Regenerative power control device and power control device

Abstract

To provide a regenerative power control device that enables use of an external regenerative discharge unit and an external capacitor unit, and that is available at low cost.SOLUTION: This regenerative power control device comprises: an internal regenerative resistor connected to a power line; a first switching element connected in series to the internal regenerative resistor; a second switching element constituted so as to be connectable in series to an external resistor or an external capacitor; and a control unit for controlling the electrical continuity of the first and second switching elements. The control unit maintains the second switching element in an on state, and establishes electrical continuity of the first switching element when the voltage of the power line becomes a prescribed value or higher in a first mode where the external capacitor is connected in series to the second switching element. Furthermore, the control unit establishes electrical continuity of the first switching element when the voltage of the power line becomes a prescribed value or higher, and establishes electrical continuity of the second switching element when the voltage of the power line becomes a prescribed value or higher in a second mode where the external resistor is connected in series to the second switching element.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a regenerative power control device and a power control device.

Background Art

[0002] In a servo control device, a servo control device having a resistor and a transistor for regenerative power consumption inside is known. Also, a technique of additionally connecting an external regenerative discharge unit to the servo control device to increase the regenerative power consumption ability is widely known (see, for example, Patent Document 1). In this technique, when the transistor inside the servo control device is turned on, regenerative power is supplied to the resistor inside the servo control device and the resistor of the external regenerative discharge unit, and thus more regenerative power is consumed. Further, a technique of connecting an external capacitor unit to the servo control device to store regenerative power and assisting the power supply to the motor with this stored power is also known.

[0003] However, in order to connect an external regenerative discharge unit to the servo control device or an external capacitor unit as needed so that any unit can be used effectively, a first connection interface (terminal) for connecting the external regenerative discharge unit and a second connection interface (terminal) for connecting the external capacitor unit need to be provided separately in the servo control device. This has a problem of leading to an increase in the cost of the device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a regenerative power control device and a power control device that can utilize an external regenerative discharge unit and an external capacitor unit and have a low cost.

Means for Solving the Problems

[0006] The regenerative power control device according to the present invention is a regenerative power control device that controls regenerative power regenerated from a load, and includes an internal regenerative resistor connected to a power line connected to the load, and a first switching element connected in series with the internal regenerative resistor and through which a regenerative current from the power line flows, a second switching element configured to be connectable in series to an external resistor or an external capacitor and through which a regenerative current from the power line flows, and a control unit that controls conduction of the first switching element and the second switching element. In a first mode in which the external capacitor is connected in series to the second switching element, the control unit maintains the second switching element in an on state and conducts the first switching element when the voltage of the power line becomes equal to or higher than a predetermined value. In a second mode in which the external resistor is connected in series to the second switching element, the control unit conducts the first switching element when the voltage of the power line becomes equal to or higher than a predetermined value, and conducts the second switching element when the voltage of the power line becomes equal to or higher than a predetermined value.

[0007] The power control device according to the present invention includes a rectifier circuit that converts AC power into DC power, a smoothing capacitor that smooths the DC power converted by the rectifier circuit, the above-described regenerative power control device, and an inverter that converts the DC power into AC power.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a regenerative power control device and a power control device that can utilize an external regenerative discharge unit and an external capacitor unit and have a low cost.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 10

Embodiments for Carrying Out the Invention

[0010] Hereinafter, this embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may sometimes be denoted by the same reference numerals. Note that the accompanying drawings show embodiments and implementation examples in accordance with the principles of the present disclosure, but these are for the purpose of understanding the present disclosure and are by no means used for interpreting the present disclosure in a limiting manner. The description in this specification is merely a typical example and does not limit the scope of the claims or application examples of the present disclosure in any sense.

[0011] In this embodiment, although the description is provided in sufficient detail for those skilled in the art to implement the present disclosure, other implementation forms are also possible, and it is necessary to understand that configuration and structural changes and replacement of various elements can be made without departing from the scope and spirit of the technical idea of the present disclosure. Therefore, the following description should not be construed as being limited thereto.

[0012] [First Embodiment] First, referring to FIG. 1, a power control device 20 according to a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram for explaining the power control device 20 according to the first embodiment of the present invention and an actuator 30 to be controlled.

[0013] This power control device 20 is configured to rectify the power from the AC power supply 10, convert it into DC power, and further convert it into AC power to supply it to the actuator 30. The actuator 30 includes, as an example, an encoder 31, a servo motor 32 (hereinafter referred to as motor 32), a feed screw 33, a feed nut 34, and a slider 35.

[0014] More specifically, in the power control device 20, a control signal is output to the motor 32 by controlling the drive of a driver (inverter circuit 26) described later. When the motor 32 is driven according to the control signal, the drive amount is converted into a feedback signal by the encoder 31 and fed back to the power control device 20. The rotational motion of the motor 32 is converted into linear motion by the feed screw 33 and the feed nut 34, and the slider 35 moves in the direction of arrow A.

[0015] Referring to FIG. 2, an example of the circuit configuration of the power control device 20 will be described. This power control device (controller) 20 includes, as an example, a rectifier circuit 21, a smoothing capacitor 22, an internal regeneration resistor 23, a first switching element 24, a second switching element 25, an inverter circuit 26, and a microcontroller 27 (control unit). The microcontroller 27 includes a storage device such as a ROM and a RAM, and a CPU (Central Control Unit). The power control device 20 is configured to be connectable to an external regeneration discharge unit 40 (external resistor) and an external capacitor unit 50 (external capacitor) in order to enhance the ability to consume and store the regeneration power returning from the actuator 30 to the power control device 20. The external regeneration discharge unit 40 includes a resistor for enhancing the consumption ability of the regeneration current. The external capacitor unit 50 includes a capacitor for imparting the power storage ability of the regeneration power.

[0016] The rectifier circuit 21 is, for example, a full-bridge type full-wave rectifier circuit, and rectifies the AC power output from the AC power supply 10. The smoothing capacitor 22 is connected between the power lines L1 and L2 connecting the rectifier circuit 21 and the inverter circuit 26, and has a function of smoothing the full-wave rectified current output by the rectifier circuit 21 and converting it into a DC voltage with less ripple. Note that the rectifier circuit 21 is not limited to a full-wave rectifier circuit, and may be a half-wave rectifier circuit or a voltage doubler rectifier circuit.

[0017] The internal regeneration resistor 23 and the first switching element 24 are connected in series between the power lines L1 and L2, and constitute a regeneration current path through which the regeneration current flows during deceleration of the motor 32 of the actuator 30. The second switching element 25 is also connected in series between the power lines L1 and L2 together with the additionally connected external regeneration discharge unit 40 or the external capacitor unit 50 to form a regeneration current path. The internal regeneration resistor 23, the first switching element 24, and the second switching element 25 constitute a regeneration power control device for controlling the regeneration power. Note that the flow of the regeneration current is not limited to during the deceleration of the motor 32. For example, when the actuator 30 is vertically installed such that the axial direction of the output shaft of the motor 32 is in the vertical direction, a regeneration current also flows when the output shaft of the motor 32 rotates due to an external force during an operation of processing the slider 35 using gravity as well.

[0018] The first switching element 24 and the second switching element 25 are semiconductor switching elements that can switch between conduction and non-conduction according to a control signal. Here, as an example, an example where both the first switching element 24 and the second switching element 25 are npn-type bipolar transistors is described, but it is not limited thereto, and it is also possible to substitute with pnp-type bipolar transistors, MOSFETs, IGBTs, thyristors, etc.

[0019] Connection terminals T1 and T2 are connected to the collector of the second switching element 25 and the power line L1 (high voltage side), respectively. The aforementioned external regeneration discharge unit 40 or the external capacitor unit 50 is selectively connected between the connection terminals T1 and T2. The second switching element 25 is a switching element that provides a regeneration current path when connecting the external regeneration discharge unit 40 or the external capacitor unit 50 to execute control of the regeneration power. It is possible to execute control of the regeneration power without using the external regeneration discharge unit 40 or the external capacitor unit 50. In this case, only the first switching element 24 functions as the switching element of the regeneration current path.

[0020] The external regenerative discharge unit 40 is an external resistor that, when connected between connection terminals T1 and T2 (by connecting terminals T11 and T12 to connection terminals T1 and T2), becomes parallel to the internal regenerative resistor 23 and can function as an additional (external) regenerative resistor. The external capacitor unit 50 (external capacitor), when connected between connection terminals T1 and T2 (by connecting terminals T21 and T22 to connection terminals T1 and T2), can function as a charge storage element (external capacitor) that stores regenerative power. The inverter circuit 26 converts the DC power converted from AC power by the rectifier circuit 21 etc. back into AC power. The inverter circuit 26 can be, for example, a three-phase inverter circuit.

[0021] The microcontroller 27 (control unit) controls the base-emitter voltages VBE1 and VBE2 (control signals) between the first switching element 24 and the second switching element 25 based on the detection results of the voltages of the power lines L1 and L2 or the behavior of the voltages of the power lines L1 and L2, thereby controlling their conduction / non-conduction. As will be described later, the microcontroller 27 changes the base-emitter voltages VBE1 and VBE2 applied to the first switching element 24 and the second switching element 25 according to whether the first mode in which the external regenerative discharge unit 40 is connected is set or the second mode in which the external capacitor unit 50 is connected is set. The setting of the first mode or the second mode can be pre-selected by the operator using an input device (not shown).

[0022] Referring to FIG. 3, a conventional power control device 20C as a comparison target will be described. In FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals as in FIG. 2, and redundant descriptions are omitted. As a regenerative power control device, this power control device 20C is provided with only the internal regenerative resistor 23 and the first switching element 24, and an external regenerative discharge unit 40' can be connected between the connection terminals T2 and T4 in parallel with the internal regenerative resistor 23 via terminals T11' and T12'.

[0023] Even in this prior art power control device 20C, it is possible to promote the consumption of regenerative power by connecting an external regenerative discharge unit. However, in this power control device 20C, it is not possible to connect an external capacitor unit in parallel with the internal regenerative resistor 23, or at least it is not effective. This is because most of the regenerative power is consumed by the internal regenerative resistor 23 in parallel, so sufficient power cannot be stored in the capacitor, and power saving cannot be achieved.

[0024] Therefore, in order to make it possible to connect an external capacitor unit as well, it is necessary to separately provide connection terminals for connecting the external capacitor unit, but this complicates the configuration of the power control device. For the sake of simplifying the configuration, it is preferable that the external regenerative discharge unit and the external capacitor unit can be connected to the same connection terminals.

[0025] In the case of the configuration of the first embodiment in FIG. 2, a second switching element 25 is provided in parallel with the first switching element 24, and an external regenerative discharge unit 40 or an external capacitor unit 50 is selectively connected in series with this second switching element 25. The external regenerative discharge unit 40 and the external capacitor unit 50 can be connected to the same connection terminals T1 and T2, and the configuration of the connection mechanism can be made simple.

[0026] Since the first switching element 24 and the second switching element 25 are independently controlled, even when the external capacitor unit 50 is connected, it is possible to consume the regenerative power while accumulating charge in the capacitor. Also, when the external regenerative discharge unit 40 is connected, by appropriately switching and controlling the first switching element 24 and the second switching element 25, the regenerative power can be consumed in the internal regenerative resistor 23 and the external regenerative resistor connected in parallel.

[0027] Referring to FIG. 4, the switching control in the microcontroller 27 in the first mode in which the external capacitor unit 50 is connected will be described. As described above, the external capacitor unit 50 can be connected to the connection terminals T1 and T2.

[0028] When the motor 32 is not decelerating and no regenerative power is generated by the motor 32, the voltage of the power line L1 is normally maintained below a predetermined value. On the other hand, when the motor 32 stops or decelerates, the motor 32 becomes a generator, and the rotational energy of the motor 32 is converted into electrical energy to become regenerative power, increasing the voltage of the power line L1. In the first mode, when the voltage of the power line L1 becomes equal to or higher than the predetermined value, the microcontroller 27 executes control to change the base-emitter voltage VBE1 of the first switching element 24 to Von1 that is equal to or higher than the threshold voltage in order to turn on (conduct) the first switching element 24.

[0029] When the first switching element 24 is turned on, a regenerative current flows through the current path composed of the internal regenerative resistor 23 and the first switching element 24, and the regenerative power is consumed. When the regenerative power is consumed and the voltage of the power line L1 drops below the predetermined value, the microcontroller 27 changes the base-emitter voltage VBE1 to less than the threshold voltage (for example, 0V) and switches the first switching element 24 to the non-conducting state (OFF). During the first mode, the above operation is repeated (see FIG. 4(A)). In this way, the first switching element 24 is switched between conduction and non-conduction according to the detection result of the power line L1, and the regenerative power is consumed.

[0030] During the first mode, the microcontroller 27 maintains the base-emitter voltage VBE2 of the second switching element 25 at a voltage Von2 that is always equal to or higher than the threshold voltage in order to keep the second switching element 25 in a constantly conducting state (see Fig. 4(B)). As a result, the capacitor of the external capacitor unit 50 is constantly charged during the first mode. While the first switching element 24 is in a non-conducting state, the regenerative current only flows through the external capacitor unit 50 via the second switching element 25, so that charging based on the regenerative current can be efficiently performed.

[0031] Referring to Fig. 5, the switching control in the microcontroller 27 in the second mode in which the external regenerative discharge unit 40 is connected will be described. The external regenerative discharge unit 40 can be connected to the connection terminals T1 and T2, similar to the external capacitor unit 50.

[0032] In the second mode, when the voltage of the power line L1 becomes equal to or higher than a predetermined value, the microcontroller 27 turns on both the first switching element 24 and the second switching element 25, and when the voltage of the power line L1 becomes lower than the predetermined value, both the first switching element 24 and the second switching element 25 are switched to a non-conducting state (OFF) (see Fig. 5(A) and Fig. 5(B)). Since the regenerative current flows through two current paths, a first current path consisting of the first switching element 24 and the internal regenerative resistance 23, and a second current path consisting of the second switching element 25 and the external regenerative discharge unit 40, the consumption of regenerative power is promoted. In the example of Fig. 5, an example in which the two switching elements 24 and 25 are simultaneously turned on and off is described, but the switching timing of the two does not necessarily have to be simultaneous.

[0033] As described above, according to the power control device 20 of the first embodiment, the external regenerative discharge unit 40 or the external capacitor unit 50 can be selectively used for controlling the regenerative power, and both units 40 and 50 can be connected in series to the second switching element 25, so that the configuration can be simplified.

[0034] [Second Embodiment] Next, with reference to FIG. 6, the power control device 20 according to the second embodiment of the present invention will be described. In FIG. 6, since the same components as those in the first embodiment (FIG. 2) are denoted by the same reference numerals, redundant descriptions will be omitted below.

[0035] The power control device 20 of the second embodiment is substantially the same as the power control device 20 of the first embodiment in terms of the configuration of the electric circuit. That is, the power control device 20 of the second embodiment is configured to be able to selectively connect the external regeneration discharge unit 40 and the external capacitor unit 50 in series to the second switching element 25, similarly to the power control device 20 of the first embodiment. However, in this second embodiment, it is configured to be able to detect a case where a unit different from the unit assumed by the mode set by the microcontroller 27 is erroneously connected. The microcontroller 27 can determine whether the external regeneration discharge unit 40 or the external capacitor unit 50 is connected to the second switching element 25 according to the behavior of the voltages of the power lines L1 and L2 (including determination of which of the external regeneration discharge unit 40 or the external capacitor unit 50 is connected).

[0036] For detecting an erroneous connection of a unit, the power control device 20 of the second embodiment includes a power amount determination unit 28 and a pulsation determination unit 29 that determines the magnitude of the pulsation component of the voltages of the power lines L1 and L2. The power amount determination unit 28 and the pulsation determination unit 29 may be realized as software by a CPU inside the microcontroller 27, or may be realized by a hardware circuit.

[0037] The power amount determination unit 28 has a function of determining whether or not the amount of power consumed in the internal regeneration resistor 23 is equal to or greater than a threshold value Tth in the second mode (using the external regeneration discharge unit 40).

[0038] As shown in the schematic diagram of FIG. 7, even though the second mode (using the external regenerative discharge unit 40) is set, when the external capacitor unit 50 is erroneously connected in series to the second switching element 25, the power amount determination unit 28 determines this based on the power amount W at a predetermined time. An alarm is issued when the power amount W exceeds the threshold value Tth. As an example, the power amount determination unit 28 calculates the instantaneous value of the power consumption in the internal regenerative resistor 23 every 1 ms at a predetermined time (for example, 100 ms), and calculates the cumulative power amount obtained by time-integrating the instantaneous value. Then, the power amount determination unit 28 compares the value obtained by applying a first-order lag filter process to the calculated cumulative power amount with the threshold value Tth, and outputs an alarm when the threshold value Tth is exceeded. Such determination and alarm issuance processing are executed at a predetermined cycle after a predetermined time has elapsed.

[0039] When the external regenerative discharge unit 40 is correctly connected, the first switching element 24 and the second switching element 25 frequently switch between the conducting / non-conducting states.

[0040] On the other hand, if the external capacitor unit 50 is erroneously connected instead of the external regenerative discharge unit 40 despite the second mode, since the consumption of the regenerative current is performed only by the internal regenerative resistor 23, the voltage of the power line L1 tends to remain high and the power consumption of the internal regenerative resistor 23 tends to increase. Therefore, by calculating the power consumption amount of the internal regenerative resistor 23 at a predetermined time and comparing this with the threshold value Tth, it is possible to determine the erroneous connection of the external capacitor unit 50. When it is determined that there is an erroneous connection, an alarm can be issued by an alarm device (not shown) or the like to notify the operator.

[0041] The pulsation determination unit 29 has a function of determining whether or not the magnitude of the pulsation component of the voltage of the power line L1 has become equal to or greater than a predetermined value. As shown in the schematic diagram of FIG. 8, even though the first mode (using the external capacitor unit 50) is set, when the external regenerative discharge unit 40 is erroneously connected in series to the second switching element 25, the pulsation determination unit 29 determines this based on the magnitude of the pulsation component of the power line L1.

[0042] As shown in Fig. 9, the AC waveform output from the AC power supply 10 is full-wave rectified by the rectifier circuit 21 and then smoothed by passing through the smoothing capacitor 22. Even though the first mode is set, if the external regeneration discharge unit 40 is erroneously connected instead of the external capacitor unit 50, since the second switching element 25 is always on, power is consumed by the external regeneration discharge unit 40, so that the pulsation component of the voltage appearing in the power line L1 becomes large. The pulsation determination unit 29 determines the voltage fluctuation of the power line L1 and determines whether or not the magnitude of the pulsation component exceeds a predetermined value. When it is determined that the value exceeds the predetermined value, it can be suspected that there is a misconnection, and an alarm can be issued by an alarm device (not shown) or the like to notify the operator. More specifically, the pulsation determination unit 29 executes the above determination when power is output from the AC power supply 10 to the rectifier circuit 21 of the power control device 20 (when the power is turned on). That is, by executing the above determination when the power to the power control device 10 is turned on, it is possible to notify the operator that a misconnection is suspected before the regenerative current flows.

[0043] [Third Embodiment] Next, with reference to Fig. 10, the power control device 20 according to the third embodiment of the present invention will be described. In Fig. 10, the same components as those in the foregoing embodiments (Figs. 2 and 6) are denoted by the same reference numerals, and thus redundant descriptions will be omitted below.

[0044] The power control device 20 according to the third embodiment is substantially the same as the power control device 20 in the foregoing embodiment in terms of the configuration of the electric circuit. In this third embodiment, as a configuration for detecting a misconnection, instead of or in addition to the electric energy determination unit 28, an on-time determination unit 28A is provided.

[0045] The on-time determination unit 28A has a function of determining whether or not the total time (cumulative addition amount) Tsum of the on-times of at least one of the first switching element 24 and the second switching element 25 at a predetermined time in the second mode (using the external regenerative discharge unit 40) is equal to or greater than the threshold value Ttho (Tsum ≧ Ttho). Since the on-times of the first switching element 24 and the second switching element 25 are correlated with the consumed power amount, the on-time determination unit 28A can also be regarded as an aspect of the power amount determination unit 28. Instead of comparing the total time Tsum with the threshold value Ttho, the on-time per unit time may be calculated by dividing the total time Tsum by a predetermined time, and an alarm may be issued when this is equal to or greater than an appropriate threshold value.

[0046] [Others] The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0047] For example, in the above example, the single external regenerative discharge unit 40 or the external capacitor unit 50 is connected in series to the second switching element 25, but the present invention is not limited to this, and a configuration in which a plurality of units are connected in parallel or in series is also included in the scope of the present invention. And an alarm can be issued when characteristics different from those provided by the plurality of units assumed to be connected are detected.

Explanation of Reference Numerals

[0048] 10…AC power supply 20, 20C…Power control device 21…Rectifier circuit 22…Smoothing capacitor 23…Internal regeneration resistance 24…First switching element 25…Second switching element 26…Inverter circuit 27…Microcontroller 28…Power amount determination unit 28A…On-time determination unit 29…Pulsation determination unit 30…Actuator 31…Encoder 32…Servo motor 33…Feed screw 34…Feed nut 35…Slider 40…External regeneration discharge unit 50…External capacitor unit L1, L2…Power lines T1, T2…Connection terminals T11, T12, T21, T22, T11´, T12´…Terminals

Claims

1. In a regenerative power control device that controls regenerative power regenerated from a load, an internal regenerative resistor connected to a power line connected to the load, a first switching element connected in series with the internal regenerative resistor and through which a regenerative current from the power line flows, a second switching element configured to be connectable in series with an external resistor or an external capacitor and through which a regenerative current from the power line flows, a control unit that controls conduction of the first switching element and the second switching element are provided, the control unit in a first mode in which the external capacitor is connected in series with the second switching element, maintains the second switching element in an on state, and when the voltage of the power line becomes equal to or higher than a predetermined value, conducts the first switching element, in a second mode in which the external resistor is connected in series with the second switching element, when the voltage of the power line becomes equal to or higher than a predetermined value, conducts the first switching element, and when the voltage of the power line becomes equal to or higher than a predetermined value, conducts the second switching element A regenerative power control device characterized by the above.

2. The regenerative power control device according to claim 1, wherein the control unit determines the external capacitor or the external resistor connected to the second switching element according to the behavior of the voltage of the power line.

3. The regenerative power control device according to claim 2, wherein the control unit issues an alarm when the power consumption amount in the internal regenerative resistor becomes equal to or higher than a threshold value when the second mode is set.

4. The regenerative power control device according to claim 2, wherein the control unit issues an alarm when the pulsating component of the voltage of the power line is equal to or higher than a predetermined value when the first mode is set.

5. The regenerative power control device according to claim 2, wherein the control unit issues an alarm when the conduction time of at least one of the first switching element and the second switching element becomes equal to or longer than a predetermined time when the second mode is set.

6. A power control device including a rectifier circuit that converts AC power into DC power, a smoothing capacitor that smooths the DC power converted by the rectifier circuit, the regenerative power control device according to any one of claims 1 to 4, and an inverter circuit that converts the DC power into AC power.

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