Converter control unit

Abstract

The present invention provides a converter control device that can reduce the power consumption of a converter by shortening the boost operation time and regenerative operation time of the converter. [Solution] The power regeneration converter control device 1 comprises a converter circuit 2 that converts AC power from a three-phase AC power supply 200 to DC power, a converter control unit 10 that controls the switching of the converter circuit 2, and an AC reactor ACL positioned between the three-phase AC power supply 200 and the converter circuit 2. The converter control unit 10 has a regenerative current controller 45 that generates a regenerative energizing command through a hysteresis comparator from the difference between the regenerative current command and the DC current of the converter circuit 2. The converter control unit 10 is characterized in that it stops the regenerative operation if the regenerative energizing command is off for a predetermined period of time during regenerative operation.

Description

Technical Field

[0001] The present invention relates to a converter control device.

Background Art

[0002] A converter control device with a power regeneration function is composed of an AC reactor, a converter, a smoothing capacitor, and an inverter. When performing the power running operation of the motor, the converter converts AC power into DC power, and the inverter converts DC power into AC power to drive the motor. When performing the regenerative operation of the motor, the AC power generated by the motor is converted into DC power by the inverter, and the converter converts the DC power into AC power to regenerate to the power source. For the control method of such a converter with a power regeneration function, there are a PWM method that prioritizes performance and a 120° conduction method that prioritizes cost.

[0003] As an example of a PWM method, Patent Document 1 discloses a motor drive control device that aims to make the converter smaller, lighter, and more efficient. This motor drive control device includes a power operation voltage setting means for setting the power operation voltage of the converter, a power operation start control means for starting the power operation of the converter when the DC voltage of the converter is less than or equal to the set power operation voltage, a power operation stop control means for stopping the power operation of the converter when the DC voltage of the converter exceeds the set power operation voltage, a regenerative operation voltage setting means for setting the regenerative operation voltage of the converter to a voltage higher than the set power operation voltage, a regenerative operation start control means for starting the regenerative operation of the converter when the DC voltage of the converter is equal to or greater than the set regenerative operation voltage, and a regenerative operation stop control means for stopping the regenerative operation of the converter when the DC voltage of the converter is less than the set regenerative operation voltage. By providing sections in which the power operation and regenerative operation are stopped by the power operation voltage setting means and the regenerative operation voltage setting means, unnecessary operation of the semiconductor switching elements of the converter can be reduced, and the amount of heat generated by the switching operation can be suppressed. This reduces the switching losses of the converter's semiconductor switching elements and the AC reactor losses associated with switching, allowing for a smaller cooling fin.

[0004] Furthermore, as an example of a 120° energization method, Patent Document 2 discloses a power regeneration control device that controls the start and stop operation of a converter. This power regeneration control device includes an AC reactor provided in a connection path that connects the AC side of a rectifier and regeneration circuit to a multiphase AC power supply, a first capacitor connected in parallel to the DC side of the rectifier and regeneration circuit, a bridge-type rectifier circuit that converts the AC output of the multiphase AC power supply to a DC output, a second capacitor connected in parallel to the bridge-type rectifier circuit, a detection circuit that detects the start and end of regeneration based on the difference voltage between the charging voltages of the first capacitor and the second capacitor, and an electric valve drive circuit that receives a detection signal for the start of regeneration from the detection circuit and sequentially supplies drive signals to the electric valve of the rectifier and regeneration circuit. In this way, the power regeneration control device controls the start and stop of power regeneration operation based on the difference voltage between the peak value of the AC power supply voltage and the output voltage of the power regeneration converter. Specifically, the system is controlled so that power regeneration begins when the DC voltage of the converter rises relative to the peak value of the AC power supply voltage, and stops when the DC voltage of the converter falls. Therefore, the semiconductor switching elements of the converter operate only when the motor is decelerating (during regenerative operation). During acceleration, full-wave rectification is performed by the diodes of the converter, so the semiconductor switching elements do not operate. Also, the semiconductor switching elements do not operate when the motor is stopped. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-178584 [Patent Document 2] Japanese Patent Application Publication No. 187268 / 1983 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] When the control method disclosed in Patent Document 1 is applied to a spindle motor with low mechanical friction torque and load torque, the motor continues to operate even when it has finished accelerating and is rotating at a constant speed. When the motor starts to decelerate and enters regenerative mode, the DC voltage of the converter rises and the motor stops. Similarly, when the motor has finished decelerating and is stopped, the motor continues to operate regeneratively. When the motor starts to accelerate and enters motor mode, the DC voltage of the converter drops and the motor stops. Thus, the control method disclosed in Patent Document 1 performs motor and regenerative operations not only during acceleration and deceleration, but also when rotating at a constant speed and when stopped, resulting in a problem in that the switching loss of the converter and the AC reactor loss associated with switching cannot be sufficiently reduced. Furthermore, when the AC power supply voltage fluctuates, the operator has to set the motor operation voltage and regenerative operation voltage each time, which creates a burden on the operator.

[0007] The control method disclosed in Patent Document 2 can appropriately start and stop regenerative operation even when the AC power supply voltage fluctuates. However, when the DC voltage of the converter rises during motor deceleration and power regeneration is started, the DC voltage of the converter drops and power regeneration stops, and when power regeneration stops and the DC voltage of the converter rises, power regeneration is started again. In this way, power regeneration is performed intermittently during motor deceleration, which has the problem of generating ripple in the DC voltage of the converter. When ripple occurs in the DC voltage of the converter, torque ripple occurs in the motor, so it is desirable to suppress the ripple in the DC voltage of the converter as much as possible.

[0008] Therefore, the present invention aims to provide a converter control device that can reduce the power consumption of a converter by shortening the boost operation time and regenerative operation time of the converter. [Means for solving the problem]

[0009] A converter control device with a power regeneration function according to one aspect of the present invention is: A converter circuit that converts AC power from a three-phase AC power supply to DC power, A converter control unit that controls the switching of the converter circuit, An AC reactor is placed between the three-phase AC power supply and the converter circuit, Equipped with, The converter control unit has a regenerative current controller that generates a regenerative current command through a hysteresis comparator from the difference between the regenerative current command and the DC current of the converter circuit. The converter control unit is characterized in that, if the regenerative energization command is turned off for a predetermined period of time during regenerative operation, it stops the regenerative operation.

[0010] A converter control device with a power regeneration function according to one aspect of the present invention is: A converter circuit that converts AC power from a three-phase AC power supply to DC power, A converter control unit that controls the switching of the converter circuit, An AC reactor is placed between the three-phase AC power supply and the converter circuit, Equipped with, The converter control unit has a boost current controller that generates a boost current command through a hysteresis comparator from the difference between the boost current command and the DC current of the converter circuit. The converter control unit is characterized in that, if the boost power supply command is off for a predetermined period of time during the boost operation, it stops the boost operation.

[0011] A converter control device with a power regeneration function according to one aspect of the present invention is: A converter circuit that converts AC power from a three-phase AC power supply to DC power, A converter control unit that controls the switching of the converter circuit, A smoothing capacitor, Equipped with, The converter control unit, A regenerative voltage command calculator that generates a regenerative voltage command by adding a first predetermined value to the voltage peak value of the three-phase AC power supply, A regenerative voltage control unit that generates a regenerative current command from the difference between the regenerative voltage command and the DC voltage of the converter circuit; A regenerative current controller that generates a regenerative energization command through a first hysteresis comparator from the difference between the regenerative current command and the DC current of the converter circuit; A boost voltage command calculator that generates a boost voltage command by adding a second predetermined value to the peak value of the voltage of the three-phase AC power supply; A regenerative voltage control unit that generates a boost current command from the difference between the boost voltage command and the DC voltage of the converter circuit; A boost current controller that generates a boost energization command through a second hysteresis comparator from the difference between the boost current command and the DC current of the converter circuit; It has The first predetermined value is larger than the second predetermined value.

Effect of the Invention

[0012] It is possible to provide a converter control device that can reduce the power consumption of the converter by shortening the boost operation time and the regenerative operation time of the converter.

Brief Description of the Drawings

[0013] [Figure 1] ​​​​​​​​​​​​​​​​​​Figure 1 is a block diagram of a motor control device 100 according to an embodiment of the present invention. As shown in Figure 1, the motor control device 100 comprises a converter control device 1 with a power regeneration function and an inverter circuit 4. The converter control device 1 also comprises a converter circuit 2, a smoothing capacitor 3, an AC reactor ACL, a current detector 5, a voltage detection unit 6, and a converter control unit 10. A three-phase AC power supply 200 is connected to the input side of the motor control device 100, and a motor M is connected to the output side.

[0016] During powering operation, the motor control device 100 energizes the semiconductor switching elements of the converter circuit 2 in a 120° interval of the phase with the maximum voltage among the three-phase AC power supply, based on a gate signal from the converter control unit 10, thereby supplying power from the three-phase AC power supply 200 to the motor M. Furthermore, during regenerative operation, the motor control device 100 energizes the semiconductor switching elements of the converter circuit 2 in a 120° interval of the phase with the maximum voltage among the three-phase AC power supply, based on a gate control signal from the converter control unit 10, thereby regenerating power to the three-phase AC power supply 200.

[0017] Converter circuit 2 is a three-phase (R-phase, S-phase, T-phase) full-bridge circuit and consists of six semiconductor switching elements. The semiconductor switching elements are, for example, IGBTs. During the motor M's power operation, converter circuit 2 converts the three-phase AC power input from the three-phase AC power supply 200 into DC. During the motor M's regenerative operation, converter circuit 2 converts the DC into three-phase AC.

[0018] The smoothing capacitor 3 is, for example, an electrolytic capacitor, which smooths the DC voltage.

[0019] The inverter circuit 4 is a three-phase (U-phase, V-phase, W-phase) full-bridge circuit and consists of six semiconductor switching elements. The semiconductor switching elements are, for example, IGBTs. The inverter circuit 4 converts the DC from the smoothing capacitor 3 or the DC output of the converter circuit 2 into three-phase AC for motor drive and supplies it to the motor M.

[0020] The AC reactor ACL is located between the three-phase AC power supply 200 and the converter circuit 2.

[0021] The current detector 5 detects the power supply current of each phase flowing between the three-phase AC power supply 200 and the converter circuit 2.

[0022] The voltage detection unit 6 detects the power supply voltage of the three-phase AC power supply 200.

[0023] The converter control unit 10 includes a DC current estimation unit 20, a power supply voltage detection unit 30, a regenerative voltage control unit 40, a boost voltage control unit 50, a regenerative operation determination unit 60, a boost operation determination unit 70, and a gate control unit 80. The DC current estimation unit 20 includes a phase detector 21, a current selection signal generation unit 22, and a selector 23. The power supply voltage detection unit 30 includes a full-wave rectified voltage calculator 31 and a peak value calculator 32. The regenerative voltage control unit 40 includes a regenerative voltage command calculator 41, a regenerative voltage controller 42, a regenerative limiter 43, a regenerative filter 44, and a regenerative current controller 45. The boost voltage control unit 50 includes a boost voltage command calculator 51, a boost voltage controller 52, a boost limiter 53, a boost filter 54, and a boost current controller 55. The regenerative operation determination unit 60 includes a regenerative start detector 61 and a regenerative stop detector 62. The boost operation determination unit 70 includes a boost start detector 71 and a boost stop detector 72. The gate control unit 80 includes a gate controller 81.

[0024] The DC current estimation unit 20 estimates the DC current flowing from the converter circuit 2 to the smoothing capacitor 3 and calculates the DC current Id. The phase detector 21 detects the phase of the 120° interval in which the voltage of each phase of the three-phase AC power supply 200 is maximum and outputs a phase signal. The current selection signal generation unit 22 generates an AC current selection signal for current selection based on the phase signal. The AC current selection signal is generated to select the power supply current of the phase in which the voltage is increasing or decreasing from among the two phases through which current is flowing.

[0025] Here, the process of selecting the alternating current will be explained in detail using Figure 2. Figure 2 is a diagram showing the power supply voltage, phase signal, current selection signal, power supply current (alternating current) selected based on the current selection signal, and DC current Id in an embodiment of the present invention. For example, in the first 60° section of the 120° section where the voltage of the R phase is maximum, indicated by reference numeral 22a, power supply currents for the R phase and S phase are flowing, and since the voltage of the R phase is increasing, the R phase is selected. Also, in the latter 60° section of the 120° section where the voltage of the R phase is maximum, indicated by reference numeral 22b, power supply currents for the R phase and T phase are flowing, and since the voltage of the T phase is increasing in the negative direction, the power supply current of the T phase is selected by inverting its sign. The reason for inverting the sign is to make the sign of the DC current Id during regenerative operation negative.

[0026] Returning to the explanation of Figure 1, the selector 23 selects the power supply current of each phase flowing between the three-phase AC power supply 200 detected by the current detector 5 and the converter circuit 2 based on the AC current selection signal from the current selection signal generation unit 22, and estimates the DC current of the DC power converted by the converter circuit 2 to calculate the DC current Id. Furthermore, it outputs the estimated DC current Id to the regenerative current controller 45 and the boost current controller 55. Here, the selection of the power supply current by the selector 23 is equivalent to AC-DC conversion.

[0027] In this way, the DC current estimation unit 20 can accurately estimate the DC current of the converter circuit 2 by detecting the phase with the maximum voltage among the phases of the AC power and selecting the current of one of the phases of the AC power based on the detected phase.

[0028] The power supply voltage detection unit 30 estimates the peak power supply voltage Vp for each cycle of the three-phase AC power supply 200. The full-wave rectified voltage calculator 31 calculates and outputs the full-wave rectified voltage from the power supply voltage detected by the voltage detection unit 6. The peak value calculator 32 calculates and outputs the peak power supply voltage Vp for each cycle of the three-phase AC power supply 200 from the full-wave rectified voltage.

[0029] The regenerative voltage command calculator 41 calculates and outputs a regenerative voltage command by adding a first predetermined value to the power supply voltage peak value Vp from the peak value calculator 32. Here, the first predetermined value is, for example, about 40V. The regenerative voltage controller 42 calculates and outputs a regenerative current command based on the difference between the regenerative voltage command from the regenerative voltage command calculator 41 and the DC voltage Vd of the smoothing capacitor 3 during regenerative operation, passing it through the regenerative limiter 43 and the regenerative filter 44. The regenerative voltage controller 42 is configured, for example, as a proportional-integral controller. The regenerative limiter 43 limits the range of regenerative current to the three-phase AC power supply 200. The regenerative filter 44 removes the ripple component included in the regenerative current command. The regenerative current controller 45 controls the regenerative current by controlling the semiconductor switching elements of the converter circuit 2 during regenerative operation through the gate controller 81 as an internal loop of regenerative voltage control. Specifically, the regenerative current controller 45 is composed of, for example, a hysteresis comparator, and outputs a regenerative energizing command of 1 when the difference between the regenerative current command and the DC current Id falls below the first threshold Th1, and outputs a regenerative energizing command of 0 when it falls above the second threshold Th2. Note that the second threshold Th2 is a value greater than the first threshold Th1.

[0030] The boost voltage command calculator 51 adds a second predetermined value to the power supply voltage peak value Vp from the peak value calculator 32 and outputs it as a boost voltage command. Here, the second predetermined value is a value smaller than the first predetermined value, for example, about 5V. Alternatively, the second predetermined value may be 0V. The boost voltage controller 52 calculates and outputs a boost current command based on the difference between the boost voltage command from the boost voltage command calculator 51 and the DC voltage Vd of the smoothing capacitor 3, passing it through a boost limiter 53 and a boost filter 54. The boost voltage controller 52 is configured, for example, as a proportional-integral controller. The boost limiter 53 limits the range of the power current. The boost filter 54 removes the ripple component included in the boost current command. The boost current controller 55, as an internal loop of the boost voltage control, controls the semiconductor switching elements of the converter circuit 2 during boost operation through a gate controller 81 and controls the boost current. Specifically, the regenerative current controller 45 is composed of, for example, a hysteresis comparator, and outputs a boost current command of 1 when the difference between the boost current command and the DC current Id is greater than or equal to the third threshold Th3, and outputs a boost current command of 0 when it is less than or equal to the fourth threshold Th4. Note that the third threshold Th3 is a value greater than the fourth threshold Th4.

[0031] Thus, the converter control unit 10 is configured to generate a regenerative voltage command higher than the boost voltage command based on the peak value Vp of the power supply voltage, thereby controlling the DC voltage Vd to a constant value. Furthermore, as an internal loop, for example, a hysteresis comparator is used to directly drive the semiconductor switching elements of the converter circuit 2 based on the instantaneous value of the DC current Id. This prevents the DC voltage from dropping due to the voltage drop across the AC reactor during acceleration of the motor M, increasing the voltage applied to the motor M, and also increases the voltage applied to the motor M during deceleration, reducing field weakening of the motor M. As a result, the output torque of the motor M is increased, and the acceleration and deceleration times of the motor M can be shortened. Consequently, the boost operation time and regenerative operation time of the converter circuit 2 are shortened, and the switching losses of the converter circuit 2 and the losses of the AC reactor ACL associated with switching can be reduced.

[0032] Furthermore, since the regenerative voltage command and boost voltage command are generated based on the peak power supply voltage Vp, even if the power supply voltage of the three-phase AC power supply 200 fluctuates, it is not necessary for the operator to set the power operation voltage or regenerative operation voltage.

[0033] Furthermore, by controlling the DC voltage Vd of the converter circuit 2 to a constant value during acceleration and deceleration of the motor M, ripple in the DC voltage Vd can be suppressed.

[0034] The regenerative start detector 61 compares the DC voltage Vd across the smoothing capacitor 3 with the peak value Vp of the power supply voltage. If the DC voltage Vd is greater than or equal to the fifth threshold Th5, which is a third predetermined value higher than the peak value Vp of the power supply voltage, the regenerative signal is turned on. Here, the third predetermined value is set to be slightly higher than the first predetermined value.

[0035] The regenerative braking stop detector 62 turns off the regenerative signal if it detects, for example, that the regenerative energizing command is off (for example, the regenerative energizing command is 0) for a first predetermined time. Here, the first predetermined time is a time slightly longer than the operating cycle of the regenerative energizing command during regenerative operation, for example, in the range of 5ms to 10ms.

[0036] The regenerative signal generated by the regenerative operation determination unit 60 is output to the gate controller 81.

[0037] The boost start detector 71 compares the DC voltage Vd across the smoothing capacitor 3 with the peak value Vp of the power supply voltage. If the DC voltage Vd is less than or equal to the sixth threshold Th6, which is lower than the peak value Vp of the power supply voltage by a fourth predetermined value, the boost signal is turned on. Here, if the motor control device 100 has not performed a boost operation since starting operation, it is sufficient to detect that the DC voltage Vd has decreased, so the fourth predetermined value is set to a small value. Also, if the motor control device 100 has started operation and performed a boost operation, the fourth predetermined value is set to 0 to prevent an increase in the power current at the start of the boost.

[0038] The boost stop detector 72 turns off the boost signal if it detects, for example, that the boost power supply command is off (for example, the boost power supply command is 0) for a second predetermined time. Here, the second predetermined time is a time slightly longer than the operating cycle of the boost power supply command during boost operation, for example, in the range of 5ms to 10ms.

[0039] The boost signal generated by the boost operation determination unit 70 is output to the gate controller 81.

[0040] The gate controller 81 generates a gate signal based on the phase signal from the phase detector 21, the regenerative current command from the regenerative current controller 45, the boost current command from the boost current controller 55, the regenerative signal from the regenerative operation determination unit 60, and the boost signal from the boost operation determination unit 70. The gate controller 81 also outputs the gate signal to the converter circuit 2, which controls the semiconductor switching elements of the converter circuit 2.

[0041] Specifically, the gate controller 81 starts regenerative operation when the regenerative signal is turned on, and controls the lower semiconductor switching element based on the 120° periodic phase signal from the phase detector 21. Furthermore, based on the logical AND of the phase signal and the regenerative energization command, it controls the gate of the upper 120° energized phase semiconductor switching element to turn on when the regenerative energization command is on (for example, the regenerative energization command is 1), and to turn off when the regenerative energization command is off (for example, the regenerative energization command is 0). Here, the upper and lower semiconductor switching elements refer to the semiconductor switching elements arranged in the upper and lower sections of the circuit diagram, respectively.

[0042] Thus, the gate controller 81 controls only the upper semiconductor switching element based on the logical AND of the phase signal and the regenerative current command in order to reduce the switching frequency of the semiconductor switching element as much as possible. As a result, the DC current Id is controlled with a hysteresis width relative to the regenerative current command, and the DC voltage Vd of the smoothing capacitor 3 is controlled to match the regenerative voltage command. The reason for introducing a hysteresis width to the DC current Id relative to the regenerative current command is to reduce the switching frequency of the upper and lower semiconductor switching elements as much as possible during regenerative operation.

[0043] Alternatively, within the 120° interval where the voltage of each phase is high, the lower semiconductor switching element may be controlled based on the logical AND of the phase signal and the regenerative energizing command, and the upper semiconductor switching element may be controlled based on the normal 120° periodic phase signal. Or, the phase to be controlled may be changed based on the logical AND of the phase signal and the regenerative energizing command every 1 / 6 cycle of the power supply.

[0044] Furthermore, when the boost signal is turned on, the gate controller 81 starts the boost operation and controls the lower semiconductor switching element of the phase where the 120° period phase signal from the phase detector 21 is at its maximum, based on the boost power command. In addition, during the boost operation, the gate of the upper semiconductor switching element is controlled to turn off.

[0045] As a result, the DC current Id is controlled with a hysteresis width relative to the boost current command, and the DC voltage Vd of the smoothing capacitor 3 is controlled to match the boost voltage command. The reason for introducing a hysteresis width to the DC current Id relative to the boost current command is to reduce the switching frequency of the lower semiconductor switching element as much as possible during boost operation.

[0046] Figure 3 shows the waveforms of the boost and regenerative operations when the motor M is accelerated and decelerated. As shown in Figure 3, when the motor M accelerates at time t0, the DC voltage Vd decreases and the boost operation begins. Due to the boost operation, the DC voltage Vd is controlled to the same value as the peak power supply voltage Vp (=280V). Here, since the difference between the boost current command and the DC current Id is controlled by hysteresis, the on / off frequency of the boost current command is lower than, for example, the on / off frequency of a PWM converter.

[0047] At time t1, the motor speed Vm is 7000 [min -1 When the voltage reaches [value] and motor M's acceleration ends, the voltage boosting operation stops. Subsequently, the voltage boosting operation remains stopped while motor M rotates at a constant speed.

[0048] At time t2, as motor M decelerates, the DC voltage Vd rises to a fifth threshold Th5 (325V) or higher, which is 45V higher than the peak value Vp (280V) of the power supply voltage. This initiates regenerative operation, and the DC voltage Vd is controlled to 320V. Here, because the difference between the regenerative current command and the DC current Id is controlled by hysteresis, the on / off frequency of the regenerative energization command is lower than, for example, the on / off frequency of a PWM converter. Furthermore, since the DC voltage Vd during motor M deceleration is controlled to be higher than the DC voltage Vd during motor M acceleration, field weakening of motor M during deceleration can be reduced. This shortens the deceleration time of motor M. Additionally, during the period T1 from the start of motor M deceleration until the DC voltage Vd reaches the fifth threshold Th5, which initiates regenerative operation, the regenerative current does not flow to the three-phase AC power supply 200, and the regenerative energy of motor M is stored in the smoothing capacitor 3.

[0049] When motor M's deceleration is complete, the regenerative operation stops at time t3. After that, the regenerative operation remains stopped while motor M is stopped. After the regenerative operation stops, the DC voltage Vd is maintained at 320V. From the start of motor M's re-acceleration (time t4), the motor speed Vm reaches 1200 [min]. -1During the period T2 until the voltage reaches [value], the regenerative energy stored in the smoothing capacitor 3 is used for the motor M's powering operation. Therefore, no powering current flows from the three-phase AC power supply 200, and the boost operation does not start immediately. As the regenerative energy stored in the smoothing capacitor 3 is consumed for the motor M's powering operation, the DC voltage Vd decreases, and when it falls below the peak value Vp (=280V) of the power supply voltage, the boost operation resumes.

[0050] As described above, in the embodiment of the present invention, the regenerative operation time of the converter can be shortened by stopping the regenerative operation if the regenerative energizing command is off for a predetermined period of time during regenerative operation. This reduces switching losses in the converter circuit and losses in the AC reactor ACL associated with switching, thereby reducing power consumption. In addition, the DC voltage of the converter circuit can be maintained at a high level after regeneration is stopped.

[0051] Furthermore, since regenerative operation is initiated when the DC voltage of the converter circuit is above a predetermined value compared to the peak value of the power supply voltage, the operator does not need to set the regenerative operation voltage even if the voltage of the three-phase AC power supply fluctuates.

[0052] Furthermore, by controlling the DC voltage of the converter circuit to remain constant during regenerative operation, ripple in the DC voltage of the converter circuit can be suppressed.

[0053] Furthermore, by adding a predetermined value to the peak voltage of the three-phase AC power supply and using that value as the regenerative voltage command, the voltage applied to the motor during motor deceleration can be increased. As a result, the motor's output torque increases, shortening the motor's deceleration time and reducing the regenerative operation time, thereby reducing the power consumption of the converter circuit.

[0054] Furthermore, if the boost-up power supply command is off for a predetermined period of time during the boost-up operation, the boost-up operation time of the converter can be shortened by stopping the boost-up operation. This reduces switching losses in the converter circuit and losses in the AC reactor ACL associated with switching, thereby reducing power consumption.

[0055] Furthermore, since the boost operation starts when the DC voltage of the converter circuit is below a predetermined value compared to the peak voltage of the three-phase AC power supply, it eliminates the need for the operator to set the power operation voltage even if the voltage of the three-phase AC power supply fluctuates.

[0056] Furthermore, by controlling the DC voltage of the converter circuit to remain constant during boost operation, ripple in the DC voltage of the converter circuit can be suppressed.

[0057] Furthermore, by using the voltage peak value of the three-phase AC power supply as the boost voltage command, the decrease in DC voltage due to the voltage drop across the AC reactor when accelerating the motor without boosting the voltage can be suppressed. This allows the applied voltage applied to the motor through the inverter circuit during motor operation to be increased, reducing the field weakening of the motor and thereby increasing the motor's output torque and shortening the motor's acceleration time. This shortens the boost operation time of the converter circuit and reduces the power consumption of the converter circuit.

[0058] Furthermore, by setting the regenerative voltage command higher than the boost voltage command, the electrical energy stored in the smoothing capacitor during regenerative operation is utilized for the motor's power operation. This shortens the boost operation time and reduces the power consumption of the converter circuit. Furthermore, the current control, which is an internal loop of the voltage control, is configured to directly drive the semiconductor switching elements of the converter circuit based on the instantaneous value of the DC current, for example, by using a hysteresis comparator. This reduces the switching frequency of the semiconductor switching elements during boost operation and regenerative operation, thereby reducing the power consumption of the converter circuit.

[0059] Although embodiments of the present invention have been described above, it goes without saying that the technical scope of the present invention should not be interpreted as being limited by the description of these embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications to the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and the scope of its equivalents. [Explanation of Symbols]

[0060] 1: Converter control unit 2: Converter circuit 3: Smoothing Capacitor 4: Inverter circuit 5: Current detector 6: Voltage detection unit 10: Converter Control Unit 20: DC current estimation section 21: Phase detector 22: Current selection signal generation unit 23: Selector 30: Power supply voltage detection unit 31: Full-wave rectified voltage calculator 32: Wave height calculator 40: Regenerative Voltage Control Unit 41: Regenerative Voltage Command Calculator 42: Regenerative voltage controller 43: Regenerative Limiter 44: Regenerative filter 45: Regenerative current controller 51: Boost Voltage Command Calculator 52: Boost Voltage Controller 53: Boost limiter 54: Boost filter 55: Boost current controller 60: Regenerative Action Determination Unit 61: Regeneration Start Detector 62: Regenerative braking stop detector 70: Boost operation determination unit 71: Boost Start Detector 72: Boost Stop Detector 80: Gate Control Unit 81: Gate controller 100: Motor control device 200: Three-phase AC power supply M: motor ACL: AC Reactor

Claims

1. A converter control device with a power regeneration function, A converter circuit that converts AC power from a three-phase AC power supply to DC power, A converter control unit that controls the switching of the converter circuit, An AC reactor is placed between the three-phase AC power supply and the converter circuit, Equipped with, The converter control unit has a regenerative current controller that generates a regenerative current command through a hysteresis comparator from the difference between the regenerative current command and the DC current of the converter circuit. The converter control unit is characterized in that, if the regenerative power supply command is off for a predetermined period of time during regenerative operation, it stops the regenerative operation.

2. The converter control device according to claim 1, wherein the converter control unit starts regenerative operation when the DC voltage of the converter circuit is greater than or equal to a predetermined value than the peak voltage of the three-phase AC power supply.

3. The converter control unit further includes a regenerative voltage control unit, The converter control device according to claim 1, wherein the regenerative voltage control unit controls the DC voltage of the converter circuit to be constant during regenerative operation.

4. The converter control unit further includes a regenerative voltage command calculator, The regenerative voltage command calculator generates a regenerative voltage command by adding a predetermined value to the peak voltage value of the three-phase AC power supply. The converter control device according to claim 3, wherein the regenerative voltage control unit generates the regenerative current command from the difference between the regenerative voltage command and the DC voltage of the converter circuit.

5. A converter control device, A converter circuit that converts AC power from a three-phase AC power supply to DC power, A converter control unit that controls the switching of the converter circuit, An AC reactor is placed between the three-phase AC power supply and the converter circuit, Equipped with, The converter control unit has a boost current controller that generates a boost current command through a hysteresis comparator from the difference between the boost current command and the DC current of the converter circuit. The converter control unit is characterized in that, if the boost-up power supply command is off for a predetermined period of time during the boost-up operation, the boost-up operation is stopped.

6. The converter control device according to claim 5, wherein the converter control unit starts a boost operation when the DC voltage of the converter circuit is less than or equal to a predetermined value than the peak voltage of the three-phase AC power supply.

7. The converter control unit further includes a boost voltage control unit, The converter control device according to claim 5, wherein the boost voltage control unit controls the DC voltage of the converter circuit to be constant during boost operation.

8. The converter control unit further includes a boost voltage command calculator, The aforementioned boost voltage command calculator generates the boost voltage command using the voltage peak value of the three-phase AC power supply as the boost voltage command. The converter control device according to claim 7, wherein the boost voltage control unit generates the boost current command from the difference between the boost voltage command and the DC voltage of the converter circuit.

9. A converter control device with a power regeneration function, A converter circuit that converts AC power from a three-phase AC power supply to DC power, A converter control unit that controls the switching of the converter circuit, A smoothing capacitor, Equipped with, The converter control unit, A regenerative voltage command calculator that generates a regenerative voltage command by adding a first predetermined value to the voltage peak value of the three-phase AC power supply, A regenerative voltage control unit generates a regenerative current command from the difference between the regenerative voltage command and the DC voltage of the converter circuit, A regenerative current controller that generates a regenerative current command through a first hysteresis comparator from the difference between the regenerative current command and the DC current of the converter circuit, A boost voltage command calculator that generates a boost voltage command by adding a second predetermined value to the voltage peak value of the three-phase AC power supply, A regenerative voltage control unit generates a boost current command from the difference between the boost voltage command and the DC voltage of the converter circuit, A boost current controller that generates a boost current command through a second hysteresis comparator from the difference between the boost current command and the DC current of the converter circuit, It has, A converter control device characterized in that the first predetermined value is greater than the second predetermined value.

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