JP4077990B2 - Brushless motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brushless motor control device that supplies power to an armature coil while sequentially switching the conduction state of a plurality of switching elements, and provides an overlapping time for simultaneously switching the switching elements to a conduction state at the time of switching. The present invention relates to a technique that allows a period to be set in accordance with the characteristics of a brushless motor and without using software.
[0002]
[Prior art]
Generally, in a brushless motor, the conduction state of a plurality of switching elements is sequentially switched by a microcomputer, and current supply to the armature coil is controlled. In order to prevent torque pulsation, control (referred to as overlap control) is performed so as to provide an overlapping time in which the switching elements to be switched are simultaneously turned on when switching the conduction state of each switching element.
[0003]
FIG. 8A is a configuration diagram of a conventional brushless motor control device for performing overlap control. When a rotation command is input, the microcomputer a is configured in each switching circuit b. Gate signals are sequentially supplied to the field effect transistors. The switching circuit b drives each field effect transistor with the supplied gate signal to energize and rotate the three-phase brushless motor body c. When the brushless motor main body c rotates, the magnetic sensor d disposed on the stator detects the rotor magnetic pole and feeds back the detection signal to the microcomputer a. The microcomputer a obtains the actual rotational speed and the overlap time data ta corresponding to the rotational speed from the returned detection signal.
[0004]
Then, the internal timer is operated from a predetermined current switching timing (for example, switching of the rotor magnetic pole in the detection signal), and at the same time, the timing of the gate signal that should be turned off is delayed, and the time corresponding to the overlap time data ta When the timer has elapsed, the timer is stopped and the delayed gate signal is turned off, thereby providing an overlap time (overlap time) in the on period of the transistors Q1 and Q2, for example, as shown in FIG. 8B.
[0005]
Therefore, the control for providing the overlapping time makes it possible to smoothly switch the energization current of the armature coil, prevent torque pulsation, and reduce noise due to resonance with the casing.
[0006]
[Problems to be solved by the invention]
However, in the conventional brushless motor control device, since the calculation of the rotation speed and the setting of the overlap time are performed by software, whenever the characteristics of the brushless motor change, the software is matched to the characteristics. You have to start development again. This development work includes the creation of a source program, the work of compiling the created source program and translating it into a machine language, the verification (debugging) work, and the like, leading to a prolonged development period. As a result, it has become difficult to answer the desire to shorten the development period.
[0007]
Therefore, the present invention has been made in view of the above-described conventional circumstances, and as its purpose, the overlapping time for switching the switching elements to be switched simultaneously when switching the switching elements at the same time without depending on software, An object of the present invention is to provide a brushless motor control device that can be set in accordance with the characteristics of the brushless motor.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, a brushless motor control device according to a first aspect of the present invention supplies power to an armature coil while sequentially switching the conduction state of a plurality of switching elements, and at the time of switching, the plurality of switching elements. In a brushless motor control device that provides an overlap time for simultaneously switching switching elements to be switched among elements, the change frequency of the rotor magnetic pole detected by the magnetic sensor of the brushless motor corresponds to the change frequency. A frequency voltage conversion circuit for converting the voltage into a voltage and a capacitor, and when the rotor magnetic pole detected by the magnetic sensor changes, charging of the capacitor starts, and the voltage of the capacitor is changed by the frequency voltage conversion circuit. When the overlap occurs based on the length of charge time to reach the converted voltage Characterized by comprising the overlap time setting circuit for setting the.
[0009]
In the brushless motor control device according to the first aspect of the present invention, the change frequency of the rotor magnetic pole detected by the magnetic sensor of the brushless motor is converted into a voltage corresponding to the change frequency by the frequency voltage conversion circuit, and the overlap time setting is performed. In the circuit, charging of the capacitor is started when the rotor magnetic pole detected by the magnetic sensor changes, and based on the length of charging time until the voltage of the capacitor reaches the voltage converted by the frequency voltage conversion circuit. Overlap time is set. The overlap time at that time is short at high rotation and long at low rotation, depending on the number of rotations. Then, by changing the capacitance of the capacitor, the voltage rise rate is adjusted to adjust the overlap time.
[0010]
A brushless motor control device according to a second aspect of the present invention is the brushless motor control device according to the first aspect, wherein the frequency-voltage conversion circuit includes an adjustment circuit for adjusting a conversion rate. .
[0011]
In the brushless motor control device according to the second aspect of the present invention, the conversion rate is varied by the adjustment circuit, and the magnitude of the voltage output from the frequency voltage conversion circuit is adjusted.
[0012]
The brushless motor control device according to a third aspect of the present invention is the brushless motor control device according to the first or second aspect, wherein the overlap time setting circuit charges the capacitor with a constant current source. It is characterized by being used.
[0013]
In the brushless motor control device according to the third aspect of the present invention, since the capacitor is charged by the constant current source, the voltage rise is linear.
[0014]
A brushless motor control device according to a fourth aspect of the present invention is the brushless motor control device according to the third aspect, wherein the constant current source has a current value for setting a current value of the constant current source. A setting circuit is added.
[0015]
In the brushless motor control device according to the fourth aspect of the present invention, the voltage increase rate of the capacitor during charging is adjusted by the current value setting circuit.
[0016]
According to a fifth aspect of the present invention, there is provided the brushless motor control device according to any one of the first to fourth aspects, wherein the overlap time setting circuit is used for charging the capacitor. The capacitor voltage is once lowered to a preset charging start voltage by discharging, and then charging is started.
[0017]
In the brushless motor control device according to the fifth aspect of the present invention, the length of the charging time is adjusted by adjusting the magnitude of the voltage for starting the charging of the capacitor by setting the charging start voltage.
[0018]
A brushless motor control device according to a sixth aspect of the present invention is the brushless motor control device according to any one of the first to fifth aspects, wherein the frequency-voltage conversion circuit has a preset rotational speed. A constant voltage is output in the region.
[0019]
In the brushless motor control device according to the sixth aspect of the present invention, by setting the rotation speed region in the frequency voltage conversion circuit, the length of the charging time is constant in the rotation speed region.
[0020]
【The invention's effect】
As described above, according to the brushless motor control device of the present invention according to claim 1, the frequency change circuit converts the change frequency of the rotor magnetic pole into the voltage, and the overlap time setting circuit changes the rotor magnetic pole. Since the overlap time is set based on the length of the charge time until the capacitor voltage that started charging reaches the converted voltage, the overlap time in the overlap control is not used by software. Can be set. In addition, by changing the capacitance of the capacitor, it is possible to adjust the overlap time according to the characteristics of the brushless motor.
[0021]
According to the brushless motor control device of the present invention according to claim 2, the overlap time can be adjusted by adjusting the conversion rate by the adjustment circuit and adjusting the magnitude of the voltage output from the frequency voltage conversion circuit. It becomes possible.
[0022]
According to the brushless motor control device of the present invention according to claim 3, since the capacitor is charged by the constant current source and the voltage rise becomes linear, linear overlap control that is easy to adjust is possible. Become.
[0023]
Further, according to the brushless motor control device of the present invention according to claim 4, since the voltage increase rate of the capacitor at the time of charging can be set by the current value setting circuit, there is an effect that it is possible to adjust the overlap time. can get.
[0024]
Further, according to the brushless motor control device of the present invention according to claim 5, by adjusting the length of the charging time by adjusting the magnitude of the voltage to start charging the capacitor by setting the charging start voltage. The overlap time can be adjusted.
[0025]
Further, according to the brushless motor control device of the present invention according to claim 6, by setting the rotation speed region in the frequency voltage conversion circuit, the length of the charging time is constant in the rotation speed region. The rotation of the brushless motor can be stabilized by keeping the overlap time constant at the time, before the rotation is stopped, or in the high rotation range.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a brushless motor according to the present invention will be described in detail with reference to FIGS.
[0027]
FIG. 1 is a diagram showing a first embodiment of a brushless motor control apparatus according to the present invention. The brushless motor 200 is used as a blower motor for an automobile air conditioner, and includes a motor body 10, a switching circuit 20 for energizing armature coils 4a to 4f disposed in the motor body 10, a custom IC 100, and a custom IC. The rotor 100 (not shown) of the motor main body 10 is rotated at the indicated rotation speed indicated by the rotation instruction signal Vin from the auto amplifier.
[0028]
Here, the custom IC 100 is a circuit in which circuits shared by various motors are integrated and accommodated in a dedicated package, and the dedicated package is provided with terminals for connecting peripheral circuits.
[0029]
The switching circuit 20 includes field effect transistors (hereinafter simply referred to as transistors) Q1 to Q6 and resistors R1 to R6 connected in series to the gates of the respective transistors. Transistors Q1, Q2 and Q3 have their drain terminals connected to a power supply (DC power supply), while transistors Q4, Q5 and Q6 have their source terminals grounded. The source of transistor Q1 and the drain of Q4, the source of Q2 and the drain of Q5, the source of Q3 and the drain of Q6 are connected as a U point, a V point, and a W point, respectively.
[0030]
The switching circuit 20 receives the gate signal generated by the drive control circuit 70 based on the rotation instruction signal Vin via the terminals T71 to T76, and switches the current from the power source, thereby switching the U point, V point, W Current is supplied to the armature coils 4a to 4f of the motor body 10 through the points.
[0031]
The magnetic sensors IC <b> 1 to IC <b> 3 detect the magnetic pole of the sensor magnet (rotor magnetic pole) 5 formed in the motor main body 10, and in accordance with the rotation operation, a pulse shape corresponding to the polarity of the magnetic pole or a non-inverted sine wave Magnetic sensor signals S1L, S2L, and S3L and inverted magnetic sensor signals S1H, S2H, and S3H in which the on / off periods of these signals are inverted are respectively generated, and are supplied to a sensor input circuit 30 to be described later via terminals T31 to T36. Send it out.
[0032]
The custom IC 100 and its peripheral circuits shown in this figure are a sensor input circuit 30, a clock generation circuit 40, a three-phase control circuit 50, an overlap addition circuit 60, a drive control circuit 70, an F / V conversion circuit 80, and an OB timer circuit 90. Thus, by performing overlap control using these circuits, appropriate torque control of the brushless motor 200 is performed.
[0033]
The sensor input circuit 30 includes comparators 30a to 30c having hysteresis characteristics, and inputs the non-inverted magnetic sensor signals S1L, S2L, and S3L to the non-inverted input terminals via the terminals T31, T32, and T33, respectively. The inverted magnetic sensor signals S1H, S2H, and S3H are input to the terminals via terminals T34, T35, and T36, respectively. The outputs of the comparators 30a to 30c are sent to the clock generation circuit 40 and the three-phase control circuit 50 as signals S1, S2, and S3, respectively.
[0034]
Based on the signals S1, S2, and S3 output from the sensor input circuit 30, the clock generation circuit 40 continuously outputs a control clock (CKM) at a repetition period corresponding to an electrical angle of 30 degrees (1/12 rotation). To do. Then, in response to a signal from an OB timer circuit 90 described later, a charging signal CHG is output. The control clock signal CKM and the charging signal CHG function as a trigger signal for closing or opening the opening / closing circuit SW1 of the OB timer circuit 90.
[0035]
The three-phase control circuit 50 receives the signals S1, S2, and S3 and uses the internal logic circuit to generate a gate signal, and the signals G1, G2, and G3 having an on time corresponding to an electrical angle of 60 degrees are generated. , G4, G5, G6 (corresponding to transistors Q1, Q2, Q3, Q4, Q5, and Q6, respectively) are generated and sent to the overlap adder circuit 60. The overlap addition circuit 60 performs an overlap addition process described later on these signals and supplies the signals to the drive control circuit 70.
[0036]
The drive control circuit 70 controls the pulse width of the output signals G1 to G6 of the overlap adding circuit 60 at a higher frequency based on the rotation instruction signal Vin given from the auto amplifier via the terminal T77, and A gate signal is supplied to each transistor.
[0037]
The F / V conversion circuit 80 is a circuit that generates a signal FV1 obtained by converting the magnetic pole change frequency of the sensor magnet 5 detected by the magnetic sensors IC1 to IC3 into a voltage, and includes a comparator 80a, operational amplifiers 80b and 80c in the custom IC 100. It has. The comparator 80a inputs a sawtooth signal OSC whose frequency changes with a change in the magnetic pole of the sensor magnet 5 to its inverting input terminal, and compares it with a DC reference voltage REF input to a non-inverting input terminal. This is for outputting a wave pulse signal.
[0038]
The output terminal of the comparator 80a is connected to the terminal T81 via the resistor R81, and the positive terminal of the capacitor C81 whose negative electrode is grounded outside the custom IC 100 is connected to the terminal T81. The resistor R81 and the capacitor C81 are provided to smooth the output signal of the comparator 80a. Then, the F / V conversion circuit 80 inputs the smoothed voltage to the non-inverting input terminal of the operational amplifier 80b. The operational amplifier 80b constitutes a buffer circuit by connecting its output terminal and inverting input terminal.
[0039]
The output terminal of the operational amplifier 80b is connected to the terminal T82, the resistor R82 is connected between the terminals T82 and T83, and the terminal T83 is connected to the inverting input terminal of the operational amplifier 80c. The signal is input to the inverting input terminal of the operational amplifier 80c.
[0040]
On the other hand, the bias voltage Vb is applied to the non-inverting input terminal of the operational amplifier 80c via the terminal T84. A feedback resistor R83 is connected between the terminal T85 to which the output terminal of the operational amplifier 80c is connected and the terminal T83. With such a configuration, by causing the operational amplifier 80c to function as an inverting amplifier, a DC signal FV1 that generates a lower voltage as the actual motor rotation speed becomes higher is generated.
[0041]
The OB timer circuit 90 generates an overlap time setting signal OBR having a pulse width corresponding to the overlap time by using a capacitor charging / discharging operation. The OB timer circuit 90 includes a Min / Max limiting circuit 90a, comparators 90b and 90c, a constant current source IS1 and an open / close circuit SW1 inside a custom IC, and on the outside, a positive electrode is connected to a terminal T93 and a negative electrode is connected. A capacitor C91 to be grounded and a resistor R91 externally connected via a terminal T95 are provided.
[0042]
The Min / Max limiting circuit 90a receives the signal FV1 from the F / V conversion circuit 80, limits this to the range of voltages Vmax and Vmin input via the terminals T91 and T92, and generates the signal FV2. And sent to the non-inverting input terminal of the comparator 90b. On the other hand, the non-inverting input terminal of the comparator 90c is connected to the inverting input terminal of the comparator 90b, and in addition, the terminal T93 to which the positive electrode of the capacitor C91 is connected is connected. Further, a constant current source IS1 is connected to the terminal T93 via the switching circuit SW1, thereby enabling a constant current supply to the capacitor C91.
[0043]
The charging start voltage Vinob is input to the inverting input terminal of the comparator 90c through the terminal T94. Note that the current value of the constant current source IS1 can be changed by the resistance value of the resistor R91 externally attached via the terminal T95. In this embodiment, the output signal of the comparator 90b is referred to as an overlap time setting signal OBR, and the ON time is referred to as an overlap time.
[0044]
FIG. 2 is a cross-sectional view of the motor body 10 with respect to the rotation axis direction. The motor main body 10 has an outer rotor type structure including a three-phase armature coil, and the inner peripheral side stator 3 shown in the figure is formed with six protruding portions 3a to 3f in a radial manner. Armature coils 4 (4a to 4f) are arranged with the protruding portion as a core. A cylindrical rotor 1 provided with main magnets 2 (field permanent magnets) is arranged outside the stator 3 at intervals of 90 degrees in the circumferential direction.
[0045]
Also, the sensor magnet 5 shown in this figure is formed with two N poles and two S poles alternately magnetized at equal angles, and is attached to a shaft 6 that rotates integrally with the rotor 1, so that the rotor magnetic poles Is configured. Magnetic sensors IC <b> 1 to IC <b> 3 that detect the magnetic poles of the sensor magnet 5 are evenly arranged on the inner periphery of the stator 3 with an angle of 120 degrees.
[0046]
An alternating current is supplied from the switching circuit 2 to the armature coil 4 (4a to 4f) configured as described above, and the magnetic force generated from the armature coil 4 and the attractive force / repulsive force of the main magnet 2 are used. The rotor 1 is driven to rotate.
[0047]
3A is a timing chart when the overlap control is not performed in the brushless motor 200, and FIG. 3B is a connection between the transistors Q1 to Q6 and the armature coils 4a to 4f shown in FIG. The relationship is modeled for convenience of explanation.
[0048]
Since the sensor magnet 5 is magnetized with two N poles and two S poles alternately, the non-inverted magnetic sensor signals S1L, S2L, and S3L from the magnetic sensors IC1 to IC3 are detected during one rotation of the rotor 1. Changes for two cycles. Although not shown in the figure, the non-inverted magnetic sensor signals S1H, S2H, and S3H are in the on / off state opposite to the non-inverted magnetic sensor signals.
[0049]
The sensor input circuit 30 generates signals S1, S2, and S3 from the magnetic sensor signals (six signals) and sends them to the three-phase control circuit 50. The three-phase control circuit 50 uses an internal logic circuit, Signals G <b> 1 to G <b> 6 having an on time corresponding to an electrical angle of 60 degrees are generated and sent to the drive control circuit 70 via the overlap addition circuit 60. In the sensor input circuit 30, since the comparators 30a to 30c have hysteresis characteristics, it is possible to prevent the noise superimposed on the magnetic sensor signal and the influence of chattering.
[0050]
The drive control circuit 70 generates a gate signal that repeats ON / OFF at a higher frequency during the ON time by pulse width control based on the input rotation instruction signal Vin, and supplies the gate signal to the switching circuit 20. Although this gate signal is shown in FIG. 5A, the high-frequency on / off waveform is omitted, and therefore the timing is substantially the same as that of the signals G1 to G6.
[0051]
Therefore, based on the magnetic sensor signals (6 signals) from the magnetic sensors IC1 to IC3, the combinations of transistors that are turned on are sequentially switched to energize the armature coils 4a to 4f to generate a rotating magnetic field. Further, as shown in FIG. 5A, when overlap control is not performed, switching control of the gate signal is performed so that the power supply side transistors Q1 to Q3 and the ground side transistors Q4 to Q6 are turned on one by one. Has been done.
[0052]
Next, the operation of the brushless motor control device of the present embodiment will be described.
[0053]
In this embodiment, by using the overlap time setting signal OBR from the OB timer circuit 90, the overlap addition circuit 60 performs an overlap process for providing an overlap time at the switching portion of the gate signal, thereby generating a pulsation of torque. In addition, resonance with the casing and vibration noise are prevented.
[0054]
First, in the F / V conversion circuit 80 shown in FIG. 1, the signal FV1 is generated as follows. That is, the comparator 80a generates a square wave pulse signal that is turned on for a fixed time every electrical angle 30 degrees from the sawtooth signal OSC that outputs a sawtooth pulse for a fixed time every electrical angle 30 degrees and the voltage ref. This is smoothed by a smoothing circuit formed by a resistor R81 and a capacitor C81, and a DC voltage that becomes higher as the engine speed is higher is obtained.
[0055]
The DC voltage is inverted and amplified by the operational amplifier 80c via the operational amplifier 80b as a buffer. Therefore, the amplified signal FV1 (DC signal) shows a lower voltage during high-speed rotation and a higher voltage during low-speed rotation. Then, the signal FV1 is sent to the OB timer circuit 90.
[0056]
FIG. 4 is a waveform diagram of the clock generation circuit 40 and the OB timer circuit 90.
Based on the signals S1, S2, S3 output from the sensor input circuit 30, the clock generation circuit 40 outputs a control clock (CKM) at a repetition period corresponding to an electrical angle of 30 degrees. In response to the rise of the control clock signal CKM, the switching circuit SW1 is opened, and the OB timer circuit 90 starts discharging the capacitor C91 by a discharge circuit (not shown).
[0057]
When the voltage Vc91 of the capacitor C91 becomes lower than the signal FV2, the output of the comparator 90b, that is, the overlap setting time signal OBR is inverted to the high voltage level. When the voltage Vc91 becomes lower than the charging start voltage Vinob, the output of the comparator 90c is inverted to the low voltage level.
[0058]
In response to the output inversion of the comparator 90c, the clock generation circuit 40 sends out the charging signal CHG, closes the switching circuit SW1, forms a charging path, and starts charging the capacitor C91 by the constant current source IS1. That is, charging is started after the voltage of the capacitor C91 is once lowered to the charging start voltage Vinob by discharging.
[0059]
The OB timer circuit 90 inverts the output of the comparator 90b (overlap time setting signal OBR) to a low voltage level when the voltage Vc91 of the capacitor C91 rises and exceeds the voltage level of the signal FV2. As described above, since the signal FV2 is lower at high speed rotation and higher at low speed rotation, the pulse width of the overlap time setting signal OBR is shorter at high speed rotation and longer at low speed rotation. Thereafter, the OB timer circuit 90 opens the switching circuit SW1 in response to the next rise of the control clock signal CKM, and discharges the capacitor C91 again.
[0060]
In this way, the overlap time setting signal OBR shown in FIG. Since the signal FV2 is limited by the Min / Max limiting circuit 90a so as to be equal to or lower than the voltage Vmax and equal to or higher than the voltage Vmin, the overlap time is within the range indicated by the diagonal lines in FIG. It is variable.
[0061]
Further, since the capacitor C91 is charged from the constant current source IS1, the voltage rise is linear, facilitating overlap control.
[0062]
FIG. 5 is a diagram for explaining the processing in the overlap addition circuit 60. The overlap addition circuit 60 performs overlap addition processing for providing an overlap time (overlap time) at the gate signal switching portion using the overlap time setting signal OBR generated by the OB timer circuit 90. In the three-phase control circuit 50, signals G1 to G6 having an ON period corresponding to an electrical angle of 60 degrees are generated from the signals S1, S2, and S3 and are input to the overlap adding circuit 60.
[0063]
This figure (a) shows the energization state in a certain electrical angle 30 degree period (1st period). In this period, the transistors Q1 and Q5 are turned on, and the power supply voltage is applied between the connection point U and the connection point V. FIG. 6C shows the energization state in the electrical angle 30 degree period (second period) next to the first period. In this period, the transistors Q3 and Q5 are turned on and connected to the connection point W. A power supply voltage is applied between the point V and the point V.
[0064]
Then, when switching from the first period to the second period by the overlap addition process by the overlap addition circuit 60, both the transistors Q1 and Q3 are turned on for the overlap time as shown in FIG. Energization is performed with both connection points U and W on the power source side. Accordingly, during this period, no current flows between the U point and the W point, so that a rapid change in torque is mitigated, and vibration noise and resonance can be prevented. In this embodiment, an overlap time is also provided at the switching portion of the gate signal to the transistor on the ground side, thereby enabling more fine torque control.
[0065]
FIG. 6 is a timing chart of each part in the present embodiment.
In contrast to the signals S1, S2, and S3 shown in the figure, the overlap time setting signal OBR is turned on when any of the signals is inverted, and is turned off after being kept on for the overlap time.
[0066]
In the overlap adding circuit 60, the overlap time of the overlap time setting signal OBR is added to the signals G1 to G6 from the three-phase control circuit 50 to delay the falling timing of each gate signal as shown in this figure. On the other hand, the rising timing is kept when the overlap control is not performed. Therefore, an overlap time (overlap time) can be provided in the switching portion of the gate signal. The gate signal is supplied to the transistors Q1 to Q6 of the switching circuit 20, and the transistors Q1 to Q6 pass current through the armature coil to rotate the rotor 1.
[0067]
FIG. 7 shows the change of the overlap time with respect to the rotation speed in this embodiment. As shown in the figure, in the “overlap MAX region” below the increase / decrease point (number of revolutions) A set by the voltage Vmax input to the Min / Max limiting circuit 90a, the overlap time becomes maximum and the transistor is turned on / off Control. As a result, it is possible to prevent resonance or the like that easily occurs during a period in which the rotation speed is not stable, such as when the motor is started.
[0068]
In the “overlap variable region” from the increase / decrease point A to the increase / decrease point B set by the voltage Vmin, the signal FV2 can be changed, so that the overlap time can be changed as shown in FIG. The lap time is smoothly changed from the maximum to the minimum according to the increase in the rotation speed, and the rotation torque is changed due to a sudden change in the overlap time, thereby preventing the rotation unevenness. In the “overlap MIN region” above the increase / decrease point B, since the signal FV2 is constant at the minimum voltage even when the rotational speed increases, control is performed to keep the overlap time constant.
[0069]
As is apparent from the above description, in this embodiment, the configuration shown in FIG. 1 is used to perform the overlap control of the brushless motor without software control, and to generate torque pulsation, vibration noise, or resonance. Can be prevented.
[0070]
Further, by changing the capacity of the external capacitor C91, it is possible to adjust the overlap time as a whole short or long.
[0071]
Then, by varying the resistor R82 or R83 and varying the amplification factor of the operational amplifier 80c, the voltage variable range of the signal FV1 (the same applies to the signal FV2) in the operating rotation range is adjusted, and the overlap time is adjusted. Is possible.
[0072]
It is also possible to adjust the overlap time by adjusting the resistance value of the resistor R91 externally attached to the custom IC and changing the rate of increase of the charging voltage. The resistor R91 is used as a terminal of the custom IC 100. Since it is externally attached, it is very easy to change the setting.
[0073]
On the other hand, the charge start voltage can be adjusted by changing the setting of the charge start voltage Vinob. That is, if this is set to a high voltage, the voltage of the signal FV2 can be reached in a short time from the start of charging, and conversely, if it is set to a low voltage, the time to reach can be lengthened. Note that the voltage Vmax and the voltage Vmin are preferably set to be equal to or higher than the charging start voltage Vinob.
[0074]
With such a circuit configuration having a high degree of freedom of setting, it is possible to adjust overlap control according to the characteristics of various brushless motors.
[0075]
Further, since the capacitor C91 is charged using the constant current source IS1, the voltage rise becomes linear, and there is an effect that linear overlap control that is easy to adjust is possible.
[0076]
Further, by providing the Min / Max limiting circuit 90a and limiting the signal FV1 by the external signals Vmax and Vmin, a minimum overlap time can be ensured even near the upper limit of the used rotation range, On the other hand, it is possible to prevent the overlap time from becoming longer than necessary at the time of starting or before stopping the rotation. In addition, the signals Vmax and Vmin can be adjusted according to the characteristics of the motor by a resistor voltage dividing circuit or the like.
[0077]
The addition processing in the overlap addition circuit 60 may be performed after correcting the overlap time defined by the overlap time setting signal OBR.
[0078]
The brushless motor control device according to the present invention is not limited to the blower motor described in the above embodiment, and can be applied to various brushless motors such as a radiator motor.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first embodiment of a brushless motor control device according to the present invention;
FIG. 2 is a diagram showing a configuration of a motor main body in the form shown in FIG.
3A is a timing chart when the overlap control is not performed in the embodiment shown in FIG. 1, and FIG. 3B is a connection diagram of an armature coil and a transistor.
4 is a waveform diagram of a clock generation circuit and an OB timer circuit in the form shown in FIG. 1. FIG.
FIG. 5 is a diagram for explaining overlap addition processing in the embodiment shown in FIG. 1;
6 is a timing chart of each part in the embodiment shown in FIG.
7 is a diagram showing a change in overlap time with respect to the rotational speed in the embodiment shown in FIG. 1; FIG.
FIG. 8 is a configuration diagram (a) of a conventional brushless motor control device and an explanatory diagram (b) of overlap control.
[Explanation of symbols]
10 Motor body
20 Switching circuit
30 Sensor input circuit
40 Clock generation circuit
50 Three-phase control circuit
60 Overlap addition circuit
70 Drive control circuit
80 F / V conversion circuit
90 OB timer circuit
100 Custom IC
200 brushless motor

Claims (6)

A brushless motor that supplies power to the armature coil while sequentially switching the conduction states of a plurality of switching elements, and provides an overlapping time during which the switching elements to be switched among the plurality of switching elements are simultaneously turned on. In the control device of
A frequency voltage conversion circuit (80) for converting the change frequency of the rotor magnetic pole (5) detected by the magnetic sensors (IC1 to IC3) of the brushless motor (200) into a voltage corresponding to the change frequency;
When the rotor magnetic pole (5) detected by the magnetic sensors (IC1 to IC3) changes, the capacitor (C91) starts to be charged, and the voltage of the capacitor (C91) An overlap time setting circuit (90) for setting the overlap time based on the length of charging time until the voltage converted by the frequency voltage conversion circuit (80) is reached. Control device. The brushless motor control device according to claim 1, wherein the frequency-voltage conversion circuit (80) includes an adjustment circuit (R82, R83) for adjusting a conversion rate. The brushless motor control device according to claim 1 or 2, wherein the overlap time setting circuit (90) charges the capacitor (C91) using a constant current source (IS1). The brushless motor according to claim 3, wherein a current value setting circuit (R91) for setting a current value of the constant current source (IS1) is added to the constant current source (IS1). Control device. When the capacitor (C91) is charged, the overlap time setting circuit (90) starts charging after the voltage of the capacitor (C91) is once lowered to a preset charging start voltage by discharging. The brushless motor control device according to any one of claims 1 to 4, wherein: The brushless motor control device according to any one of claims 1 to 5, wherein the frequency voltage conversion circuit (80, 90a) outputs a constant voltage in a preset rotation speed range.

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