L2, there are a bypass circuit 4 (for example, a resistor R2) and a switching circuit 3 (for example, a transistor Q1 as a switching element) that control the drive coils L1 and L2. And they are connected to a power supply voltage (positive voltage power supply) Vcc. Accordingly, as is apparent from FIGS. 1 and 2, the drive coils L1 and L2 are subjected to two-phase unipolar energization by the drive circuit IC1, and with the output of the Hall element HE corresponding to the rotation of the rotor R, Currents IA and IB are alternately supplied to the drive coils L1 and L2. On the other hand, a kickback voltage detection circuit 5 (for example, by a combination of diodes D1, D2 and ZD1) is provided at each one end of the drive coils L1, L2, and this output unit is a charge / discharge circuit 6 (for example, the next stage). Connected to resistor 6, transistor Q2, resistor R5 and capacitor C1). The output of the charging / discharging circuit 6 is connected to the comparison circuit 7 (for example, the comparator IC2).
[0011]
By the way, in this embodiment, in order to vary the rotation speed of the fan motor, the rotation speed is varied according to the temperature change around the fan, and the heat detection circuit 8 (for example, the thermistor TH and resistor R4) provided in the vicinity of the fan. ). The output of the heat detection circuit 8 due to this temperature change is input to the comparison circuit 7. Thereafter, the comparison circuit 7 compares the output from the charge / discharge circuit 6 with the output from the heat detection circuit 8 (assuming a rotation control signal), and the output based on this is connected to the switching circuit 3.
[0012]
In the above configuration, the switching circuit 3 turns on and off the excitation current that is passed through the drive coils L1 and L2. The kickback voltage detection circuit 5 is a circuit that detects a signal by using a back electromotive (kickback) voltage generated in the drive coils L1 and L2 as the rotor R rotates. That is, due to the counter electromotive voltage, voltages having an electrical angle of 180 degrees shown in A and B of FIG. 5 appear alternately at one end A and B of each coil shown in FIGS. These signals are rectified by the diodes D1 and D2, and a signal indicated by C in FIG. 5 is output to the output terminal C of the Zener diode ZD1 by the Zener diode ZD1 commonly connected to the diodes D1 and D2.
[0013]
Based on the detection output of the kickback voltage detection circuit 5 (C in FIG. 5), the charge / discharge circuit 6 is intermittently connected by the switching operation of the transistor Q2, and accordingly, between the resistor R5 and the capacitor C1, Charging / discharging of the capacitor C1 is repeated. That is, as shown in FIG. 5D, a charging waveform is obtained which is discharged at the leading edge (waveform) having an electrical angle of 180 degrees and becomes the maximum voltage at the trailing edge (waveform), and this signal is sent to the comparison circuit 7 in the next stage. Sent.
[0014]
In the comparison circuit 7, the output signal from the charge / discharge circuit 6 is input to the negative input terminal of the comparator IC2, and the voltage change from the heat detection circuit 8 (thermistor TH), which is a rotation control signal, is input to one positive input terminal. Is entered. In the comparator IC2, when the charging waveform is lower than the voltage from the thermistor TH, the output of the comparator IC2 becomes high level. Conversely, when the charging waveform is higher than the voltage from the thermistor TH, the output of the comparator IC2 becomes low level. It becomes. Accordingly, a signal indicated by F in FIG. 5 is output to the output terminal of the comparator IC2 as a high / low level signal as an on / off signal. Note that when the ambient temperature rises, the voltage of the heat detection circuit 8 constituted by the thermistor TH decreases as indicated by a part E in D of FIG.
[0015]
The ON / OFF signal of the comparison circuit 7 is connected via the resistor 3 to the transistor Q1 of the switching circuit 3 serving as control means. That is, in response to the on / off signal of the comparison circuit 7, the transistor Q1 is turned off when the on / off signal is at a high level, and is turned on when the signal is at a low level. Appears like I in 5. As shown in I of FIG. 5, the excitation current is composed of a portion with a small current (rest time) and a portion with a large current in an electrical angle of 180 degrees. As shown in FIG. 6, when the rotational speed of the fan motor is low, the excitation current applied to the drive coils L1 and L2 is in the waveform state of FIG. 6A, and conversely when the rotational speed is high. Then, the waveform state of FIG.
[0016]
The energization of the excitation current to the drive coils L1 and L2 is provided at an electrical angle of 180 degrees, so that the energization ratio can be maximized within this range, and controllability is improved. . Since the switching circuit 3 for controlling the excitation current is provided between the drive coils L1 and L2 and the power supply voltage Vcc, the excitation current can be easily controlled and the circuit configuration can be simplified. Since the switching circuit 3 is provided with a bypass circuit 4, further improvements are made as follows.
[0017]
Next, in the bypass circuit 4, when the transistor Q1 (of the switching circuit 3) is off, a small current (bypass current) is supplied to the drive coils L1 and L2 through the resistor R2. By causing this bypass current to flow, for example, even if the transistor Q1 of the switching circuit 3 is in an off state at all portions of an electrical angle of 180 degrees, a kickback voltage can be generated for the drive coils L1 and L2. The charging / discharging circuit 6 can be easily charged and discharged, so that the charging waveform can be reliably generated at a cycle of an electrical angle of 180 degrees.
[0018]
Assuming that the bypass current does not flow, for example, when the rotation of the fan motor suddenly increases due to load fluctuation, the cycle of the electrical angle of 180 degrees is suddenly shortened. For this reason, during the rest period, that is, before the transistor Q1 (of the switching circuit 3) is turned from OFF to ON, the cycle of the electrical angle of 180 degrees is completed. Since the kickback voltage is generated when the excitation current energized in one (side) phase of the drive coils L1 and L2 is switched from on to off, the kickback voltage is generated before the excitation current flows through the drive coils L1 and L2. When the period of 180 degrees is finished, no kickback voltage is generated. For this reason, the charging waveform of the charging / discharging circuit 6 is not discharged, and the charging waveform output from the charging / discharging circuit 6 is disturbed. According to the configuration of the present invention, the bypass circuit 4 can realize a stable operation even when the rotational speed of the fan motor changes.
[0019]
In the bypass circuit 4, a resistor R2 is connected in parallel to the transistor Q1 as shown in the figure, and a Zener diode ZD2 can be used instead, as shown in FIG. Alternatively, although not shown, a configuration in which a resistor and a Zener diode are connected in series may be connected in parallel to the transistor Q1.
[0020]
The circuit configuration diagram of FIG. 3 shown below is a fan motor driving apparatus according to the second embodiment of the present invention, and FIG. 4 is a specific circuit diagram of FIG. In the first embodiment described above, the rotation control signal is obtained from the heat detection circuit 8 (thermistor TH) in order to vary the rotation speed of the fan motor. However, in the second embodiment, the outside of the fan motor is obtained. Is configured to receive a rotation control signal. Accordingly, other configurations are substantially the same as those of the first embodiment except for the change of the Zener diode ZD2.
[0021]
The rotation control signal for controlling the rotation of the fan motor uses the signal output from the detection means for detecting light, gas, etc., in addition to the heat detection circuit 8 such as the thermistor TH, thereby rotating the fan motor. The present invention can also be applied to a configuration to be controlled. In the drive device of the present invention, a fan having a two-phase drive coil is shown. However, the present invention can also be applied to a fan motor having a three-phase or more multi-phase drive coil.
[0022]
【The invention's effect】
The fan motor drive device according to the present invention has the above-described configuration. For example, even if the fan motor stops once with a predetermined temperature condition and the condition is removed, the power is turned on to restart. As a result, the starting torque is insufficient, and as a result, problems such as a case where the fan motor does not restart or a long time to reach a predetermined rotation are eliminated, and a highly reliable fan motor driving device is obtained. In order to control the excitation current, the signal from the charge / discharge signal output has a cycle of an electrical angle of 180 degrees, so that the variable range of the energization ratio of the excitation current can be maximized and the controllability can be improved. Further, since the bypass circuit 4 is provided in the switching circuit 3, a stable control operation is realized and the reliability is further improved.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of a fan motor driving apparatus according to a first embodiment of the present invention.
FIG. 2 is a specific circuit diagram of FIG. 1;
FIG. 3 is a circuit configuration diagram of a fan motor driving apparatus according to a second embodiment of the present invention.
4 is a specific circuit diagram of FIG. 3. FIG.
FIG. 5 is a timing chart of signal waveforms during operation according to the fan motor drive device of the present invention;
FIG. 6 is a timing chart of signal waveforms during operation according to the fan motor drive device of the present invention;
FIG. 7 is a circuit configuration diagram of a conventional fan motor driving device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotation detection circuit 2 Drive circuit 3 Switching circuit 4 Bypass circuit 5 Kickback voltage detection circuit 6 Charging / discharging circuit 7 Comparison circuit 8 Thermal detection circuit D1, D2, D3 Diode HE Hall element IC1 Driving integrated circuit IC2 Comparator L1, L2 Drive coil Q1, Q2 Transistor R Rotor R1, R2, R3 Resistance

Claims (3)

To rotate the rotor,
Drive means for sequentially exciting the drive coils in accordance with the rotational position of the rotor;
Kickback voltage detection means for detecting a back electromotive voltage of the drive coil and outputting a signal;
Based on the detection signal output from the kickback voltage detection means, charge / discharge signal output means for outputting a signal at a predetermined cycle by charge / discharge;
Comparing means for comparing the output signal output by the charge / discharge signal output means with the rotation control signal for varying the rotor rotational speed and outputting an on-off signal;
Control means for controlling the excitation current to the drive coil by the on-off signal;
Equipped with a,
The control means is provided between the drive coil and a positive voltage power source,
The control means includes a bypass circuit that bypasses energization of the drive coil and a switching circuit that intermittently energizes the drive coil by the on-off signal.
Drive device for fan motor. 2. The fan motor drive device according to claim 1, wherein the signal output from the charge / discharge signal output means has a cycle of an electrical angle of 180 degrees. 3. The fan motor drive device according to claim 1, wherein the rotation control signal is a signal output from a temperature detecting means.

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