JP5264639B2 - Motor drive device - Google Patents

Description

  The present invention converts the DC voltage rectified by the rectifier circuit and the smoothing capacitor into a periodic voltage, determines whether the rectified DC voltage is a predetermined value or more, and uses the converted periodic voltage to drive the motor. The present invention relates to a motor drive device that opens an open / close circuit with a power source when it is determined that the driven and rectified DC voltage is equal to or greater than a predetermined value.

FIG. 6 is a block diagram showing a schematic configuration when the inertial body 400 to which the inertial force is applied is driven by the brushless DC motor 100 with a reduction gear.
The brushless DC motor 100 with a reduction gear is driven by a motor driving device 200a.
The brushless DC motor 100 with a speed reducer decelerates the rotational speed of the brushless DC motor 101 and transmits it to the inertial body 400, and the rotor position detection that detects the rotational position of the rotor (rotor) of the brushless DC motor 101. Device 103. The rotor position detector 103 is operated by a control DC voltage, and is connected to the control unit 21a in the motor driving device 200a by a detector cable 105 having at least five wires.

The brushless DC motor 101 is connected to the inverter 4 in the motor driving device 200a by a three-phase motor cable 104.
In motor drive device 200a, converter 1a rectifies the AC voltage applied through power supply switching relay contacts 41a and 41a, and smoothing capacitor 2 smoothes the rectified DC voltage and applies it to inverter 4. The DC voltage smoothed by the smoothing capacitor 2 is also applied to the control power supply circuit 20. The control power supply circuit 20 steps down the supplied DC voltage and converts it to a control voltage that is a control power supply voltage, and the converted control voltage is supplied to the control unit 21a. As shown in FIG. 9, the control unit 21a controls on / off of the six transistors of the inverter 4 configured in a three-phase bridge circuit.

In the brushless DC motor 100 with a reduction gear and the motor driving device 200a configured as described above, the control unit 21a turns on / off the six transistors of the inverter 4 based on the rotational position detected by the rotor position detector 103. Control. The inverter 4 converts the DC voltage into a three-phase AC voltage, for example, by turning on and off each of the six transistors, and supplies the brushless DC motor 101 for rotation.
The rotation operation of the brushless DC motor 101 is decelerated by the speed reducer 102 and transmitted to the inertial body 400 to rotate the inertial body 400.

FIG. 7 is a block diagram showing in more detail a configuration example of the conventional motor driving device 200a shown in FIG.
The motor driving device 200a is supplied with the voltage E from the AC power source when the power switching unit 300a to which the voltage E from the AC power source is applied and the power switching relay contact 41a of the power switching unit 300a are closed. (Brushless DC motor) 101 is provided.
In the power switching unit 300a, a power switching relay 41 and an NPN transistor 44 are connected in series between connection terminals D1 and D2 to which a DC power source 6 is externally attached. An operation switch 7 is externally connected between the connection terminal D1 and the connection terminal D3 to which the positive pole of the DC power supply 6 is externally attached. The connection terminal D3 is connected to the base of the transistor 44 through the resistor 46.

One terminal of each of the a contacts 41a and 41a of the power switching relay 41 is connected to the input terminals L1 and L2 of the power switching unit 300a to which the AC power is connected. The other terminals are connected to the output terminals L11 and L21 of the power supply opening / closing part 300a, respectively. The output terminals L11 and L21 are connected to the input terminals L12 and L22 of the motor driving unit 201a, respectively.
The input terminal L12 of the motor drive unit 201a is connected to one input terminal of the converter 1a, and the input terminal L22 of the motor drive unit 201a is connected to the other input terminal of the converter 1a.

  The plus output terminal of the converter 1a is connected to the (plus) connection terminal p, the minus output terminal is connected to the (minus) connection terminal n, and the smoothing capacitor 2 is connected between the connection terminal p and the connection terminal n. . The converter 1 a and the smoothing capacitor 2 constitute a DC power source 1. The (plus) connection terminal p is connected to the plus side input terminal p 1 of the inverter 4, and the (minus) connection terminal n is connected to the minus side input terminal n 1 of the inverter 4 through the resistor 33.

  The inverter 4 converts the input DC voltage into, for example, a three-phase AC voltage under the control of the control unit 21 a and drives the (brushless DC) motor 101. The motor 101 includes a rotor position detector 103 that detects the rotational position of the rotor (rotor). The rotor position detector 103 is operated by the control voltage Vcc and gives a detection signal to the control unit 21a.

As shown in FIG. 9, the inverter 4 is connected in parallel with three circuits in which two NPN transistors are connected in series, and each transistor is connected with a free-wheeling diode in antiparallel, and each phase voltage is connected in series. This is a configuration that is taken out from a connection node of two connected transistors.
Based on the rotor position detected by the rotor position detector 103, the control unit 21a performs on / off control with PWM (Pulse Width Modulation) control on each transistor of the inverter 4, and outputs a three-phase AC voltage. At the time of startup, the control unit 21a gradually increases the voltage supplied to the motor 101 by PWM control of each transistor.

A control power supply circuit 20 is connected between the connection terminals p and n. The control power supply circuit 20 steps down the DC voltage Ea smoothed by the smoothing capacitor 2 and outputs a control voltage Vcc, which is given to the control unit 21a and the like. .
A voltage dividing circuit 3 comprising resistors 31 and 32 is connected between the connection terminals p and n, and the divided voltage Ed is detected by voltage detecting means 21b and 21c built in the control unit 21a.
The motor current flowing in the motor 101 is detected by the current detection means 21c and 21d built in the control unit 21a by the voltage across the resistor 33 connected between the connection terminal n and the input terminal n1 of the inverter 4.

Hereinafter, the operation of the motor driving device 200a having such a configuration will be described with reference to the flowchart of FIG.
When the operation switch 7 is on, the transistor 44 is turned on, the power switching relay 41 is excited, the a contacts 41a and 41a are closed (S1), and the AC voltage E is applied to the converter 1a. The AC voltage E applied to the converter 1 a is rectified, and the rectified DC voltage is smoothed by the smoothing capacitor 2. The control power supply circuit 20 steps down the voltage Ea smoothed by the smoothing capacitor 2 and outputs a control voltage Vcc.

  When the control unit 21a is supplied with the control voltage Vcc and is turned on, the voltage detection means 21b and 21c detect the divided voltage Ed of the voltage dividing circuit 3 to thereby connect the connection terminal pn smoothed by the smoothing capacitor 2. A voltage Ea is detected (S3). Next, the control unit 21a determines whether or not the smoothed voltage Ea is higher than a predetermined voltage value e22 (S5). The predetermined voltage value e22 is determined based on the startable voltage of the motor 101.

The controller 21a detects the smoothed voltage Ea until the smoothed voltage Ea becomes higher than the predetermined voltage value e22 (S3), and if the smoothed voltage Ea becomes higher than the predetermined voltage value e22 (S5), The inverter 4 is turned on (S7).
Next, the controller 21a detects the motor current flowing through the motor 101 by the current detection means 21c and 21d (S9), and determines whether or not the detected motor current is an overcurrent (S11). If the motor current is an overcurrent, the control unit 21a turns off the inverter 4 (S21), displays an alarm (not shown), and ends (S23).

If the detected motor current is not an overcurrent (S11), the controller 21a detects the smoothed voltage Ea (S13). Next, the control unit 21a determines whether or not the detected voltage Ea is an overvoltage that damages the smoothing capacitor 2, the inverter 4 or the control power supply circuit 20 (S15). It is turned off (S21), an alarm (not shown) is displayed (S23), and the process ends.
If the detected voltage Ea is not an overvoltage (S15), the controller 21a determines whether the detected voltage Ea is lower than the predetermined voltage e16 (S17). The predetermined voltage e16 is determined based on a voltage at which the motor 101 cannot continue operation.

  If the detected voltage Ea is not lower than the predetermined voltage e16 (S17), the controller 21a detects the motor current flowing through the motor 101 (S9). If the detected voltage Ea is lower than the predetermined voltage e16 (S17), the controller 21a turns off the inverter 4 (S19) and ends.

In Patent Document 1, the voltage of the DC power supply to the drive unit is detected, and when the detected voltage becomes a predetermined value or less, the armature windings are short-circuited via a resistor to form a non-commutator motor. A control method of a non-commutator motor that consumes generated power generation energy by resistance is disclosed.
Japanese Patent Laid-Open No. 2004-26883 discloses that the switching of the magnetic pole of the detection signal from the rotation position detection means is eliminated when the rotation number of the permanent magnet rotor based on the detection signal from the rotation position detection means becomes a specified value or less. When detected, a motor control circuit is disclosed in which the output current to each phase coil is set to an intermittent current with a constant duty ratio to prevent coil burnout.

Japanese Patent Laid-Open No. 7-184390 JP-A-9-163786

FIG. 10 is a characteristic diagram showing the relationship between the rotational speed and torque of the brushless DC motor 101.
When the brushless DC motor 100 with a speed reducer connected to the inertial body 400 is driven by the conventional motor driving device 200a, the motor driving device 200a supplies the motor 101 with a shock (reaction) caused by acceleration at the time of startup. The voltage is gradually increased by PWM control. At that time, the output torque of the motor 101 (drive torque when the rotation speed is 0) increases as T1, T2, and T3 as the time advances from t1, t2, and t3, and the inertial body 400 is gradually accelerated.

However, when the motor 101 is stopped, the inertial body 400 is rotated by applying an external force, and the motor 101 is already rotating in the forward rotation direction or the reverse rotation direction (idle; rotation not depending on the drive power supply) immediately before starting. There is.
In this case, each transistor of the inverter 4 (FIG. 9) is naturally turned off, but when viewed from the motor 101 side, it is a three-phase full-wave rectifier circuit composed of six diodes (freewheeling diodes). Therefore, the motor 101 generates an electromotive force so that idling is suppressed, and the generated power is charged to the smoothing capacitor 2 through the three-phase full-wave rectifier circuit (inverter 4). However, the polarity of the electric power to be charged is constant regardless of the idling direction, and is the same as when the converter 1a operates. Further, the generated power is charged in the smoothing capacitor 2, and when the charging voltage rises and exceeds the operating voltage of the control power circuit 20 (FIG. 6), the control power circuit 20 (FIG. 6) operates to control the control voltage. Although it is supplied to the unit 21a (FIG. 6) and consumed, the power consumption is small, so that the braking torque for suppressing the idling of the motor 101 is small.

For example, in FIG. 10, when the motor 101 is idly rotated by an external force at the rotational speed Nf2 and the driving torque Td2 in the forward rotation direction (point P2), energization of the motor 101 is started at time t1, and the torque T1 Is output, the torque T1 (point P2a) at the speed Nf2 is below the point P2, so that the braking torque acts on the inertial body 400.
Subsequently, when the voltage is increased so that torques T2 and T3 are output at times t2 and t3, the torque changes upward in FIG. 10, and the torque acting on inertial body 400 is reduced from the deceleration torque on the way. Switching to the acceleration torque, the inertial body 400 is accelerated and balanced at a point P2x indicating the driving torque Td2 on the line indicating the voltage for outputting the torque T3.

  For example, when the motor 101 is idling due to an external force at a rotational speed Nr2 and a braking torque Td12 in the reverse direction (point P12), energization of the motor 101 is started at time t1 and torque T1 is output. The driving torque Tr2 in the forward rotation direction acts on the inertial body 400 that is rotating in the reverse direction (point P12a). In other words, in this case, the electromotive force in the direction of suppressing reverse idling at the reverse idling speed Nr2 and the electric power for generating the torque T1 are added with the same polarity, and thus larger than the torque T1 (in the forward rotation direction). Drive torque).

Inversely rotating inertial body 400 decelerates to reverse idling speed Nr1 with a driving torque larger than torque T1 (in the forward rotation direction) (point P12b). At time t1a, the voltage is increased so that torque T1a is output. Then, the drive torque Tr2a in the forward rotation direction acts on the inertial body 400 that is rotating in the reverse direction and decelerates (point P12c).
Subsequently, when the voltage is increased so that the torques T2 and T3 are output at time t2 and t3, the rotation direction of the inertial body 400 is reversed to the positive rotation direction in the middle, and the inertial body 400 is accelerated and torque is increased. The point P2x indicating the driving torque Td2 on the line indicating the voltage for outputting T3 is balanced.

Here, when the inertial body 400 is rotated by an external force when the motor 101 is not energized, the speed reducer 102 of the brushless DC motor 100 with a speed reducer becomes a speed increaser with respect to the motor 101, and the motor 101 is at high speed. May rotate.
For example, it is assumed that the motor 101 is idling by an external force at a relatively high rotational speed Nf3 and driving torque Td2 in the forward rotation direction (point P3). In this state, energization of the motor 101 is started at time t1, and when the torque T1 is output, the braking torque Tf3 is applied to the inertial body 400 on the broken line that deviates from the solid line portion indicating the voltage for outputting the torque T1. Trying to act (point P3).

However, in this case, the voltage Ea generated by the electromotive force in the direction of suppressing idling at the idling speed Nf3 and smoothed by the smoothing capacitor 2 becomes an overvoltage (S15), and the control unit 21a turns off the inverter 4 ( Since S19), the power supply to the motor 101 is stopped.
That is, when the motor 101 is idling at a high rotation speed (including reverse rotation) that generates an electromotive force such that the voltage Ea smoothed by the smoothing capacitor 2 becomes an overvoltage, the motor 101 cannot be started.

  The motor 101 outputs a driving torque that is substantially proportional to the energized current, but prevents damage due to overcurrent of the inverter 4, prevents demagnetization due to overcurrent of the permanent magnet used in the rotor of the motor 101, and decelerates. In order to use the mechanical brushless DC motor 100 within the mechanical strength, a limit is imposed on the energization current from the inverter 4 (S43). Therefore, the motor 101 cannot output torque exceeding the maximum output torque TLm.

  For example, when the motor 101 is idling with an external force at a rotational speed Nr3 and a braking torque Td12 in the reverse direction (point P13), energization of the motor 101 is started at time t1 and torque T1 is output. The driving torque Tr3 tries to act on the inertial body 400 on the broken line that is out of the solid line portion indicating the voltage for outputting the torque T1 (point P13a).

However, in this case, the drive torque Tr3 exceeds the maximum output torque TLm, an overcurrent flows through the motor 101 that attempts to output the drive torque Tr3 (S11), and the control unit 21a turns off the inverter 4 (S21). Therefore, energization to the motor 101 is stopped.
That is, when the motor 101 is idling at a high reverse rotation speed that generates a driving torque exceeding the maximum output torque TLm, the motor 101 cannot be started.
Therefore, when the motor 101 immediately before starting is idling at a rotational speed as indicated by points P3 and P13, conventionally, the inertial body 400 naturally decelerates and the rotational speed range Nr2 in which the motor 101 can be started. There is a problem in that it is necessary to wait until the rotational speed is reduced to the speed indicated by points P2 and P12 included in -Nf2.

  The present invention has been made in view of the above-described circumstances, and provides a motor drive device that can start a motor without waiting for a natural deceleration even when the motor is idling at high speed. The purpose is to provide.

  A motor driving apparatus according to a first aspect of the present invention is a periodic circuit that applies a rectifying circuit and a smoothing capacitor for rectifying a voltage from an AC power source, a switching circuit for opening and closing the AC power source and the rectifying circuit, and a DC voltage smoothed by the smoothing capacitor. A conversion circuit that converts the voltage into a voltage and a voltage determination unit that determines whether or not the value of the DC voltage is equal to or higher than a predetermined voltage value. When a motor having a permanent magnet is driven and the voltage determination means determines that the voltage is greater than or equal to a predetermined voltage value, the motor drive device that opens the open / close circuit includes the rotation direction of the rotor at startup. An idling speed detecting means for detecting an idling speed, an idling speed determining means for judging whether or not the idling speed detected by the idling speed detecting means is within a predetermined rpm range, and the smoothing converter And a discharge circuit for discharging the discharge circuit, and when the rotational speed determining means determines that the rotational speed is not included in a predetermined rotational speed range, the open / close circuit is opened and the discharge circuit is turned on. It is characterized by that.

In this motor drive device, the rectifier circuit and the smoothing capacitor rectify the voltage from the AC power source, and the switching circuit opens and closes between the AC power source and the rectifier circuit. The conversion circuit converts the DC voltage smoothed by the smoothing capacitor into a periodic voltage, and the voltage determination means determines whether the value of the smoothed DC voltage is equal to or greater than a predetermined voltage value. A motor having a permanent magnet in the rotor or stator is driven by the periodic voltage converted by the conversion circuit, and when the voltage determination means determines that the voltage is greater than or equal to a predetermined voltage value, the switching circuit is opened.
The idling speed detecting means detects the idling speed including the rotation direction of the rotor at the time of start-up, the revolution speed determining means judges whether or not the detected idling speed is included in a predetermined revolution speed range, and the discharge circuit Discharge the smoothing capacitor. When the rotational speed determining means determines that the rotational speed is not included in the predetermined rotational speed range, the switching circuit is opened and the discharge circuit is turned on.

  According to a second aspect of the present invention, the motor drive device according to the second aspect of the present invention is configured such that after the open / close circuit is opened and the discharge circuit is turned on, the idling speed detected by the idling speed detecting means is included in a predetermined rotation speed range. Is determined, the discharge circuit is turned off and the open / close circuit is closed.

  In this motor drive device, when the rotation speed determination means determines that the idling speed detected by the idling speed detection means is included in the predetermined rotation speed range after the open / close circuit is opened and the discharge circuit is turned on, the discharge circuit Is turned off and the open / close circuit is closed.

  The motor driving apparatus according to a third aspect is characterized in that the predetermined rotational speed range is determined based on an idling speed allowed when the motor is started.

  According to a fourth aspect of the present invention, when the open / close circuit is open, the voltage determination means, the idling speed detection means, the rotation speed determination means, and the discharge circuit are configured to operate with electric power from the smoothing capacitor. It is characterized by being.

  In this motor drive device, when the open / close circuit is open, the voltage determination means, the idling speed detection means, the rotation speed determination means, and the discharge circuit are operated by the electric power from the smoothing capacitor.

  According to the motor drive device of the present invention, it is possible to realize a motor drive device that can start a motor without waiting for a natural deceleration even when the motor is idling at high speed.

It is a block diagram which shows schematic structure of embodiment of the motor drive device which concerns on this invention. FIG. 2 is a circuit diagram illustrating an internal configuration example of a discharge circuit illustrated in FIG. 1. It is a flowchart which shows operation | movement of embodiment of the motor drive device which concerns on this invention. It is a flowchart which shows operation | movement of embodiment of the motor drive device which concerns on this invention. It is a characteristic view which shows the relationship between the rotational speed of the brushless DC motor driven by the motor drive device which concerns on this invention, the voltage between pn, and a torque. It is a block diagram which shows the general | schematic structure in the case of driving the inertial body which an inertial force acts with a brushless DC motor with a reduction gear. It is a block diagram which shows the example of a structure of the conventional motor drive device shown in FIG. 6 in detail. It is a flowchart which shows the example of operation | movement of the conventional motor drive device. It is a circuit diagram which shows the structural example of an inverter. It is a characteristic view which shows the relationship between the rotational speed and torque of a brushless DC motor.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a motor drive device according to the present invention.
The motor driving device 200 drives a motor (brushless DC motor) 101 used in the brushless DC motor 100 with a reduction gear shown in FIG. 6 instead of the motor driving device 200a.
The motor driving device 200 is provided with a power supply opening / closing unit 300 to which a voltage E from an AC power supply is applied, and a voltage E from the AC power supply when the power supply opening / closing unit 300 is closed, and a motor (brushless DC motor) 101 And a motor drive unit 201 for driving.

  In the power switching unit 300, a power switching relay 41 and an NPN transistor 44 are connected in series between a connection terminal D1 to which a DC power source 6 is externally attached and a (minus) connection terminal n. An operation switch 7 is externally connected between the connection terminal D1 and the connection terminal D3 to which the positive pole of the DC power supply 6 is externally attached. The connection terminal D 3 is connected to the connection terminal n through the resistor 46 and is connected to one input terminal of the AND circuit 43.

The other input terminal of the AND circuit 43 is connected to the connection terminal n through the resistor 45 and also connected to the connection terminal C1. The output terminal of the AND circuit 43 is connected to the base of the NPN transistor 44.
The connection terminal C1 is connected to the control terminal of the discharge circuit 60 through the NOT circuit 50. The discharge circuit 60 is also connected to a (plus) connection terminal p and a (minus) connection terminal n.

One terminal of each of the a contacts 41a and 41a of the power switching relay 41 is connected to the input terminals L1 and L2 of the power switching unit 300 to which the AC power is connected. Each other terminal is connected to the output terminals L11 and L21 of the power supply switching unit 300, respectively. The output terminals L11 and L21 are connected to the input terminals L12 and L22 of the motor drive unit 201, respectively.
The input terminal L12 of the motor drive unit 201 is connected to one input terminal of the converter (rectifier circuit) 1a, and the input terminal L22 of the motor drive unit 201 is connected to the other input terminal of the converter 1a.

  The plus output terminal of the converter 1a is connected to the (plus) connection terminal p, the minus output terminal is connected to the (minus) connection terminal n, and the smoothing capacitor 2 is connected between the connection terminal p and the connection terminal n. . The converter 1 a and the smoothing capacitor 2 constitute a DC power source 1. The connection terminal p is connected to the positive input terminal p 1 of the inverter (conversion circuit) 4, and the connection terminal n is connected to the negative input terminal n 1 of the inverter 4 through the resistor 33.

  The inverter 4 converts the input DC voltage into, for example, a three-phase AC voltage under the control of the control unit 21 and drives the (brushless DC) motor 101. The motor 101 includes a rotor position detector 103 that detects the rotational position of the rotor (rotor). The rotor position detector 103 is operated by the control voltage Vcc and gives a detection signal to the control unit 21.

As shown in FIG. 9, the inverter 4 is connected in parallel with three circuits in which two NPN transistors are connected in series, and each transistor is connected with a free-wheeling diode in antiparallel, and each phase voltage is connected in series. This is a configuration that is taken out from a connection node of two connected transistors.
Based on the rotor position detected by the rotor position detector 103, the control unit 21 performs on / off control with PWM control on each transistor of the inverter 4, and outputs a three-phase AC voltage. At startup, the control unit 21 gradually increases the voltage supplied to the motor 101 by PWM control of each transistor.

A control power supply circuit 20 is connected between the connection terminals p and n. The control power supply circuit 20 steps down the DC voltage Ea smoothed by the smoothing capacitor 2 and outputs a control voltage Vcc, which is supplied to the control unit 21 and the like. .
A voltage dividing circuit 3 including resistors 31 and 32 is connected between the connection terminals p and n, and the divided voltage Ed is detected by voltage detecting means 21b and 21c built in the control unit 21.
The motor current flowing in the motor 101 is detected by the current detection means 21c and 21d built in the control unit 21 based on the voltage across the resistor 33 connected between the connection terminal n and the negative input terminal n1 of the inverter 4.

Based on the rotor position detected by the rotor position detector 103, the control unit 21 detects a rotation speed including the rotation direction of the rotor, and determines whether or not the detected rotation speed is included in a predetermined range. . The control unit 21 incorporates an idling detection circuit 28 that is activated when it is determined that the detected rotation speed is not included in the predetermined range.
The idling detection circuit 28 includes a control relay 281, and the b contact 281 a of the control relay 281 is connected between the connection terminals D 1 and C 1.

FIG. 2 is a circuit diagram showing an internal configuration example of the discharge circuit 60 shown in FIG.
The discharge circuit 60 includes an N-channel FET 63 whose gate is connected to the output terminal of the NOT circuit 50. The drain of the FET 63 is connected to the connection terminal p through the resistor 61. The source of the FET 63 is connected to the connection terminal n. The gate of the FET 63 is connected to the connection terminal n through the resistor 62.
In the discharge circuit 60, when the output voltage E2 of the NOT circuit 50 becomes H level, the FET 63 becomes conductive. As a result, the discharge current Ibr from the smoothing capacitor 2 connected between the connection terminals p and n flows to the connection terminal n through the resistor 61.

Hereinafter, the operation of the motor driving apparatus 200 having such a configuration will be described with reference to the flowcharts of FIGS.
When the operation switch 7 is on and the control relay 281 is off, the output voltage E5 of the AND circuit 43 is at the H level, the transistor 44 is turned on, the power switching relay 41 is excited, and the contact a 41a. , 41a are closed (S31), and an AC voltage E is applied to the converter 1a. At this time, the output voltage E2 of the NOT circuit 50 is at L level, and the discharge circuit 60 is off.

The AC voltage E applied to the converter 1 a is rectified, and the rectified DC voltage is smoothed by the smoothing capacitor 2. The control power supply circuit 20 steps down the voltage Ea smoothed by the smoothing capacitor 2 and outputs a control voltage Vcc.
When the control unit 21 is supplied with the control voltage Vcc and is turned on, the voltage detection means 21b and 21c detect the divided voltage Ed of the voltage dividing circuit 3, thereby the connection terminal pn smoothed by the smoothing capacitor 2. The voltage Ea is detected (S33). Next, the control unit 21 determines whether or not the smoothed voltage Ea is higher than the predetermined voltage value e22 (S35). The predetermined voltage value e22 is determined based on the startable voltage of the motor 101.

The control unit 21 detects the smoothed voltage Ea until the smoothed voltage Ea becomes higher than the predetermined voltage value e22 (S33). When the smoothed voltage Ea becomes higher than the predetermined voltage value e22 (S35), the control unit 21 detects the rotational speed N including the rotational direction of the rotor based on the rotor position detected by the rotor position detector 103 (S37). ).
Next, the control unit 21 determines whether or not the detected rotation speed N (S37) is the forward rotation direction and is higher than the rotation speed Nf2 (S39). The controller 21 determines whether the rotational speed N is in the reverse direction and higher than the rotational speed Nr2 unless the rotational speed N is in the forward rotation direction and higher than the rotational speed Nf2. Is determined (S41). Here, Nf2 is a normal rotation speed at which the motor 101 can be started, and Nr2 is a reverse rotation speed at which the motor 101 can be started.

When the rotational speed N is the forward rotation direction and higher than the rotational speed Nf2 (S39), or the rotational speed N is the reverse rotation direction and higher than the rotational speed Nr2. When the speed is reached (S41), the control relay 281 is excited to open the b-contact 281a (S59 in FIG. 4).
As a result, the output voltage E5 of the AND circuit 43 becomes L level, the transistor 44 is turned off, the power switching relay 41 is de-energized, the a contacts 41a and 41a are opened (S61), and the AC voltage E is Blocked. At this time, the output voltage E2 of the NOT circuit 50 becomes H level, the discharge circuit 60 is turned on (S63), and the voltage Ea between the connection terminals pn decreases. At this time, the AC voltage E is cut off, but the control voltage Vcc is maintained by the power stored in the smoothing capacitor 2.

Next, the control unit 21 detects the rotational speed N including the rotational direction of the rotor based on the rotor position detected by the rotor position detector 103 (S65), and the detected rotational speed N is the forward rotation direction. And it is determined whether it is below rotation speed Nf2 (S67). The control unit 21 determines whether or not the rotation speed N is the reverse rotation direction and is equal to or less than the rotation speed Nr2 if the rotation speed N is the normal rotation direction and is not equal to or less than the rotation speed Nf2. (S69).
If the rotational speed N is in the reverse rotation direction and not lower than the rotational speed Nr2 (S69), the control unit 21 again detects the rotational speed N including the rotational direction of the rotor (S65).

When the rotational speed N is the forward rotation direction and is equal to or lower than the rotational speed Nf2 (S67), or the rotational speed N is the reverse rotation direction and is equal to or lower than the rotational speed Nr2. (S69) The control relay 281 is de-energized and the b-contact 281a is closed (S71).
As a result, the output voltage E2 of the NOT circuit 50 becomes L level, and the discharge circuit 60 is turned off (S73). Further, the output voltage E5 of the AND circuit 43 becomes H level, the transistor 44 is turned on, the power switching relay 41 is excited, the a contacts 41a and 41a are closed (S75), and the AC voltage E is converted to the converter 1a. Given to.

When AC voltage E is applied to converter 1a, control unit 21 detects voltage Ea between connection terminals pn smoothed by smoothing capacitor 2 (S33).
When the smoothed voltage Ea becomes higher than the predetermined voltage value e22 (S35), the control unit 21 detects the rotational speed N including the rotational direction of the rotor based on the rotor position detected by the rotor position detector 103 (S37). ).

Next, the control unit 21 determines whether or not the detected rotation speed N (S37) is the forward rotation direction and is higher than the rotation speed Nf2 (S39). The controller 21 determines whether the rotational speed N is in the reverse direction and higher than the rotational speed Nr2 unless the rotational speed N is in the forward rotation direction and higher than the rotational speed Nf2. (S41), if the rotational speed N is in the reverse direction and is not higher than the rotational speed Nr2 (S41), the inverter 4 is turned on (S43).
Next, the control unit 21 detects the motor current flowing through the motor 101 by the current detection means 21c and 21d (S45), and determines whether or not an overload is caused based on the detected motor current (S47). If the motor 101 is overloaded, the control unit 21 turns off the inverter 4 (S57), displays an alarm (not shown), and ends (S58).

If the motor 101 is not overloaded (S47), the controller 21 detects the smoothed voltage Ea (S49). Next, the control unit 21 determines whether or not the detected voltage Ea is an overvoltage that damages the smoothing capacitor 2, the inverter 4 or the control power supply circuit 20 (S51). It is turned off (S57), an alarm (not shown) is displayed (S58), and the process ends.
If the detected voltage Ea is not an overvoltage (S51), the controller 21 determines whether the detected voltage Ea is lower than the predetermined voltage e16 (S53). The predetermined voltage e16 is determined based on a voltage at which the motor 101 cannot continue operation.

  If the detected voltage Ea is not lower than the predetermined voltage e16 (S53), the controller 21 detects the motor current flowing through the motor 101 (S45). If the detected voltage Ea is lower than the predetermined voltage e16 (S53), the control unit 21 turns off the inverter 4 (S55) and ends.

FIG. 5 is a characteristic diagram showing the relationship between the rotational speed and the pn voltage (a) and the relationship between the rotational speed and torque (b) of the brushless DC motor 101 driven by the motor driving apparatus 200 according to the present invention. is there.
When the brushless DC motor 100 with a speed reducer connected to the inertial body 400 is driven by the motor driving device 200, the motor driving device 200 supplies a voltage to be supplied to the motor 101 in order to reduce the impact (reaction) due to acceleration at the time of startup. It is gradually raised by PWM control. At that time, the output torque of the motor 101 (drive torque when the rotation speed is 0) increases as T1, T2, and T3 as the time advances from t1, t2, and t3, and the inertial body 400 is gradually accelerated.

However, as described above, when the motor 101 is stopped, the inertial body 400 is rotated by applying an external force, and the motor 101 has already been rotated in the normal rotation direction or the reverse rotation direction (idle rotation; rotation not dependent on the drive power supply) immediately before starting. ).
In this case, each transistor of the inverter 4 (FIG. 9) is naturally turned off, but when viewed from the motor 101 side, it is a three-phase full-wave rectifier circuit composed of six diodes (freewheeling diodes). Therefore, the motor 101 generates an electromotive force so that idling is suppressed, and the generated power is charged to the smoothing capacitor 2 through the three-phase full-wave rectifier circuit (inverter 4). The polarity of the electric power to be charged is constant regardless of the idling direction, and is the same as when the converter 1a operates.

Here, as described above, the discharge circuit 60 is turned on (S63), and the process of decreasing the voltage Ea between the connection terminals pn decreases the rotational speed of the motor 101 at that time in the forward direction Nf3. This will be described as (point Pn3).
When the a contacts 41a and 41a are opened (S61) and the AC voltage E is interrupted (point Pn3), the pn voltage Ea is En, and the motor 101 is idling at the rotational speed Nf3 due to an external force. Generates an induced voltage Ef3, and Ea = En> Ef3.
When the discharge circuit 60 is turned on (S63) and the discharge current Ibr flows from the smoothing capacitor 2 through the resistor 61, the pn voltage Ea decreases from En and becomes Ea = Ef3 (point Pf3).

When the pn voltage Ea becomes En <Ef3, the induced voltage Ef3 generated in the motor 101 idling at the rotational speed Nf3 due to the external force is passed through the diode bridge (full-wave rectifier circuit) of the inverter 4 to the smoothing capacitor 2. To charge.
When the induced voltage Ef3 generated in the motor 101 is larger than the charging current for charging the smoothing capacitor 2, the discharging current Ibr that the discharging circuit 60 discharges from the smoothing capacitor 2 is larger, the pn voltage Ea decreases. That is, since the rotational energy of the motor 101 is consumed by the discharge circuit 60 (that is, the load is large), the braking torque acts on the motor 101, and the rotational speed decreases faster than the natural rotation (point Pf3 → point Pf2). ).

  When the rotational speed of the motor 101 decreases and decreases to Nf2 (point Pn2) in the forward rotation direction, the discharge circuit 60 is turned off (S73), the a contacts 41a and 41a are closed (S75), and the AC voltage E is given to the converter 1a, and the pn voltage Ea rises from Ef2 to En (point Pf2 → point Pn2).

The operation described above is the same even when the motor 101 is rotating in the reverse direction. When the motor 101 is started, if the rotation speed N is higher than Nf2 in the forward rotation direction or higher than Nr2 in the reverse rotation direction. Then, the AC voltage E is cut off, the smoothing capacitor 2 is discharged by the discharge circuit 60, and the rotational speed N is reduced.
When the rotation speed N decreases and the rotation speed N becomes Nf2 or less in the forward direction or Nr2 or less in the reverse direction, the discharge of the smoothing capacitor 2 by the discharge circuit 60 is stopped, and the AC voltage E is converted to the converter 1a. The motor 101 is returned to the startup operation.

1 DC power supply 1a Converter (rectifier circuit)
2 Smoothing capacitor 3 Voltage divider circuit (voltage detection means)
4 Inverter (conversion circuit)
20 control power circuit 21 control unit (voltage determination means, idling speed detection means, rotation speed determination means)
21b, 21c Voltage detection means 21c, 21d Current detection means 28 Idling detection circuit 41 Power supply switching relay 41a a contact 60 Discharge circuit 100 Brushless DC motor with reduction gear 101 Motor (brushless DC motor)
DESCRIPTION OF SYMBOLS 103 Rotor position detector 200 Motor drive device 201 Motor drive part 281 Control relay 300 Power supply opening / closing part (open / close circuit)

Claims (4)

A rectifier circuit and a smoothing capacitor for rectifying a voltage from an AC power supply; an open / close circuit for opening and closing between the AC power supply and the rectifier circuit; a conversion circuit for converting a DC voltage smoothed by the smoothing capacitor into a periodic voltage; Voltage determination means for determining whether the value of the DC voltage is equal to or greater than a predetermined voltage value, and a motor having a permanent magnet in the rotor or stator is driven by the periodic voltage converted by the conversion circuit. When the voltage determining means determines that the voltage is equal to or higher than a predetermined voltage value, in the motor drive device that opens the open / close circuit,
An idling speed detecting means for detecting an idling speed including the rotation direction of the rotor at the time of startup, and an idling speed determining means for judging whether or not the idling speed detected by the idling speed detecting means is included in a predetermined rotation speed range; A discharge circuit for discharging the smoothing capacitor, and configured to open the open / close circuit and turn on the discharge circuit when the rotational speed determining means determines that the smoothing capacitor is not included in a predetermined rotational speed range. The motor drive device characterized by the above-mentioned.   After the open / close circuit is opened and the discharge circuit is turned on, when the rotational speed determination means determines that the idle speed detected by the idle speed detection means is within a predetermined rotational speed range, the discharge circuit is The motor driving device according to claim 1, wherein the motor opening and closing circuit is configured to be closed.   The motor driving apparatus according to claim 1, wherein the predetermined rotation speed range is determined based on an idling speed allowed when the motor is started.   The voltage determination unit, the idling speed detection unit, the rotation speed determination unit, and the discharge circuit are configured to be operated by electric power from the smoothing capacitor when the open / close circuit is open. The motor drive device of Claim 1.

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