JP4696818B2 - DC motor drive control device and pump unit - Google Patents

Description

  The present invention relates to a DC motor drive control device and a pump unit.

2. Description of the Related Art Conventionally, there has been known a motor driving device that detects a rotor rotational position with an encoder provided in the vicinity of a DC brushless motor, performs PWM control based on the detected rotor rotational position information, and drives the motor (for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-80178

  However, since the conventional motor drive device employs a simple power supply that outputs a fixed voltage as the drive power supply for the motor, PWM control is required to control the rotational speed of the motor. That is, it is necessary to turn on and off the switching means for each PWM carrier frequency in order to supply an appropriate current from the drive power supply to the motor winding. As a result, the conventional motor driving apparatus has the following problems.

  First, the conventional motor driving device frequently performs switching, and the switching means generates heat. Secondly, in the conventional motor driving apparatus, ripples are generated in the current to the motor winding as a result of switching, causing motor vibration and noise. Third, when the switching means is turned on and off, a harmonic current having a PWM carrier frequency as a fundamental frequency is generated, which causes noise.

  The present invention has been proposed in view of the above-described circumstances, and adopts a simple power source that outputs a fixed voltage as a driving power source of a motor, while also generating heat of the switching means, vibration and noise of the motor, and harmonics. An object of the present invention is to provide a DC motor drive control device and a pump unit capable of suppressing the generation of wave current.

  The DC motor drive control device of the present invention detects the rotor rotational position of the DC motor, determines the energization state from the DC power source that outputs a fixed voltage based on the detected rotational position to the multi-phase motor windings, The drive control of the DC motor is performed based on the determined energization state. The DC motor drive control device includes peak current value determining means, first drive control means, and second drive control means. The peak current value determining means determines the maximum value of the current to be supplied to the motor windings of the plurality of phases in accordance with the capacity variable instruction voltage that controls the capacity of the DC motor. The first drive control means supplies current to the motor windings of a plurality of phases at a duty ratio of 100% when the current value supplied to the motor winding is equal to or less than the maximum value determined by the peak current value determining means. Is. When the current value energized in the motor winding exceeds the maximum value determined by the peak current value determining unit, the second drive control unit is configured to output a plurality of phases regardless of the determined energization state of the plurality of phases of motor windings. The current supply to the motor winding is turned off for a preset time.

  According to the present invention, when the current value supplied to the motor winding is equal to or less than the determined maximum value, the current supply to the motor windings of the plurality of phases is performed with a duty ratio of 100%, and the motor winding is supplied with current. When the current value exceeds the maximum value, the current supply to the motor windings of the plurality of phases is turned off for a predetermined set time regardless of the energized state of the motor windings of the plurality of phases. As described above, the DC motor is driven by the current supply with the duty ratio of 100% and the current supply OFF at the set time, and the fixed voltage power source is used by the above two without performing the PWM control. PAM control is realized in a pseudo manner. Thereby, the DC motor drive control device can reduce the number of times of switching of the switching means, and can suppress the heat generation of the switching means. In addition, since PWM control is not performed, generation of ripple current and harmonic current can be suppressed. Therefore, while adopting a simple power supply that outputs a fixed voltage as a driving power supply for the motor, it is possible to suppress the heat generation of the switching means, the vibration and noise of the motor, and the generation of harmonic current.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or similar elements are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 1 is a functional block diagram of a pump unit according to the first embodiment of the present invention. As shown in the figure, the pump unit 1 includes a DC motor 10, a DC motor drive control device 20, a DC power supply 30, and a pump unit 40, and the DC motor 10 is controlled by the DC motor drive control device 20. By being driven, the pump unit 40 is activated to deliver fluid. Hereinafter, the above configuration will be described in detail.

  The DC motor 10 includes a stator 11 on which thin iron plates (thickness of about 0.5 mm) are stacked, a multi-phase motor winding 12 wound around the stator 11, a magnet rotor 13 as a rotor, It comprises rotational position detecting means 14 for detecting the rotational position of the rotor 13. Here, the rotational position detection means 14 is comprised by a Hall sensor, Hall IC, etc. Further, the rotational position detecting means 14 may be configured to detect the rotational position of the rotor 13 using the induced voltage of the motor winding 12.

  In such a DC motor 10, information on the rotor rotational position detected by the rotational position detection means 14 is transmitted to the DC motor drive control device 20, and the DC motor drive control device 20 energizes the motor windings 12 of multiple phases. Is determined, and current is supplied to the motor windings 12 of the plurality of phases according to the determined energization state. Thus, the DC motor 10 is driven by the stator 11 acting as an electromagnet, and the magnetic field of the electromagnet and the magnetic poles of the magnet rotor 13 are attracted and repelled to generate rotational torque in the rotor 13.

  The DC motor drive control device 20 includes an ON / OFF control circuit 21, a distribution circuit 22, an inverter circuit 23, a current-voltage conversion circuit 24, an amplification circuit 25, a peak current threshold generation circuit 26, and a peak current comparison circuit. 27 and an OFF time control circuit 28.

  First, in general, the DC motor drive control device 20 is input with a variable capacity instruction voltage Va so that the capacity of the DC motor 10 can be changed according to the load. In the present embodiment, the variable capacity instruction voltage Va is input to the ON / OFF control circuit 21 and the peak current threshold generation circuit 26.

  The ON / OFF control circuit 21 determines the operation / stop of the DC motor 10 according to the magnitude of the input capacity variable instruction voltage Va. The ON / OFF control circuit 21 is configured to transmit the determined operation / stop information to the distribution circuit 22. When the ON / OFF control circuit 21 determines that the DC motor 10 is to be operated, the distribution circuit 22 is supplied from the DC power supply 30 to the multi-phase motor windings 12 based on the information on the rotor rotational position from the rotational position detecting means 14. Is to determine the energization state (a state indicating how the current flows). The inverter circuit 23 includes a number of switching elements (transistors, MOSFETs, etc.) corresponding to the motor windings 12 of the plurality of phases, and switches the switching elements to supply the motor windings 12 of the plurality of phases from the DC power supply 30. Energize.

  Here, in the case of a general three-phase DC motor, the distribution circuit 22 generates six signals indicating how current flows through the motor windings 12 of the plural phases, and these six signals are input to the inverter circuit 23. Is done. The inverter circuit 23 includes six switching elements, and the six signals are switching signals for turning on and off the six switching elements. The inverter circuit 23 energizes the multi-phase motor windings 12 from the DC power supply 30 by switching the switching elements.

  However, in the DC motor drive control device 20 according to the present embodiment, the OFF time control circuit 28 is interposed between the distribution circuit 22 and the inverter circuit 23, and the inverter circuit 23 only has a switching signal from the distribution circuit 22. In addition, the switching element is controlled by a signal from the OFF time control circuit 28.

  More specifically, in the case of a general three-phase DC motor, the distribution circuit 22 generates six signals so as to perform PWM control, and the inverter circuit 23 performs PWM control to perform multi-phase motor windings 12. A current is supplied to the DC motor 10 to drive it. However, in this embodiment, the distribution circuit 22 does not generate 6 signals so as to perform PWM control, but basically 6 signals so as to supply current to the motor windings 12 of a plurality of phases with a duty ratio of 100%. Is generated.

  The current-voltage conversion circuit 24 takes in a current corresponding to the value of the current supplied to the multi-phase motor winding 12 and converts this current into a voltage waveform. Here, the converted voltage has a magnitude of about several tens to several hundreds mV, for example. The amplifier circuit 25 amplifies the voltage converted by the current-voltage conversion circuit 24. Specifically, the amplifier circuit 25 amplifies the input voltage signal several times to several tens of times. For example, when a voltage signal of several tens to several hundreds mV is input, the voltage signal of about several V (2 to 4 V). Amplify to.

  The peak current threshold generation circuit 26 determines the maximum value of the current to be supplied to the motor windings 12 of the plurality of phases according to the magnitude of the variable capacity instruction voltage for controlling the capacity of the DC motor 10, and according to the maximum value. The threshold voltage is determined.

  The peak current comparison circuit 27 inputs the threshold voltage signal determined by the peak current threshold generation circuit 26 and the voltage signal amplified by the amplification circuit 25 and compares them. Further, the peak current comparison circuit 27 has a current value supplied to the motor winding 12 when the voltage signal amplified by the amplification circuit 25 is higher than the threshold voltage determined by the peak current threshold generation circuit 26. The maximum current value determined by the peak current threshold generation circuit 26 is determined to be exceeded. Further, when the peak current comparison circuit 27 determines that the current value supplied to the motor winding 12 exceeds the maximum value of the current determined by the peak current threshold generation circuit 26, the peak current comparison circuit 27 outputs an H level signal. When it is determined that the value is less than the maximum value, an L level signal is output.

  When the signal from the peak current comparison circuit 27 is at the L level, the OFF time control circuit 28 determines whether the multi-phase motor winding 12 is independent of the energized state of the multi-phase motor winding 12 determined by the distribution circuit 22. An OFF control signal is output so as to turn off the current supply to the power supply for a preset time. When the inverter circuit 23 receives the OFF control signal from the OFF time control circuit 28, the inverter circuit 23 controls the switching means to turn off the current supply to the motor windings 12 of a plurality of phases for a set time.

  Due to the above configuration, the inverter circuit 23 drives the DC motor 10 in the energized state (duty ratio 100%) determined by the distribution circuit 22, but the L level signal from the peak current comparison circuit 27 is received. When input to the OFF time control circuit 28, the current supply to the motor windings 12 of a plurality of phases is turned off for a set time.

  That is, in the present embodiment, the DC motor drive control device 20 drives the DC motor 10 by two current supply at a duty ratio of 100% and current supply off at a set time, and without performing PWM control, With the above two, PAM control is realized in a pseudo manner using a DC power supply 30 with a fixed voltage. Thereby, the DC motor drive control device 20 can reduce the number of times of switching of the switching means, and can suppress the heat generation of the switching means. In addition, since PWM control is not performed, generation of ripple current and harmonic current can be suppressed. Therefore, while adopting a simple power supply that outputs a fixed voltage as a driving power supply for the motor, it is possible to suppress the heat generation of the switching means, the vibration and noise of the motor, and the generation of harmonic current.

  Note that the DC power supply 30 of the present embodiment is configured to output a fixed voltage by rectifying a commercial power supply (AC 100/200 V 50/60 Hz) with a diode and smoothing with a capacitor.

  FIG. 2 is a circuit configuration diagram of the DC motor 10 and the DC motor drive control device 20 of the pump unit 1 shown in FIG. The resistor R1 converts the current supplied to the multi-phase motor winding 12 into a voltage, and corresponds to the current-voltage conversion circuit 24 shown in FIG. The operational amplifier OP1 amplifies the voltage value of the resistor R1 to an amplification degree (several times to several tens times) determined by the resistance values of the resistors R2 and R3. The operational amplifier OP1 and the resistors R2 and R3 correspond to the amplifier circuit 25 shown in FIG. Note that the operational amplifier OP1 faithfully amplifies the current (total current) waveform supplied to the motor windings 12 of a plurality of phases (does not generate waveform rounding), so that a slew rate of several V / μS or less is used. Has been.

  The output signal of the operational amplifier OP1 is input to the non-inverting input terminal of the comparator CMP1. On the other hand, the variable capacity indicating voltage Va is input to the inverting input terminal of the comparator CMP1 after being divided by the resistance values of the resistors R4 and R5. The comparator CMP1 outputs an H level signal when the voltage from the operational amplifier OP1 is higher than the divided voltage of the resistors R4 and R5, and otherwise outputs an L level signal. Here, the resistors R4 and R5 correspond to the peak current threshold generation circuit 26 shown in FIG. 1, and the comparator CMP1 corresponds to the peak current comparison circuit 27 shown in FIG.

  The variable capability instruction voltage Va is input to the non-inverting input terminal of the comparator CMP2. On the other hand, a voltage division value (V0) obtained by dividing the control power supply (+5 V or the like) by the resistors R6 and R7 is input to the inverting input terminal of the comparator CMP2. The comparator CMP2 outputs an H level signal when the variable capability instruction voltage Va is higher than the divided voltage value V0, and outputs an L level signal otherwise. The resistor R8 is a hysteresis resistor for removing noise. Further, the comparator CMP2, resistors R6, R7, etc. correspond to the ON / OFF control circuit 21 shown in FIG.

  The output signal of the comparator CMP2 is input to the inverting input terminal of the comparator CMP3. A constant voltage signal is input to the inverting input terminal of the comparator CMP3. When the H level signal is output from the comparator CMP2, the constant voltage signal becomes lower than the output signal from the comparator CMP2, and the output of the comparator CMP3 becomes L level. On the other hand, when the L level signal is output from the comparator CMP2, the constant voltage signal becomes higher than the output signal from the comparator CMP2, and the output of the comparator CMP3 becomes H level. Note that a triangular wave signal may be input to the inverting input terminal of the comparator CMP3.

  An NPN transistor TR1 is provided on the output side of the comparator CMP3. The NPN transistor TR1 is turned on when the output signal from the comparator CMP3 is at the H level and turned off when the output signal is at the L level. When the NPN transistor TR1 is off, the H level voltage from the control power supply (+ 5V or the like) is input to the AND circuit AND. On the other hand, when the NPN transistor TR1 is on, an L level voltage is input to the AND circuit AND.

  The output signal of the comparator CMP1 is input to the latch circuit L. When the output signal of the comparator CMP1 is at H level, the latch circuit L is latched at H level and turns on the NPN transistor TR2. When the NPN transistor TR2 is turned on, even if the NPN transistor TR1 is turned off, an L level voltage is input to the AND circuit AND.

  A reset signal is input to the latch circuit L. The reset signal is input to the latch circuit L every time the current of the motor winding 12 is switched (phase switching), and the H level latch state is released. When a reset signal is input to the latch circuit L, the NPN transistor TR2 is turned off. When the NPN transistor TR1 is in an on state, the voltage signal input to the AND circuit AND changes from L level to H level. It becomes.

  Here, when an H level voltage signal is input to the AND circuit AND, the inverter circuit 23 supplies current to the motor windings 12 of a plurality of phases with a duty ratio of 100%. On the other hand, when an L level voltage signal is input to the AND circuit AND, the inverter circuit 23 turns off the current supply to the motor windings 12 of a plurality of phases for a set time regardless of the energization state determined by the distribution circuit 22. .

  At this time, the inverter circuit 23 turns off all of the plurality of upper arm side switching elements that perform switching between one of the terminals of the motor winding 12 of the plurality of phases and the positive terminal of the DC power supply 30, All of the plurality of lower arm side switching elements that perform switching between one terminal of the winding 12 and the negative terminal of the DC power supply 30 are turned on. Thus, in the inverter circuit 23, there is always an on-state switching element even when the current supply is off. Note that the inverter circuit 23 may turn off all of the plurality of upper arm side switching elements and turn on all of the plurality of lower arm side switching elements. The NPN transistors TR1 and TR2, the comparator CMP3, the latch circuit L, and the like correspond to the OFF time control circuit 28 shown in FIG.

  FIG. 3 is a time chart showing the operation of the DC motor drive control device 20 according to the present embodiment. In FIG. 3, it is assumed that current switching (so-called phase switching) of the motor winding 12 is performed at times t2, t4, t6, t8, and t10.

  First, at time 0, the variable capacity instruction voltage Va is higher than the voltage V0 (FIG. 3A), and the output signal of the comparator CMP2 is at the H level (FIG. 3B). Therefore, the output signal of the comparator CMP3 becomes L level, and the input voltage of the AND circuit AND becomes H level (FIG. 3 (e)). At this time, the inverter circuit 23 supplies current to the motor windings 12 of a plurality of phases with a duty ratio of 100%.

  Next, the output voltage from the operational amplifier OP1 gradually increases during the period from time 0 to time t1, and when the output voltage of the operational amplifier OP1 exceeds the divided value corresponding to the variable capacity instruction voltage Va at time t1 (FIG. 3 ( f)), the output signal of the comparator CMP1 becomes the H level (FIG. 3C). As a result, the latch circuit L is latched at the H level, the NPN transistor TR2 is turned on, and the input voltage to the AND circuit AND becomes the L level (FIG. 3 (e)). At this time, the inverter circuit 23 turns off the current supply to the multi-phase motor windings 12.

  Thereafter, a reset signal is output at time t2 (FIG. 3D). As a result, the latch state is released, the NPN transistor TR2 is turned off, and the input voltage to the AND circuit AND returns to the H level (FIG. 3 (e)). As a result, the inverter circuit 23 supplies current to the motor windings 12 of a plurality of phases with a duty ratio of 100%.

  Thereafter, the operation from time 0 to time t2 is repeatedly performed. At times t4, t6, and t10, the value of the variable capacity instruction voltage Va changes. For this reason, the input voltage to the inverting input terminal of the comparator CMP1 also changes, and the timing at which the comparator CMP1 becomes H level is different as shown in FIG.

  As is clear from FIG. 3D, the reset signal is input to the latch circuit L every time the phase is switched. Therefore, during the time Δt from when the latch circuit L is latched to the H level until the reset signal is input, the current supply is turned off regardless of whether the NPN transistor TR1 is turned on or off (FIG. 3E). ). Regardless of whether the NPN transistor TR1 is on or off, the time during which the current supply is turned off corresponds to the set time described above.

  Note that the latch circuit L is latched at the H level when the output voltage of the operational amplifier OP1 exceeds the threshold voltage determined by the peak current threshold generation circuit 26. Further, in the present embodiment, the comparator CMP1 compares the magnitudes of the voltages, but when this is replaced with a voltage, the current value supplied to the motor winding 12 is the peak current threshold generation circuit 26 during the set time Δt. It can be expressed as the time from when the maximum value of the current determined by is exceeded until the current switching of the motor winding 12 is performed next.

  FIG. 4 is a graph showing the correlation between the variable capacity instruction voltage Va and the PWM duty. In FIG. 4, the vertical axis represents the PWM duty (%), and the horizontal axis represents the variable capacity instruction voltage Va (V). In FIG. 4, the solid line indicates the control of this embodiment, and the broken line indicates the conventional PWM control.

As shown in FIG. 4, in the present embodiment, when the variable capacity instruction voltage Va is equal to or lower than the voltage V0, the output voltage of the comparator CMP2 becomes L level, and an L level voltage signal is input to the AND circuit AND. For this reason, the current supply is turned off, and the duty ratio becomes 0%. On the other hand, when the capacity variable instruction voltage Va exceeds the voltage V0, the output voltage of the comparator CMP2 becomes H level, and an H level voltage signal is input to the AND circuit AND. At this time, as described above, current is supplied with a PWM duty ratio of 100%. For this reason, in this embodiment, the DC motor 10 is driven by two current supply off and PWM duty ratio 100%.

  On the other hand, in the conventional PWM control, the capacity variable instruction voltage Va increases as the capacity variable instruction voltage Va increases until the capacity variable instruction voltage Va exceeds the voltage V0 and reaches the voltage V1 (a value larger than the voltage V0). It becomes. For this reason, in this section, the switching frequency of the inverter circuit 23 becomes very high, about 10 to 20 times that of the present embodiment.

  As described above, in the present embodiment, the DC motor 10 is driven by the current supply with the duty ratio of 100% and the current supply OFF at the set time Δt, and the above two are performed without performing the PWM control. PAM control is realized in a pseudo manner using a DC power supply 30 with a fixed voltage. Thereby, in this embodiment, since switching frequency becomes very small with about 1 / 20-1 / 10 compared with the conventional PWM control, the heat_generation | fever etc. of a switching element can be suppressed.

  FIG. 5 is a graph showing a temperature rise of the FET as a switching element. In FIG. 5, the vertical axis indicates the FET temperature rise value (K), and the horizontal axis indicates the current value (A). In FIG. 5, the solid line shows Example 1 (pseudo PAM control 1) in the present embodiment, the two-dot chain line shows Example 2 (pseudo PAM control 2) in the present embodiment, and the broken line shows conventional PWM control. Show. Furthermore, it is assumed that the set time Δt is longer in the pseudo PAM control 2 than in the pseudo PAM control 1.

  As shown in the figure, in the PAM control 2, the switching amount of the FET is the smallest, and only the loss when the FET is ON is involved in the temperature rise of the FET. For this reason, in the pseudo PAM control 2, as the supply current from the DC power supply 30 increases, the loss increases in a nearly square relationship, and the temperature rise value behaves in the same manner.

  Further, in the pseudo PAM control 1, since the switching amount increases as the current value decreases, the switching loss and the ON loss affect the temperature rise. For this reason, the temperature rise is large until the current value ranges from 0 to 0.5 (A), and even in the region where the current value ranges from 0.5 to 1.4 (A), the pseudo PAM control 2 The temperature rise is increasing.

  Also, during PWM control, both the ON loss and the switching loss increase dramatically as the current value increases. Therefore, as shown in FIG. 5, until the current value becomes 1.4 A at a duty ratio of 100%, the temperature rises rapidly. It has become. Since the duty ratio becomes 100% when the current value becomes 1.4 A, the temperature rise is the same for all of the pseudo PAM control 2, the pseudo PAM control 1, and the PWM control. When the capacity of the so-called DC motor 10 that contributes to the most energy saving is varied, the temperature rise of the FET is considerably reduced. In the example of FIG. 5, it can be seen that a difference of about 20K occurs.

FIG. 6 is a graph showing the relationship between the rotational speed of the DC motor 10 and the torque. In FIG. 6, the vertical axis represents the torque T (N · m), and the horizontal axis represents the rotational speed N (min ⁻¹ ). In FIG. 6, a solid line shows an example in the present embodiment, and a broken line shows conventional PWM control. Further, in FIG. 6, two solid lines showing an example of the present embodiment are drawn. Of these, the one with higher torque shows the case where the ability variable instruction voltage Va is higher than the other. Similarly, two broken lines showing the conventional example are also drawn. Of these, the one with higher torque shows the case where the variable capacity instruction voltage Va is higher than the other.

  As shown in FIG. 6, in the conventional PWM control, the torque T increases monotonously as the rotational speed N decreases. On the other hand, in the present embodiment, in a section where the rotational speed N of the DC motor 10 is 4500 N or less, the torque T decreases as the rotational speed N decreases.

  This is because the set time Δt increases as the rotational speed N of the DC motor 10 decreases. FIG. 3 will be referred to again. In the period from time 0 to time t2 shown in FIG. 3, the variable capacity instruction voltage Va is lower than in other time zones, and high rotation is not required. Thus, in the case of a low rotation that does not require high rotation, the set time Δt is longer than other time zones. On the other hand, in the period from time t6 to time t8, the capacity variable instruction voltage Va is higher than that in the period from time 0 to time t2, and higher rotation is required than during the same period, and the set time Δt is from time 0 to time It becomes shorter than the period of t2.

  As described above, in the present embodiment, the setting time Δt increases as the rotational speed N of the DC motor 10 decreases, and when the setting time Δt increases, the current supply to the motor windings 12 of a plurality of phases takes a long time. As a result, the magnitude of the torque T decreases. Thus, the DC motor 10 of this embodiment has a characteristic that the magnitude of the torque T becomes small in the low rotation region. Therefore, when the DC motor 10 and the DC motor drive control device 20 are applied to a pump or the like that does not require a large amount of work during low rotation, generation of unnecessary work due to the characteristics shown in FIG. 6 can be suppressed. .

  In both the example of the present embodiment and the conventional example, the torque T is equal in a section where the rotational speed N of the DC motor 10 exceeds 4500N. This is because in a section where the rotational speed N exceeds 4500 N, the duty ratio of the PWM control becomes 100%, and the set time Δt approaches “0” in the control according to the present embodiment, so the difference between the two decreases.

  FIG. 7 is a graph showing the characteristics of the pump unit 1 shown in FIG. 1 and the pump unit when conventional control is performed. In FIG. 7, the left vertical axis indicates the total head Ht (m), the right vertical axis indicates the power consumption Win (W), and the horizontal axis indicates the flow rate Q (L / min). In FIG. 7, the thin solid line indicates the total lift when PWM control (duty ratio 90%) is performed as in the past, and the thick solid line indicates the total lift when the control of this embodiment is performed. Further, the thin broken line indicates the power consumption when the PWM control is performed as in the past, and the thick solid line indicates the power consumption when the control according to the present embodiment is performed.

  First, as shown in the conventional example, when the flow rate Q of the pump unit is increased, the power consumption Win increases proportionally. Further, the total head Ht decreases as the flow rate Q increases. On the other hand, in the present embodiment, when the flow rate Q exceeds 15 (L / min), the current value supplied to the motor winding 12 exceeds the maximum value determined by the peak current threshold generation circuit 26. The current supplied to the multi-phase motor winding 12 is limited. For this reason, in the region where the flow rate Q exceeds 15 (L / min), the total head Ht and the power consumption Win are significantly reduced.

  As described above, in the pump unit 1 according to the present embodiment, when it is not necessary to push up the water to a high place, a high flow rate and low power consumption can be realized, and a high flow rate is realized while achieving energy saving. be able to.

  In the conventional PWM control shown in FIG. 7, when the duty ratio is reduced, the characteristics of FIG. 7 are similarly reduced.

  As described above, according to the DC motor drive control device 20 according to the first embodiment, when the current value supplied to the motor winding 12 is equal to or less than the determined maximum value, the multi-phase motor winding 12 is used. Is supplied at a duty ratio of 100%, and when the current value supplied to the motor winding 12 exceeds the maximum value, regardless of the current supply state to the determined motor winding 12 of the plurality of phases The current supply to the motor winding 12 is turned off for a predetermined set time Δt.

  As described above, the DC motor 10 is driven by the current supply with the duty ratio of 100% and the current supply OFF at the set time Δt, and the fixed voltage direct current power source is operated by the above two without performing the PWM control. 30 is used to realize PAM control in a pseudo manner. Thereby, the DC motor drive control device 20 can reduce the number of times of switching of the switching means, and can suppress the heat generation of the switching means. In addition, since PWM control is not performed, generation of ripple current and harmonic current can be suppressed. Therefore, while adopting a simple power supply that outputs a fixed voltage as a driving power supply for the motor, it is possible to suppress the heat generation of the switching means, the vibration and noise of the motor, and the generation of harmonic current.

  Further, the time from when the current value supplied to the motor winding 12 exceeds the maximum value until the current switching of the motor winding 12 is performed next is set time Δt. Further, when the current supply to the motor windings 12 of the plurality of phases is turned off for the set time Δt, all the upper arm side or lower arm side switching elements are turned off and all other arm side switching elements are turned on. It is said.

  Here, when PWM control is performed, the switching elements are all turned off when the phase of the current to the motor winding 12 is switched, and the counter electromotive force of the winding current may be regenerated to the DC power supply 30. In particular, when the DC power supply 30 and the inverter circuit 23 are connected with high impedance, there is a possibility that the power supply voltage rises due to regeneration of the counter electromotive force and the withstand voltage of the switching means is exceeded. However, in this embodiment, all the upper arm side or lower arm side switching elements are turned off at the time of phase switching, and all other arm side switching elements are turned on. Exists. As a result, discharge is performed between the inverter circuit 23 having the switching means and the motor winding 12, and the increase in the power supply voltage is reduced. Therefore, it is possible to suppress overvoltage endurance of the switching means.

  Further, since the set time Δt is increased as the motor rotational speed N decreases, the torque T when the DC motor 10 rotates at a low speed can be suppressed, and the work amount at the time of low rotation can be suppressed. .

  In addition, according to the pump unit 1 including the DC motor 10 that is driven by the DC motor drive control device 20 and sends out fluid, a simple power source that outputs a fixed voltage is employed as the motor drive power source, as described above. However, heat generation of the switching means, vibration and noise of the motor, and generation of harmonic current can be suppressed. Furthermore, according to the pump unit 1, unnecessary work on the large flow rate side can be suppressed.

  Next, a second embodiment of the present invention will be described. The pump unit 1 according to the second embodiment is the same as that of the first embodiment, but the configuration and processing contents are different from those of the first embodiment.

  FIG. 8 is a circuit configuration diagram of the DC motor 10 and the DC motor drive control device 20 of the pump unit 1 according to the second embodiment. As shown in the figure, the DC motor drive control device 20 in the second embodiment includes an operational amplifier OP2 instead of the comparator CMP2. For this reason, the capacity variable instruction voltage Va is input to the operational amplifier OP2 and amplified with an amplification degree determined by the resistors R7 and R8.

  The output voltage of the operational amplifier OP2 is input to the inverting input terminal of the comparator CMP3. Also, a Zener diode ZD is provided on the output side of the operational amplifier OP2. When the output voltage of the operational amplifier OP2 becomes a certain voltage value (for example, 5 V) or more, it is clamped by the Zener diode ZD. When the output voltage of the operational amplifier OP2 is clamped by the Zener diode ZD, the clamped voltage is input to the inverting input terminal of the comparator CMP3.

  A triangular wave signal is input to the non-inverting input terminal of the comparator CMP3. Note that the voltage clamped by the Zener diode ZD is higher than the upper limit voltage value of the triangular wave signal.

  Here, how the output signal of the comparator CMP3 changes when the output voltage of the operational amplifier OP2 gradually increases from “0” will be described. First, when the output voltage of the operational amplifier OP2 is “0” or the like, the output voltage of the operational amplifier OP2 is lower than the lower limit voltage value of the triangular wave signal input to the non-inverting input terminal of the comparator CMP3. For this reason, the output of the comparator CMP3 becomes H level.

  Furthermore, when the output voltage of the operational amplifier OP2 rises from “0” and becomes equal to or higher than the lower limit voltage value and lower than the upper limit voltage value, the output of the comparator CMP3 alternately changes between the H level and the L level. At this time, the higher the output voltage of the operational amplifier OP2 within the range between the lower limit voltage value and the upper limit voltage value, the higher the output of the comparator CMP3 is at the L level.

  Thereafter, when the output of the operational amplifier OP2 exceeds the upper limit voltage value, the output of the comparator CMP3 becomes L level. As described above, since the output signal of the comparator CMP3 changes, the DC motor 10 is driven with the following duty ratio as the capability variable instruction voltage Va increases.

  FIG. 9 is a graph showing the correlation between the variable capacity instruction voltage Va and the PWM duty in the DC motor drive control device 20 according to the second embodiment. In FIG. 9, the vertical axis represents the PWM duty (%), and the horizontal axis represents the variable capacity instruction voltage Va (V). In FIG. 9, the solid line indicates the present embodiment, and the broken line indicates the conventional PWM control.

  As shown in the figure, in the control of this embodiment, when the variable capacity instruction voltage Va is equal to or lower than the voltage V0, an L level voltage signal is input to the AND circuit AND. For this reason, the current supply is turned off, and the duty ratio becomes 0%. Further, when the capability variable instruction voltage Va exceeds the voltage V0 and is equal to or lower than the voltage V2, voltage signals of H level and L level are alternately input to the AND circuit AND. For this reason, the DC motor 10 is driven with a duty ratio corresponding to the magnitude of the capacity variable instruction voltage Va. When the variable capacity instruction voltage Va exceeds the voltage V2, an H level voltage signal is input to the AND circuit AND, and current is supplied with a duty ratio of 100%.

  From the above, in the second embodiment, in the process of gradually increasing the capacity variable instruction voltage Va in order to start the DC motor 10 and perform high rotation, etc., the DC motor in the order of stop, PWM control, and duty ratio 100% control. 10 will be driven. That is, PWM control is performed in the initial stage of driving of the DC motor 10, and the motor can be started more smoothly than when the DC motor 10 is suddenly driven with a duty ratio of 100% from the stopped state. It is like that. The conventional PWM control shown in FIG. 9 is the same as the example shown in FIG. As shown in FIG. 9, the DC motor 10 is driven when the current value supplied to the motor winding 12 is equal to or less than the maximum value determined by the peak current threshold generation circuit 26, that is, a latch circuit. Needless to say, L is not latched at the H level.

  FIG. 10 is a time chart showing the operation of the DC motor drive control device 20 according to the second embodiment. First, as shown in FIG. 10, at time 0, the variable capacity instruction voltage Va is higher than the voltage V0 but lower than the voltage V2 (FIG. 10 (a)). For this reason, as described with reference to FIG. 9, the input voltage of the AND circuit AND alternately repeats the H level and the L level (FIG. 10B), and is apparent from the output voltage of the operational amplifier OP1. Thus, it can be said that the current is alternately supplied to the motor windings 12 of the plural phases (FIG. 10C), and the DC motor 10 is driven by PWM control. Then, PWM control is performed in the period from time 0 to time t22. A section in which this control is performed is called a PWM control phase.

  If the variable capacity instruction voltage Va exceeds the voltage V2 at time t22 (FIG. 10A), the current supply with the duty ratio of 100% and the current supply off at the set time Δt described in the first embodiment are performed. Control is performed (FIGS. 10B and 10C).

  In the examples shown in FIGS. 8 to 10, the PWM control is performed when the ability variable instruction voltage Va is amplified and the amplified voltage is not less than the lower limit voltage value and not more than the upper limit voltage value of the triangular wave signal. However, the present invention is not limited to this, and current supply to the motor windings 12 of a plurality of phases may be performed by PWM control until a predetermined time has elapsed since the start of the DC motor 10. This also makes it possible to smoothly start the motor.

  Furthermore, PWM control may be performed until the motor rotation speed N reaches a predetermined rotation speed. FIG. 11 is a time chart showing a modified example of the operation of the DC motor drive control device 20 according to the second embodiment.

  For example, as shown in FIG. 11A, the rotational speed N of the DC motor 10 gradually increases in the section from time 0 to time t32, and the rotational speed N of the DC motor 10 in the section from time t32 to time t33. Is kept constant, and then the rotational speed N of the DC motor 10 decreases in the section after time t33.

  In this case, the DC motor drive control device 20 generates a voltage value corresponding to the rotational speed N of the DC motor 10 (FIG. 11B). Then, PWM control is performed until the generated voltage value exceeds the specific voltage value V3, and when the generated voltage value exceeds the specific voltage value V3, current supply with a duty ratio of 100% may be performed (FIG. 11). (C)). Thus, even if the PWM control is performed until the rotational speed N reaches the predetermined rotational speed, the motor can be started smoothly as described above.

  Further, the DC motor drive control device 20 fixes the maximum value of the current supplied to the multi-phase motor windings 12 to a constant value when supplying current to the multi-phase motor windings 12 by PWM control. It is desirable to supply current in a range below a certain value.

  FIG. 12 is a graph showing the maximum value of the current flowing through the motor windings 12 of a plurality of phases. In FIG. 12, the vertical axis represents the maximum current value (I), and the horizontal axis represents the variable capacity instruction voltage Va (V).

  As shown in FIG. 12, the maximum value of the current supplied to the motor windings 12 of a plurality of phases in the PWM control phase is fixed to a constant value Ia, and the DC motor drive control device 20 is in a range below the constant value Ia. Supply current with. Here, the constant value Ia is determined within the absolute rating of the switching means constituting the inverter circuit 23. As a result, the DC motor drive control device 20 does not cause destruction of the switching means even in an electrical stress applied at startup. Furthermore, by determining the constant value Ia as high as possible within the absolute rating, it is possible to obtain a sufficient torque at the time of startup.

  As shown in FIG. 12, in the peak current control phase, as in the first embodiment, the maximum value of the current supplied to the motor windings 12 of the plurality of phases is increased as the capacity variable instruction voltage Va increases. The

  In this way, according to the DC motor drive control device 20 according to the second embodiment, as in the first embodiment, a simple power supply that outputs a fixed voltage is adopted as the drive power supply for the motor. Heat generation of the means, vibration and noise of the motor, and generation of harmonic current can be suppressed. Moreover, the overvoltage endurance of the switching means can be suppressed. Moreover, the work amount at the time of low rotation can be suppressed.

  In addition, according to the pump unit 1 according to the second embodiment, as in the first embodiment, while adopting a simple power source that outputs a fixed voltage as a driving power source for the motor, Generation of vibration, noise, and harmonic current can be suppressed. Furthermore, unnecessary work on the large flow rate side can be suppressed.

  Furthermore, according to the DC motor drive control device 20 according to the second embodiment, when the current value supplied to the motor winding 12 is equal to or less than the maximum value, the capacity variable instruction voltage Va is a predetermined first predetermined voltage. When the voltage is equal to or lower than the second predetermined voltage higher than the first predetermined voltage, current supply to the motor windings 12 of the plurality of phases is performed by PWM control. As a result, the DC motor 10 is driven in the order of stop, PWM control, and duty ratio 100% control in the process of gradually increasing the capacity variable instruction voltage Va in order to start the DC motor 10 and perform high rotation or the like. It becomes. That is, PWM control is performed in the initial stage of driving of the DC motor 10, and the motor can be started more smoothly than when the DC motor is suddenly driven with a duty ratio of 100% from the stopped state.

  Further, in the case where the current value supplied to the motor winding 12 is equal to or less than the maximum value, the motor winding 12 having a plurality of phases is required until the motor rotation speed N reaches a predetermined rotation speed (rotation speed corresponding to the voltage V3). The current supply to is performed by PWM control. For this reason, similarly to the above, PWM control is performed in the initial stage of starting of the DC motor 10, and smooth motor starting can be performed.

  Further, when the current value supplied to the motor winding 12 is equal to or less than the maximum value, the current supply to the motor windings 12 of a plurality of phases is performed by PWM control until a predetermined time elapses after the DC motor 10 is started. I'm doing it. For this reason, similarly to the above, PWM control is performed in the initial stage of starting the DC motor, and smooth motor starting can be performed.

  In addition, when performing current supply to the motor windings 12 of the plurality of phases by PWM control, the maximum value of the current supplied to the motor windings 12 of the plurality of phases is fixed to a constant value Ia, and within a range of the constant value Ia or less. It is supposed to supply current. For this reason, by determining the constant value Ia within the absolute rating of the switching means constituting the inverter circuit 23, the switching means can be operated in the safe operation region, and the quality is improved without destroying the switching means. Can be achieved. Further, by determining the constant value Ia as high as possible within the absolute rating, it is possible to obtain a sufficient torque at the time of startup.

  As described above, the present invention has been described based on the embodiment, but the present invention is not limited to the above embodiment, and may be modified without departing from the gist of the present invention. It goes without saying that various modifications can be made in accordance with the design and the like as long as the technical idea according to the present invention is not deviated from other embodiments.

  For example, in the above-described embodiment, the set time Δt is the current switching of the motor winding 12 after the current value supplied to the motor winding 12 exceeds the maximum value of the current determined by the peak current threshold generation circuit 26. However, the fixed time may be set. Further, the DC motor drive control device 20 stores a plurality of fixed times in advance, selects an appropriate one from the plurality of fixed times according to the number of rotations of the DC motor 10, and only the selected fixed time, The current supply may be turned off.

It is a functional block diagram of the pump unit concerning a 1st embodiment of the present invention. It is a circuit block diagram of the DC motor of the pump unit shown in FIG. 1, and a DC motor drive control apparatus. It is a time chart which shows operation | movement of the DC motor drive control apparatus which concerns on this embodiment, (a) shows the input signal of comparator CMP2, (b) shows the output signal of comparator CMP2, (c) shows comparator CMP1. An output signal is shown, (d) is a reset signal, (e) is an input signal of the AND circuit AND, and (f) is an output signal of the operational amplifier OP1. It is a graph which shows the correlation of a capability variable instruction voltage and PWM duty. It is a graph which shows the temperature rise of FET which is a switching element. It is the graph which showed the relationship between the rotation speed of a DC motor, and a torque. It is a graph which shows the characteristic of the pump unit when performing the pump unit shown in FIG. 1, and conventional control. It is a circuit block diagram of the DC motor of the pump unit which concerns on 2nd Embodiment, and a DC motor drive control apparatus. It is a graph which shows the correlation with a capability variable instruction | indication voltage and PWM duty in the DC motor drive control apparatus which concerns on 2nd Embodiment. It is a time chart which shows operation | movement of the DC motor drive control apparatus which concerns on 2nd Embodiment, (a) shows the input signal of operational amplifier OP1, (b) shows the input signal of AND circuit AND, (c) is operational amplifier. The output signal of OP1 is shown. It is a time chart which shows the modification of operation | movement of the DC motor drive control apparatus 20 which concerns on 2nd Embodiment, (a) shows rotation of the DC motor 10, (b) respond | corresponds to the rotation speed N of the DC motor 10. A voltage signal is shown, and (c) shows an input signal of the AND circuit AND. It is a graph which shows the maximum value of the electric current energized to the motor winding of a plurality of phases.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pump unit 10 ... DC motor 11 ... Stator 12 ... Motor winding 13 ... Rotor 14 ... Rotation position detection means 20 ... DC motor drive control device 21 ... ON / OFF control circuit 22 ... Distribution circuit 23 ... Inverter circuit 24 ... Current -Voltage conversion circuit 25 ... Amplifier circuit 26 ... Peak current threshold generation circuit 27 ... Peak current comparison circuit 28 ... OFF time control circuit 30 ... DC power supply 40 ... Pump unit R1-R8 ... Resistor ZD ... Zener diodes CMP1-CMP3 ... Comparator OP1 , OP2 ... operational amplifiers TR1, TR2 ... NPN transistors

Claims (6)

The rotor rotation position of the DC motor is detected, and the energization state from the DC power source that outputs a fixed voltage to the multi-phase motor winding is determined based on the detected rotation position, and the DC motor is determined based on the determined energization state. A DC motor drive control device that performs drive control,
A peak current value determining means for determining a maximum value of a current to be applied to the motor windings of the plurality of phases according to a capability variable instruction voltage for controlling the capability of the DC motor;
First drive control for supplying current to the motor windings of the plurality of phases at a duty ratio of 100% when the current value supplied to the motor winding is equal to or less than the maximum value determined by the peak current value determining means. Means,
When the current value energized to the motor winding exceeds the maximum value determined by the peak current value determining means, a plurality of phase motor windings regardless of the energized state of the determined plurality phase motor windings And a second drive control means for turning off the current supply to the preset set time ,
The first drive control means is configured such that when the current value supplied to the motor winding is equal to or less than the maximum value determined by the peak current value determining means, the capacity variable instruction voltage is a predetermined first predetermined voltage. When the second predetermined voltage is higher than the first predetermined voltage and lower than the second predetermined voltage, current supply to the motor windings of the plurality of phases is performed by PWM control,
The first drive control means, within the rated current of the switching means constituting the inverter circuit connected to the motor windings of the plurality of phases, when supplying current to the motor windings of the plurality of phases by PWM control, and the A DC motor drive control device characterized in that a maximum value of a current applied to a motor winding of a plurality of phases is fixed to a constant value, and current is supplied within a range below the constant value . The second drive control means includes
The time from when the current value energized to the motor winding exceeds the maximum value determined by the peak current value determining means until the next switching of the current of the motor winding is the set time,
In turning off the current supply to the motor windings of the plurality of phases for the set time,
All of the plurality of upper arm side switching elements for switching between one of the terminals of the motor windings of the plurality of phases and the positive terminal of the DC power supply are turned off, and one of the terminals of the motor windings of the plurality of phases Turn on all of the plurality of lower arm side switching elements that perform switching with the negative terminal of the DC power supply,
2. The DC motor drive control device according to claim 1, wherein all of the plurality of upper arm side switching elements are turned on and all of the plurality of lower arm side switching elements are turned off.   2. The DC motor drive control device according to claim 1, wherein the second drive control unit increases the set time as the motor rotation speed decreases.   In the case where the current value supplied to the motor winding is equal to or less than the maximum value determined by the peak current value determination unit, the first drive control unit is configured such that the motor rotation number reaches a predetermined rotation number. 4. The DC motor drive control device according to claim 1, wherein current supply to the motor windings of a plurality of phases is performed by PWM control. 5.   In the case where the current value energized to the motor winding is equal to or less than the maximum value determined by the peak current value determining unit, the first drive control unit is 4. The DC motor drive control device according to claim 1, wherein current supply to the motor windings of a plurality of phases is performed by PWM control. 5. DC motor drive control device according to any one of claims 1 to 5 ,
A DC motor that is driven by the DC motor drive control device and serves as a drive source for delivering fluid;
A pump unit comprising:

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