JP2011176942A - Rotation detecting device and dc motor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation detecting device for highly accurately detecting a rotation angle in stopping of a DC motor with a brush, whose rotation state can be detected, irrespective of the magnitude of a DC component of a motor current without providing a sensor; and to provide a DC motor device. <P>SOLUTION: The motor includes a variable mechanism in which reactance between brushes periodically changes in accordance with rotation. A power supply voltage obtained by superimposing an AC voltage over a DC voltage is applied to the motor. A motor controller turns a braking command signal to "H" in short circuit braking the motor, and if a detection pulse generated from an AC component after the motor current passes HPF is "H", Q-output of a flip-flop becomes "H", and short circuit braking starts. At this point, a surge current 300 occurs in the motor current and a component 302 of the surge current 300 is detected during a period when the amplitude of the AC component after HPF is large. The component 302 is absorbed as shown by a dotted line 304 during the "H" period of the detection pulse, so that a new pulse signal is not generated due to the surge current. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotation detection device and a DC motor device that detect a rotation state such as a rotation angle, a rotation direction, and a rotation speed of a brushed DC motor.

  For example, in a vehicle, a DC motor with a brush (hereinafter also referred to simply as “DC motor”) is an opening / closing angular position of an air mix damper for temperature adjustment and a mode damper for switching an outlet in an air conditioner, and a vertical position of a power window. For example, it is used to adjust the position of the movable member of each device. When controlling a DC motor used in such applications, the rotation state such as the rotation angle, rotation direction, and rotation speed of the DC motor is detected, and the position of each movable member is accurately adjusted based on the detected rotation state. There is a need to.

  As a general method for detecting the rotation state of a DC motor, a method of providing a sensor such as a rotary encoder or a potentiometer and detecting based on a detection signal from the sensor is well known. For this reason, a method of detecting the rotational state by providing such a sensor is also adopted in the vehicle.

  However, in the method of detecting the rotational state by providing the sensor in this way, a space for installing the sensor is required for each DC motor, and the detection signal from the sensor is separated from the harness for supplying DC power to the DC motor. Is also required for each DC motor, which increases the weight and cost of the vehicle.

  Therefore, there is an increasing demand for a sensorless system in order to reduce sensors and associated harnesses. Various sensorless methods for detecting the rotation state of a DC motor without using a large-scale sensor such as a rotary encoder have been proposed (see, for example, Patent Document 1).

  In Patent Document 1, a resistor is connected in parallel to any one of the armature coils composed of a plurality of phase coils, so that the electrical resistance between the brushes periodically changes as the motor rotates. The configuration is adopted. When a direct current is supplied to the armature coil via the brush, the current value of the current flowing through the motor (also referred to as a motor current) also changes as the armature rotates. In Patent Document 1, the rotation state of the motor is detected by detecting a change in the motor current as a detection pulse.

JP 2003-111465 A

  However, in Patent Document 1, since a direct current flowing in the motor circuit is changed by connecting a resistor to any one of the phase coils in parallel, when the direct current value for driving the motor decreases, The fluctuation of the motor current is also reduced.

  Further, when the supply of the direct current that drives the motor is stopped in order to stop the motor, the current flows due to the induced electromotive force, but the magnitude decreases as the rotational speed of the motor decreases. And when a motor stops, the electric current which flows with an induced electromotive force also becomes zero.

Thus, when the direct current value decreases or becomes zero, it becomes difficult to detect the rotational state of the motor based on the fluctuation of the direct current.
In addition, it is known to electrically brake the DC motor with, for example, a power generation brake or a regenerative brake when the DC motor is stopped. However, since a surge current is generated when such braking control is executed, if this surge current is detected as the motor current when the motor is stopped, the rotation angle at which the motor stops may be erroneously detected as the rotation state.

  The present invention has been made in order to solve the above-described problems. The rotation angle of a brushed DC motor that can detect the rotation state regardless of the magnitude of the DC component of the motor current without providing a sensor is increased. An object of the present invention is to provide a rotation detection device and a DC motor device that detect the accuracy.

  According to the first to ninth aspects of the present invention, in the rotation detecting device for detecting the rotation state of the motor, the DC motor is connected to the armature having an armature coil composed of at least three phase coils and the armature coil. A commutator having a plurality of commutator pieces, at least a pair of brushes slidably contacting the commutator, and a variable mechanism in which impedance periodically changes between the pair of brushes as the armature rotates. The rotation detection device includes a braking unit that electrically brakes the DC motor, and a common energization path that serves as an energization path for the motor current that flows between the pair of brushes both when the DC motor is constantly rotated and when the DC motor is braked. And an AC superimposing means for superimposing an AC voltage on a DC voltage for driving the DC motor, and an AC superimposing means electrically connected to a common energization path. An energization detecting means for detecting an electric quantity related to an alternating current supplied to the flow motor, and an amplitude of an AC component of the electric quantity detected by the energizing detection means periodically changing by a variable mechanism as the armature rotates. Based on the rotation state detection means for detecting at least one of the rotation angle and the rotation speed of the DC motor, and the start timing of the braking executed by the braking means based on the amplitude change of the AC component detected by the energization detection means. Timing control means for controlling.

  As described above, a configuration in which an AC voltage is superimposed on a DC voltage and applied to a brushed DC motor is not present and is novel. And even if the alternating voltage is superimposed on the direct current voltage and applied to the motor, the torque of the direct current motor is generated by the direct current component of the motor current flowing in the motor by the power supply voltage in which the alternating current voltage is superimposed on the direct current voltage, The AC current component does not affect the torque of the DC motor.

  Thus, a constant AC voltage is always applied to the DC motor regardless of the state of the DC motor (accelerating, decelerating, constant speed, stopping, etc.) and without affecting the motor torque. AC current can flow.

  Then, by adopting a configuration in which the AC superimposing means and the energization detecting means are electrically connected to a common energization path that is an energization path for the motor current both when the DC motor is normally rotated and when the brake is braked, the braking is temporarily performed. Even if the DC voltage applied from the power supply means sometimes becomes zero, the rotation state can be detected even during deceleration to stop by continuing to apply the AC voltage.

  Further, since the DC motor has a variable mechanism in which the impedance periodically changes between the pair of brushes as the armature rotates, the amplitude of the AC component also changes periodically. Therefore, even if the DC voltage applied from the power supply unit decreases or the DC voltage applied from the power supply unit becomes zero during braking and the DC component of the motor current fluctuates, the constant AC voltage continues to be applied. Thus, the rotational state can be detected with high accuracy based on the change in the amplitude of the AC component of the motor current.

  Then, the energization detecting unit detects the amount of electricity related to the AC current supplied to the DC motor by the AC superimposing unit, and the rotation state detecting unit is based on the amplitude change of the AC component of the detected amount of electricity. Thus, either the rotation angle or the rotation speed can be detected as the rotation state of the DC motor without providing a sensor such as an encoder. In addition, as an electric quantity relevant to an alternating current, an electric current, a voltage, electric power etc. can be considered, for example.

  Here, when the DC motor is forcibly braked when the DC motor is stopped, a surge current flows to the DC motor at the start of braking. When braking is started ignoring the timing of the amplitude change of the AC component, for example, braking of the DC motor is started in a state where the impedance between the brushes of the DC motor is low, and the surge current has the amplitude of the AC component for detecting rotation. When it occurs when the current is large, the generated surge current is included in the AC component for rotation detection, so that rotation detection is not erroneous.

  However, if the DC motor braking starts when the impedance between the brushes of the DC motor is low and the surge current is generated when the amplitude of the AC component for rotation detection is small, the generated surge current is used for rotation detection. May be detected as a state in which the amplitude of the AC component is large, and rotation detection may be erroneous.

  As described above, since a surge current is generated during braking, if the change in amplitude of the AC component is erroneously detected, the stop angle position of the DC motor cannot be detected with high accuracy. Furthermore, when the motor is driven continuously, there is a problem that erroneous detection accumulates.

  Therefore, by controlling the start timing of braking based on the timing of the amplitude change of the AC component detected by the energization detection means, either when the amplitude of the AC component is large or when the amplitude of the AC component is small, It is possible to determine whether a surge current is generated due to braking.

  As a result, when a surge current due to braking is generated when the amplitude of the AC component is large, the generated surge current is included in the AC component having a large amplitude. The rotation state of the DC motor may be detected based on the above. On the other hand, when generating a surge current due to braking when the amplitude of the AC component is small, the rotational state of the DC motor may be detected in consideration of the fact that the surge current is detected as an AC component having a large amplitude.

As a result, it is possible to prevent erroneous detection of the rotational angle of the DC motor during braking, and to detect the rotational speed from the start to the stop of braking or the rotational angle at which the DC motor stops.
According to the second aspect of the present invention, the energization detecting unit includes a pulse generating unit that generates a pulse signal according to an amplitude change of the AC component, and the rotation state detecting unit is configured to generate the pulse signal generated by the pulse generating unit. The timing control means controls the start timing of braking by the braking means based on the pulse signal generated by the pulse generating means.

  As a result, braking is started based on a pulse signal in which a period in which the amplitude of the AC component is larger and a period in which the amplitude of the AC component is smaller than that in the AC component itself is represented by a binary signal of “High (H)” and “Low (L)”. The timing can be easily controlled.

According to a third aspect of the present invention, the timing control means starts braking by the braking means when the pulse signal is at a high level.
As described above, when braking is started when the pulse signal is at a high level (“H”), a surge current due to braking is generated within the period “H” of the pulse signal. In this case, since the surge current is included and processed in the “H” portion of the pulse signal, the surge current due to braking is not generated as a pulse signal. Therefore, the rotation state detection unit can detect the rotation angle at which the DC motor stops based on the pulse signal with high accuracy without performing any processing on the pulse signal generated by the pulse generation unit.

According to the fourth aspect of the invention, the timing control means starts the braking by the braking means in synchronization with the rising edge of the pulse signal.
Thus, when braking is started in synchronization with the rise of the pulse signal, a surge current due to braking is generated at the beginning of the period when the pulse signal is “H”. As a result, it is possible to prevent a surge current from occurring after the braking start timing is delayed and the pulse signal changes from “H” to “L”.

  As a result, since the surge current can be generated within the period when the pulse signal is “H”, the surge current due to braking is not newly generated as the pulse signal. Therefore, the rotation state detection unit can detect the rotation angle at which the DC motor stops based on the pulse signal with high accuracy without performing any processing on the pulse signal generated by the pulse generation unit.

  According to the fifth aspect of the present invention, the timing control means starts the braking by the braking means in synchronization with the falling edge of the pulse signal, and the rotation state detecting means performs the next pulse after the braking means starts braking. The rotation state is detected except for one pulse signal generated by the generation means.

  As described above, when braking is started in synchronization with the falling edge of the pulse signal, a surge current due to braking is generated within a period “L” starting from the falling edge of the pulse signal. In this case, the surge current is generated as a pulse signal generated next to the pulse signal that starts braking in synchronization with the falling edge. This pulse signal is an error signal when the stop angle position of the motor is detected.

  Therefore, the rotation state detecting means can detect the rotation angle at which the DC motor stops based on the pulse signal with high accuracy by excluding the pulse signal generated next to the pulse signal that started braking in synchronization with the falling edge. .

  Here, as a variable mechanism of a DC motor in which the impedance periodically changes between a pair of brushes as the armature rotates, for example, a configuration in which a resistance value is periodically changed as an impedance by connecting a resistor to a phase coil. In this case, the magnitude of the direct current component of the motor current fluctuates and torque fluctuation occurs in the motor. The torque fluctuation of the motor causes the noise of the motor itself or the noise of the drive target driven by the motor.

  Therefore, according to the invention described in claim 9, an armature having an armature coil composed of at least three-phase coils, a commutator having a plurality of commutator pieces to which the armature coils are connected, and a commutator The DC motor having at least a pair of brushes in sliding contact and a variable mechanism in which impedance reactance changes periodically between the pair of brushes as the armature rotates, according to any one of claims 1 to 8. A rotation detecting device.

  Thus, in the DC motor, the configuration of the variable mechanism in which the reactance of the impedance periodically changes between the pair of brushes as the armature rotates is compared with the variable mechanism in which the resistance value is periodically changed as the impedance. The fluctuation of the direct current component of the current can be minimized. Therefore, torque fluctuations of the DC motor can be reduced as much as possible.

1 is a schematic configuration diagram showing a DC motor device according to a first embodiment. The characteristic diagram of the power supply voltage applied to a motor. The block diagram showing the circuit structure of a rotation signal detection part. (A) is explanatory drawing showing 3 types of motor circuits while a motor rotates 180 degrees, (B) is a characteristic view showing the relationship between the frequency and impedance in 3 types of motor circuits. The time chart which shows the motor current waveform and detection pulse which flow during rotation of a motor. The time chart which shows the braking command signal at the time of a motor stop, a detection pulse, a flip-flop output, a motor current, and the detection current after HPF. (A) is a truth table for controlling the motor drive, and (B) is a truth table of an actual product of a flip-flop that realizes the (A) truth table. The flowchart which shows a motor control routine. The schematic circuit diagram which shows the DC motor apparatus by 2nd Embodiment. Truth table for controlling motor drive. The schematic circuit diagram which shows the DC motor apparatus by 3rd Embodiment. Truth table for controlling motor drive. The schematic circuit diagram which shows the DC motor apparatus by 4th Embodiment. (A) is a truth table for controlling motor drive, and (B) is a time chart showing a braking command signal, detection pulse, flip-flop output, motor current, and detected current after HPF when the motor is stopped. The schematic circuit diagram which shows the DC motor apparatus by 5th Embodiment. The schematic circuit diagram which shows the motor driver by 6th Embodiment. The schematic circuit diagram which shows the DC motor apparatus by 6th Embodiment. The signal table which shows a driver signal and the switching signal of a motor driver. Truth table for controlling driver signals. The flowchart which shows a motor control routine. The schematic block diagram which shows the motor by 7th Embodiment. The schematic block diagram which shows the motor by 8th Embodiment. The time chart which shows the motor current waveform and detection pulse which flow during rotation of a motor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows a DC motor device 2 according to the first embodiment. The DC motor device 2 mainly includes a motor 20 and a rotation detection device 100 that detects the rotation state of the motor 20.

(Motor 20)
The motor 20 includes a pair of brushes 22 and 24 and an armature 30 that are disposed 180 degrees apart from each other in the rotation direction, and a three-phase DC with a brush having a three-phase coil as an armature coil. It is a motor. The armature 30 includes a commutator 40 including three commutator pieces 41, 42, and 43 that are in contact with the brushes 22 and 24. Each of the three (three-phase) phase coils L1, L2, and L3 constituting the armature coil is delta-connected.

  That is, the first phase coil L1 is connected between the third commutator piece 43 and the first commutator piece 41, and the second phase coil L2 is connected between the first commutator piece 41 and the second commutator piece 42. Are connected, and the third phase coil L3 is connected between the second commutator piece 42 and the third commutator piece 43. An armature 30 is configured by the armature coil and the commutator 40 including the three phase coils L1, L2, and L3.

  In addition, the inductance of each phase coil L1, L2, L3 is the same value (L1 = L2 = L3). Further, the phase coils L1, L2, and L3 are arranged so as to be separated from each other by 2π / 3 in electrical angle.

  The lengths of the commutator pieces 41, 42, 43 in the rotational direction are equal, and any two of the three commutator pieces 41, 42, 43 are in contact with the brushes 22, 24, respectively. As the commutator 40 is rotated by the rotation of the armature 30, the two commutator pieces in contact with the brushes 22 and 24 are switched.

  The motor 20 of this embodiment has a yoke housing (not shown), and a field made of a permanent magnet is provided on the inner wall side of the yoke housing, and the armature 30 is arranged to face this field. Has been placed.

  Furthermore, in the present embodiment, in the motor 20, a capacitor C1 is connected in parallel with the first phase coil L1. That is, the capacitor C <b> 1 connects the first commutator piece 41 and the third commutator piece 43.

  Therefore, the AC superimposed voltage that is output from the AC power source 106 described later and superimposed on the DC voltage from the DC power source 102 by the coupling capacitor 108 is the brushes 22 and 24 and any two commutator pieces in contact with them. Is applied to the motor circuit including the phase coils L1, L2, L3 and the capacitor C1 inside the motor 20. By applying the power supply voltage in which the AC voltage is applied to the DC voltage in this way, a current including an AC current component flows in the motor circuit.

  As is well known, the capacitor C1 functions as a very high resistance in which a current hardly flows in a direct current, and has a low reactance characteristic in which a current easily flows in an alternating current, that is, a low impedance characteristic.

  Therefore, when viewed from the DC power source 102, the capacitor C1 can be handled as not equivalently present. Therefore, the direct current from the direct current power source 102 flows only to the phase coils L1, L2, and L3.

  On the other hand, when viewed from the AC power source 106, each phase coil L1, L2, L3 has high reactance, that is, high impedance, whereas the capacitor C1 has low impedance, and the difference between the two is large. Therefore, for example, when the armature 30 rotates clockwise from the state shown in FIG. 1 and the first commutator piece 41 comes into contact with the brush 24, the first phase coil L1 and the capacitor C1 are interposed between the brushes 22 and 24. The parallel circuit is formed.

  That is, an energization path of only the capacitor C1 is formed between the brushes 22 and 24. In this state, the impedance of the motor circuit between the brushes 22 and 24 is different from the state shown in FIG.

  That is, from the viewpoint of direct current, the motor circuit can be regarded as a circuit including only three phase coils L1, L2, and L3. Therefore, the presence of the capacitor C1 does not affect the rotational speed and torque of the motor 20 that is rotated by the direct current from the direct current power source 102.

  On the other hand, in terms of alternating current, the configuration of the motor circuit formed between the brushes 22 and 24 changes each time the two commutator pieces contacting the brushes 22 and 24 are switched according to the rotation angle of the motor 20. Therefore, the capacitance value, that is, the impedance changes as reactance in the motor circuit. However, in this embodiment, since one capacitor C1 is connected only to the first phase coil L1, switching of the commutator piece occurs three times while the armature 30 of the motor 20 rotates 180 °. The change in impedance is two stages. This will be described in detail later with reference to FIG.

  The change in impedance (reactance) is caused by a change in amplitude of an alternating current component (alternating current component) included in the motor current flowing through the motor 20, or an alternating current component (path voltage) included in the voltage (path voltage) of the energization path through which the motor current flows. It appears as a change in amplitude of the AC voltage component.

  Therefore, if the change in the amplitude of the AC component of the motor current or the path voltage that changes according to the rotation angle can be detected, the rotation angle and the rotation speed can be detected as the rotation state of the motor 20. Therefore, in the rotation detection device 100 of the present embodiment, the rotation signal detection unit 120 detects a change in the amplitude of the AC component included in the motor current. Thereby, the change in the reactance of the motor circuit between the brushes is indirectly detected from the change in the AC component. Based on the detected change in the amplitude of the alternating current component, a detection pulse Sp is generated as will be described later.

(Rotation detection device 100)
The rotation detection device 100 is a device for detecting the rotation angle of the motor 20, and includes a DC power supply 102, an AC superposition unit 104, switches (SW) 110 and 112, NOT circuits 114 and 116, a rotation signal detection unit 120, and a rotation. A state detection unit 150, a flip-flop (hereinafter also simply referred to as “FF”) 160, and the like are provided. The rotation detection device 100 is used, for example, to detect the rotation angle of a motor that drives each damper in a vehicle air conditioner or a motor that drives a power window. Of course, application to a vehicle air conditioner or power window is merely an example as an embodiment of the present invention.

(Power supply part)
The power supply unit of the present embodiment includes a DC power supply 102 and an AC superimposing unit 104. The DC power source 102 generates a voltage for generating a torque for rotating the motor 20.

  The AC superimposing unit 104 is composed of an AC power source 106 and a coupling capacitor 108, and is a common energization functioning as an energization path for the motor current flowing between the brushes 22 and 24 both during steady rotation of the motor 20 and during short-circuit braking. It is electrically connected to the path. The AC power source 106 generates an AC voltage having a predetermined frequency. The coupling capacitor 108 superimposes the AC voltage output from the AC power source 106 on the DC voltage output from the DC power source 102.

  As shown in FIG. 2, the AC superimposed voltage applied to the motor 20 is an AC / DC mixture (a kind of pulsating flow) in which an AC voltage having an amplitude Vs and a frequency f is superimposed on the DC voltage Vb. When this alternating current superimposed voltage is applied to the motor 20, the motor current flowing through the motor 20 also becomes a current in which the alternating current is superimposed on the direct current.

  Whether the motor 20 is normally rotated or stopped by controlling the power supply voltage applied to the motor 20 is determined by switching the energization path of the motor 20 by turning on and off the SWs 110 and 112.

  As shown in FIG. 1, the logic value of the output of the Q terminal of the FF 160 (also referred to as Q output) is directly added to the SW 110, and the logic value of the Q output of the FF 160 is inverted and added to the SW 112 by the NOT circuit 114. Therefore, if one of the SWs 110 and 112 is on, the other is off.

  When SW 110 is on and SW 112 is off, a DC voltage is applied to motor 20 from DC power supply 102, so motor 20 rotates normally. When SW 110 is off and SW 112 is on, the connection between the motor 20 and the DC power source 102 is cut off, and the circuit is short-circuited between the brushes 22 and 24. Then, the motor 20 operates as a generator, and the generated energy is consumed by the current detection resistor R1, thereby causing the motor 20 to be short-circuit braked and eventually stop.

(Rotation signal detector 120)
The rotation signal detection unit 120 includes a current detection unit 122 and a signal processing unit 130, and is electrically connected to the common energization path described above in the same manner as the AC superposition unit 104. The rotation signal detection unit 120 detects the amount of electricity related to the AC current supplied from the AC superimposing unit 104 to the DC motor 20, and generates a detection pulse Sp corresponding to the rotation angle of the motor 20 based on the detected amount of electricity. And output. In addition, as an electric quantity relevant to an alternating current, an electric current, a voltage, electric power etc. can be considered, for example.

  The current detection unit 122 is provided on the common energization path of the motor 20 (specifically, on the energization path from the brush 24 on the ground potential side to the ground potential). The signal processing unit 130 performs various signal processing based on the energization current (motor current) detected by the current detection unit 122 to generate the detection pulse Sp.

  The current detection unit 122 includes a current detection resistor R1 inserted on the common energization path of the motor 20, and the voltage at both ends of the current detection resistor R1 is taken into the signal processing unit 130 as a detection signal corresponding to the motor current. . The motor current will be described later.

In the current detection unit 122, a coil may be installed instead of the current detection resistor R1 installed on the energization path of the motor 20.
As shown in FIG. 3, the signal processing unit 130 includes a high-pass filter (HPF) 132, an amplification unit 134, an envelope detection unit 138, a low-pass filter (LPF) 140, and a comparison unit 142.

  The HPF 132 has a known configuration including a capacitor C10 and a resistor R2. The detection signal from the current detection resistor R1 captured by the signal processing unit 130 is cut by the HPF 132 in a band of a predetermined cutoff frequency or less including a DC current component, and the AC voltage generated by the AC power supply 106 is cut. A frequency component including the frequency that is higher than the cutoff frequency is extracted and input to the amplifying unit 134. Therefore, the DC current component of the detected motor current (detection signal) is blocked by the HPF 132, and only the AC current component is input to the amplifying unit 134.

Instead of the HPF 132, for example, a band pass filter that passes only a predetermined band including the frequency of the alternating current component may be used.
The detection signal (alternating current component) detected by the current detection resistor R1 and extracted by the HPF 132 is amplified by the amplification unit 134.

  The amplifying unit 134 includes an operational amplifier 136, a resistor R3 connected between the output terminal and the inverting input terminal of the operational amplifier 136, and a resistor R4 connected between the inverting input terminal of the operational amplifier 136 and the ground potential. The detection signal input from the HPF 132 to the non-inverting input terminal is amplified at a predetermined amplification factor.

  The detection signal amplified by the amplification unit 134 is subjected to envelope detection by the envelope detection unit 138. The envelope detector 138 includes a rectifying diode D1, a resistor R5 having one end connected to the cathode of the diode D1 and the other end connected to the ground potential, and one end connected to the cathode of the diode D1. And a capacitor C11 connected to the ground potential. The detection signal amplified by the amplification unit 134 is input to the anode of the diode D1.

  The envelope detection unit 138 envelope-detects the AC detection signal input from the amplification unit 134 and generates a constant signal (hereinafter referred to as “detection signal”) according to the amplitude of the AC current component. Note that the trailing edge of the detection signal output from the envelope detection unit 138 changes according to the time constants of the resistor R5 and the capacitor C11.

  The detection signal output from the envelope detection unit 138 is input to the comparison unit 142 after the high frequency component is cut by the LPF 140. The LPF 140 has a known configuration including a resistor R6 and a capacitor C12. A diode D2 is connected in parallel to the resistor R6. The connection direction of the diode D2 is opposite to the direction in which the detection signal is input.

  The comparator 142 is connected between the comparator 144, a resistor R7 having one end connected to the non-inverting input terminal of the comparator 144 and the other end connected to the LPF 140, and the output terminal and the inverting input terminal of the comparator 144. The resistor R8 includes a resistor R9 having one end connected to the inverting input terminal of the comparator 144 and the other end connected to the resistor R10.

  The detection signal output from the envelope detection unit 138 is input to the comparison unit 142 via the LPF 140, and is input to the non-inverting input terminal of the comparator 144 via the resistor R7 in the comparison unit 142. On the other hand, a threshold set through the resistors R9 and R10 is input to the inverting input terminal of the comparator 144. Thereby, the comparator 144 compares the detection signal with the threshold value, and outputs the comparison result.

  In this embodiment, the threshold value input to the comparison unit 142 is larger than the detection signal in the period where the amplitude is small in the motor current waveform shown in FIG. 5 and smaller than the detection signal in the period where the amplitude is large. A predetermined value is set.

  Therefore, in a period with a small amplitude, the detection signal input from the envelope detection unit 138 to the comparison unit 142 via the LPF 140 is smaller than the threshold value input to the inverting input terminal of the comparator 144. Is output. On the other hand, in a period in which the amplitude is large, the detection signal input from the envelope detection unit 138 to the comparison unit 142 via the LPF 140 is larger than the threshold value input to the inverting input terminal of the comparator 144. A level signal is output.

The low-level and high-level pulse signals output from the comparator 144 are input to the rotation state detection unit 150 as detection pulses Sp.
As described above, the signal processing unit 130 performs various signal processing such as cutting of the low frequency region, amplification of the alternating current component, and envelope detection on the motor current (detection signal) detected by the current detection resistor R1. Since the detection pulse Sp is generated above, an accurate detection pulse Sp with reduced disturbance and noise is generated.

(Rotation state detection unit 150)
As shown in FIG. 1, the rotation state detection unit 150 includes a pulse count unit 152 and a motor control unit 154, and based on the detection pulse Sp output from the rotation signal detection unit 120, Detect the rotation speed.

  The pulse count unit 152 counts up each time a pulse signal is output as a detection pulse from the comparison unit 142. Note that the waveform shaping and level adjustment may be appropriately performed before the pulse signal output from the comparator 144 is input to the pulse count unit 152.

  The motor control unit 154 is mainly composed of, for example, a microcomputer (hereinafter also referred to as “microcomputer”), and based on the number of detected pulses input from the pulse count unit 152, the rotation angle and rotation of the motor 20. Calculate the speed. The rotation angle is calculated based on the count number that the pulse counting unit 152 counts the detection pulses. The rotation speed is calculated based on the number of detection pulses counted per unit time.

  The motor control unit 154 uses the detected rotation angle as a feedback signal for driving and controlling the motor 20 in order to control the position of an air conditioning damper, a power window, and the like that are driven by the motor 20.

Further, the motor control unit 154 outputs a braking command signal for stopping the motor 20 by short-circuit braking. The braking command signal will be described later in detail.
FF160 (74HC74AP: manufactured by Toshiba) switches on / off of SWs 110 and 112 by a Q output that changes according to a braking command signal output from motor control unit 154 and a detection pulse output from rotation signal detection unit 120. .

(Change in motor circuit with rotation)
Next, a change in the connection state inside the motor 20 during the rotation of the motor 20 by 180 °, that is, a change in the motor circuit formed between the brushes 22 and 24 is shown in FIG. As shown in FIG. 4A, the motor circuit of the motor 20 of the present embodiment changes into three types of state A, state B, and state C while the motor 20 rotates 180 °.

  In the state A, the first commutator piece 41 is in contact with the brush 22 on the positive electrode side (hereinafter also referred to as “Vb side”) of the DC power source 102 and the brush 24 on the ground potential side (hereinafter also referred to as “GND side”). The second commutator piece 42 is in contact with each other. An equivalent circuit of the motor 20 in this state A, that is, a motor circuit formed between the brushes 22 and 24 is a circuit shown on the right side in the drawing. Note that Vb indicates a DC voltage output from the DC power supply 102 as described in FIG.

  In this state A, since the capacitor C1 and the third phase coil L3 are connected in series, there is no current path of only the capacitor C1 between the brushes 22 and 24, and one brush 22 One phase coil always exists on the path from the first brush 24 to the other brush 24. Therefore, in this state A, since the impedance of the entire circuit becomes high, the amplitude of the alternating current component included in the motor current is small.

  The state B is a state rotated about 50 ° clockwise from the state A, and the commutator piece contacting the brush 22 on the Vb side is changed from the first commutator piece 41 to the third commutator piece 43 in the state A. It is switched to. The second commutator piece 42 is in contact with the brush 24 on the GND side.

  Even in this state B, since the capacitor C1 and the second phase coil L2 are connected in series, there is no current path of only the capacitor C1 between the brushes 22 and 24, and one brush 22 One of the coils always exists on the path from the first brush 24 to the other brush 24. Therefore, even in this state B, the impedance of the entire circuit is high, and therefore the amplitude of the AC current component included in the motor current is small. Note that, in this state B and the state A, the impedance of the entire circuit is the same, as is clear by comparing the equivalent circuits in the figure. Therefore, the amplitude of the alternating current component is also the same size.

  The state C is a state further rotated by about 50 ° clockwise from the state B, and the commutator piece in contact with the GND-side brush 24 is moved from the second commutator piece 42 in the states A and B to the first commutation. It has switched to the child piece 41. The third commutator piece 43 is in contact with the brush 22 on the Vb side. That is, in the state C, the pair of brushes 22 and 24 are simultaneously in contact with both the pair of first commutator piece 41 and the third commutator piece 43 to which the capacitor C1 is connected.

  In this state C, the series circuit of the second phase coil L2 and the third phase coil L3, the first phase coil L1, and the capacitor C1 are respectively connected in parallel. Therefore, an energization path of only the capacitor C1 exists between the brushes 22 and 24. Thereby, since the impedance of the whole circuit becomes low, the amplitude of the alternating current component included in the motor current increases.

  Thus, during the rotation of the motor 20 by 180 °, the commutator piece that contacts the brushes 22 and 24 is switched three times, and accordingly, the motor circuit between the brushes 22 and 24 is in the state A, B, Switch to 3 types of C. However, as described above, since the impedance of the entire circuit is the same in the state A and the state B, the impedance change that occurs during the 180 ° rotation is two stages.

  In the process of rotation of the motor 20, there is a switching period in which one brush contacts two adjacent commutator pieces at the same time, and the impedance between the brushes also changes during this switching period. It only occurs instantaneously during one rotation of the motor 20, and the accompanying impedance change is instantaneous. Therefore, in this embodiment, this switching period is not considered.

  When the rotation further proceeds from the state C, the commutator piece that contacts the brush 22 on the Vb side is switched from the third commutator piece 43 in the state C to the second commutator piece 42. The first commutator piece 41 is in contact with the brush 24 on the GND side. This state is a state in which the Vb-side brush 22 and the GND-side brush 24 are interchanged in the state A described above, and the impedance of the entire circuit is the same as in the state A. Therefore, this state is referred to as a state A ′ in the following description.

  When the rotation further proceeds from this state A ′, the commutator piece contacting the GND-side brush 24 is switched from the first commutator piece 41 in the state A ′ to the third commutator piece 43. The second commutator piece 42 is in contact with the brush 22 on the Vb side. This state is a state in which the Vb brush 22 and the GND brush 24 are interchanged in the state B described above, and the impedance of the entire circuit is the same as in the state B. Therefore, in the following description, this state is referred to as state B ′.

  When the rotation further proceeds from this state B ′, the commutator piece contacting the brush 22 on the Vb side is switched from the second commutator piece 42 in the state B ′ to the first commutator piece 41. The third commutator piece 43 is in contact with the brush 24 on the GND side. This state is a state in which the Vb-side brush 22 and the GND-side brush 24 are interchanged in the state C described above, and the impedance of the entire circuit is the same as in the state C. Therefore, this state is referred to as a state C ′ in the following description.

  Then, when the rotation further proceeds from the state C ′, the state is switched again to the state A. Hereinafter, as the rotation proceeds, the state B → the state C → the state A ′ → the state B ′ → the state C ′ → the state A → Switch.

  That is, the motor 20 is switched sequentially into six types of states A, B, C, A ′, B ′, and C ′ according to the rotation angle during one rotation, and the state is changed every 60 °. Will be switched. Among these, the states A, B, A ′, and B ′ all have the same impedance (high impedance). Further, the states C and C ′ have the same impedance, and the value thereof is much lower than the impedance of the state A or the like.

Therefore, as shown in FIG. 5, the motor current has a small amplitude of the alternating current component in the states A, B, A ′, and B ′, and a large amplitude of the alternating current component in the states C and C ′. .
In addition, in the present embodiment, the impedance difference that varies depending on the rotation angle of the motor 20 is configured to be large. That is, as described with reference to FIG. 4A, the impedances of the states A, B, A ′, and B ′ are high because there is no path of the capacitor C1 between the brushes 22 and 24. On the other hand, the impedance of the states C and C ′ is a very low impedance due to the path of the capacitor C1 only between the brushes 22 and 24.

  Thus, since there is a large difference between the impedance in the states A, B, A ′, and B ′ and the impedance in the states C and C ′, the amplitude of the alternating current component in the motor current is also in the states A and B. , A ′, B ′ and states C, C ′ have a large difference as shown in FIG. FIG. 5 illustrates a waveform when the impedance in the states A, B, A ′, and B ′ is about four times the impedance in the states C and C ′.

  Therefore, the threshold value to be input to the inverting input terminal of the comparator 144 of the comparison unit 142 in the signal processing unit 130 can be set within a higher degree of freedom and range. For example, if the threshold value is set to a value near the intermediate value between the detection signal in the state A and the detection signal in the state C, the comparison by the comparison unit 142 is performed more accurately, as shown in FIG. In addition, it is possible to reliably generate an accurate detection pulse Sp according to the rotation angle.

  Here, as described above, while the armature 30 rotates 180 °, the motor circuit changes into three types of state A, state B, and state C, and the impedance of state C is higher than that of state A and state B. Get smaller. That is, the amplitude of the AC component is small during the 120 ° period while the armature 30 rotates 180 °, and the amplitude is large during the 60 ° period. Therefore, if Ton is a period with a large amplitude and Toff is a period with a small amplitude, Ton: Toff = 1: 2 at the time of steady rotation.

  By the way, the frequency of the alternating voltage output from the alternating current power supply 106 is the resonance frequency in the motor circuit in the states A, B, A ′, and B ′ in the present embodiment. Is set to a frequency different from each of these resonance frequencies. More specifically, the AC power supply 106 is configured to supply an alternating current having a predetermined frequency that is higher than any of these frequencies f1 and f2.

  FIG. 4B shows the frequency characteristics of the impedance in each state shown in FIG. As described above, the impedances of the motor circuits in the states A, B, A ′, and B ′ are the same. In this state A, B, A ', B', there is almost no influence of the capacitor C1, and a small peak value is generated at the resonance frequency f1, and as a whole, the impedance increases as the frequency increases.

  On the other hand, in the states C and C ′, the impedance characteristics change greatly due to the resonance between the phase coils L1, L2, and L3 and the capacitor C1, and the impedance becomes small with the resonance frequency f2 as the center (maximum value). Therefore, the states A, B, A ', B' and the states C, C 'have different impedances except for the frequency f3 where the impedances match (characteristics intersect). In particular, the impedance ratio is large in a predetermined band centered on the resonance frequency f1 and in a band equal to or higher than a frequency somewhat higher than the frequency f3. In particular, in a region above a frequency somewhat higher than the frequency f3, for example, even if the capacitance value of the capacitor C1 changes due to a change in the ambient temperature and the resonance frequencies f1 and f2 change, the impedance ratio changes little. From the viewpoint of circuit design, it is an area that can be easily used as the frequency of the AC voltage of the AC power source 106.

Therefore, in the present embodiment, the frequency of the AC voltage of the AC power supply 106 is set to a predetermined frequency higher than the frequency f3.
(Motor current during short-circuit braking)
Next, FIG. 6 shows the motor current when the rotating motor 20 stops. In FIG. 6, during the period in which the impedance is large and the amplitude of the alternating current component is small (period in which states A, B, and A′B ′), the waveform of the alternating current component of the motor current is very small. Omitted.

  In the example shown in FIG. 6, when the rotating motor 20 is stopped by applying short-circuit braking, the application of the DC voltage from the DC power source 102 to the motor 20 is stopped by turning off the SW 110. Let On the other hand, the AC voltage (AC current) from the AC power source 106 is not involved in driving the motor 20, but is supplied only for the purpose of detecting the rotation angle of the motor 20, so that it is rotating or short-circuited. Regardless of whether braking or not, the motor 20 is always applied while the rotation of the motor 20 is controlled.

  For this reason, the motor current after the start of short-circuit braking (after the application of the DC voltage from the DC power supply 102 is stopped) is obtained by superimposing the AC current from the AC power supply 106 on the current generated by the induced electromotive force as shown in the figure. Among these, since the magnitude of the current due to the induced electromotive force becomes smaller as the rotational speed of the motor 20 becomes lower, the current due to the induced electromotive force gradually decreases, and this current becomes zero when the motor 20 stops.

  On the other hand, since the alternating current is always supplied from the AC power source 106 for detecting the rotation angle as described above, the AC current depends on the rotation angle regardless of the rotation speed of the motor 20, as shown in FIG. An alternating current with an amplitude (according to the change in impedance of the motor circuit) flows. Therefore, the rotation angle of the motor 20 can be detected regardless of the rotation speed of the motor 20.

When the motor 20 is stopped, the rotation speed of the armature 30 is slowed down, so that the detection pulse generation interval and the pulse width accompanying the change in impedance also become long as shown in FIG.
In this embodiment, the detection pulse Sp is generated every time the motor 20 rotates 180 °. Therefore, the rotation angle of the motor 20 can be detected on the assumption that the motor 20 has rotated 180 ° each time the detection pulse Sp is generated.

(Short-circuit braking start timing)
The motor control unit 154 sets the braking command signal to “Low (L)” and outputs it to the FF 160 during steady rotation while the motor 20 is rotating. As shown in FIG. 1, since the D terminal and CK (clock) terminal of the FF 160 are connected to the ground, the inputs of the D terminal and the CK terminal (also referred to as D input and CK input) are always “L”. . Therefore, as shown in the truth table of FIG. 7A, when the braking command signal that is an input to the notPR terminal (also referred to as a notPR input) representing a negative input is “L”, the Q output is “H”. become.

A truth table of a Toshiba FF (74HC74AP) in which the D terminal and the CK terminal are not connected to the ground is shown in FIG.
When the Q output is “H”, SW110 is turned on and SW112 is turned off. Thereby, since the DC voltage of the DC power supply 102 is applied to the motor 20, the motor 20 rotates.

  On the other hand, when the motor control unit 154 detects from the count number output by the pulse count unit 152 that the air-conditioning damper, power window, and the like that are driven by the motor 20 have reached the target position, as shown in FIG. In addition, the braking command signal is set to “High (H)” and output to the FF 160.

  When the braking command signal serving as the notPR input becomes “H”, the Q output is determined by the input of the notCLR terminal representing the negative input (also referred to as a notCLR input). A detection pulse that is an output of the signal processing unit 130 is input to the notCLR terminal via the NOT circuit 116.

  When the braking command signal (notPR input) is changed from “L” to “H” and the detection pulse is “L”, that is, the not CLR input is “H”, the value of the Q output is the value of the previous Q output. Value. The value of the previous Q output at this time is “H” because it is the value when the notPR input is “L”.

  When the Q output is “H”, SW110 is turned on and SW112 is turned off. In this state, application of the DC voltage to the motor 20 continues, and short circuit braking is not executed. That is, even when the braking command signal becomes “H”, short-circuit braking is not executed while the detection pulse is “L”. When the braking command signal (notPR input) is “H” and the detection pulse is “H” from “L”, that is, when the not CLR input is changed from “H” to “L”, the Q output becomes “L”. .

  When the Q output becomes “L”, the SW 110 is turned off and the SW 112 is turned on. Therefore, the application of the DC voltage to the motor 20 is cut off, and the brushes 22 and 24 are short-circuited. Therefore, short circuit braking is started.

The negative signal of the Q output applied to the SW 112 via the NOT circuit 114 is also referred to as a braking start signal.
On the other hand, if the detection pulse is “H” when the braking command signal (notPR input) is changed from “L” to “H”, that is, if the notCLR input is already in the “L” state, the Q output becomes “L”. Become. In this case, when the brake command signal (notPR input) changes from “L” to “H”, SW110 is turned off and SW112 is turned on, so that the application of the DC voltage to the motor 20 is interrupted. The brushes 22 and 24 are short-circuited.

Thus, if the detection pulse is “H” when the braking command signal (notPR input) is “H”, short-circuit braking is started.
As shown in FIG. 6, when short-circuit braking is started, a surge current 300 is generated in the motor current. Therefore, the component 302 of the surge current 300 is detected during a period in which the amplitude of the detected current after HPF is large. This component 302 is absorbed as indicated by a dotted line 304 in the “H” portion of the pulse signal generated by the comparison unit 142 of the signal processing unit 130 as an output of an AC component having a large amplitude. As a result, even if a surge current is generated by short-circuit braking, no new pulse signal is generated by the surge current.

  Thus, even if the motor control unit 154 detects that the driving target of the motor 20 has reached the target position and sets the braking command signal to “H”, when the detection pulse is “L”, the Q output negative signal, That is, the braking start signal does not become “H”, and the braking start signal becomes “H” when the detection pulse is “H”.

  Thereby, the pulse component generated by the surge current is not generated in the “L” period of the detection pulse corresponding to the period in which the amplitude of the AC component is small, and “ It is generated during the period of “H”. Therefore, the pulse component generated by the surge current can be absorbed during the “H” period of the detection pulse.

  In this way, no new pulse signal is generated even if a surge current is generated by starting the short-circuit braking, so the motor control unit 154 stops the motor 20 based on the count number output by the pulse count unit 152. The rotation angle can be detected with high accuracy without erroneous detection.

(Motor control routine)
FIG. 8 shows a motor control routine. In FIG. 8, “S” represents a step.
First, in a state where the motor 20 is not driven and the motor 20 is stopped, the motor control unit 154 sets the braking command signal to “H” in S400. As a result, the notPR input of the FF 160 becomes “H”. Since an AC voltage is applied to the motor 20 from the AC power supply 106, the value of the not CLR input, which is the output of the signal processing unit 130, is either “H” or “L”.

  However, since the Q output is “L” at the start of energization of the rotation detection device 100, if the notPR input is “H”, the Q output is “L” regardless of the value of the notCLR input. In this state, since SW110 is off and SW112 is on, the application of the DC voltage to the motor 20 is interrupted, and the motor 20 continues to be in a rotation stopped state.

  Next, in S402, the motor control unit 154 determines whether or not a condition for driving the motor 20 is satisfied. The establishment of the driving condition of the motor 20 is determined based on, for example, whether an air volume adjustment for air conditioning is commanded or a power window raising / lowering is commanded. When the drive condition of the motor 20 is not satisfied (S402: No), the motor control unit 154 ends this routine.

  When the driving condition of the motor 20 is satisfied (S402: Yes), the motor control unit 154 sets the braking command signal to “L” in S404. As a result, the notPR input becomes “L”, and the Q output becomes “H” regardless of the value of the notCLR input. In this state, SW110 is on and SW112 is off.

Thereby, since a DC voltage is applied to the motor 20, the motor 20 rotates (S406).
When the motor 20 rotates, the motor control unit 154 calculates a rotation angle and a rotation speed as the rotation state of the motor 20 based on the count number output from the pulse count unit 152 (S408).

  Next, the motor control unit 154 determines whether a braking condition for the motor 20 is satisfied (S410). The establishment of the braking condition of the motor 20 is determined by the count number of the pulse count unit 152 as to whether or not the air conditioning damper or power window that is the driving target of the motor 20 has reached the target position. If the drive target has not reached the target position, it is determined that the motor braking condition is not satisfied (S410: No). In this case, the motor control unit 154 ends this routine.

  When the drive target reaches the target position and the motor braking condition is satisfied (S410: Yes), in S412, the motor control unit 154 sets the braking command signal to “H”. As a result, the notPR input becomes “H”.

  When the braking command signal (notPR input) is “H” and the detection pulse is “H”, that is, the notCLR input is “L” (S414: Yes), the Q output becomes “L” (S416). .

  If the Q output is “L”, SW110 is turned off and SW112 is turned on (S418). Thereby, the application of the DC voltage to the motor 20 is interrupted, and the brushes 22 and 24 are short-circuited, so that short-circuit braking on the motor 20 is started.

Then, the motor 20 stops completely after a certain time. Accordingly, no new detection pulse is generated, so that the counting by the pulse counting unit 152 is ended (S420).
In the first embodiment described above, even if the motor 20 rotates to the target rotation angle and the braking command signal output from the motor control unit 154 becomes “H”, the detection pulse is “L”, that is, the output of the HPF 132. In the period in which the amplitude of the AC component is small, the Q output of the FF 160, which is a braking start signal, is “L” and short circuit braking is not started.

  On the other hand, when the braking command signal output from the motor control unit 154 is “H” and the detection pulse is “H”, that is, when the amplitude of the AC component is large in the output of the HPF 132, short-circuit braking is started.

  Thus, even if a surge current is generated in the motor current when short-circuit braking is started, it is absorbed in a period in which the amplitude of the AC component is large, so that no new detection pulse is generated even if a surge current is generated. Therefore, it is possible to prevent the detection pulse generated by the surge current from being counted and to prevent erroneous detection of the rotation state of the motor 20.

In the present invention, the rotational state of the motor 20 may be detected based on the change in the amplitude of the AC component, with the AC component output from the HPF 132 instead of the detection pulse.
In the present embodiment, the configuration in which the capacitor C1 is connected in parallel to the phase coil L1 and the reactance periodically changes between the brushes 22 and 24 as the armature 30 rotates corresponds to the variable mechanism of the present invention. The AC superimposing unit 104 corresponds to the AC superimposing unit of the present invention, and the rotation signal detecting unit 120 including the current detecting unit 122 and the signal processing unit 130 corresponds to the energization detecting unit of the present invention. Further, the rotation state detection unit 150 having the pulse count unit 152 and the motor control unit 154 corresponds to the rotation state detection unit of the present invention, SW110 and SW112 correspond to the braking unit of the present invention, the NOT circuit 116, the motor control unit. 154 and FF160 correspond to the timing control means of the present invention, and the signal processing unit 130 corresponds to the pulse generation means of the present invention.

8 corresponds to the function executed by the braking means and timing control means of the present invention.
[Second Embodiment]
A second embodiment of the present invention is shown in FIGS. As shown in FIG. 9, the rotation detection device 170 of the DC motor device 4 of the second embodiment uses a microcomputer 172 instead of the FF 160 of the first embodiment and removes the NOT circuit 116 of the first embodiment. It is a thing.

The microcomputer 172 receives a braking command signal (IN1) from the motor control unit 154 and a detection pulse (IN2) from the signal processing unit 130, respectively.
When the motor 20 is rotating normally, “L” is output from the motor control unit 154 to IN1 as a braking command signal. In this case, as shown in the truth table of the input / output signals of the microcomputer 172 shown in FIG. 10, the OUT output of the microcomputer 172 is “H”. In this case, since the SW 110 is on, a DC voltage is applied to the motor 20 from the DC power source 102, and the motor 20 rotates. On the other hand, since the SW 112 is off, the brushes 22 and 24 are not short-circuited, and no braking force is applied to the motor 20.

  When the motor 20 rotates to the target rotation angle, the motor control unit 154 sets the braking command signal to “H”. When the braking command signal (IN1) is changed from “L” to “H” and the detection pulse (IN2) is “L”, the microcomputer 172 changes the OUT output to the value of the previous OUT output. To do. The value of the previous OUT output at this time is “H” because it is the value when the braking command signal (IN1) is “L”.

  When the OUT output is “H”, SW110 is on and SW112 is off. In this state, application of the DC voltage to the motor 20 continues, and short circuit braking is not executed. That is, even when the braking command signal becomes “H”, short-circuit braking is not executed while the detection pulse is “L”. When the braking command signal (IN1) is “H” and the detection pulse (IN2) is changed from “L” to “H”, the OUT output becomes “L”.

  When the OUT output becomes “L”, SW 110 is turned off and SW 112 is turned on, so that the application of the DC voltage to the motor 20 is cut off and the brushes 22 and 24 are short-circuited. Therefore, short circuit braking is started.

  On the other hand, if the detection pulse (IN2) is already “H” when the braking command signal (IN1) changes from “L” to “H”, the OUT output becomes “L”. In this case, when the braking command signal changes from “L” to “H”, SW 110 is turned off and SW 112 is turned on, so that the application of the DC voltage to the motor 20 is cut off and the brushes 22, 24 are turned off. They are short-circuited.

  In the second embodiment, the microcomputer 172 detects that the motor control unit 154 detects that the motor 20 has rotated to the target rotation angle and outputs the braking command signal that is output from the signal processing unit 130. The pulse was used as the input signal for IN2.

  On the other hand, the microcomputer 172 does not receive the detection pulse from the signal processing unit 130 and the braking command signal from the motor control unit 154, and the AC component signal extracted by the HPF 132 of the signal processing unit 130 and amplified by the amplification unit 134. May be entered directly.

  If the processing speed of the microcomputer 172 is high, the microcomputer 172 can detect the rotation state of the motor 20 from the change in the amplitude of the AC component after HPF, and can detect that the motor 20 has rotated to the target rotation angle. The braking start signal (OUT) can be output during a period in which the motor 20 rotates to the target rotation angle and the amplitude of the AC component is large.

In the second embodiment, the motor control unit 154 and the microcomputer 172 correspond to the timing control means of the present invention.
[Third Embodiment]
A third embodiment of the present invention is shown in FIGS. The rotation detection device 180 of the DC motor device 6 of the third embodiment is different from the rotation detection devices of the first and second embodiments in that a braking start signal is output in synchronization with the rising edge of the detection pulse.

As shown in FIG. 11, the D input of the FF 160 is fixed to “L”, and the notCLR input is fixed to “H”. A detection pulse is input to the CK terminal.
Thereby, as shown in FIG. 12, when the braking command signal (notPR input) output from the motor control unit 154 is “L”, the Q output is “H” regardless of the value of the detection pulse (CK input). It is. In this case, since SW 110 is on and SW 112 is off, short circuit braking is not started for motor 20.

  When the braking command signal (notPR input) is “H”, the Q output becomes “L” at the rising edge of the detection pulse (CK input). When the Q output becomes “L”, the SW 110 is turned off and the SW 112 is turned on, so that the short-circuit braking for the motor 20 is started. That is, when the braking command signal output from the motor control unit 154 is “H”, short-circuit braking is started in synchronization with the rising edge of the detection pulse.

  At the fall of the detection pulse (CK input), the previous Q output is held. Therefore, even if the braking command signal is “H”, if the previous Q output is “H”, the Q output remains “H”, so that short-circuit braking is not started for the motor 20. If the previous Q output is “L”, the Q output remains “L”, so that the short-circuit braking that has been executed for the motor 20 is continued.

  In the third embodiment, when the braking command signal is “H”, short circuit braking to the motor 20 is started in synchronization with the rising edge of the detection pulse, so that a short circuit occurs at the beginning of the period when the detection pulse becomes “H”. A surge current is generated by braking. Therefore, it is possible to prevent a surge current from occurring after the start timing of the short-circuit braking is delayed and the pulse signal changes from “H” to “L”.

  As a result, a surge current can be generated within a period in which the detection pulse becomes “H”, so that a surge current due to short-circuit braking is not newly generated as a detection pulse. Therefore, the rotation angle when the DC motor 20 stops based on the detection pulse can be detected with high accuracy without performing any processing on the detection pulse generated by the signal processing unit 130.

  In the third embodiment, the motor control unit 154 and the FF 160 correspond to the timing adjustment unit of the present invention that starts short-circuit braking for the motor 20 in synchronization with the rising edge of the detection pulse when the braking command signal is “H”. .

  Note that when the braking command signal is “H”, a function of starting short-circuit braking for the motor 20 in synchronization with the rising edge of the detection pulse may be executed by a microcomputer instead of the motor control unit 154 and the FF 160.

[Fourth Embodiment]
A fourth embodiment of the present invention is shown in FIGS. The rotation detection device 190 of the DC motor device 8 of the fourth embodiment is different from the rotation detection device 180 of the third embodiment in that it outputs a braking start signal in synchronization with the fall of the detection pulse. The other configuration is substantially the same as that of the third embodiment.

As shown in FIG. 13, the detection pulse output from the signal processing unit 130 is input to the CK terminal of the FF 160 via the NOT circuit 192.
Thereby, when the braking command signal (notPR input) is “H”, the Q output becomes “L” at the rising edge of the CK input, that is, the falling edge of the detection pulse. When the Q output becomes “L”, the SW 110 is turned off and the SW 112 is turned on, so that the short-circuit braking for the motor 20 is started. That is, when the braking command signal output from the motor control unit 154 is “H”, short-circuit braking is started in synchronization with the falling edge of the detection pulse.

  At the fall of the CK input, that is, the rise of the detection pulse, the previous Q output is held. Therefore, even if the braking command signal is “H”, if the previous Q output is “H”, the Q output remains “H”, so that short-circuit braking is not started for the motor 20. If the previous Q output is “L”, the Q output remains “L”, so that the short-circuit braking that has been executed for the motor 20 is continued.

  In the fourth embodiment, when the braking command signal is “H”, the short-circuit braking for the motor 20 is started in synchronization with the falling edge of the detection pulse. Therefore, the period when the detection pulse falls and becomes “L”. Initially, as shown in FIG. 14B, a surge current 310 due to short-circuit braking is generated in the motor current. Then, the component 312 of the surge current 310 is detected in a period in which the amplitude of the detection current after HPF is small.

  As a result, a surge current is generated during the period in which the detection pulse is “L”, so that a surge current 310 due to short circuit braking is newly generated as a detection pulse 314 indicated by a dotted line. Since this detection pulse 314 is an error signal when the rotation angle of the motor 20 is detected, the motor control unit 154 sets the pulse count number counted by the pulse count unit 152 to −1 to stop the motor 20. Can be detected correctly.

  In the fourth embodiment, the motor control unit 154, the FF 160, and the NOT circuit 192 start the short-circuit braking for the motor 20 in synchronization with the falling edge of the detection pulse when the braking command signal is “H”. It corresponds to the adjusting means.

  In addition, when the braking command signal is “H”, the function of starting short-circuit braking for the motor 20 in synchronization with the falling edge of the detection pulse is executed by the microcomputer instead of the motor control unit 154, the FF 160, and the NOT circuit 192. May be.

[Fifth Embodiment]
FIG. 15 shows a fifth embodiment of the present invention. 15 is different from the first to fourth embodiments in that the short-circuit braking SW 112 is removed and the diode 202 is connected in parallel with the SW 110. In FIG. 15, switching on / off of the SW 110 may be controlled by a combination of the rotation state detection unit 150 and the FF as in the first to fourth embodiments, or the SW 112 is removed. Since only the SW 110 is switched, it may be controlled only by the rotation state detection unit 150.

  The diode 202 is connected in a direction that allows a current flow from the DC power source 202 to the motor 20 but prohibits a current flow from the motor 20 to the DC power source 102. Then, SW 110 is turned on when the motor 20 is normally rotated, and SW 110 is turned off when the motor 20 is braked.

  Even when the SW 110 is turned off, the energization path between the motor 20 and the DC power source 102 is maintained via the diode 202. Therefore, when the SW 110 is turned off while the motor 20 is rotating and the power supply from the DC power supply 102 to the motor 20 is interrupted, the rotating motor 20 operates as a generator, and the current flows to the DC power supply 102 side through the diode 202. Shed. Thereby, since the regenerative braking force acts on the motor 20, the motor 20 stops.

In the fifth embodiment, the SW 110 and the diode 202 correspond to the braking means of the present invention.
[Sixth Embodiment]
A sixth embodiment of the present invention is shown in FIGS. As shown in FIGS. 16 and 17, the rotation detection device 210 of the DC motor device 12 of the sixth embodiment is mainly composed of a DC power source 102, an AC superposition unit, as compared with the first to fifth embodiments. The difference is that power is supplied from the motor 104 to the motor 20 via the motor driver 212. In addition, the same code | symbol as 1st Embodiment is attached | subjected to the same component as the rotation detection apparatus 100 of 1st Embodiment, and the detailed description is abbreviate | omitted.

As shown in FIG. 16, the motor driver 212 is configured by a known H-bridge circuit (so-called full bridge) including four switches.
The motor driver 212 includes SW1, SW2, SW3, and SW4 made of, for example, MOSFETs. A connection point between SW1 on the high side and SW3 on the low side (that is, one midpoint of the H bridge circuit) is connected to one brush 22 in the motor 20. Similarly, the connection point between the other SW 2 on the high side and the SW 4 on the low side (the other midpoint of the bridge circuit) is connected to the other brush 24 in the motor 20.

The driver control unit 214 controls on / off of the SWs 1, 2, 3, and 4 as shown in the truth table shown in FIG.
(Stop control)
When the motor 20 stops and the rotation angle of the motor 20 is not detected, the motor control unit 222 of the rotation state detection unit 220 illustrated in FIG. 17 sets the braking command signals 1 and 2 to “L”.

  When the braking command signals 1 and 2 are “L”, the not PR input, D input, and not CLR input of the FFs 160 and 162 are “L”, so that the Q output of the FFs 160 and 162 is “H” from the truth table of FIG. become. However, since the braking command signals 1 and 2 are “L”, the driver signals 1 and 2 that are the outputs of the AND circuits 230 and 232 are “L”.

  As illustrated in FIG. 18, when the driver signals 1 and 2 are “L”, the driver control unit 214 turns off SW <b> 1 to SW <b> 4 of the motor driver 212. Therefore, when the braking command signals 1 and 2 are “L”, the DC voltage is not applied from the DC power source 102 to the motor 20, so the motor 20 continues to be stopped. Further, since no AC voltage is applied, the rotation angle of the motor 20 is not detected.

(Forward rotation control)
In the normal rotation control, the motor control unit 222 sets the braking command signal 1 to “H” and sets the braking command signal 2 to “L”.

  When the braking command signal 1 is “H” and the braking command signal 2 is “L”, the notPR input and D input of the FF 160 are “L” and the not CLR input is “H”. The Q output is “H”. Since the braking command signal 1 is “H”, the driver signal 1 that is the output of the AND circuit 230 is “H”.

  On the other hand, when the braking command signal 1 is “H” and the braking command signal 2 is “L”, the notPR input and D input of the FF 162 are “H”, and the notCLR input is “L”. From the table, the Q output of the FF 162 is “L”. Since the braking command signal 2 is “L”, the driver signal 2 that is the output of the AND circuit 232 is “L”.

  As shown in FIG. 18, when the driver signal 1 becomes “H” and the driver signal 2 becomes “L”, the driver control unit 214 turns on SW1 and SW4 of the motor driver 212, and turns off SW2 and SW3. To do. Therefore, when the braking command signal 1 is “H” and the braking command signal 2 is “L”, the motor 20 rotates forward.

(Reverse rotation control)
In the case of reverse rotation control, the motor control unit 222 sets the braking command signal 1 to “L” and sets the braking command signal 2 to “H”.

  When the braking command signal 1 is “L” and the braking command signal 2 is “H”, the notPR input and D input of the FF 160 are “H” and the not CLR input is “L”. The Q output is “L”. Since the braking command signal 1 is “L”, the driver signal 1 that is the output of the AND circuit 230 is “L”.

  On the other hand, when the braking command signal 1 is “L” and the braking command signal 2 is “H”, the not PR input and D input of the FF 162 are “L” and the not CLR input is “H”. From the table, the Q output of the FF 162 is “H”. Since the braking command signal 2 is “H”, the driver signal 2 that is the output of the AND circuit 232 is “H”.

  As shown in FIG. 18, when the driver signal 1 becomes “L” and the driver signal 2 becomes “H”, the driver control unit 214 turns off SW1 and SW4 of the motor driver 212, and turns on SW2 and SW3. To do. Therefore, when the braking command signal 1 is “L” and the braking command signal 2 is “H”, the motor 20 rotates in the reverse direction.

(Short-circuit braking control)
When the motor 20 reaches the target rotation angle, the motor control unit 222 sets the braking command signals 1 and 2 to “H”.

  When the braking command signals 1 and 2 are “H”, the notPR input, D input, and notCLR input of the FFs 160 and 162 are “H”, so that the Q output of the FFs 160 and 162 is CK input from the truth table of FIG. It becomes “H” at the rising edge and becomes the previous Q output value at the falling edge.

  During forward rotation control and reverse rotation control, the Q output of one of the FFs 160 and 162 is “H” and the other is “L”, so the not PR input, D input, and not CLR of the braking command signals 1 and 2 and FF 160 and 162 When the input is “H”, both Q outputs are “H”, that is, the driver signals 1 and 2 become “H” at the rising edge of the CK input.

  If the not PR input, D input and not CLR input of the braking command signals 1 and 2 and FFs 160 and 162 are “H” and both Q outputs are “H”, the state of the Q output and the driver signals 1 and 2 is “ Continue with “H”.

  As shown in FIG. 18, when the driver signals 1 and 2 become “H”, the driver control unit 214 turns off SW1 and SW2 and turns on SW3 and SW4. Thereby, since the brushes 22 and 24 of the rotating motor 20 are short-circuited, energy due to the back electromotive force of the motor 20 generated at the time of the short-circuit is consumed by the low-side SWs 3 and 4 and the motor 20. As a result, the motor 20 is braked and eventually stops.

(Motor control routine)
Next, a motor control routine of the sixth embodiment will be described based on FIG. In FIG. 20, “S” represents a step.

  First, in a state where the motor 20 is not driven and the motor 20 is stopped, the motor control unit 222 sets the braking command signals 1 and 2 to “L” in S430. As a result, since the driver signals 1 and 2 become “L”, SW1 to SW4 are turned off. In this case, the DC voltage and the AC voltage are not applied to the motor 20, and the motor 20 continues the rotation stop state.

  Next, in S432, the motor control unit 222 determines whether a condition for driving the motor 20 is satisfied. The establishment of the driving condition of the motor 20 is determined based on, for example, whether an air volume adjustment for air conditioning is commanded or a power window raising / lowering is commanded. When the drive condition of the motor 20 is not satisfied (S432: No), the motor control unit 222 ends this routine.

  When the driving condition of the motor 20 is satisfied (S432: Yes), in S434, the motor control unit 222 sets the braking command signal 1 to “H” and sets the braking command signal 2 to “ L ”. As a result, the Q output of the FF 160 becomes “H”, and the Q output of the FF 160 becomes “L”. The driver signal 1 becomes “H” and the driver signal 2 becomes “L”. As a result, SW1 and 4 are turned on and SW2 and 3 are turned off, so that the motor 20 rotates in the forward rotation direction (S436).

  When the motor 20 rotates, the motor control unit 222 calculates a rotation angle and a rotation speed as the rotation state of the motor 20 based on the count number output from the pulse count unit 152 (S438).

  Next, the motor control unit 222 determines whether or not the braking condition for the motor 20 is satisfied based on whether or not the air conditioning damper or power window that is the driving target of the motor 20 has reached the target position (S440). . The motor control unit 222 determines whether or not the drive target has reached the target position based on whether or not the rotation angle of the motor 20 has reached the target rotation angle.

If the drive target has not reached the target position, it is determined that the motor braking condition is not satisfied (S440: No). In this case, the motor control unit 222 ends this routine.
When the driving target reaches the target position and the motor braking condition is satisfied (S440: Yes), the motor control unit 222 sets the braking command signals 1 and 2 to “H” in S442. As a result, the Q output of the FF 160 remains “H”, which is the previous state, and the Q output of the FF 160 remains “L”, which is the previous state, until CK rises. Therefore, the driver signal 1 is “H” and the driver signal 2 is “L”.

When CK rises (S444: Yes), both Q outputs of the FFs 160 and 162 become “H”, so that both the driver signals 1 and 2 become “H” (S446).
As a result, SW1 and SW2 are turned off and SW3 and 4 are turned on, so that short-circuit braking for the motor 20 is held (S448).

  Then, the motor 20 stops completely after a certain time. Accordingly, no new detection pulse is generated, so that the counting by the pulse count unit 152 ends (S450). When the motor is completely stopped, the motor control unit 222 sets the braking command signals 1 and 2 to “L” (S452). As a result, since the driver signals 1 and 2 become “L”, SW1 to SW4 are turned off. As a result, the motor 20 continues the rotation stop state.

  When the motor 20 is reversely rotated, the braking command signal 1 is set to “L” and the braking command signal 2 is set to “H” in S434. Thereby, in S436, SW1 and 4 are turned off, and SW2 and 3 are turned on.

As described above, in the sixth embodiment, the motor 20 can be rotated forward or backward by the motor driver 212 configured by an H-bridge circuit.
In the sixth embodiment, the motor driver 212 corresponds to the braking means of the present invention, the rotation state detection unit 220 having the pulse count unit 152 and the motor control unit 222 corresponds to the rotation state detection means of the present invention, and the motor control unit 222 and FFs 160 and 162, and AND circuits 230 and 232 serve as timing adjustment means of the present invention that starts short-circuit braking for the motor 20 in synchronization with the rising edge of the detection pulse when the braking command signals 1 and 2 are “H”. Equivalent to.

20 corresponds to the function executed by the braking means and the timing control means of the present invention.
In the sixth embodiment, when the motor 20 is braked, the motor 20 is short-circuit braked by turning off SW1 and SW2 and turning on SW3 and 4 of the motor driver 212 shown in FIG.

On the other hand, you may perform the PWM braking which brakes the motor 20 by switching ON, OFF of SW1, 2, 3, 4 by a predetermined | prescribed duty ratio.
Specifically, by turning on SW1 and SW4 and turning off SW2 and SW3, a period in which one brush 22 of motor 20 is at a high potential (that is, a period in which motor 20 is about to rotate forward), SW2 and SW3 By turning on and turning off SW1 and SW4, the period in which the other brush 24 is at a high potential (that is, the period in which the motor 20 is going to reverse) is alternately switched based on the duty ratio.

  For example, the duty ratio is set to 50 [%] so that the average value of the DC voltage applied to the motor 20 becomes zero. In this way, by switching the polarity of the DC power source applied to the motor 20 with a duty ratio of 50% (switching the rotation direction), the motor 20 is not given a rotational torque in a specific direction, and the rotating motor 20 is rotating. Will be stopped by braking.

Note that the duty ratio Sw is set to 50 [%] only as an example, and the duty ratio can be appropriately set to a value within a range where the rotation of the motor 20 can be stopped.
In addition, when switching the polarity of the DC voltage applied from the DC power supply 102 applied to the motor 20 at the duty ratio, the switching PWM frequency can be set as appropriate. However, it is necessary to set the frequency different from the frequency of the AC voltage applied from the AC superimposing unit 104 (that is, the frequency of the AC voltage output from the AC power source 106). More specifically, the frequency of the AC voltage should be higher than the PWM frequency.

  As a result, the HPF 132 in the input stage of the signal processing unit 130 can easily remove only the AC component due to the AC voltage from the AC superimposing unit 104 by removing the PWM frequency component. If the alternating current component by the alternating current superimposing unit 104 can be taken out in this way, then the envelope detection unit 138 can perform envelope detection and generate the rotation pulse Sp based on the detection signal after the envelope detection. .

[Seventh Embodiment]
A seventh embodiment of the present invention is shown in FIG. In the first to sixth embodiments, an example in which a plurality of phase coils are delta-connected has been described. However, in the motor 240 of the seventh embodiment, three phase coils L11, L12, and L13 are star-connected. .

  Capacitors C1 and C2 are connected in parallel to the coils L11 and L12, respectively. Thereby, with the rotation of the armature 242, the reactance between the brushes 22 and 24 changes, and the magnitude of the amplitude of the AC component output from the HPF 132 changes. Therefore, the start timing of the short-circuit braking for the motor 240 can be determined based on the detection pulse generated from the change in the amplitude of the AC component, as in the first to sixth embodiments.

In the seventh embodiment, the capacitors C1 and C2 correspond to the variable mechanism of the present invention.
[Eighth Embodiment]
An eighth embodiment of the present invention is shown in FIGS.

  As shown in FIG. 22, the motor 250 includes brushes 22 and 24, a commutator 40, a housing 252, an armature 270 accommodated in the housing 252, and a rotating shaft 280. The armature 270 is fixed to a rotating shaft 280 disposed at the axis of the housing 252 and rotates together with the rotating shaft 280.

  The motor 250 of the eighth embodiment is different from the motor 20 of the first embodiment in that the capacitor C1 is not connected in parallel to the phase coil L1 and the convex portion 254 is provided on the inner peripheral surface of the housing 252. Is different. On the other hand, other configurations, that is, the configurations of the brushes 22 and 24, the commutator 40, the phase coils L1, L2, and L3, and the housing 252 and the permanent magnet 260 are not shown in FIG. 1 of the first embodiment. , 262, rotor core 272, and rotating shaft 280 are substantially the same as those of the motor 20 of the first embodiment.

  The housing 252 has a substantially cylindrical shape, and two permanent magnets 260 and 262 for generating a magnetic field are fixed to the inner peripheral surface thereof so as to face each other in the radial direction. When viewed in the circumferential direction, the two permanent magnets are fixed at a predetermined interval. One of the permanent magnets 260 and 262 on the surface facing the rotor core 272 of the armature 270 is N-pole and the other is S-pole. That is, the motor 250 according to the present embodiment is configured as a DC motor having a two-pole field.

  The housing 252 is formed of a yoke that is a soft magnetic material, and constitutes a magnetic circuit of the motor 250 together with two permanent magnets 260 and 262 fixed to the inner peripheral surface.

  The armature 270 is mainly composed of a rotor core 272 and an armature coil 278. The rotor core 272 is formed of a soft magnetic material, has three teeth (saliency poles) 274, 275, and 276, and an armature coil 278 is wound thereon. Specifically, the first phase coil L1 is wound around the first tooth 274, the second phase coil L2 is wound around the second tooth 275, and the third phase coil L3 is wound around the third tooth 276. Yes. These three phase coils L 1, L 2, L 3 are delta-connected, and constitute an armature coil 278.

  A commutator 40 is fixed to the rotary shaft 280, and a pair of brushes 22 and 24 arranged opposite to each other (that is, 180 ° apart in the rotation direction) are in sliding contact with the commutator 40. ing.

  A convex portion 254 is provided between the two permanent magnets 260 and 262 on the inner peripheral surface of the housing 252. Since two permanent magnets 260 and 262 are fixed at a predetermined interval in the circumferential direction on the inner peripheral surface of the housing 252, there is a region (inter-magnet region) where the permanent magnets 260 and 262 do not exist in the circumferential direction. There are two places. In the present embodiment, as shown in FIG. 22, a convex portion 254 is provided in one area between the magnets so as to protrude radially inward from the inner peripheral surface of the housing 252. Further, the convex portion 254 is provided at a predetermined interval from each of the permanent magnets 260 and 262 in the circumferential direction so as not to come into contact with either of the two permanent magnets 260 and 262.

  The convex portion 254 is formed of a soft magnetic material, has a predetermined length in the circumferential direction, and has a predetermined thickness in the radial direction. And by providing this convex part 254, the magnetic resistance of the magnetic circuit comprised by the rotor core 272 and the housing 252 changes with rotation of the rotor core 272. In the following description, “magnetic resistance” means the magnetic resistance of a magnetic circuit constituted by the rotor core 272 and the housing 252 unless otherwise specified.

Here, the gap between the rotor core 272 and the housing 252 and the magnetic resistance in the motor 250 will be specifically described.
As described above, the rotor core 272 and the housing 252 are both made of a soft magnetic material, and the magnetic permeability thereof is much larger than the magnetic permeability of air. Therefore, the magnetic resistance of the motor 250 is such that the air gap between the rotor core 272 (specifically, the outer peripheral surface of each tooth 274, 275, 276) and the inner peripheral surface of the housing 252 or the permanent magnets 260, 262, and each permanent magnet 260 , 262 greatly depends on the sum of the thicknesses. That is, the larger the air gap, the larger the magnetic resistance, and conversely, the smaller the air gap, the smaller the magnetic resistance.

  However, the magnetic permeability of the permanent magnets 260 and 262 is substantially the same as that of air. Therefore, each permanent magnet 260, 262 is equivalent to the presence of air when viewed magnetically. In other words, in consideration of the magnetic resistance of the motor 250, the presence of the permanent magnets 260 and 262 having the same permeability as air can be ignored, and each permanent magnet 260 and 262 can be treated as an air gap. it can. Therefore, if there is no projection 254, the air gap between the rotor core 272 and the inner peripheral surface of the housing 252 is constant even when the rotor core 272 rotates, and therefore the magnetic resistance does not change with the rotation. .

  However, in the present embodiment, a soft magnetic convex portion 254 having substantially the same permeability as the housing 252 is provided on the inner peripheral surface of the housing 252. Therefore, the magnetic resistance of the motor 250 has a different value depending on the rotation angle of the armature 270, that is, whether or not the outer peripheral surface of each of the teeth 274, 275, 276 of the rotor core 272 is opposed to the convex portion 254. That is, as the armature 270 rotates, its magnetic resistance changes. When the magnetic resistance changes, the inductance, that is, the reactance also changes as the impedance of the motor circuit, so that the amplitude of the AC component of the current flowing through the motor circuit changes.

  As shown in FIG. 22A, in the state A where the convex portion 254 faces the rotor core 272, the air gap between the rotor core 272 and the convex portion 254 becomes small, so that the magnetic resistance of the motor 250 is As smaller. In general, since the inductance is proportional to the reciprocal of the magnetic resistance, if the magnetic resistance changes, the inductance of the motor circuit changes accordingly. Therefore, when the magnetic resistance decreases as in state A, the inductance of the motor circuit increases.

  On the other hand, as shown in FIG. 22B, in the state B where the rotor core 272 does not face the convex portion 254, the air gap becomes larger than that in FIG. As will grow. Therefore, the inductance of the motor circuit is reduced.

Thus, the inductance of the motor circuit changes periodically with the rotation of the armature 270.
In the present embodiment, since the rotor core 272 includes the three teeth 274, 275, and 276, a periodic inductance change accompanying the rotation occurs every time the armature 270 rotates 120 °. For this reason, the amplitude change of the AC component described above also occurs periodically every time the armature 270 rotates 120 °.

  FIG. 23 shows an example of the motor current waveform and the detection pulse output from the comparison unit 142. In the present embodiment, a rotation pulse is generated every time the motor 250 rotates 120 °.

  Therefore, in this embodiment, the inductance changes with the rotation of the armature 270, and a change in the amplitude of the AC component caused by the change in the inductance is detected. And the start timing of the short circuit braking with respect to the motor 250 can be determined based on the detection pulse generated from the amplitude change of the AC component output from the HPF 132, as in the first to sixth embodiments.

In the present embodiment, the convex portion 254 corresponds to the variable mechanism of the present invention, and the inductance between the brushes 22 and 24 changes as the armature 270 rotates.
Instead of installing the convex portion 254, which is a separate member from the housing 252, as the variable mechanism, the housing itself at a position corresponding to the convex portion 254 protrudes toward the inner peripheral side, and as the armature 270 rotates, the brush 22 , 24 may be changed.

[Other Embodiments]
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the above-described embodiment, an example (first embodiment) in which the capacitor C1 is connected to only one phase coil of the three phase coils L1, L2, and L3 as the DC motor has been described. Capacitors with different capacities may be connected to each of the coils. According to this configuration, the AC component amplitude changes in three stages due to the change in reactance accompanying the rotation of the motor. Therefore, by detecting the order of the amplitude change, in addition to the rotation angle and the rotation speed, the rotation direction can be detected. Is possible.

For example, if the order of amplitude change is “Large”, “Medium”, “Small”, it can be detected as forward rotation, and if it is “Small”, “Medium”, “Large”, it can be detected as reversed. .
When a capacitor is connected to each of the three phase coils, any two of the capacitors can have the same capacitance value. However, in that case, the rotation angle and the rotation speed can be detected, but the rotation direction cannot be detected.

  In each of the above embodiments, a three-phase DC motor having three phases of armature coils has been described as an example. However, the application of the present invention is not limited to a three-phase motor. Even a motor having a phase or higher can be applied.

In a motor having four or more phases, if a capacitor is connected in parallel to only one of the phase coils, at least the rotation angle and the rotation speed can be detected.
In motors with three or more phases, if capacitors with different capacitance values are connected to at least two phase coils, the direction of rotation is based on the AC component change pattern due to the stepwise change pattern of impedance accompanying rotation. Can be detected.

  In the first to sixth embodiments, in the three-phase motor 20, the capacitor C <b> 1 connects the pair of commutator pieces 41 and 43, and the brush is simultaneously applied to both the pair of commutator pieces 41 and 43. The variable mechanism 22 and 24 are in sliding contact with each other has been described. On the other hand, in a motor having four or more phases, when the capacitor is connected to a pair of commutator pieces, a variable mechanism is configured so that the brushes 22 and 24 do not slide simultaneously with both of the pair of commutator pieces. May be.

  Also in the configuration of the variable mechanism, the reactance between the pair of brushes 22 and 24 changes with the rotation of the armature, so that the amplitude of the AC component changes. Therefore, the start timing for braking the DC motor can be controlled based on the change in the amplitude of the AC component.

  In addition, the configuration described in the above embodiment is not limited to the configuration in which a capacitor is connected in parallel to the phase coil, and the configuration in which a magnetic convex portion is provided on the inner peripheral surface of the motor housing. As long as the reactance changes, the variable mechanism may be realized with any configuration.

  For example, a configuration in which a capacitor is connected in parallel to the phase coil and a configuration in which a magnetic convex portion is provided on the inner peripheral surface of the motor housing may be used in combination, or a coil having a different inductance may be installed in each phase coil. Also good.

  In addition, even in the case of a normal DC motor that does not employ the configuration of the above-described embodiment and includes an armature coil composed of phase coils having the same inductance, two commutators are used when the commutator piece that contacts the brush is switched. When the pieces touch one brush at the same time, the configuration of the motor circuit changes and the reactance changes. Therefore, even in a normal DC motor, an AC voltage is superimposed on a DC voltage, and the rotation state of the motor can be detected based on a change in the amplitude of an AC component that changes as the armature rotates.

  In the above embodiment, the reactance between the pair of brushes is changed as the armature rotates as the impedance of the variable mechanism of the motor. On the other hand, as the impedance of the variable mechanism, for example, a resistance is connected in parallel to one of the three phase coils L1, L2, and L3, and the resistance value between the pair of brushes is changed as the armature rotates. May be.

  In this configuration, the DC component of the motor current varies with the amplitude of the AC component of the motor current due to the change in resistance value. Also in this case, it is possible to remove the DC component from the motor current and extract the AC component by passing HPF as the AC component extracting means. Based on the change in the amplitude of the alternating current component that changes with the rotation of the armature, the rotational state of the motor can be detected even during braking, for example, regardless of the magnitude of the direct current component of the motor current.

  In the above embodiment, the DC power supply 102 and the AC power supply 106 are separately provided as power supply units for applying a DC voltage and an AC voltage to the motor (that is, supplying DC current and AC current). The voltage (current) is superimposed via the coupling capacitor 108 and applied (supplied) to the motor. However, such a configuration of the power supply unit is merely an example. For example, a direct current and an alternating current are One power supply unit that generates and supplies superimposed AC / DC mixed current (pulsating flow) may be used. As a result, when rotating the motor, AC current and DC current are supplied to the motor and braking is performed. The specific configuration of the power supply is not particularly limited as long as the supply of the direct current is interrupted and the alternating current can be supplied.

  Moreover, although the H bridge circuit (full bridge) which consists of four switching elements was shown as a motor driver in the said 6th Embodiment, you may comprise a motor driver in circuits other than an H bridge circuit.

  2, 4, 6, 8, 10, 12: DC motor device, 20, 240, 250: motor, 22, 24: brush, 30, 242 and 270: armature, 40: commutator, 41, 42, 43: Commutator piece, 160, 162: FF (timing adjusting means), 100, 170, 180, 190, 200, 210: Rotation detection device, 102: DC power supply (power supply unit), 104: AC superposition unit, 106: AC power supply (AC superposition unit, power supply unit), 108: coupling capacitor (AC superposition unit, power supply unit), 110, 112: SW (braking unit), 112: NOT circuit (braking unit), 116: NOT circuit (timing adjusting unit) ), 120: rotation signal detection unit, 122: current detection unit (energization detection unit), 130: signal processing unit (energization detection unit), 132: HPF, 134: amplification unit, 138: envelope detection , 140: LPF, 142: comparison unit, 150, 220: rotation state detection unit (rotation state detection unit), 152: pulse count unit, 154, 222: motor control unit (timing adjustment unit), 160, 162: FF (Timing adjusting means), 212: motor driver (braking means), 230, 232: AND circuit (timing adjusting means), 254: convex portion (variable mechanism), 278: armature coil, C1, C2: capacitor (variable mechanism) ), L1, L2, L3: Phase coil, R1: Current detection resistor

Claims (9)

In the rotation detection device that detects the rotation state of the DC motor,
The DC motor is
An armature having an armature coil comprising at least three phase coils;
A commutator having a plurality of commutator pieces to which the armature coils are connected;
At least a pair of brushes in sliding contact with the commutator;
A variable mechanism in which impedance periodically changes between the pair of brushes as the armature rotates,
With
The rotation detection device includes:
Braking means for electrically braking the DC motor;
The DC motor is electrically connected to a common energizing path, which is an energizing path for the motor current flowing between the pair of brushes, both when the DC motor is normally rotated and braked, and the DC voltage driving the DC motor is changed to AC. AC superimposing means for superimposing a voltage;
An energization detecting unit that is electrically connected to the common energization path and detects an amount of electricity related to an AC current supplied to the DC motor by the AC superimposing unit;
Based on the fact that the amplitude of the AC component of the quantity of electricity detected by the energization detecting means periodically changes by the variable mechanism as the armature rotates, at least one of the rotation angle and the rotation speed of the DC motor Rotation state detection means for detecting one;
Timing control means for controlling the start timing of braking executed by the braking means based on the amplitude change of the alternating current component detected by the energization detecting means;
It is characterized by providing. The energization detection unit includes a pulse generation unit that generates a pulse signal according to an amplitude change of the AC component,
The rotation state detection means detects the rotation state based on the pulse signal generated by the pulse generation means,
The timing control means controls the start timing of the braking by the braking means based on the pulse signal generated by the pulse generating means.
The rotation detection device according to claim 1.   The rotation detection device according to claim 2, wherein the timing control unit starts the braking by the braking unit when the pulse signal is at a high level.   The rotation detection device according to claim 2, wherein the timing control unit starts the braking by the braking unit in synchronization with a rise of the pulse signal. The timing control means starts the braking by the braking means in synchronization with the fall of the pulse signal,
The rotation state detection means detects the rotation state except for one pulse signal generated by the pulse generation means after the braking means starts the braking.
The rotation detection device according to claim 2.   The rotation detecting device according to claim 1, wherein the braking unit short-circuits the pair of brushes to short-circuit the DC motor.   The rotation detecting device according to any one of claims 1 to 5, wherein the braking means brakes the DC motor by regenerative braking. Switching means for switching the polarity of a DC voltage applied to the DC motor;
The braking means brakes the DC motor by PWM control of the polarity switching by the switching means.
The rotation detection device according to claim 1, wherein the rotation detection device is a rotation detection device. An armature having an armature coil comprising at least three phase coils;
A commutator having a plurality of commutator pieces to which the armature coil is connected;
At least a pair of brushes in sliding contact with the commutator;
A variable mechanism in which the reactance of impedance periodically changes between the pair of brushes as the armature rotates,
A DC motor having
The rotation detection device according to any one of claims 1 to 8,
A direct-current motor device comprising:

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