JP5439262B2 - Discharge treatment apparatus, discharge treatment method, and discharge treatment program - Google Patents

Description

  The present invention relates to a capacitive element discharge processing apparatus, a discharge processing method, and a discharge processing program.

  In a system in which an output from a DC power source is converted into an AC voltage by an inverter and an AC motor is driven, the inverter has an element that performs high-speed switching in order to control the voltage applied to the AC motor. A capacitor for smoothing the fluctuating DC voltage is disposed between the inverter and the DC power source.

  In the invention described in Patent Document 1, after the DC power supply and the inverter are disconnected, the harmonic voltage is applied to all phases of the AC motor by the inverter. As a result, a current flows through the winding of the AC motor, and power is consumed by the impedance of the winding. As a result, capacitor discharge is performed in a short time. During this discharge, torque including harmonic components is generated in the AC motor. However, since the positive value and the negative value of the torque are canceled out, the rotor of the AC motor remains stationary by its own inertia.

Japanese Patent No. 4241163

  However, in the conventional technique of applying a harmonic voltage to an AC motor, it is necessary to energize all phases of the AC motor for discharging. Therefore, for some reason due to a disconnection failure or a failure of a switch with a built-in inverter. When there is a phase through which no current can flow, an unintended current may occur in the remaining phases.

A discharge processing apparatus according to the present invention is disposed between a power conversion means for applying a predetermined voltage to a winding of an electric motor of three or more phases by power supplied from a DC power supply, and between the DC power supply and the power conversion means. And in the state where the power supply from the DC power source to the power conversion means is cut off, any two phases of the winding by the power conversion means A first process of applying a voltage of the capacitive element between the two phases so that a current from the first phase to the second phase flows, and a second of the two phases of the winding by the power conversion means The second process of applying the voltage of the capacitive element between the two phases so that a current from the first phase to the first phase flows, and the electric motor so that the average value of the current flowing between the two phases becomes substantially zero. Sufficiently shorter than the mechanical time constant of By repeating alternately, and control means to consume power to discharge process of the capacitor element in the winding, said control means, the voltage of the capacitive element by the discharge treatment lower than the first predetermined value If not, the discharge process is repeated by a combination of two phases different from the two phases of the electric motor until the voltage of the capacitive element falls below the first predetermined value .
The discharge processing method according to the present invention is arranged between power conversion means for applying a predetermined voltage to windings of a motor having three or more phases by power supplied from a DC power supply, and between the DC power supply and the power conversion means. A discharge processing method for a system comprising a capacitive element and a voltage detection means for detecting a voltage of the capacitive element, wherein the power is supplied from the DC power source to the power conversion means. A first processing step of applying a voltage of the capacitive element between the two phases so that a current flowing from a first phase to a second phase of any two phases of the winding flows by the conversion means; and the power conversion And a second processing step of applying a voltage of the capacitive element between the two phases so that a current flowing from the second phase of the two phases of the winding toward the first phase flows by the means. So that the average value of the current is approximately zero By repeating alternately at a sufficiently shorter period than the mechanical time constant of the electric motor, when allowed to consume power to discharge process of the capacitor element in the winding, the voltage of the capacitive element by the discharge treatment first If the voltage does not fall below the predetermined value, the discharge process is repeated by a combination of two phases different from the two phases of the electric motor until the voltage of the capacitive element drops below the first predetermined value .
A discharge processing program according to the present invention is arranged between power conversion means for applying a predetermined voltage to windings of a motor having three or more phases by power supplied from a DC power supply, and between the DC power supply and the power conversion means. A discharge processing program for a system comprising a capacitive element and a voltage detection means for detecting a voltage of the capacitive element, wherein the power is supplied from the DC power source to the power conversion means. A first processing step of applying a voltage of the capacitive element between the two phases so that a current flowing from a first phase to a second phase of any two phases of the winding flows by the conversion means; and the power conversion And a second processing step of applying a voltage of the capacitive element between the two phases so that a current flowing from the second phase of the two phases of the winding toward the first phase flows by the means. The average value of current is abbreviated By repeating alternately at a sufficiently shorter period than the mechanical time constant of the motor so that, when allowed to consume power to discharge process of the capacitor element in the winding, by the discharge treatment of said capacitive element When the voltage does not decrease below the first predetermined value, the discharge processing is repeatedly performed by a combination of two phases different from the two phases of the electric motor until the voltage of the capacitive element decreases below the first predetermined value. Is described in the form of a program for causing the computer to function.

  According to the present invention, after an inverter that drives an AC motor having three or more phases is disconnected from the DC power source, even if there is a phase that cannot be energized in the AC phase, the two phases that can be energized without rotating the AC motor Since the combination is selected, power can be consumed by the windings of the AC motor, and the capacitor disposed between the inverter and the DC power supply can be discharged in a short time.

1 is an overall configuration diagram of a system including a DC power supply, an AC motor, and a device for performing a capacitor discharge process according to an embodiment of the present invention. It is a flowchart which shows the control procedure from starting to a stop in the system of FIG. It is a flowchart which shows the subroutine of the discharge process step shown in FIG. In the 1st process in this Embodiment, it is explanatory drawing which shows the switching pattern of the switching element in an inverter, and the flow of an electric current at that time. In the 2nd process in this Embodiment, it is explanatory drawing which shows the switching pattern of the switching element in an inverter, and the flow of an electric current at that time. It is a wave form diagram which shows the 1st timing form for implementing a 1st process and a 2nd process in this Embodiment. It is a wave form diagram which shows the 2nd timing form for implementing a 1st process and a 2nd process in this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 is an overall configuration diagram of a system including a DC power source, an AC motor, and a device for performing discharge processing of a capacitor according to an embodiment of the present invention. The system includes a DC power source 1, a contactor 2, an AC motor 3, a magnetic pole position detection circuit 4 of the AC motor 3, an inverter 5, a capacitor 6, a voltage detection circuit 7 for the capacitor 6, and a current detection circuit 8. And a control device 9.

  In this system, the voltage of the DC power source 1 is converted into an AC voltage by the inverter 5, and the AC motor 3 is controlled by the control device 9. For example, it is applied to a drive system of a hybrid vehicle. In that case, the DC power source 1 is a secondary battery such as a nickel metal hydride battery or a lithium ion battery, and its voltage may be several hundred volts, and the output shaft of the AC motor 3 is connected to the axle.

  The power supply from the DC power source 1 to the inverter 5 is performed by closing the contactor 2, whereby the voltage of the capacitor 6 becomes substantially the same as the voltage of the DC power source 1. The power from the DC power source 1 to the inverter 5 is cut off when the contactor 2 is opened. When the contactor 2 is in the open state and the AC motor 3 is not rotating, no voltage is applied to the capacitor 6.

  The AC motor 3 includes a stator having windings for three phases (here, U phase, V phase, and W phase) and two rotors that generate rotational force due to magnetic flux that changes as a current flows through the windings. Mainly composed of parts. The AC motor 3 is provided with a magnetic pole position detection circuit 4 for detecting a magnetic pole position that changes as the rotor rotates. The current flowing through the AC motor 3 is detected by the current detection circuit 8 and transmitted to the control device 9.

  In the inverter 5, elements that perform switching at high speed, such as IGBTs, are arranged for each of three phases on the positive electrode side and the negative electrode side of the DC power supply 1, and are generated by switching of these six elements (Tr1 to Tr6) in total. A pulse width modulation method is used in which the pulse width of the voltage is changed and a predetermined voltage is applied to the AC motor 3.

  The capacitor 6 is disposed between the DC power source 1 and the inverter 5 in order to smooth the DC voltage that fluctuates due to the switching, and the voltage (Vdc) is transmitted from the voltage detection circuit 7 to the control device 9.

  The control device 9 acquires the three-phase current and the magnetic pole position of the AC motor 3 by the current detection circuit 8 and the magnetic pole position detection circuit 4, respectively, in order to control the current of the AC motor 3. Although not shown, the control device 9 converts the acquired three-phase current into a d-axis current in the magnetic flux direction of the rotor of the AC motor 3 and a q-axis current orthogonal to the d-axis, and the acquired d-axis current and q The voltage command value to be applied to the AC motor 3 is determined so that the difference between the shaft current and the target d-axis current and q-axis current is zero, and the switching element of the inverter 5 is controlled. The target d-axis current and the q-axis current are determined from the target torque value of the AC motor 3.

  The flow from the start to the stop of this system will be described with reference to the flowchart of FIG. When the system is started in step S1, the contactor 2 is closed in step S2, whereby the DC power source 1 and the inverter 5 are connected, and a voltage is applied to the contactor 6. As a result, the AC motor 3 in step S3 can be controlled, and the control device 9 controls the d-axis current and the q-axis current of the AC motor 3 based on the target torque value.

  When a stop request to the system is confirmed in step S4, the contactor 2 is opened, and the DC power source 1 and the inverter 5 are disconnected. Next, in order to discharge the voltage remaining in the capacitor 6, the discharge process of step S6 is performed. When it is confirmed in step S7 that the discharge process is completed, the system stops in step S8.

  Details of the discharge process will be described with reference to the flowchart of FIG. In step S <b> 22, the control device 9 acquires the voltage of the capacitor 6 from the voltage detection circuit 7. Next, in step S23, arbitrary two phases are selected from the three phases of the U phase, the V phase, and the W phase of the AC motor 3. In the present embodiment, a U phase and a V phase are selected as arbitrary two phases.

  In step S24, a first process of applying a voltage of the capacitor 6 between the U phase and the V phase so that a current from the U phase to the V phase flows, and a voltage of the capacitor 6 so that a current flows from the V phase to the U phase. To alternately repeat the second process applied between the U phase and the V phase at a cycle sufficiently shorter than the mechanical time constant of the AC motor 3 (preferably not more than one tenth of the mechanical time constant of the AC motor 3). Give instructions. Although not shown, the control of the switching element of the inverter 5 for executing the first process and the second process is executed by this instruction until there is an instruction to end the first process and the second process. The

  The switching pattern and current flow of the inverter 5 when the first process and the second process are performed will be described with reference to FIGS. 4 and 5. 4 and 5 show the capacitor 6 shown in FIG. 1, the six switching elements Tr1 to Tr6 in the inverter 5, and the star connection in which the stator winding 10 in the AC motor 3 is simplified. . U, V, and W in the figure indicate the names of the respective phases.

  First, when Tr1 and Tr5 in FIG. 4 are turned on to perform the first process, the U phase is connected to the positive electrode of the capacitor 6 and the V phase is connected to the negative electrode of the capacitor 6, so that the dotted arrow in FIG. Current flows from the U-phase to the V-phase.

  Next, when Tr2 and Tr4 in FIG. 5 are turned on to perform the second processing, the V phase is connected to the positive electrode of the capacitor 6 and the U phase is connected to the negative electrode of the capacitor 6, so that the dotted line arrow in FIG. Current flows from the V-phase to the U-phase. By repeating the first process and the second process in this way, an alternating current is generated between the U phase and the V phase.

  6 and 7, the horizontal axis takes time, the switching timing for repeating the first processing and the second processing shown in FIGS. 4 and 5, and the line voltage between the U phase and the V phase due to switching. Two forms are shown. In any form, when the line voltage between the U phase and the V phase is a positive voltage + Vdc (voltage of the capacitor 6), a current flows from the U phase to the V phase, and when the negative voltage is -Vdc, the V phase changes to the U phase. The current that flows is flowing. T0 is a period for performing the first process and the second process.

  In the first mode shown in FIG. 6, an instruction to alternately repeat the first process and the second process in step S24 of FIG. 3 is issued at point A. First, Tr1 and Tr5 are used to perform the first process. An operation is performed to turn on during time T1, and then Tr2 and Tr4 are operated to turn on during time T1 in order to perform the second process. By setting the time for performing the first process and the second process in the period T0 to be the same time, the line voltage between the U phase and the V phase becomes + Vdc and −Vdc for the same time, and the U phase The average value of the alternating current generated between the V phase and the V phase is substantially zero. Although not shown in FIG. 6, the line voltage between the U phase and the V phase approaches 0 as the voltage of the capacitor 6 decreases.

  In the second form shown in FIG. 7, an instruction to alternately repeat the first process and the second process in step S24 in FIG. 3 is issued at point A. Tr1 and Tr5 are first used to perform the first process. The switches are turned on at the same time during the time T2, and the operation is performed so that the times when Tr2 and Tr4 are turned on do not overlap. Subsequently, in order to perform the second processing, Tr2 and Tr4 are simultaneously turned on for the time T2, and an operation is performed so that the times for which Tr1 and Tr5 are turned on do not overlap. By setting the time for performing the first process and the second process during the period T0 to be the same time, the line voltage between the U phase and the V phase becomes + Vdc and −Vdc for the same time. As in the first embodiment shown in FIG. 6, the average value of the alternating current generated between the U phase and the V phase is substantially zero. Although not shown in FIG. 7, the line voltage between the U phase and the V phase approaches 0 as the voltage of the capacitor 6 decreases.

  In FIGS. 6 and 7, for the sake of simplification, the illustration of dead time for preventing the switching elements on the positive and negative sides of each phase from being turned on simultaneously is omitted.

  Even when the other two phases are selected, an alternating current can be generated between the selected two phases by operating the corresponding switching elements as described above.

  In this way, an alternating current is generated between the U phase and the V phase, and power is consumed by the impedance of the winding 10 of the alternating current motor 3 to start discharging the capacitor 6. The AC current generated between the U phase and the V phase has a period sufficiently shorter than the mechanical time constant of the AC motor 3 and an average value thereof is substantially 0. Therefore, the rotor of the AC motor 3 cannot be rotated. Absent.

  Since the effective value of the alternating current flowing between the U phase and the V phase is proportional to T1 or T2, the power consumption in the winding 10 is increased by increasing T1 or T2, and the voltage of the capacitor 6 is discharged quickly. be able to. In order to shorten the discharge time from this, it is desirable to set the period T0 to about 1/10 of the mechanical time constant of the AC motor 3, for example.

  If it is confirmed in step S25 of FIG. 3 that the predetermined time threshold 1 has elapsed since the start of the first process and the second process, step S26 is performed, and if not, the process exits from step S35.

In step S26, the voltage of the capacitor 6 is compared with the voltage of the capacitor 6 before the start of the first process and the second process between the U phase and the V phase. When the voltage is 200V, the voltage threshold 1 is set to 190V)
If it is lower, step S27 is performed, and if not, step S30 is performed.

  In step S27, when the voltage of the capacitor 6 falls below the voltage threshold 2 (for example, when the battery voltage is 200V, the voltage threshold 2 is set to 60V), the first process and the first process are performed in steps S28 and S29. An instruction to end the process 2 is issued to complete the discharge process. If not, the process exits from step S35.

  In step S30, if there is another two-phase combination that has not been selected among the three phases, another two-phase combination is selected in step S31, the voltage of the capacitor 6 is acquired in step S32, and step S24. To implement.

  In step S30, if there is no other two-phase combination that has not yet been selected among the three phases, the first process and the second process are terminated in step S33, and the discharge process is completed in step S34. Since this is a case where discharge cannot be achieved even when all two phases are combined, it is preferable to perform processing (not shown) for notifying the outside of the abnormality.

  In this way, by changing the combination of the two phases until the voltage of the capacitor 6 falls below the voltage threshold 1 and repeating the energization, even if one of the selected two phases is broken, the AC motor 3 can be Since no current flows, the rotor of the AC motor 3 does not rotate. On the other hand, in the conventional method of controlling the current so that the rotor is not rotated by the three-phase energization, an unintended current may flow to the AC motor 3 when one phase cannot be energized due to a disconnection failure or the like.

  Further, in a system that can detect in advance a state in which normal energization such as a phase disconnection failure cannot be detected in advance, the discharge process can be performed by energizing between two phases excluding the fault phase.

  Whether the voltage threshold 1 is normally energized between the two phases by setting the minimum value of the voltage of the capacitor 6 that decreases when the energization can be continuously performed between the two phases for the time threshold 1 Can be determined. The time threshold value 1 is set from a time specification from when a stop request is issued to the system until discharge is completed. The voltage threshold 2 is set to a value that can ensure the safety of work when repairing the device after the system is stopped.

  In the present embodiment, when a voltage is applied between two phases that cannot be energized, the voltage of the capacitor 6 does not decrease. As a result, it can be detected that there is a phase that cannot be energized. Abnormality notification or the like can also be performed.

  Furthermore, in this embodiment, since the magnetic pole position detection circuit 4 and the current detection circuit 8 shown in FIG. 1 are not used, even if these circuits are faulty or in a system in which these circuits do not exist, the discharge Processing can be performed reliably.

-Actions and effects of the first embodiment-
According to the present embodiment, the following actions and effects can be achieved.
(1) An inverter 5 that applies a predetermined voltage to the windings of the three-phase motor 3 by electric power supplied from the DC power supply 1, a capacitor 6 disposed between the DC power supply 1 and the inverter 5, and a terminal of the capacitor 6 In the state in which the power supply from the DC power source 1 to the inverter 5 is cut off from the DC power source 1 and the voltage detection circuit 7 that detects the inter-voltage, the inverter 5 moves from the first phase to the second phase of any two phases of the winding. A first process of applying a voltage between terminals of the capacitor 6 between the two phases so that a current flows, and a current from the second phase of the two phases of the winding to the first phase by the inverter 5 flow. The second process in which the voltage between the terminals of the capacitor 6 is applied between the two phases is alternated with a period sufficiently shorter than the mechanical time constant of the motor 3 so that the average value of the current flowing between the two phases becomes substantially zero. By repeating the previous And a control device 9 that dissipates power in the winding and discharges the capacitive element. Therefore, even when there is a phase in which no current can flow in the motor 3, the winding is energized without rotating the motor 3. The capacitor can be discharged in a short time by performing power consumption.

  (2) By changing the combination of the two phases until the voltage of the capacitor 6 drops below the voltage threshold 1 and repeating the energization, the AC motor 3 can be used even when one of the selected two phases is broken. Since no current flows, the rotor of the AC motor 3 does not rotate. In addition, by providing a means for detecting a state in which normal energization cannot be performed due to a phase disconnection failure or the like, the discharge process can be performed by energizing between the two phases excluding the fault phase.

  (3) By setting the minimum value of the voltage of the capacitor 6 that drops when the voltage threshold 1 is continuously energized between the two phases for the time threshold 1, whether or not the energization was normal between the two phases. It can be determined whether or not. By appropriately setting the voltage threshold 2, it is possible to safely repair the device after the system is stopped.

  (4) When a voltage is applied between two phases that cannot be energized, the voltage of the capacitor 6 does not decrease. Therefore, the presence of a phase that cannot be energized can be detected by monitoring the voltage of the capacitor 6.

  (5) In this embodiment, since the magnetic pole position detection circuit 4 and the current detection circuit 8 are not required, even when the magnetic pole position detection circuit 4 and the current detection circuit 8 are out of order, the discharge process is reliably performed. be able to. Further, even in a motor control system that does not include a magnetic pole position detection circuit and a current detection circuit, the discharge process according to the present embodiment can be performed.

(6) Generally, while a DC power supply and an inverter are connected during system operation and electric power is supplied from the DC power supply to the inverter, electric charges are accumulated in the capacitor, and the voltage of the capacitor is substantially the same as the voltage of the DC power supply. become. In a system that requires an output of several tens of kW such as a hybrid vehicle or an electric vehicle, the voltage of the DC power supply is usually 100V or more. Even after the DC power supply and the inverter are disconnected when the operation of this system is stopped, the capacitor retains a voltage because electric charge remains in the capacitor. It is desirable to discharge the capacitor voltage to a low voltage in a short time when the system is stopped in order to ensure the safety of work when repairing the equipment after the system is stopped.
Conventionally, as a method for discharging a capacitor, means for reducing the voltage of the capacitor by connecting a resistor in parallel to the capacitor and consuming power by this resistor after disconnecting the DC power source and the inverter has been widely used. In order to reduce the power loss due to this resistor during the operation of the system where the DC power supply and inverter are connected, it is necessary to select a resistor with a high resistance value, and it was difficult to shorten the discharge time of the capacitor . In addition, there is a method of discharging a capacitor in a short time by connecting a capacitor with a dedicated discharge circuit for consuming power after disconnecting the DC power supply and the inverter, but a dedicated discharge circuit is required. The device becomes complicated and expensive.
On the other hand, a method has been proposed in which power is consumed by passing an electric current through an AC motor to discharge a capacitor. However, in a system in which it is not preferable that the AC motor rotates during discharge, energization is performed so as not to rotate the AC motor. Need to do. For example, in a system in which the output shaft of an AC motor is connected to the axle such as a hybrid vehicle or an electric vehicle, the behavior of the vehicle may be affected if the AC motor rotates during discharge.
In consideration of such points, the present embodiment allows power to be consumed by energizing the windings of the AC motor without rotating the AC motor even when there is a phase in which no current can flow in the AC motor. The capacitor can be discharged in a short time.

<Embodiment 2>
The present invention can also be applied to a discharge processing program. More specifically, power conversion means for applying a predetermined voltage to the windings of a motor having three or more phases by electric power supplied from a DC power supply, and a capacitive element disposed between the DC power supply and the power conversion means And a voltage detection means for detecting the voltage of the capacitive element, wherein the power conversion means in a state where power supply from the DC power source to the power conversion means is cut off. A first processing step of applying a voltage of the capacitive element between the two phases so that a current from an arbitrary two-phase first phase to a second phase of the winding flows, and the power conversion means A second processing step of applying a voltage of the capacitive element between the two phases so that a current from the second phase of the two phases of the winding toward the first phase flows, and an average of the current flowing between the two phases So that the value is approximately zero. It is described in the form of a program that causes the computer to function as means for consuming electric power in the windings and performing discharge processing of the capacitive element by alternately repeating with a cycle sufficiently shorter than the mechanical time constant of the motive. A discharge processing program can be provided.

-Actions and effects of the second embodiment-
According to the present embodiment, the following actions and effects can be achieved.
(1) Even when there is a phase in which no current can flow in the AC motor, the capacitor is discharged in a short time by energizing the windings of the AC motor and consuming power without rotating the AC motor. Can create programs.

<Other variations>
(1) In the above description, the case where the present embodiment is applied to a system in which a three-phase AC motor is mounted as a load has been described. However, the present embodiment is not limited to this and is not limited to three or more phases. The present invention can also be applied to an AC motor or a system having an AC load of three or more phases.
(2) The present invention is not limited to the flowcharts shown in FIGS. 2 and 3, and a step configuration for implementing the same function can be adopted.

The above description is merely an example, and the present invention is not limited to the above-described embodiments and modifications unless the features of the present invention are impaired.
It is also possible to combine the embodiment and one of the modified examples, or to combine the embodiment and a plurality of modified examples.
It is possible to combine the modified examples in any way.
Furthermore, other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Contactor 3 AC motor 4 Magnetic pole position detection circuit 5 Inverter 6 Capacitor 7 Voltage detection circuit 8 Current detection circuit 9 Control apparatus

Claims (4)

Power conversion means for applying a predetermined voltage to windings of a motor having three or more phases by power supplied from a DC power supply;
A capacitive element disposed between the DC power source and the power conversion means;
Voltage detection means for detecting the voltage of the capacitive element;
In a state where the power supply from the DC power source to the power conversion unit is cut off, the power conversion unit causes the current from any first phase of the winding to flow to the second phase of the winding to flow. A first process for applying a voltage of the capacitive element between the two phases; and a current flowing from the second phase of the winding to the first phase of the winding by the power conversion means. By alternately repeating the second process of applying a voltage between the two phases at a cycle sufficiently shorter than the mechanical time constant of the electric motor so that the average value of the current flowing between the two phases becomes substantially zero, Control means for consuming electric power in the winding and discharging the capacitive element ;
The control means separates from the two phases of the electric motor until the voltage of the capacitive element falls below the first predetermined value when the voltage of the capacitive element does not fall below the first predetermined value by the discharge process. A discharge treatment apparatus that repeatedly performs the discharge treatment by a combination of the two phases . The discharge treatment apparatus according to claim 1 ,
The control means is a case where the voltage of the capacitive element is lowered from the first predetermined value by the discharging process , and the voltage of the capacitive element is reduced to a second predetermined value (first by the discharging process ). The discharge treatment apparatus is characterized in that the discharge treatment is stopped when the value falls below ( predetermined value> second predetermined value) . A power conversion means for applying a predetermined voltage to a winding of a three or more-phase motor by power supplied from a DC power supply; a capacitive element disposed between the DC power supply and the power conversion means; and A discharge processing method for a system comprising a voltage detection means for detecting a voltage,
In a state where the power supply from the DC power source to the power conversion unit is cut off, the power conversion unit causes the current from any first phase of the winding to flow to the second phase of the winding to flow. A first processing step of applying a voltage of a capacitive element between the two phases;
A second processing step of applying a voltage of the capacitive element between the two phases so that a current from the second phase of the two phases of the winding to the first phase flows by the power conversion means;
By alternately repeating with a period sufficiently shorter than the mechanical time constant of the electric motor so that the average value of the current flowing between the two phases becomes substantially zero, electric power is consumed in the windings, and the discharging process of the capacitive element is performed. When performing , if the voltage of the capacitive element does not fall below the first predetermined value by the discharge process, the two different from the two phases of the electric motor until the voltage of the capacitive element falls below the first predetermined value. A discharge treatment method comprising repeatedly performing the discharge treatment by a combination of phases . A power conversion means for applying a predetermined voltage to a winding of a three or more-phase motor by power supplied from a DC power supply; a capacitive element disposed between the DC power supply and the power conversion means; and A discharge processing program for a system including a voltage detection means for detecting a voltage,
In a state where the power supply from the DC power source to the power conversion unit is cut off, the power conversion unit causes the current from any first phase of the winding to flow to the second phase of the winding to flow. A first processing step of applying a voltage of the capacitive element between the two phases, and the capacitive element so that a current from the second phase of the winding to the first phase of the winding flows by the power conversion means. And a second processing step of applying a voltage of 2 to the two phases alternately with a cycle sufficiently shorter than the mechanical time constant of the motor so that the average value of the current flowing between the two phases becomes substantially zero. Thus, when performing the discharge process of the capacitive element by consuming electric power in the winding, if the voltage of the capacitive element does not drop below a first predetermined value by the discharge process, the voltage of the capacitive element is Until it falls below the specified value Examples motor of the unit to repeat the discharge treatment with a combination of different two-phase and two-phase, discharge treatment program characterized by what is stated in the form of a program to cause a computer to function.

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