JP2010104173A - Motor drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a mounting space and reduce cost to achieve a regenerative operation and a power operation that do not affect the operation of a motor. <P>SOLUTION: In regenerative operation, a regenerative power accumulating/discharging unit 50 controls a transistor drive circuit 70 to change a regenerative power charging transistor 52 restricted on current supply by first and second transistor current limiting circuits 54 and 60, from an active region to a saturated region to cause the regenerative power charging transistor 52 to charge a regenerative power accumulating capacitor 51. In power operation, the regenerative power accumulating/discharging unit 50 controls the regenerative power accumulating capacitor 51 to discharge its accumulated charges to an inverter 30 via a regenerative power discharging diode 53. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor driving device for driving a motor.

  FIG. 4 shows a general configuration of a motor drive device using an inverter circuit. In FIG. 4, 301 is a three-phase or single-phase AC power source, 302 is a rectifier that converts AC voltage into DC voltage, 303 is an inrush current suppression circuit, and 304 is smoothing DC voltage. Smoothing capacitor. The rectifier 302, the inrush current suppression circuit 303, and the smoothing capacitor 304 constitute a converter unit 305. Reference numeral 311 denotes an inverter, 312 denotes a motor control unit, and 313 denotes a motor. The inverter 311 converts a DC voltage into an AC voltage, performs control by the motor control unit 312, and supplies necessary power to the motor 313. 321 is a regenerative absorption resistor, 322 is a surge absorption diode, and 323 is a regenerative absorption switch.

When the motor 313 is driven using the inverter 311 as shown in FIG. 4, generally, the PWM switching method is adopted to reduce the power loss in the inverter circuit.
In this motor drive device, when the motor 313 is driven, a power running operation in which power is supplied to the motor 313 for driving, and a regenerative operation in which power (regenerative power) is returned from the motor 313 when the motor 313 is decelerated. Repeatedly. When powering operation is performed, a large current is required for steep acceleration, and power consumption in the inverter 311 also increases. When regenerative operation is performed, regenerative power returns from the motor 313 to the smoothing capacitor 304 via the inverter 311. Here, it is known that the regenerative electric power from the motor 313 increases as the speed decreases sharply from the high speed rotation. For this reason, the DC voltage of the smoothing capacitor 304 rises and may exceed the withstand voltage of the power element of the inverter 311, so some kind of regenerative absorption measure is required.

  For this reason, as in this motor drive device, a regenerative absorption resistor 321 and a regenerative absorption switch 323 are generally provided as a regenerative absorption measure. As a result, when the DC voltage of the smoothing capacitor 304 becomes larger than an appropriate threshold with a margin with respect to the breakdown voltage of the power element of the inverter 311, the regenerative absorption switch 323 is turned on, and the regenerative power is generated by the regenerative absorption resistor 321. Is consumed. This prevents the DC voltage of the smoothing capacitor 304 from increasing. The surge absorbing diode 322 is provided as necessary to prevent noise due to the inductance component of the regenerative absorption resistor when the regenerative absorption switch 323 is turned off.

FIG. 5 shows an operation example of a general regenerative absorption circuit using a resistor, and the shaded portion is power loss due to the regenerative absorption resistor. As shown in FIG. 5, in a general regenerative absorption circuit, power loss is not small.
In recent years, the demand for power saving has been increasing. For this reason, there has been an effort to save power by storing the regenerative power from the motor 313 in the smoothing capacitor 304 without wastefully using the regenerative absorption resistor 321.

  FIG. 6 shows a motor driving device disclosed in Patent Document 1 that achieves such power saving. As shown in FIG. 6, in this motor drive device, the inrush current suppression circuit 303 shown in FIG. 4 is replaced with a coil 306 for power factor improvement. Furthermore, this motor drive device includes a reverse blocking diode 332 instead of the regenerative absorption resistor 321 shown in FIG. The reverse blocking diode 332 is provided at a portion connected to the inverter 311 so as to prevent the regenerative absorption series capacitor 331 from being charged in the reverse direction. Thereby, in this motor drive device, regenerative electric power is accumulated in regenerative absorption series capacitor 331 at the time of deceleration. During powering operation, the smoothing capacitor 304 and the regenerative absorption series capacitor 331 are connected in series by switching the regenerative absorption changeover switch 333, and the charge stored in the regenerative absorption series capacitor 331 is effectively used. By adopting such a configuration, power loss due to the regenerative absorption resistor 321 as shown in FIG. 4 is eliminated, and power saving is achieved.

FIG. 7 shows a motor driving device disclosed in Patent Document 2. As shown in FIG. In this motor drive device, a method of charging the regenerative power storage capacitor 342 via the charging converter 341 is adopted as a regenerative power absorption method with high power saving effect.
The motor drive device includes first current detection means 343 that detects an input current and second current detection means 344 that detects a current that charges a regenerative power storage capacitor 342 as current detection means. In addition, the motor drive device includes first voltage detection means 345 that detects the voltage of the smoothing capacitor 304 and second voltage detection means 346 that detects the voltage of the regenerative power storage capacitor 342 as voltage detection means. In this motor drive device, the control circuit 347 and the memory 348 control the charging converter 341 while calculating the input power capacity, thereby controlling the accumulation and discharge of regenerative power. As described above, this motor drive device realizes a configuration suitable for a relatively large-capacity load due to a complicated configuration.
Japanese Patent No. 3678582 JP 11-299275 A

By the way, in the motor drive device disclosed in Patent Document 1 (FIG. 6), the regenerative power is stored using the regenerative absorption series capacitor 331, and the stored electric charge can be used during power running. However, the motor driving device disclosed in Patent Document 1 has some problems in actual use.
First, a switching current always flows through the regenerative absorption series capacitor 331 inserted in series both during powering operation and during regenerative operation. Therefore, the regenerative absorption series capacitor 331 needs to be a low impedance capacitor. In addition, since the regenerative absorption series capacitor 331 is inserted in series with the smoothing capacitor 304, it is necessary to increase the capacity of the regenerative absorption series capacitor 331 so as not to damage the breakdown voltage of the power element of the inverter 311. However, when the capacity of the regenerative absorption series capacitor 331 becomes large, restrictions on the arrangement space of the regenerative absorption series capacitor 331 or other circuits increase, and the cost also increases, which becomes a practical obstacle.

  Furthermore, in the motor drive device disclosed in Patent Document 1, the regenerative absorption switching switch 333 is switched during regenerative operation (during deceleration), and the negative side of the regenerative absorption series capacitor 331 is connected to zero potential. For this reason, the DC voltage of the inverter 311 is significantly reduced during the regenerative operation, and therefore, the movement of the motor in response to the command changes, which makes the motor operation unfavorable.

  Further, in the motor drive device disclosed in Patent Document 2 (FIG. 7), a large-capacity regenerative power storage capacitor 342 is provided to store regenerative power. The charging converter 341 is controlled so that the accumulated regenerative power can be discharged during powering operation. Such a configuration is intended to calculate the input power, and to reliably store and discharge the regenerative power, and is characterized by the fact that the charge accumulated by the regeneration can be used effectively for power outages and the like. . However, in this motor drive device, two current detection means 343, 344 and two voltage detection means 345, 346 are provided, taken into the memory 348 of the control circuit 347, and control is performed by calculating input power, etc. Complex processing is required. For this reason, the motor driving device is expected to be considerably increased in cost, and is difficult to put into practical use in small and medium capacity applications of about several kW.

Further, regarding the method of the charging converter 341 considered to be the most important in order to save power, the current / voltage and power loss flowing through the charging converter 341, and the regenerative power storage / discharge unit 340 immediately after the input power is turned on Important operational matters such as the initial operation and the influence of the regenerative power storage / discharge unit 340 on the input power supply unit and the converter unit 305 are unknown. However, depending on these methods, the ability and performance to store and discharge regenerative power will be affected. And the cost and mounting space will also change.
An object of the present invention is to realize a regenerative operation and a power running operation that can easily secure a mounting space, suppress cost, and do not affect the operation of a motor.

  In order to solve the above-mentioned problem, the motor drive device according to claim 1 according to the present invention converts an AC power source and an AC voltage output from the AC power source by a rectifier into a DC voltage, and rushes by the converted DC voltage. A converter that charges a smoothing capacitor via a current suppression circuit, an inverter that converts the DC voltage output from the converter into an AC voltage, and drives the motor, and regenerative power that is generated when the motor decelerates is stored. Regenerative power storage and discharge means, and the regenerative power storage and discharge means includes a regenerative power storage capacitor that stores the regenerative power, a current-voltage control element that supplies a charging current to the regenerative power storage capacitor, and the current-voltage control Based on the current difference means for limiting the current of the element and the potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor, Element driving means for driving a current-voltage control element; and a regenerative power discharging element for realizing a path for discharging the charge of the regenerative power storage capacitor to the inverter during a power running operation, and storing the regenerative power In the regenerative operation, the discharging means is configured such that the element driving means is current-limited by the current limiting means based on a potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor. While changing the voltage control element from the active region to the saturation region, the current / voltage control element performs control to accumulate regenerative power in the regenerative power storage capacitor, and during powering operation, the charge stored in the regenerative power storage capacitor is stored. , And control to discharge to the inverter through the regenerative power discharge element.

According to a second aspect of the present invention, there is provided the motor driving device according to the first aspect, wherein the element driving means includes a voltage value of the smoothing capacitor and a voltage value of the regenerative power storage capacitor. Is greater than the first threshold value, the regenerative power storage capacitor is controlled to start storing regenerative power, and is less than the first threshold value and less than the second threshold value. Control for stopping the accumulation of regenerative power in the regenerative power storage capacitor, and when the potential difference exceeds the first threshold, accumulation of regenerative power in the regenerative power storage capacitor is started. In this case, the current-voltage control element that is current-limited by the current-limiting means is changed from an active region to a saturation region.
According to a third aspect of the present invention, in the motor driving device according to the second aspect, the current limiting means includes a voltage value of the smoothing capacitor and a voltage value of the regenerative power storage capacitor. When the potential difference exceeds the first threshold value and exceeds the third threshold value, the degree of limiting the current flowing through the current-voltage control element is increased.

According to the present invention, the regenerative power is stored in the regenerative power storage capacitor by the current / voltage control element while changing the current / voltage control element whose current is limited by the current limiting means from the active region to the saturation region. Thus, it is possible to prevent the direct current voltage of the inverter from rapidly decreasing and to suppress a change in the inclination of the motor.
In addition, according to the present invention, the regenerative power storage capacitor is charged by a single current / voltage control element, so that a mounting space can be easily secured and the cost can be reduced.

According to the second aspect of the present invention, the monitoring of the smoothing capacitor when starting and stopping the accumulation of regenerative power in the regenerative power storage capacitor is performed by monitoring with the first threshold value and the second threshold value. The potential difference between the voltage value and the voltage value of the regenerative power storage capacitor can be controlled appropriately.
According to the invention of claim 3, the current / voltage control element can be appropriately operated by monitoring with the third threshold value.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
(First embodiment)
(Constitution)
The first embodiment is a motor drive device for driving a motor.
FIG. 1 shows the configuration of the motor drive device of the first embodiment. The motor drive device shown in FIG. 1 is a motor drive device using an inverter circuit.
As shown in FIG. 1, the motor drive device includes a converter unit 10, an inverter 30, a regenerative power storage / discharge unit 50, a motor 101, and a motor control unit (motor control circuit) 102.

  The converter unit 10 includes a power source 11, a rectifier 12, an inrush current suppression circuit 20, and a smoothing capacitor 14. The power source 11 is a three-phase or single-phase AC power source. For example, the power supply 11 is AC100V ± 15% or AC200V ± 15%, and is a three-phase or single-phase AC voltage of 50 Hz or 60 Hz. The rectifier 12 converts the AC voltage output from the power supply 11 into a DC voltage. The inrush current suppression circuit 20 includes a resistor 21 that suppresses an inrush current from the power source 11 when the power is turned on, and an input current bypass switch 22 that bypasses the resistor 21 after the power source 11 starts up. The resistor 21 has several Ω to several tens Ω. The smoothing capacitor 14 is a smoothing capacitor that smoothes the DC voltage.

The inverter 30 is configured by combining a semiconductor element (power semiconductor element) and a passive element. The inverter 30 converts the DC voltage from the converter unit 10 or the regenerative power storage / discharge unit 50 into an AC voltage, and supplies the motor 101 with necessary power. At this time, the motor control unit 102 controls the inverter 30 to supply necessary power to the motor 101.
The regenerative power storage / discharge unit 50 is connected to lines 111 and 112 to which the smoothing capacitor 14 and the inverter 30 are connected. The regenerative power storage / discharge unit 50 includes a regenerative power storage capacitor 51, a regenerative power charge transistor 52, a regenerative power discharge diode 53, a first transistor current limit circuit 54, a DISABLE 55, a second transistor current limit circuit 60, a transistor drive circuit 70, and a discharge. Part 80.

  The regenerative power storage capacitor 51 is a capacitor that mainly stores regenerative power during a regenerative operation (deceleration operation). The regenerative power charging transistor 52 is a current / voltage control element for flowing a charging current for the regenerative power storage capacitor 51. The regenerative power charging transistor 52 may be a current / voltage control element capable of controlling the current / voltage, and is, for example, an IGBT, a MOSFET, a bipolar transistor, or the like.

The regenerative power discharge diode 53 provides a path for discharging the charge of the regenerative power storage capacitor 51 to the inverter 30 during a power running operation. That is, the regenerative power discharge diode 53 is an element that forms a path for discharging regenerative power. The regenerative power discharge diode 53 may be a single diode or a parasitic diode of the regenerative power charging transistor 52.
The first transistor current limiting circuit 54 is mainly for limiting the current of the regenerative power charging transistor 52 when the power supply 11 is turned on. The first transistor current limiting circuit 54 is a resistor, for example.

The second transistor current limit circuit 60 limits the current of the regenerative power charging transistor 52 in cooperation with the first transistor current limit circuit 54. For example, the second transistor current limiting circuit 60 includes three resistors 61, 62, 63, a hysteresis comparator 64, and a switch 65.
The transistor drive circuit 70 monitors the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51, and drives the regenerative power charging transistor 52 based on the potential difference. By driving the regenerative power charging transistor 52, a charging current flows through the regenerative power storage capacitor 51. For example, the transistor drive circuit 70 includes two resistors 71 and 72 and a hysteresis comparator 73.

The discharge unit 80 is for discharging the electric charges of the smoothing capacitor 14 and the regenerative power storage capacitor 51 when the power supply 11 is shut off. For example, the discharge unit 80 includes a discharge resistor 81 and a discharge switch 82.
The control gate 73s of the hysteresis comparator 73 is configured so that the regenerative power charging transistor 52 can be turned off by a command from the motor control unit 102 when the motor speed of the motor 101 is low. 1 and 3, the motor control unit 102 and the control gate 73s are not connected, but are actually connected, and the control gate 73s is controlled by the motor control unit 102.

The connection state of the above configuration is as follows.
A regenerative power storage capacitor 51, a regenerative power charging transistor 52, and a first transistor current limiting circuit (resistor) 54 are connected in series in that order on a line 113 connecting the line 111 and the line 112. . Here, the regenerative power storage capacitor 51 is connected to the collector (C) of the regenerative power charging transistor 52, and the first transistor current limiting circuit 54 is connected to the emitter (E) of the regenerative power charging transistor 52.

  In the transistor drive circuit 70, two resistors 71 and 72 are connected in series on a line 114 connecting the line 113a and the line 112 between the regenerative power storage capacitor 51 and the regenerative power charging transistor 52. . In the transistor drive circuit 70, a hysteresis comparator 73 is connected to the line 114a in order to measure the voltage (voltage division) of the line 114a between the two resistors 71 and 72. Further, the hysteresis comparator 73 is connected to the regenerative power charging transistor 52 (base (B)).

  In the second transistor current limiting circuit 60, two resistors 61 and 62 are connected in series on the line 115 connecting the line 113a and the line 112 between the regenerative power storage capacitor 51 and the regenerative power charging transistor 52. is doing. Here, the resistance values of the two resistors 61 and 62 included in the second transistor current limiting circuit 60 are the same as the resistance values of the two resistors 71 and 72 included in the transistor drive circuit 70.

  In the second transistor current limiting circuit 60, a resistor 63 and a switch 65 are connected in series on a line 116 connecting the line 113b and the line 112 between the regenerative power charging transistor 52 and the first transistor current limiting circuit 54. Connected. In the second transistor current limiting circuit 60, a hysteresis comparator 64 is connected to the line 115a in order to measure the voltage (voltage division) of the line 115a between the two resistors 61 and 62. The hysteresis comparator 64 turns the switch 65 on and off.

  Further, the regenerative power discharge diode 53 is arranged on a line 117 connecting the line 113 a and the line 112 between the regenerative power storage capacitor 51 and the regenerative power charging transistor 52. The regenerative power discharge diode 53 has an anode connected to the line 112 and a cathode connected to the line 113a. In the discharge unit 80, a discharge resistor 81 and a discharge switch 82 are connected in series on a line 118 connecting the line 111, a line 113a between the regenerative power storage capacitor 51 and the regenerative power charging transistor 52.

  The configuration as described above will be described next along the operation of the motor drive device. The operation of the motor drive device is roughly classified into (1) an initial charging operation immediately after the power is turned on and (2) a motor operation operation (power running operation) (see (V) and (VI) in FIG. 2). Further, (2) the motor operation is changed to (2-1) acceleration operation (see (V) in FIG. 2), (2-2) acceleration operation end, constant speed operation (see (VI) in FIG. 2), ( 2-3) Deceleration operation (regenerative operation) (see (I), (II), and (III) in FIG. 2) and (2-4) Stop state (see (IV) in FIG. 2). it can. The operation of each of the above configurations will be described along these operations.

(1) Initial charging operation immediately after power-on The power source 11 supplies an AC voltage to the rectifier 12. In the rectifier 12, the AC voltage supplied from the power source 11 is full-wave rectified and converted to a DC voltage. The full-wave rectified DC voltage is supplied to the inverter 30 through the inrush current suppression circuit 20 and a power factor correction circuit such as a choke coil (not shown) as necessary, and through the smoothing capacitor 14. The inverter 30 converts a DC voltage into an AC voltage and is controlled by the motor control unit 102 to supply power to the motor 101.

  Here, it is assumed that the voltage values of the smoothing capacitor 14 and the regenerative power storage capacitor 51 are zero immediately after the power supply 11 is turned on. Then, the smoothing capacitor 14 and the regenerative power storage capacitor 51 are gradually charged while the input current is suppressed by the inrush current suppression circuit 20. At this time, the smoothing capacitor 14 starts charging first. When the charging voltage of the smoothing capacitor 14 reaches about several tens of volts, the regenerative power storage capacitor 51 starts charging. Specifically, the smoothing capacitor 14 and the regenerative power storage capacitor 51 start charging by the following operation.

  The transistor drive circuit 70 (hysteresis comparator 73) monitors the voltage value on the line 114a between the two resistors 71 and 72. Thereby, the potential difference (drop) between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is monitored by the divided voltage value. When the monitored value (divided voltage value) exceeds a predetermined first threshold value (the charging voltage of the smoothing capacitor 14 is about several tens of volts), the transistor drive circuit 70 (hysteresis comparator 73) regenerates power. The charge transistor 52 is driven. By driving the regenerative power charging transistor 52, a charging current starts to flow through the regenerative power storage capacitor 51, and the regenerative power storage capacitor 51 starts charging.

  Further, the second transistor current limiting circuit 60 also monitors the voltage value on the line 115 a between the two resistors 61 and 62. As a result, similarly to the transistor drive circuit 70, the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is monitored by a divided voltage value (the same value as the divided voltage value in the transistor drive circuit 70). Yes. Then, when the monitored value exceeds a predetermined third threshold value, the second transistor current limiting circuit 60 applies a stronger limit to the charging current passing through the regenerative power charging transistor 52. That is, in the second transistor current limiting circuit 60, when the monitored value (divided voltage value) exceeds a predetermined third threshold value, the hysteresis comparator 64 turns off the switch 65 to regenerate the regenerative power charging transistor 52. Only the first transistor current limiting circuit 54 (resistor 54) is operated on the emitter side. That is, of the resistors 54 and 63 connected in parallel to the emitter side of the regenerative power charging transistor 52, only one resistor 54 is energized. This increases the resistance between regenerative power charging transistor 52 and line 112 and places a stronger limit on the charging current through regenerative power charging transistor 52. Here, the third threshold value is larger than the first threshold value.

  As a result, the second transistor current limiting circuit 60 maintains the ON state of the switch 65 until the monitored value exceeds a predetermined third threshold value, whereby the charging current passing through the regenerative power charging transistor 52 is maintained. Is limited by two resistors 54 and 63. Further, the second transistor current limiting circuit 60 turns off the switch 65 when the monitored value exceeds a predetermined third threshold value, so that the charging current passing through the regenerative power charging transistor 52 is By connecting only one resistor 54, it is more strongly limited. That is, when a potential exceeding the third threshold value is generated between the smoothing capacitor 14 and the regenerative power storage capacitor 51, the charging current passing through the regenerative power charging transistor 52 is more strongly limited.

In this way, the first and second transistor current limiting circuits 54 and 60 (both the resistor 54 and the resistor 63 or only the resistor 54) always limit the current flowing through the regenerative power charging transistor 52, and the regenerative power charging transistor 52 A large load is not applied. As a result, the regenerative power charging transistor 52 can be operated safely during the initial charging of the regenerative power storage capacitor 51 immediately after the power supply 11 is turned on.
Then, when charging of the smoothing capacitor 14 and the regenerative power storage capacitor 51 is finished and the charging current does not flow to the regenerative power charge transistor 52, the regenerative power charge transistor 52 is turned off. Thus, the regenerative power storage capacitor 51 waits for the next driving (powering operation) of the motor 101 while holding the voltage at that time.

(2) Motor driving operation The operation of each component during the motor driving operation will be described with reference to FIG.
(2-1) Acceleration operation (operation in section (V) in FIG. 2)
A current flows from the smoothing capacitor 14 and the regenerative power storage capacitor 51 through the inverter 30 to the motor 101 that is a load. As a result, the voltage decreases in the smoothing capacitor 14 and the regenerative power storage capacitor 51. When the voltage of the smoothing capacitor 14 and the regenerative power storage capacitor 51 becomes smaller than the DC voltage supplied from the power source 11 (corresponding to the output of the rectifier 12), the current from the power source 11 also flows through the inverter 30. Thus, during the acceleration operation of the motor 101, the motor 101 consumes the electric power based on the smoothing capacitor 14, the regenerative power storage capacitor 51, and the power source 11.

  In addition, the discharge current of the regenerative power storage capacitor 51 is discharged via the regenerative power discharge diode 53 connected in series with the regenerative power storage capacitor 51. Therefore, when the regenerative power storage capacitor 51 is discharged and the voltage of the regenerative power storage capacitor 51 becomes smaller than the voltage of the power supply 11, the discharge of the regenerative power storage capacitor 51 naturally stops. As a result, the voltage of the regenerative power storage capacitor 51 is held at the lowest value during the acceleration operation.

(2-2) End of acceleration operation, constant speed operation (operation in section (VI) in Fig. 2)
The power from the power source 11 is continuously supplied to the inverter 30. At this time, the regenerative power storage capacitor 51 is in a standby state at the lowest voltage value, and a deceleration operation (operation in the section (II) in FIG. 2) is started and waiting for the regenerative power to return. State. On the other hand, the smoothing capacitor 14 is charged by the power supply 11. For this reason, the voltage of the regenerative power storage capacitor 51 is lower than the voltage of the smoothing capacitor 14. Specifically, as in the section (VI) in FIG. 2, the voltage of the regenerative power storage capacitor 51 is about 10 V lower than the voltage of the smoothing capacitor 14.

(2-3) Deceleration operation (regenerative operation)
As for the deceleration operation (regenerative operation), (2-3-1) Initial operation of the deceleration operation after completion of the constant speed operation (operation at the start of the deceleration operation after the power running operation), (2-3-2) ) It can be divided into a medium-term operation of the deceleration operation and (2-3-3) a final operation of the deceleration operation.
(2-3-1) Initial operation of deceleration operation after completion of constant speed operation (operation in section (I) in FIG. 2)
Regenerative power returns from the motor 101 to the smoothing capacitor 14 via the inverter 30. Thereby, the voltage of the smoothing capacitor 14 starts to increase. However, in the initial operation state of this deceleration operation, the regenerative power storage / discharge circuit 50 does not operate yet.

(2-3-2) Medium-term operation of deceleration operation (operation in section (II) in FIG. 2)
When the voltage of the smoothing capacitor 14 increases and rises several tens of volts from the state before the start of deceleration, the regenerative power storage / discharge circuit 50 starts operating, and the regenerative power storage capacitor 51 is charged with a charging current via the regenerative power storage transistor 52. Begins to flow. That is, in the transistor drive circuit 70 (hysteresis comparator 73), the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is about several tens of volts, and the monitored value exceeds the first threshold value. Then, the regenerative power charging transistor 52 is driven. As a result, a charging current starts to flow through the regenerative power storage capacitor 51. Note that such a charging operation to the regenerative power storage capacitor 51 is performed when the voltage of the smoothing capacitor as seen by a general regenerative absorption resistor (FIG. 4) exceeds a predetermined threshold voltage ( This is a completely different operation from the case of starting power storage by regenerative absorption resistance.

  At this time, in the second transistor current limiting circuit 60, the switch 65 is normally turned on. For this reason, the charging current passing through the regenerative power charging transistor 52 is limited by the resistors 54 and 63. Under such a state, the voltage of the potential difference between the smoothing capacitor 14 and the regenerative power storage capacitor 51 is applied to both ends of the regenerative power charging transistor 52, and the regenerative power charging transistor 52 has a slightly large charging current. (Charging current exceeding 10 (A) in the example of FIG. 2) flows. For this reason, the regenerative power charging transistor 52 instantaneously carries a large amount of power (about 240 (W) in the peak in the example of FIG. 2) and operates in a so-called active region. However, charging of the regenerative power storage capacitor 51 proceeds in a short time, and the voltage level of the regenerative power storage capacitor 51 becomes close to the voltage level of the smoothing capacitor 14 in a short time. In the example of FIG. 2, the time for operating in the active region (the operation period of (2)) is only 10 ms, which is sufficiently shorter than the acceleration / deceleration time.

(2-3-3) Final operation of deceleration operation (operation in section (III) in FIG. 2)
The potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is only a few volts. At this time, the operation of the regenerative power charging transistor 52 shifts from the active region to the saturation region. For this reason, the power loss of the regenerative power charging transistor 52 during the final operation of the deceleration operation is negligible due to the saturation loss.

  Here, the transistor drive circuit 70 (hysteresis comparator 73) monitors the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 with the divided voltage value, and the value (divided voltage value). ) Is kept charged until it becomes less than a predetermined second threshold value. Here, the second threshold value is a value less than the first threshold value. That is, the transistor drive circuit 70 maintains the drive of the regenerative power charging transistor 52 for a period in which the monitored value (divided value) is between the first threshold value and the second threshold value. . Thereby, the driving of the regenerative power charging transistor 52 is maintained during a period in which the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is several volts.

(2-4) Stop state (Operation in section (IV) in FIG. 2)
The power consumption of the motor 101 and the inverter 30 is also small, and the regenerative power charging transistor 52 is turned off when no current flows through the regenerative power charging transistor 52. That is, in the transistor drive circuit 70 (hysteresis comparator 73), the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 becomes smaller than a predetermined number V, and the monitored value (divided value) is When it becomes less than the second threshold value, the regenerative power charging transistor 52 is turned off.

Here, a summary of a series of operations of the regenerative power charging transistor 52 during the above deceleration operation (regeneration operation) is as follows.
The transistor drive circuit 70 monitors the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 during the deceleration operation (regeneration operation). Specifically, the potential difference is monitored as a partial pressure value. When the monitored value exceeds the first threshold value, the transistor drive circuit 70 drives the regenerative power charging transistor 52. As a result, a charging current flows through the regenerative power storage capacitor 51. At the same time, the upper limit of the current of the regenerative power charging transistor 52 is limited by the first and second transistor current limiting circuits 54 and 60. That is, the upper limit of the current value of the regenerative power charging transistor 52 is limited by the two resistors 54 and 63 connected in parallel. As a result, the regenerative power charging transistor 52 operates from the active region to the saturation region while flowing the current having the upper limit of the current value. Further, once the current starts to flow through the regenerative power charging transistor 52, the charged state is maintained until the current becomes less than the second threshold value.

  In the example shown in FIG. 2, the period (2) (the medium-term operation period after the start of the deceleration operation) that becomes the active region is as short as about 10 ms. In addition, in the period (3) that becomes the saturation region (the final movement period after the start of the deceleration operation), the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is small, but the second Therefore, the current of the regenerative power charging transistor 52 continues to flow.

  Note that the second transistor current limiting circuit 60 not only during the initial charging operation but also during the deceleration operation (regeneration operation) causes the regenerative power charging transistor 52 to be activated when the monitored value exceeds the third threshold value. It is also possible to place a stronger limit on the charging current that is passed (it can also be a connection with only resistor 54). Thereby, for example, when the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 becomes transiently large (for example, during a power failure), in addition to the initial charging operation, the regenerative power charging is performed. A stronger limit can be imposed on the charging current of the transistor 52.

(3) Other operations (3-1) Operation when the rotation speed of the motor 101 is low The control gate 73s of the hysteresis comparator 73 stores regenerative power according to a command from the motor control unit 102 when the rotation speed of the motor 101 is low. The discharge part 50 is stopped. Specifically, the transistor drive circuit 70 (specifically, the hysteresis comparator 73) is switched from the on state to the off state. Thereby, when the rotation speed of the motor 101 is lower than the predetermined rotation speed, since the regenerative power from the motor 101 is small, there is no need to operate the regenerative power storage / discharge section 50, so the regenerative power storage / discharge section 50 is not operated. By doing so, useless power loss due to the regenerative power storage / discharge unit 50 can be suppressed.

(3-2) Operation when it is determined that the power supply 11 has been cut off When it is determined that the power supply 11 has been cut off (turned off), the discharge switch 82 is turned on. For example, the determination of the cutoff of the power supply 11 is performed by monitoring the output voltage of the power supply 11. Thus, when the discharge switch 82 is turned on, the regenerative power storage capacitor 51 starts discharging via the discharge resistor 81. As a result, a potential difference is generated between the smoothing capacitor 14 and the regenerative power storage capacitor 51, the monitored value reaches the first threshold value, the regenerative power charging transistor 52 is started, and the regenerative power storage operation is started. As a result, the smoothing capacitor 14 is discharged, and the smoothing capacitor 14 and the regenerative power storage capacitor 51 operate so that their potentials are in an equilibrium state. On the other hand, since the discharge switch 82 is kept on, the regenerative power storage capacitor 51 continues to discharge through the discharge resistor 81, so that a potential difference is generated between the smoothing capacitor 14 and the regenerative power storage capacitor 51 again. The value to be monitored becomes the first threshold value, and the smoothing capacitor 14 discharges electric charge. Such repeated operation enables the smoothing capacitor 14 and the regenerative power storage capacitor 51 to complete the discharge promptly after the power supply 11 is shut off.

  In the first embodiment, the converter unit 10 converts the AC voltage output from the AC power supply by a rectifier into a DC voltage, and charges the smoothing capacitor with the converted DC voltage via the inrush current suppression circuit. A converter is realized. Further, the inverter 30 realizes an inverter that drives the motor by converting the DC voltage output from the converter into an AC voltage. In addition, the regenerative power storage / discharge unit 50 realizes regenerative power storage / discharge means for storing regenerative power generated when the motor decelerates. Further, the regenerative power storage capacitor 51 realizes a regenerative power storage capacitor that stores the regenerative power. The regenerative power charging transistor 52 realizes a current-voltage control element that allows a charging current to flow through the regenerative power storage capacitor. Further, the first and second transistor current limiting circuits 54 and 60 realize current limiting means for limiting the current of the current / voltage control element. The transistor driving circuit 70 realizes element driving means for driving the current / voltage control element based on the potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor. Further, the regenerative power discharge diode 53 realizes a regenerative power discharge element that realizes a path for discharging the charge of the regenerative power storage capacitor to the inverter during a power running operation. In the first embodiment, when the regenerative power storage and discharge means is in a regenerative operation, the element drive means is based on the potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor. The current voltage control element that is current-limited by the current limiting means is controlled from the active region to the saturation region, and the current / voltage control element performs control to store regenerative power in the regenerative power storage capacitor. In operation, it is realized to control to discharge the electric charge stored in the regenerative power storage capacitor to the inverter through the regenerative power discharge element.

(Function and effect)
(1) The regenerative power storage capacitor 51 receives a current from the power source 11 only at the moment when the power source 11 is turned on, and hardly flows from the power source 11 side after the power source 11 is started up. Thereby, the regenerative power storage capacitor 51 functions as a capacitor for storing regenerative power, and is not regarded as a capacitance component when viewed from the power source 11 side. That is, the regenerative power storage capacitor 51 has a configuration that does not affect the power supply 11, the rectifier 12, the inrush current suppression circuit 20, and the like. Therefore, the regenerative power storage / discharge unit 50 hardly consumes the power of the power supply 11.

  Therefore, it is possible to change only the value of the regenerative power storage capacitor 51 as necessary without changing other parts of the regenerative power storage discharge unit 50. Accordingly, the regenerative power storage / discharge unit 50 is highly flexible as a regenerative power processing circuit. Further, the regenerative power storage capacitor 51 is not restricted by other components such as the power source 11, and it is easy to secure an arrangement space, and the cost can be reduced.

(2) During the regenerative operation (deceleration operation), the charging current passing through the regenerative power charging transistor 52 is limited by the first and second transistor current limiting circuits 54 and 60, and the regenerative power charging transistor 52 is removed from the active region. Operating in the saturation region. As a result, when the regenerative power is stored in the regenerative power storage capacitor 51 during the regenerative operation, the direct current voltage of the inverter 30 is prevented from rapidly decreasing, and the change in the inclination of the motor can be suppressed.

(3) During the regenerative operation, the regenerative power charging transistor 52 is operated, and the regenerative power is accumulated in the regenerative power charging transistor 52. Further, during the power running operation, the electric charge accumulated in the regenerative power charging transistor 52 is discharged through the regenerative power discharge diode 53. Thus, the regenerative operation and the power running operation can be realized with a simple configuration.
(4) In monitoring by the first threshold value and the second threshold value, the potential difference between the voltage value of the smoothing capacitor 14 and the voltage value of the regenerative power storage capacitor 51 is determined at the start of the regenerative power storage operation (deceleration operation). (At the initial operation), it can be kept as low as several tens of volts, and at the end of the regenerative power storage operation (at the final operation of deceleration control), it can be as low as several volts. That is, by monitoring with the first threshold value and the second threshold value, the voltage value of the smoothing capacitor 14 and the regenerative power storage capacitor when starting and stopping the storage of the regenerative power in the regenerative power storage capacitor 51 are determined. The potential difference from the voltage value of 51 can be appropriately controlled. For example, this eliminates the need for a regenerative absorption resistor (regenerative absorption resistor 321 in FIG. 4) that consumes a large amount of power.

(5) In the monitoring by the third threshold, the charging current passing through the regenerative power charging transistor 52 is more strongly limited. Thereby, the regenerative power charging transistor 52 can be appropriately operated.
(6) The regenerative power charging transistor 52 shifts to the operation in the saturation region after the operation in the active region in an extremely short time (about 10 ms). Thereby, the power consumption in the regenerative power charging transistor 52 can be suppressed. As a result, the heat dissipation design of the regenerative power charging transistor 52 can be facilitated, and the regenerative power charging transistor 52 can be mounted in a space-saving manner.

(7) Conventionally, resistors are constantly provided at both ends of the smoothing capacitor 304, that is, at both ends of a high DC voltage (see FIG. 7). On the other hand, in this embodiment, such a resistor is not provided. This is because in this embodiment, it is not necessary to detect the DC voltage value across the smoothing capacitor 14. As a result, it is possible to prevent a steady power loss due to a voltage dividing resistor or the like, reduce standby power, and save power.

(8) When the motor 101 finishes the acceleration operation and becomes a constant speed operation, the regenerative power storage capacitor 51 is in a standby state at the lowest voltage. The voltage of the regenerative power storage capacitor 51 at that time is about 10 V lower than the voltage of the smoothing capacitor 14. This is equivalent to an improvement in the ability to store regenerative power during the regenerative operation. Therefore, compared to a case where a regenerative power storage capacitor is simply added in parallel to a smoothing capacitor, this embodiment can improve the regenerative power storage capability by about 10%. Thereby, the capacity of the regenerative power storage capacitor 51 can be reduced.

(9) When the power supply 11 is shut off, the charge of the smoothing capacitor 14 and the regenerative power storage capacitor 51 is discharged only by turning on the discharge switch 82. Thereby, the steady loss by the discharge resistance 81 can be made zero. Therefore, standby power can be reduced, and power saving can be achieved.
(10) The current flowing through the regenerative power charging transistor 52 during the regenerative operation is about 1/3 to 1/2 of the current during general regenerative absorption using a conventional resistor (see FIG. 4). The result is completed (simulation result). Thereby, even when the regenerative power charging transistor 52 is used, it is possible to reduce the burden on the substrate, elements, noise, and the like.

(11) A simulation under the same conditions is performed in the case where the regenerative absorption resistor 321 shown in FIGS. 4 and 5 showing the conventional example is used and the method using the regenerative power storage discharge of FIGS. Implemented and calculated power loss. As a result, in the regenerative absorption resistor 321 shown in FIGS. 4 and 5 showing the conventional example, the power loss was about 184 (W). On the other hand, in the system using the regenerative power storage discharge of FIGS. 1 and 2 according to the present embodiment, the power loss of the regenerative power charging transistor 52 falls within a sufficiently low value of about 4 (W). Furthermore, even if the loss of the discharge section of the regenerative power discharge diode 53 which is another configuration is included, the power loss as the regenerative power storage discharge section 50 is a low value of about 7 (W). Thus, it has been confirmed that the present embodiment has a power saving effect even in the simulation.

  As described above, according to the present embodiment, regenerative power can be effectively recovered and reused while reducing costs. Further, the present embodiment does not require any special calculation such as calculating the input power capacity, and does not perform voltage conversion unlike the charging converter 341 shown in FIG. The current / voltage control element is used to achieve this purpose. This embodiment is particularly suitable for small and medium capacity loads up to several kW.

(Second Embodiment)
(Constitution)
The second embodiment is a motor drive device for driving a motor.
FIG. 3 shows a motor driving apparatus according to the second embodiment. As shown in FIG. 3, in the second embodiment, the configurations of the inrush current suppression circuit 20 and the discharge unit 80 in the first embodiment are changed. That is, in the second embodiment, the inrush current suppression circuit 20 includes an inrush diode 23 in addition to the resistor 21 and the input current bypass switch 22. In the second embodiment, the discharge resistor 81 in the first embodiment is eliminated, and the discharge switch 82 is connected to the resistor 21. Further, the inrush diode 23 is provided so as to connect the line 118 and the line 111 between the discharge switch 82 and the resistor 21. The inrush diode 23 has an anode connected to the line 118 and a cathode connected to the line 111.

With such a configuration, the inrush current suppression circuit 20 can suppress the inrush current from the power source 11 by the resistor 21 when the power source 11 is turned on as usual. At this time, a path through which the current of the power supply 11 flows to the smoothing capacitor 14 via the resistor 21 is secured by the inrush diode 23. Further, after the power supply 11 is started, the resistor 21 can be bypassed by the input current bypass switch 22.
When the charging of the smoothing capacitor 14 and the regenerative power storage capacitor 51 is completed after the power supply 11 is turned on, the inrush current bypass switch 22 of the inrush current suppression circuit 20 is turned on to bypass the resistor 21. Therefore, in a normal operation state (after the power supply 11 is turned on), no current flows through the resistor 21, so that the resistor 21 does not cause power loss.

  On the other hand, when it is determined that the power supply 11 is cut off, the resistor 21 and the discharge switch 82 functioning as a discharge resistor are used as a circuit for discharging the electric charge accumulated in the smoothing capacitor 14 and the regenerative power storage capacitor 51. That is, the discharge switch 82 is turned on to start discharging the regenerative power storage capacitor 51 through the resistor 21. At this time, a path through which the current of the regenerative power storage capacitor 51 flows is secured through the diode of the input current bypass switch 22 of the inrush current suppression circuit 20 and the resistor 21.

  As described above, when the regenerative power storage capacitor 51 starts discharging, a potential difference occurs between the smoothing capacitor 14 and the regenerative power storage capacitor 51, and when the monitored value exceeds the first threshold value, the regenerative power charge transistor 52 is started and the regenerative power storage operation is started. As a result, the smoothing capacitor 14 is discharged, and the smoothing capacitor 14 and the regenerative power storage capacitor 51 operate so that their potentials are balanced. On the other hand, since the discharge switch 82 is kept on, the regenerative power storage capacitor 51 continues to discharge through the resistor 21 that functions as a discharge resistor, so that the smoothing capacitor 14, the regenerative power storage capacitor 51, When the potential difference occurs in the first and second values and the monitored value exceeds the first threshold value, the smoothing capacitor 14 discharges electric charge. Such repeated operation enables the smoothing capacitor 14 and the regenerative power storage capacitor 51 to complete the discharge promptly after the power supply 11 is shut off.

(Function and effect)
The resistor 21 functions as a resistor for suppressing the inrush current of the inrush current suppression circuit 20 when the power source 11 is turned on, and as a discharge resistor for discharging the smoothing capacitor 14 and the regenerative power storage capacitor 51 after the power source 11 is shut off. And has both functions. As a result, the power resistance of the inrush current suppression circuit 20 that is originally expensive and has a large mounting space can be effectively utilized.

It is a figure which shows the structure of the motor drive device of the 1st Embodiment of this invention. It is a characteristic view which shows the change of the voltage of a smoothing capacitor, the voltage of a regenerative electric power storage capacitor, etc. It is a figure which shows the structure of the motor drive device of 2nd Embodiment. It is a figure which shows the structure of the conventional general motor drive device. It is a characteristic view which shows the operation example of a general regenerative absorption circuit. It is a figure which shows the structure of the motor drive device disclosed by patent document 1. FIG. It is a figure which shows the structure of the motor drive device disclosed by patent document 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Converter part, 11 Power supply, 12 Rectifier, 14 Smoothing capacitor, 20 Inrush current suppression circuit, 21 Resistance, 22 Input current bypass switch, 30 Inverter, 50 regenerative power storage discharge part, 51 Regenerative power storage capacitor, 52 Regenerative power charge transistor , 53 regenerative power discharge diode, 54 first transistor current limiting circuit, 60 second transistor current limiting circuit, 70 transistor driving circuit, 73s control gate, 80 discharging unit, 81 discharging resistor, 82 discharging switch, 101 motor, 102 motor control Part

Claims (3)

AC power supply,
A converter that converts the AC voltage output from the AC power source by a rectifier into a DC voltage, and charges the smoothing capacitor via the inrush current suppression circuit by the converted DC voltage;
An inverter that converts the DC voltage output by the converter into an AC voltage and drives the motor;
Regenerative power storage discharge means for storing regenerative power generated when the motor decelerates,
The regenerative power storage and discharge means is
A regenerative power storage capacitor for storing the regenerative power;
A current-voltage control element for flowing a charging current to the regenerative power storage capacitor;
Current limiting means for limiting the current of the current-voltage control element;
Based on the potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor, element driving means for driving the current-voltage control element;
A regenerative power discharging element that realizes a path for discharging the charge of the regenerative power storage capacitor to the inverter during a power running operation,
The regenerative power storage and discharge means is
In the regenerative operation, the element driving unit is configured to change the current voltage control element that is current limited by the current limiting unit based on a potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor. While changing from the active region to the saturated region, control to accumulate regenerative power in the regenerative power storage capacitor by the current voltage control element,
In a power running operation, the motor drive device controls to discharge the charge stored in the regenerative power storage capacitor to the inverter through the regenerative power discharge element.   When the potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor exceeds a first threshold value, the element driving unit starts storing regenerative power in the regenerative power storage capacitor. Control is performed to stop accumulation of regenerative power in the regenerative power storage capacitor when it is less than the first threshold value and less than the second threshold value, and the potential difference is the first threshold value. When accumulation of regenerative power in the regenerative power storage capacitor is started when the threshold value of 1 is exceeded, the current voltage control element that is current limited by the current limiting means is changed from an active region to a saturated region. The motor drive device according to claim 1, wherein   When the potential difference between the voltage value of the smoothing capacitor and the voltage value of the regenerative power storage capacitor exceeds the first threshold and exceeds the third threshold, the current limiting means The motor driving device according to claim 2, wherein a degree of limiting a current flowing through the motor is increased.

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