JP2010035410A - Motor control apparatus, and motor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control apparatus which can appropriately protect a motor from overvoltage, even when a brushless DC motor is to be drive-controlled. <P>SOLUTION: A control circuit 5 carries out starting control on the brushless DC motor 1, wherein, the brushless DC motor is subjected to initial excitation and then to forced commutation, without having to determine the rotation state of the brushless DC motor, when a hunting state is detected in a way that an overvoltage state of driving power source voltage is detected by a comparator 15; the overvoltage state is eliminated by carrying out the forced commutation of the brushless DC motor 1; the overvoltage state causing protective operation against the overvoltage to be carried out is detected again, immediately thereafter; these phenomena are repeated in a predetermined period; and when the brushless DC motor 1 receives a starting signal during the detection of the hunting state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device that drives and controls a brushless DC motor, and a motor control method.

Patent Document 1 discloses a technology for consuming overvoltage energy by forcibly commutating a motor in order to protect the overpower applied to a power supply terminal in an apparatus for driving and controlling a brushless DC motor. . However, Patent Document 1 is premised on a configuration in which a motor is driven using a position sensor.
Further, the applicant has proposed in Japanese Patent Application No. 2007-135450 a technique for forcibly commutating a motor in order to perform overvoltage protection in a configuration in which a brushless DC motor is driven and controlled by a position sensorless system. According to these techniques, a protective element such as a Zener diode for clamping an overvoltage can be eliminated.

JP 2000-69786 A

  However, when driving and controlling a brushless DC motor by the position sensorless method, it is advantageous in terms of efficiency, quietness, etc. to change the starting method between when the motor is stopped and when it is rotating. Sometimes it is necessary to determine whether the motor is rotating. For this reason, particularly when the rotation of the motor is low speed, it takes time to detect the rotation, and accordingly, it takes a certain amount of time to shift to the starting operation. Therefore, even if the overvoltage state is resolved by the prior art, if the overvoltage state is entered again before the time required for the start-up operation elapses, the conventional overvoltage protection function is not provided even if the start signal is received. You will work first. Therefore, even if the overvoltage state is eliminated, the motor cannot be started if the overvoltage state is repeated many times in a short time.

Further, even if the overvoltage state is eliminated, a factor that causes the overvoltage state many times in a short time includes, for example, an increase in the terminal voltage of the smoothing aluminum electrolytic capacitor due to the application of a high frequency pulse. When a brushless DC motor is used in this cooling system, cooling becomes insufficient if the motor cannot be driven due to the above problems.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a motor control device and a motor control method capable of appropriately performing an overvoltage protection operation when driving and controlling a brushless DC motor.

  According to the motor control device of the first aspect, the hunting state detecting means detects the overvoltage state of the driving power supply voltage by the overvoltage detecting means, and the overvoltage protection means forcibly commutates the brushless DC motor to thereby set the overvoltage state. Even if the state is resolved, a hunting state in which an overvoltage state is detected again immediately afterward and a state in which the overvoltage protection means is activated repeatedly occurs within a predetermined time is detected. When the motor receives a start signal during detection of the hunting state, the control means performs start control so that the motor is initially excited and then forcedly commutated without determining the rotation state of the motor.

  In other words, if overvoltage energy accumulates immediately, even if the motor is forced to commutate temporarily in the case of an overvoltage condition, it will take time to start the next motor. Then, a hunting state in which the overvoltage state is detected again and the protection operation is repeated is generated. Therefore, in the present invention, when a start signal is received during detection of a hunting state, start control is performed so as to perform forced commutation after initial excitation without determining the rotation state of the motor, thereby shortening the time required for start. Can start the motor correctly.

  According to the motor control device of the second aspect, when the control means receives the motor start signal during the detection of the hunting state, the control means first determines the rotational state of the motor once and controls the start. That is, depending on the type of load that is a target for transmitting the driving force of the motor, it may be assumed that the motor is rotating at a certain speed due to the external force when the activation signal is received. Under such circumstances, it is possible to determine the rotation state of the motor within a short time, so that the hunting state can be released and the motor can be started.

  According to the motor control device of the third aspect, when the control means starts the determination of the rotation state of the motor upon receiving the motor start signal, the control means performs the determination only within a predetermined time from that point. That is, since it is assumed that the rotation state of the motor at the time of receiving the activation signal is variously different, if the determination result is not obtained within a short time, the hunting state may continue. Therefore, by giving a limit to the time for determining the rotation state, it is possible to perform start-up control from initial excitation to forced commutation when the determination result cannot be obtained within a short time.

  According to the motor control device of the fourth aspect, when the control means receives the start signal and starts determining the rotational state of the motor, the voltage level of the driving power source detected by the voltage level detection means is a predetermined upper limit. Judgment is made before the value is reached. That is, as described in claim 3, since it is assumed that the rotation state of the motor at the time of receiving the start signal is variously different, the voltage level of the driving power supply is monitored by the voltage level detecting means. It is possible to increase the possibility of performing normal start-up control by performing the determination up to the stage immediately before the voltage level reaches the upper limit and the hunting state may continue.

  According to the motor control device of the fifth aspect, the hunting state detecting means operates in the same manner as the first aspect. Then, the threshold value changing means changes the threshold voltage for determination of the overvoltage detection means so that the period during which the overvoltage protection means operates during the detection of the hunting state is made longer. If the overvoltage determination threshold value is changed, the time until the overvoltage state is detected changes accordingly, so that it is possible to secure a longer time to start the motor due to the time change.

  According to the motor control device of the sixth aspect, the threshold value changing means increases the degree of change of the threshold voltage as the period in which the hunting state is detected becomes longer. You can make the grace period longer.

  According to the motor control device of the seventh aspect, since the threshold value changing means lowers the threshold voltage for determining that the overvoltage state has been eliminated, the overvoltage energy is increased by extending the period during which the overvoltage protection operation is performed. More can be consumed. Therefore, even if energy is stored again, it is possible to lengthen the time until the overvoltage state is detected again, and to secure the time for starting the motor, thereby appropriately eliminating the overvoltage state.

  According to the motor control device of the eighth aspect, the timer constituting the hunting state detection means is a time period from when the overvoltage state is first detected until the operation of the overvoltage protection means corresponding to the detection stops. While counting the time T, the time Ts during which the operation of the overvoltage protection means is stopped is counted. When the overvoltage state is detected again before the time Ts and the predetermined reset time Treset become Ts> Treset, the time T is continuously counted, and before the overvoltage state is detected again, Ts> Treset. In this case, the operation is stopped by resetting the time T, and when the time T exceeds the threshold Tth, the occurrence of the hunting state is detected. That is, when the hunting state occurs, the overvoltage protection operation is repeated at a relatively short interval, so that the occurrence of the hunting state can be reliably detected by the action of the timer.

  According to the motor control device of the ninth aspect, the hunting state detection means includes a counter that counts the number N of times that the overvoltage state is detected, a timer that counts the interval Tint at which the overvoltage state is detected, and a timer that counts the time. Comparing means for comparing the set interval Tint with a predetermined reset time Treset. When the comparison result by the comparison means becomes Tint> Treset, the counter is cleared to zero, and when the counter value N exceeds the threshold value Nth, the occurrence of the hunting state is detected.

  As described above, when the hunting state occurs, the detection of the overvoltage state is repeated at a relatively short interval. Therefore, when the interval Tint is short, the detection number counter N is incremented, and when the interval Tint is long, it is cleared to zero. Thus, if the counter value N is equal to or greater than the threshold value Nth, the occurrence of the hunting state can be reliably detected.

1 is a diagram illustrating a schematic configuration of a motor control device according to a first embodiment of the present invention. FIG. Flow chart showing processing when control circuit receives motor start signal Flow chart showing processing for realizing the timer function The figure which shows the output state (a) of the overvoltage detection signal when a hunting generate | occur | produces, and the change (b) of a power supply voltage Flow chart showing contents of overvoltage protection operation in prior application 7 is a flowchart showing a process of realizing a counter function by the control circuit according to the second embodiment of the present invention. 4 equivalent figure FIG. 1 equivalent view showing a third embodiment of the present invention. 2 equivalent diagram 4 equivalent figure FIG. 1 equivalent view showing a fourth embodiment of the present invention. Fig. 9 equivalent Figure 10 equivalent FIG. 2 equivalent diagram showing a fifth embodiment of the present invention. FIG. 2 equivalent diagram showing a sixth embodiment of the present invention. FIG. 1 equivalent view showing a seventh embodiment of the present invention 2 equivalent diagram FIG. 2 and FIG. 3 equivalent view showing an eighth embodiment of the present invention FIG. 6 equivalent view showing the ninth embodiment of the present invention.

(First embodiment)
A first embodiment in which the present invention is applied to an apparatus for driving and controlling a vehicle fan motor mounted on a vehicle, for example, will be described below with reference to FIGS. FIG. 1 shows a schematic configuration of a motor control device. The brushless DC motor 1 is driven via an inverter circuit 2. The inverter circuit 2 is configured by connecting, for example, six power MOSFETs 3a to 3f in a three-phase bridge, and each phase output terminal of the inverter circuit 2 is connected to each phase stator coil 4U, 4V, 4W of the motor 1, respectively. Has been.

  The inverter circuit 2 is controlled by a control circuit (overvoltage protection means, hunting state detection means, control means) 5 composed of a microcomputer or a logic circuit, and a drive signal is supplied to the gate of each FET 3 via a gate driver circuit 6. Is output. The rotor rotational position of the motor 1 is detected by a low-pass filter composed of a capacitor C and a resistor R, a position detection circuit 7 composed of a comparator, etc., and the position signal is given to a control circuit 5 (for example, JP 2006-158022).

  The position detection circuit 7 compares each phase induced voltage of the inverter circuit 2 output through the low-pass filter with a virtual neutral point potential by a comparator, thereby outputting a rectangular wave-shaped rotor rotation position signal. The control circuit 5 includes a timer 8 (by software) and a memory 9 inside, and PWM for determining the rotation speed of the motor 1 in accordance with a control signal supplied from an external ECU (Electronic Control Unit) (not shown). Set the duty. At the same time, the control circuit 5 determines the commutation timing based on the position signal given from the position detection circuit 7, and outputs the drive signal to the gate driver circuit 6 when it generates the drive signal.

The inverter circuit 2 is supplied with a battery + B power (for example, 12V) via a π-type filter 13 including a coil 10 and capacitors 11 and 12 connected between both ends of the coil 10 and the ground. Yes. A series circuit of resistance elements 14 a and 14 b is connected between the common connection point of the coil 10 and the capacitor 12 and the ground, and the common connection point is a non-inverting input terminal of the comparator (overvoltage detection means) 15. It is connected to the.
In addition, a series circuit of resistance elements 16 and 17, an NPN transistor 18 (Tr1), and a resistance element 19 is connected between a predetermined reference voltage and the ground. The common connection point of the resistance elements 16 and 17 is It is connected to the inverting input terminal of the comparator 15. The output terminal of the comparator 15 is connected to the input terminal of the control circuit 5 and to the base of the transistor 18.

  The inverting input terminal of the comparator 15 is supplied with a threshold voltage Vth_H (for example, corresponding to a detection voltage of 30 V) for performing overvoltage detection in a state where the transistor 18 is off. In this case, the reference voltage is applied (overvoltage detection). Decision threshold). The comparator 15 outputs an overvoltage detection signal to the control circuit 5 when detecting that an overvoltage is applied to the positive power supply terminal of the inverter circuit 2 by comparison with the threshold voltage. At that time, when the transistor 18 is turned on, the potential of the inverting input terminal is divided by dividing the reference voltage by the resistance elements 16, 17, 19 and the threshold voltage is Vth_L (for example, corresponding to the detection voltage 25V, overvoltage protection return determination) Hysteresis characteristics are given so as to decrease to (threshold) (see FIG. 4). Note that the surge shown in FIG. 4 is due to electric charges accumulated in an aluminum capacitor (not shown).

  When the application of the overvoltage is detected by the comparator 15, the control circuit 5 performs an overvoltage protection operation using the technique proposed in Japanese Patent Application No. 2007-135450. That is, as shown in FIG. 5, the position sensorless driving method (rotational speed control) is executed in the normal operation state after the motor 1 is started (step S101), and if an overvoltage is detected (step S102: YES), the rotational position signal Based on the rotational speed at that time, which is grasped more, the drive system of the motor 1 is switched to the forced energization system (step S103). In this case, the PWM duty is set to 100%.

  When the overvoltage level decreases due to forced energization and falls below the protection return determination threshold Vth_L determined to tend to return to the normal level (step S104: YES), the comparator 15 stops the output of the overvoltage detection signal, and the control circuit 5 outputs a drive signal in accordance with it. While the predetermined time α elapses from that point (step S105), the number of rotations of the motor 1 is grasped. If overvoltage is not detected again before the predetermined time α elapses (step S106: NO), the process proceeds to step S101 to return to the sensorless drive system again. On the other hand, if overvoltage detection is performed again before the predetermined time α elapses (step S106: YES), the process returns to step S103, and forced energization based on the rotation speed of the motor 1 is retried. In the above configuration, the motor control device 20 is configured except for the motor 1.

  Next, the operation of the present embodiment will be described with reference to FIGS. FIG. 2 is a flowchart showing processing when the control circuit 5 receives a start signal of the motor 1. Note that the start signal is given as a control command from the outside (normal start command), and when the control circuit 5 generates an internal signal when the comparator 15 detects the application of an overvoltage (overvoltage protection operation). There are both sides. The activation signal shown in the flowchart of FIG. 2 indicates a normal activation command from the outside.

In FIG. 2, the control circuit 5 first determines whether or not the time T measured by the timer 8 is equal to or greater than a threshold Tth (for example, about 1 second) (step S1), and if T <Tth (NO), the motor 1 Is started based on, for example, a position signal given from the position detection circuit 7 (step S2). If the rotational speed R is equal to or greater than the threshold value Rth (step S3: YES), the position signal can be regarded as being stably output, and thus the winding 4 of the motor 1 is energized by a sensorless method as usual (step). S5).
On the other hand, if R <Rth in step S3 (NO), the motor 1 is stopped or rotating at a low speed, so that the rotor is positioned by initial excitation and then forced commutation is performed. After starting the motor 1 (step S4), the process proceeds to step S5. If T ≧ Tth in step S1 (YES), the process proceeds to step S4 without executing steps S2 and S3, and initial excitation and forced commutation are performed.

  FIG. 3 is a flowchart showing a process for realizing the function of the timer 8 that measures the time T when the overvoltage is detected, and FIG. 4 is a timing chart corresponding to the process. When the control circuit 5 detects that the overvoltage has been applied by the comparator 15, the control circuit 5 starts the time T by the timer 8 from zero (step S11). When the forced commutation of the motor 1 is performed in the process of FIG. 2 and the applied overvoltage energy is consumed and the overvoltage state is resolved, the time is stored in the memory 9 as Toff (step S12).

  Next, when the control circuit 5 obtains the value T of the timer 8 at that time (step S13), whether or not (T−Toff = Ts) exceeds a predetermined threshold value Treset (for example, about 0.3 seconds). Is determined (step S14). If (T−Toff) ≦ Treset (NO), it is determined again whether or not overvoltage detection has been performed (step S15). If no overvoltage is detected (NO), the process proceeds to step S13, and the value T of the timer 8 is acquired.

  If (T−Toff)> Treset is satisfied while the loop of steps S13 to S15 is repeated (step S14: YES), the process returns to step S11. In this case, since it is estimated that the overvoltage application state is not the hunting state, the timer 8 stops the timekeeping operation and maintains the state until the next overvoltage is detected. Note that the threshold Treset is set to a value sufficiently larger than the time (for example, 40 milliseconds) required to execute the processes of steps S2 and S3 of FIG. 2 performed before starting the motor 1.

  On the other hand, if overvoltage detection is performed in step S15 while repeating the above loop (YES), the process returns to step S12. In this case, although the application state of the overvoltage is once canceled by the protection operation, it is presumed that the overvoltage state is reached again within a short time and a hunting state in which the protection operation is repeated has occurred. A new time Toff at which the overvoltage state is resolved is stored in the memory 9 while continuing the time measuring operation.

  FIG. 4 shows the output state (a) of the overvoltage detection signal by the comparator 15 and the change (b) in the power supply voltage when the hunting state occurs. The impulse waveform represents high frequency noise. During the period in which the comparator 15 outputs the overvoltage detection signal (high level), the overvoltage protection operation shown in FIG. 5 is performed on the motor 1, and overvoltage energy is consumed and the voltage tends to decrease during that period. Further, since the transistor 18 is turned on during this period, the protection return threshold value Vth_L is given to the inverting input terminal of the comparator 15. When the power supply voltage falls below the protection return threshold value Vth_L, the protection operation ends, but when energy accumulates again as described above, the voltage rises again.

  Referring to FIG. 2 again, if the time counting operation by the timer 8 is performed as described above and T ≧ Tth in step S1 (YES), the hunting state continues for a certain period of time. Is estimated. Therefore, by omitting steps S2 and S3 and immediately performing initial excitation and forced commutation in step S4, the motor can be correctly started even if a start signal is received during hunting. (Without the present invention, since it takes longer time to start the motor, the overvoltage is again applied in the meantime, and the protection function is preferentially operated. Therefore, the motor cannot be started until the cause of occurrence of hunting disappears.)

  As described above, according to the present embodiment, the control circuit 5 detects the overvoltage state of the driving power supply voltage by the comparator 15 and immediately cancels the overvoltage state by forcibly commutating the brushless DC motor 1. When a hunting state in which an overvoltage state is detected again and a state in which the overvoltage protection operation is performed is repeatedly detected within a predetermined time is detected, the rotation state of the motor 1 is determined even if the motor 1 receives a start signal during the detection. Instead, start-up control is performed so that forced commutation occurs after initial excitation. Therefore, it is possible to shorten the time required for starting the motor 1 and appropriately start the motor 1.

  Then, the control circuit 5 starts to measure the time T after the first overvoltage state is detected by the timer 8, and obtains the period (T−Toff = Ts) during which the overvoltage protection operation is stopped. If the overvoltage state is detected again before> Treset, the time T continues to be measured. If Ts> Treset before the overvoltage state is detected again, the time T is reset and the operation is stopped. When T is equal to or greater than the threshold value Tth, the occurrence of a hunting state is detected. Therefore, the occurrence of the hunting state can be reliably detected by the action of the timer 8.

(Second embodiment)
6 and 7 show a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted. Hereinafter, different parts will be described. In the second embodiment, although not specifically shown, the control circuit (comparing means) 5 is provided with a counter N (software counter) separately from the timer 8, and the counter N counts the number of overvoltage protection operations. Based on the result, start control of the motor 1 is performed.

  In FIG. 6, when the counter N is cleared to zero (step S21), the comparator 15 detects the overvoltage and waits until the overvoltage state is canceled by executing the overvoltage protection operation ( Step S22) When the overvoltage state is resolved (YES), the timer 8 starts measuring time Tint (Step S23). Then, in the following step S24, it is determined whether or not the time Tint exceeds a predetermined time Treset (NO), and during Tint ≦ Treset (NO), whether or not overvoltage detection is performed again in the same manner as in step S15. Judgment is made (step S25).

In step S25, if Tint> Treset is satisfied without overvoltage detection (step S24: YES), the control circuit 5 stops measuring time Tint (step S26) and returns to step S21. On the other hand, if overvoltage detection is performed in step S25 before Tint> Treset (YES), the control circuit 5 increments the counter N (step S27) and proceeds to step S22. FIG. 7 is a diagram corresponding to FIG.
When the counter N is used in this way, the control circuit 5 compares the counter N with the threshold value Nth in step S28 instead of step S1 in FIG. 2, and if N ≧ Nth, “YES”: in the hunting state. And the process proceeds to step S4.

  As described above, according to the second embodiment, the control circuit 5 counts the number N of times that an overvoltage state has been detected, counts the interval Tint at which the overvoltage state has been detected by the timer 8, and sets the time Tint in advance. When the result of comparison with the defined reset time Treset is Tint> Treset, the counter N is cleared to zero, and when the counter value N exceeds the threshold value Nth, the occurrence of the hunting state is detected, so that the hunting state is the same as in the first embodiment. Can be reliably detected.

(Third embodiment)
FIGS. 8 to 10 show a third embodiment of the present invention, and different parts from the second embodiment will be described. As shown in FIG. 8, the motor control device 21 of the third embodiment includes an NPN transistor 22 (threshold changing means, Tr2) connected in parallel to the resistance element 19. The base of the transistor 22 is connected to an output port of a control circuit 23 (threshold changing means) that replaces the control circuit 5, and on / off of the transistor 22 is controlled by the control circuit 23.

  In the flowchart shown in FIG. 9, it is determined whether or not N ≧ Nth in step S6 instead of step S1, and if “YES” is determined, the control circuit 23 determines that the transistor 22 ( By turning on Tr2) and short-circuiting the resistive element 19, the overvoltage protection return threshold is lowered from Vth_L to Vth_L '(step S6). Thus, the overvoltage protection operation is continued until the power supply voltage is greatly reduced below normal, and even when the power supply voltage shows a tendency to increase, a longer time for starting the motor 1 is secured. Then, the process proceeds to step S2.

  Next, the operation of the third embodiment will be described with reference to FIG. Assume that the voltage level V exceeds Vth_H at time t1 in FIG. At this point, the counter N is counted up to N = 1 and the overvoltage protection operation is started. Thereafter, at time t2, the voltage level V has dropped to Vth_L due to the overvoltage protection operation, and thus the overvoltage protection operation is terminated. Thereafter, the voltage level V rises again.

At time t3, the voltage level V again exceeds Vth_H, the counter N is counted up to N = 2, and the overvoltage protection operation is started. Thereafter, at time t4, the voltage level V has dropped to Vth_L due to the overvoltage protection operation, and thus the overvoltage protection operation is terminated. Thereafter, the voltage level V rises again.
Thereafter, (t5) voltage level V exceeds Vth_H → overvoltage protection operation starts, counter N is counted up → (t6) voltage level V falls below Vth_L → overvoltage protection operation ends → (t7) voltage level V Hunting state in which V exceeds Vth_H is repeated, and it is determined that it is in the hunting state at time t11 when the value of the counter N becomes equal to or greater than the threshold value Nth.

  After time t11 when the value of the counter N becomes equal to or greater than the threshold value Nth, an overvoltage protection operation is performed until the voltage level V becomes equal to or lower than Vth_L ′ in order to secure a starting time. Note that Vth_L ′ is preferably a voltage lower than Vth_L. Then, after time t12 when the voltage level V becomes equal to or lower than Vth_L ′, the rotational speed is detected, and the motor 1 is started according to the rotational speed.

  As described above, according to the third embodiment, when the activation signal is given during the detection of the hunting state, the control circuit 23 returns the overvoltage protection of the comparator 15 so that the period during which the overvoltage protection means operates becomes longer. Since the threshold is lowered from Vth_L to Vth_L ′, even if the energy of the overvoltage is accumulated again, the time until the overvoltage is detected again is lengthened, and the time for starting the motor 1 is ensured to be longer. The state can be appropriately eliminated. Further, the method is not limited to the method of turning on the transistor 22 after receiving the activation signal when the hunting occurs, and the transistor 22 may be turned on at the timing when the control circuit determines that the state is the hunting state. (The same is true for the flow explanation portion of FIG. 12 of the fourth embodiment described later.)

(Fourth embodiment)
FIG. 11 to FIG. 13 show a fourth embodiment of the present invention, and parts different from the third embodiment will be described. As shown in FIG. 11, in the motor control device 24 of the fourth embodiment, the resistance elements 16, 17, 19 and the transistors 18, 22 are deleted, and the D / A converter is connected to the inverting input terminal of the comparator 15. (Threshold voltage changing means) The voltage output from 25 is given as the threshold voltage. The threshold voltage is determined according to data given from the control circuit (control means, threshold voltage changing means) 26.

  Next, the operation of the fourth embodiment will be described with reference to FIGS. In this case, the control circuit 26 also switches the threshold voltages Vth_H and Vth_L by changing the data output to the D / A converter 25. In FIG. 12, which corresponds to FIG. 9, when the control circuit 26 determines “YES” in step S6, the D / A converter reduces the threshold voltage Vth_L by a predetermined value in step S8 instead of step S7. The data to be output to 25 is changed. Therefore, the threshold voltage Vth_L is decreased by a predetermined value every time Step S8 is executed when it is determined as “YES” in Step S6 (see FIG. 13B).

  As described above, according to the fourth embodiment, the control circuit 26 increases the degree of decrease in the threshold voltage Vth_L as the period in which the hunting state is detected becomes longer. You can make changes.

(5th Example)
FIG. 14 is a view corresponding to FIG. 2 showing a fifth embodiment of the present invention. In the fifth embodiment, if a hunting state is detected when an activation signal is received, control (normal activation) for detecting the rotational speed R and starting up is executed only once. Therefore, in FIG. 14, if “YES” is determined in step S1, it is determined whether or not the “tryed flag” is set (step S31). The “try done flag” is reset in the initial state, and is a flag set in step S33 described later. If the “tried flag” is not set (NO), the process proceeds to step S2.

  That is, since the motor 1 is a fan motor, when the activation signal is received, for example, the fan 1 may be rotated at a certain speed by receiving external force such as wind. This is because, under such circumstances, it can be expected that the determination process of the rotational speed R in steps S2 and S3 will be completed within a short time. When step S2 is executed, it is determined whether or not an overvoltage is detected in step S15 during the process of FIG. 3 (step S32). If no overvoltage is detected (NO), the process proceeds to step S3.

  If an overvoltage is detected in step S32 (YES), since the motor 1 is still in a rotation stopped state or rotating at an extremely low speed, the determination process of the rotational speed R takes time, and hunting continues. Means that That is, the attempted normal activation control has failed. Therefore, if the “tried flag” is set (step S33) and the process proceeds to step S1, “YES” is determined in step S31. Then, after resetting the “tried flag” (step S34), the process proceeds to step S4.

  As described above, according to the fifth embodiment, when the control circuit 5 receives the start signal of the motor 1 during the detection of the hunting state, the control circuit 5 first determines the rotational speed R of the motor 1 and starts it only once. Since the control is performed, if the motor 1 is rotating at a certain speed due to the influence of wind or the like when the activation signal is received, the motor 1 can be activated within a short time.

(Sixth embodiment)
FIG. 15 is a view corresponding to FIG. 2 showing a sixth embodiment of the present invention. In the sixth embodiment, when the detection of the rotational speed R is started in step S2, time measurement is started simultaneously with the time (measurement time) during the detection. Then, it is determined whether or not the measurement time exceeds the predetermined time Tmes (step S35). If the measurement time does not exceed the predetermined time Tmes (NO), the process proceeds to step S3. If the measurement time exceeds the predetermined time Tmes until R ≧ Rth is determined in step S3 (step S35: YES), the process proceeds to step S4.

  That is, as described in the fifth embodiment, it is assumed that the rotation state of the motor 1 at the time of receiving the start signal is variously different. Therefore, if the determination result is not obtained within a short time, hunting is also performed. The condition may continue. Therefore, by limiting the time for determining the rotational speed R, when the determination result cannot be obtained within a short time, the activation control from the initial excitation to the forced commutation is performed. Therefore, the possibility of performing normal startup control can be increased. The predetermined time Tmes may be a preset value, or may be determined based on a hunting state monitored by a timer.

(Seventh embodiment)
16 and 17 show a seventh embodiment of the present invention. In FIG. 16 corresponding to FIG. 1, the motor control device 34 includes an A / D converter (voltage level detection means) 32, and the input terminal of the A / D converter 32 is a non-inverting input of the comparator 5. Connected to the terminal. The output terminal of the A / D converter 32 is connected to the input port of the control circuit 33. That is, the control circuit 33 monitors the voltage level of the drive power supply via the A / D converter 32.

Next, the operation of the seventh embodiment will be described with reference to FIG. When executing step S2, the control circuit 33 reads the voltage level of the drive power supply from the A / D converter 32 (step S36). Then, it is determined whether or not the voltage level has reached a limit voltage (for example, 25 V) set slightly lower than the threshold voltage Vth_H for performing overvoltage detection (step S37). If the limit voltage has not been reached (NO), the process proceeds to step S3. If the limit voltage has been reached (YES), the process proceeds to step S4.
That is, if the hunting state is continuing, the once-reduced power supply voltage rises again, so that the rotational speed R is determined until immediately before overvoltage detection is performed again during the rise process. Therefore, the same effect as in the sixth embodiment can be obtained.

(Eighth embodiment)
FIG. 18 shows an eighth embodiment. The schematic configuration of the motor control apparatus of the eighth embodiment is the same as that of FIG. 1 shown in the first embodiment, and FIG. 18 is a flowchart showing processing that is started when the power supply of the control circuit 5 is turned on. It is. In step S1801, the timer value T measured by the timer 8 of the control circuit 5 is cleared to zero, and the cancellation timer value TOff for storing the timer value T when the application state of the overvoltage described later is canceled is set to the timer after zero clearing. The value T is assumed to be the value. Note that the timer value T is calculated based on, for example, a CPU clock (not shown) included in the control circuit 5, and is counted up according to the clock from the time when it is cleared to zero.

In step S1802 following step S1801, the power supply to the motor 1 is turned off. In step S1803 following step S1802, the voltage level V of the drive power source input via the A / D converter 32 and overvoltage detection are performed. A branch determination is performed for comparison with a threshold voltage Vth_H (e.g., corresponding to a detection voltage of 30 V).
If it is determined in step S1803 that the voltage level V is equal to or higher than the threshold voltage Vth_H, that is, an overvoltage state, the process proceeds to step S1815, and the voltage level V is not equal to or higher than the threshold voltage Vth_H, that is, it is determined not to be in an overvoltage state. Advances to step S1804. In step S1804, the SI rotation speed command value applied to the control circuit 5 is fetched.

  In step S1805 following step S1804, it is determined whether the SI rotation speed command value is not 0 (zero). Here, the SI rotation speed command value of 0 (zero) means that the motor 1 is instructed to stop. If the SI rotational speed command value is not 0 (zero) in step S1805, the process proceeds to step S1806, and if the SI rotational speed command value is 0 (zero), the process returns to step S1802.

  In step S1806, a rotation speed detection process for detecting the rotation speed R of the motor 1 based on, for example, a position signal given from the position detection circuit 7 is started. In step S1807 following step S1806, branch determination is performed for comparing the voltage level V with the threshold voltage Vth_H for overvoltage detection. If it is determined in step S1807 that the voltage level V is equal to or higher than the threshold voltage Vth_H, that is, it is in an overvoltage state, step S1815 is performed, and if it is determined that the voltage level V is not higher than the threshold voltage Vth_H, that is, it is not in an overvoltage state. The process proceeds to step S1808.

  In step S1808, it is determined whether the rotation speed detection process started in step S1806 has been completed. If it is determined in step S1808 that the rotation speed detection process has been completed, the process proceeds to step S1809. If it is determined that the rotation speed detection process has not been completed, the process returns to step S1807. Whether or not the rotation speed detection process has been completed is determined by storing the timer value at step S1806 and determining that the rotation speed detection process has been completed when a predetermined time has elapsed from the stored timer value. You may do it.

In step S1809, it is determined whether or not the detected rotation speed R is equal to or greater than a threshold value Rth. In step S1809, if the detected rotation speed R is equal to or greater than the threshold value Rth, the motor 1 can be considered to be stably rotating (including rotation due to inertia), and thus the process proceeds to step S1811. On the other hand, if the detected rotational speed R is not equal to or greater than the threshold value Rth, the motor 1 is stopped or is rotating at a low speed, and thus the process proceeds to step S1810.
In step S1810, after the rotor is positioned by initial excitation, processing for starting the motor 1 by forced commutation is performed. The purpose of this step S1810 is to start up the motor 1 and accelerate it to a rotational speed capable of sensorless driving.

  In step S1811 following step S1809 or S1810, the motor 1 is driven by the position sensorless drive method based on the SI rotation speed command value. At the time when the process of step S1811 is executed, the motor 1 is in a state where the rotational speed R is equal to or greater than Rth or is activated by forced commutation, that is, in a state where it can be driven by the position sensorless driving method. It has become.

  In step S1812, following step S1811, branch determination is performed for comparing the voltage level V with the threshold voltage Vth_H for performing overvoltage detection. If it is determined in step S1811 that the voltage level V is equal to or higher than the threshold voltage Vth_H, that is, it is in an overvoltage state, the process proceeds to step S1815, and if it is determined that the voltage level V is not equal to or higher than the threshold voltage Vth_H, that is, not in an overvoltage state. Advances to step S1813.

  In step S1813, the SI rotation speed command value applied to the control circuit 5 is captured. In step S1814 following step S1813, it is determined whether or not the SI rotation speed command value is 0 (zero). If the SI rotational speed command value is not 0 (zero) in step S1814, the process returns to step S1811, and the driving of the motor 1 by the position sensorless driving method is continued. On the other hand, if the SI rotation speed command value is 0 (zero), the process returns to step S1802.

  Step S1815 is a process performed when it is determined in any of steps S1803, S1807, and S1812 that the voltage level V is equal to or higher than the threshold voltage Vth_H, that is, in an overvoltage state. In step S1815, it is determined whether or not a value (T−Toff) obtained by subtracting the cancellation timer value Toff from the timer value T exceeds a timer threshold value Treset (for example, about 0.3 seconds). If T-Toff> Treset in step S1815, the process proceeds to step S1816. If T-Toff> Treset, the process proceeds to step S1817.

  Here, T-Toff> Treset indicates that the time (= Treset or less) has not passed since the overvoltage state is eliminated, and that T-Toff> Treset does not eliminate the overvoltage state. It indicates that a considerable time (> Treset) has elapsed since then. Note that the timer threshold Treset is set to a value (for example, 0.3 seconds) that is sufficiently larger than the time (for example, 40 milliseconds) required to execute the processing of steps S1806 to S1808 performed before starting the motor 1. However, Treset is set to a value shorter than a threshold value Tth (for example, 1 second) described later.

  In step S1816, the timer value T is cleared to zero. This is because a considerable amount of time has passed since the overvoltage state has been eliminated, so that the hunting determination process in step S1819 described later is normally performed. This is because, after the overvoltage state is eliminated in step S1818, it takes time to reach the overvoltage state again, so that the timer value T is increased or the hunting state is entered, and the processing of steps S1815 to S1819 is repeated a plurality of times. This is because it is impossible to determine whether the value T has increased.

  In step S1817, the motor 1 is energized by setting the PWM duty to a value larger than normal (for example, 100%) based on the rotational speed at which the motor 1 is determined to be at the overvoltage level. Consume. In other words, if the motor 1 is rotating, it is driven by a forced commutation method, and it is forcibly energized even if the motor 1 is not rotating. As a result, the overvoltage level decreases.

  In step S1818 following step S1817, branch determination is performed by comparing the voltage level V with the protection return determination threshold Vth_L in order to determine whether or not the overvoltage level has returned to the normal level. If it is determined in step S1818 that the voltage level V is less than the protection return determination threshold Vth_L, that is, it is determined that the voltage level V has returned from the overvoltage level to the normal level, the process proceeds to step S1819. On the other hand, if it is determined that the voltage level V is not less than the protection return determination threshold Vth_L, that is, it has not returned from the overvoltage level to the normal level, the process returns to step S1817. In other words, the motor 1 is continuously energized by the forced energization method until the voltage level V becomes less than the protection return determination threshold value Vth_L.

  In step S1819, it is determined whether or not the timer value T is equal to or greater than a threshold value Tth (for example, about 1 second). If the timer value T is greater than or equal to the threshold value Tth in step S1819, the process proceeds to step S1821, and if the timer value T is not greater than or equal to the threshold value Tth, the process proceeds to step S1820. Here, the timer value T being equal to or greater than the threshold value Tth means that the process of steps S1815 →... S1819 is performed a plurality of times without passing through step S1816, and a large number of timer values T are added. In other words, after the overvoltage state is eliminated, the hunting phenomenon in which the overvoltage state is resumed without much time continues for the time Tth or more.

  In addition, when hunting in which an overvoltage state such as an overvoltage state → removal → overvoltage state and a resolving state are repeated occurs, steps S1815 → S1816 → S1817 → S1818 → S1819 → S1820 →... → S1804 →. It is expected that processing will be performed according to the following flow. During hunting, the timer value T is increased because the timer value T in step S1816 is not cleared to zero. That is, when the timer value T is equal to or greater than the threshold value Tth, it can be determined that hunting has occurred.

  In step S1821, it is determined whether the SI rotation speed command value is not 0 (zero). If the SI rotation speed command value is 0 (zero), the process proceeds to step S1820. If the SI rotation speed command value is not 0 (zero), the process returns to step S1810. That is, if “YES” is determined in step S1821, it means that the motor 1 needs to be driven although the overvoltage state has been eliminated, and therefore initial excitation and forced energization in step S1810 are performed. In step S1820, when the cancellation timer value Toff is set to the timer value T at that time, the process returns to step S1804.

  By performing the process shown in FIG. 18, the timer value T is started after the first overvoltage state is detected, and the occurrence of hunting can be detected by comparing with the threshold value Tth. In addition, when it is determined that hunting has occurred, it is possible to shift to sensorless control. In the eighth embodiment, the operation as shown in FIG. 4 is performed as in the first embodiment.

(Ninth embodiment)
FIG. 19 is a flowchart illustrating a process that is started when the power supply of the control circuit 5 is turned on according to the ninth embodiment. The schematic configuration of the motor control device of the ninth embodiment is the same as that of the second embodiment. In step S1901, the counter N is initialized (N = 1), and the timer 8 starts measuring time Tint. The processing of S1902 to S1914 following step S1901 is the same as the processing of steps S1802 to S1814 in FIG.

  Step S1915 is a process executed when it is determined in any of steps S1903, S1907, and S1912 that the voltage level V is equal to or higher than the threshold voltage Vth_H, that is, an overvoltage state. In step S1915, it is determined whether or not the time Tint is less than a timer threshold value Treset (for example, about 0.3 seconds). If Tint <Treset, the process proceeds to step S1916, and if Tint <Treset, the process proceeds to S1917. Here, the state where Tint <Treset is the case where not much time has elapsed from the time of step S1901 when the motor 1 is started, or when the overvoltage state is resolved without hunting → the overvoltage state is entered again. Indicates one of the following.

  In step S1916, the counter N is incremented (N = N + 1), and in step S1917, the counter N is initialized (N = 1). In step S1918, the motor 1 is driven with the PWM duty set to a value larger than normal (for example, 100%) based on the rotational speed at the time when the overvoltage is determined in step S1907. That is, the motor 1 is driven by a forced commutation method. And the overvoltage level falls by driving the motor 1 with this forced commutation method.

  In step S1919 subsequent to step S1918, branch determination is performed to compare the voltage level V with the protection return determination threshold value Vth_L in order to determine whether or not the overvoltage level has returned to the normal level. If it is determined that the voltage level V is less than the protection return determination threshold Vth_L, that is, it has returned from the overvoltage level to the normal level, the process proceeds to step S1920, and the voltage level V is not less than the protection return determination threshold Vth_L, that is, normal from the overvoltage level. If it is determined that the level has not been returned, the process returns to step S1918. In other words, the motor 1 continues to be energized by the forced commutation method until the voltage level V becomes less than the protection return determination threshold Vth_L.

In step S1920, branch determination is performed based on whether the counter N is equal to or greater than the counter threshold value Nth. If it is determined that the counter N is equal to or greater than the counter threshold value Nth, it is determined that the counter is in the hunting state and the process proceeds to step S1921. On the other hand, if it is determined that the counter N is not greater than or equal to the counter threshold Nth, the process proceeds to step S1922.
In step S1921, it is determined whether the SI rotational speed command value is not 0 (zero). If not, the process proceeds to step S1923, and if it is 0 (zero), the process proceeds to step S1922. That is, when “YES” is determined in step S1921, it means that the motor 1 needs to be driven although the overvoltage state has been eliminated. Therefore, after executing step S1923, initial excitation and forced commutation are performed in step S1910. And do.

  In step S1923, the value of the time Tint immediately before the execution of step S1923 is discarded, and the timer 8 starts measuring the time Tint. Further, the counter N is initialized (N = 1), and the process returns to step S1910. In step S1922, the value of the time Tint immediately before the execution of step S1922 is discarded, the timer 8 starts measuring the time Tint, and the process returns to step S1904.

  As described above, according to the ninth embodiment, the control circuit 5 counts the counter N in which the overvoltage state is detected, and measures the time Tint indicating the interval in which the overvoltage state is detected by the timer 8, and the time Tint Since the counter N is cleared to zero when the result of comparison with the predetermined timer threshold Treset becomes Tint> Treset, and the occurrence of the hunting state is detected when the counter value N exceeds the threshold Nth, the same as in the first embodiment. The occurrence of a hunting state can be reliably detected.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or expansions are possible.
In the first embodiment, the resistance element 19 may be omitted.
In the first embodiment, the comparator for comparing with the threshold voltages Vth_H and Vth_L may be divided into two.
Further, in the first embodiment, when measuring the stop period Ts of the overvoltage protection operation, when the time T is measured, the first overvoltage protection operation is started as the comparator 15 detects the overvoltage, and the protection operation ends. It is only necessary to start timing in the meantime. Further, instead of the time Toff, the time Ton at which the next overvoltage protection operation is started may be measured, and the difference from the time Ton may be obtained.
The overvoltage detection means may use an A / D converter instead of the comparator 15, and the control circuit 5 or the like may perform overvoltage detection by comparing with threshold data by a program.
The functions of the timer 8 and the counter N may be realized by hardware.

In the third or fourth embodiment, when the hunting state is detected, the overvoltage detection threshold Vth_H may be changed to be higher.
The processing of the third embodiment is not limited to the case where the activation signal is given, and may be applied to the case where the hunting state continues for a certain time.
The voltage level detection means of the seventh embodiment may be constituted by a comparator instead of the A / D conversion circuit 32. The apparatus for driving and controlling the brushless DC motor is not limited to the apparatus for driving and controlling the fan motor for vehicles. If so, it can be applied. For example, the present invention can be applied to a device that controls driving using a position sensor such as a Hall IC.

  In the drawings, 1 is a brushless DC motor, 5 is a control circuit (overvoltage protection means, hunting state detection means, control means, counter, comparison means), 7 is a position detection circuit, 8 is a timer, and 15 is a comparator (overvoltage detection means). , 20 and 21 are motor control devices, 22 is an NPN transistor (threshold changing means), 23 is a control circuit (control means, threshold changing means), 24 is a motor control device, and 25 is a D / A converter (threshold voltage changing means). ), 26 is a control circuit (control means, threshold value changing means), 31 is a motor control device, 32 is an A / D conversion circuit (voltage level detection means), and 33 is a control circuit (control means).

Claims (18)

In a motor control device that drives and controls a brushless DC motor,
Overvoltage detection means for detecting that the drive power supply voltage supplied to the motor is in an overvoltage state;
When an overvoltage state is detected by the overvoltage detection means, overvoltage protection means for forcibly canceling the overvoltage state by forcibly commutating the motor;
Even if the overvoltage state is canceled by the overvoltage protection unit, the hunting state is detected immediately after the overvoltage detection unit detects the overvoltage state again, and the hunting state in which the overvoltage protection unit is repeatedly activated within a predetermined time is detected. State detection means;
Control means for controlling the start-up so that the motor is forcedly commutated after initial excitation without determining the rotation state of the motor even if the motor-start signal is received during the detection of the hunting state. A motor control device comprising the motor control device.   2. The control unit according to claim 1, wherein, when receiving the start signal of the motor during detection of the hunting state, the control means determines the rotation state of the motor only once and performs start control. Motor control device.   2. The motor control device according to claim 1, wherein when the control unit receives a start signal of the motor and starts to determine the rotation state of the motor, the control unit performs the determination within a predetermined time from that point. . Voltage level detecting means for detecting a voltage level of a driving power source supplied to the motor;
When the control means starts the determination of the rotation state of the motor in response to the start signal of the motor, the control means makes a determination until the voltage level detected by the voltage level detection means reaches a predetermined upper limit value. The motor control device according to claim 1. In a motor control device that drives and controls a brushless DC motor,
Overvoltage detection means for detecting that the drive power supply voltage supplied to the motor is in an overvoltage state;
When an overvoltage state is detected by the overvoltage detection means, overvoltage protection means for forcibly canceling the overvoltage state by forcibly commutating the motor;
Even if the overvoltage state is canceled by the overvoltage protection unit, the hunting state is detected immediately after the overvoltage detection unit detects the overvoltage state again, and the hunting state in which the overvoltage protection unit is repeatedly activated within a predetermined time is detected. State detection means;
And a threshold value changing means for changing a threshold voltage for the overvoltage detection means to determine an overvoltage state so that a period during which the overvoltage protection means operates during the detection of the hunting state is longer. A motor control device.   The motor control device according to claim 5, wherein the threshold value changing unit increases the degree of change of the threshold voltage as the period in which the hunting state is detected becomes longer.   7. The motor control apparatus according to claim 5, wherein the threshold value changing unit changes the threshold voltage for determining that the overvoltage state has been eliminated. The hunting state detection means includes
A time T is started from the time when the overvoltage state is first detected by the overvoltage detection means until the operation of the overvoltage protection means corresponding to the detection is stopped, and the operation of the overvoltage protection means is performed. The stop period Ts is counted, the time Ts is compared with a predetermined reset time Treset,
If an overvoltage state is detected again by the overvoltage detection means before Ts> Treset, the time T is continuously counted.
When Ts> Treset before the overvoltage state is detected again by the overvoltage detection means, the timer is configured to reset the time T and stop the operation,
8. The motor control device according to claim 1, wherein occurrence of a hunting state is detected when the time T is equal to or greater than a threshold value Tth. 9. The hunting state detection means includes
A counter that counts the number N of times that an overvoltage state is detected by the overvoltage detection means;
A timer for measuring an interval Tint at which an overvoltage state is detected by the overvoltage detection means;
Comparing means for comparing the interval Tint timed by the timer with a predetermined reset time Treset;
When the comparison result by the comparison means becomes Tint> Treset, the counter is cleared to zero,
8. The motor control device according to claim 1, wherein occurrence of a hunting state is detected when the counter value N is equal to or greater than a threshold value Nth. In a motor control method for driving and controlling a brushless DC motor,
When it is detected that the drive power supply voltage supplied to the motor is in an overvoltage state, the motor is forced to commutate to eliminate the overvoltage state.
Even if the overvoltage state is canceled, the motor start signal is received while the hunting state in which the overvoltage state is detected again immediately and an operation for resolving the overvoltage state is repeated within a predetermined time is detected. In addition, the motor control method includes performing start-up control so that the motor is forcibly commutated after initial excitation without determining the rotation state of the motor.   11. The motor control method according to claim 10, wherein when a start signal of the motor is received during detection of the hunting state, the start control is performed by determining the rotation state of the motor only once.   11. The motor control method according to claim 10, wherein when the determination of the rotation state of the motor is started in response to the start signal of the motor, the determination is performed only within a predetermined time from that point.   When the determination of the rotation state of the motor is started in response to the start signal of the motor, the voltage level of the driving power supply supplied to the motor is detected, and until the voltage level reaches a predetermined upper limit value The motor control method according to claim 10, wherein the determination is performed. In a motor control method for driving and controlling a brushless DC motor,
When it is detected that the drive power supply voltage supplied to the motor is in an overvoltage state, the motor is forced to commutate to eliminate the overvoltage state.
Even if the overvoltage state is resolved, the overvoltage protection operation period is further extended while a hunting state in which an overvoltage state is detected again immediately and an operation for resolving the overvoltage state is repeated within a predetermined time is detected. A motor control method characterized by changing a threshold voltage for determining the overvoltage state.   The motor control method according to claim 14, wherein the degree of change of the threshold voltage is increased as the period in which the hunting state is detected becomes longer.   16. The motor control method according to claim 14, wherein a change is made so as to reduce a threshold voltage for determining that the overvoltage state has been eliminated. The time T is started from the time when the overvoltage state is first detected until the overvoltage protection operation corresponding to the detection stops, and the time Ts during which the overvoltage protection operation is stopped is counted. The time Ts is compared with a predetermined reset time Treset,
If the overvoltage condition is detected again before Ts> Treset, the time T continues to be measured,
If Ts> Treset before the overvoltage state is detected again, the time T is reset and the operation is stopped.
The motor control method according to any one of claims 10 to 16, wherein occurrence of a hunting state is detected when the time T becomes equal to or greater than a threshold value Tth. Counting the number N of times that the overvoltage condition was detected, and measuring the interval Tint at which the overvoltage condition was detected,
If the result of comparing the interval Tint with a predetermined reset time Treset is Tint> Treset, the count result is cleared to zero,
17. The motor control method according to claim 10, wherein occurrence of a hunting state is detected when the counter value N is equal to or greater than a threshold value Nth.

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