JP2007189763A - Motor controller, and method of protecting demagnetization of the motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which can prevent irreversible demagnetization of a magnet constituting a synchronous motor 106, by suppressing the current equivalent to the short circuit of three-phase winding of the synchronous motor 106 before a closed loop is formed between an inverter part 104 and the synchronous motor 106 and an excessive circulating current flows, when an optional switching element or a diode in the inverter part 104 goes into short circuiting failure at a high revolution of the synchronous motor 106, and to provide a method of protecting the demagnetization of the motor. <P>SOLUTION: A control circuit 108 is equipped with a fuse blowout deciding section 110 which decides the presence of blowout of a fuse 105, based on the detected signal of a fuse blowout detecting circuit 109, and a command selector 111 which selects either a normal operation command or a command at fuse blowout, based on the decision of the blowout deciding section 110. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control device for preventing irreversible demagnetization of a magnet constituting a synchronous motor and a motor demagnetization protection method thereof.

In a conventional motor demagnetization protection method using a motor control device, a motor temperature is detected by a thermistor built in the motor, and an inverter cutoff current value is switched according to the temperature (see, for example, Patent Document 1). In some cases, the motor magnet temperature is estimated by superimposing the high-frequency voltage, and the torque command is reduced according to the temperature (see, for example, Patent Document 2).
In Patent Document 1, when a temperature detection unit that detects a temperature of a switching element or a motor of an inverter and a temperature detected by the temperature detection unit is equal to or lower than a predetermined temperature, the cut-off current value of the inverter is determined as the detected temperature is the predetermined temperature. It is characterized by including a switching unit that switches lower than when it is higher.
In Patent Document 2, the speed detection means for detecting the rotational speed of the motor, and the armature linkage magnetic flux by the permanent magnet of the motor is calculated based on the rotational speed, the fundamental wave current or its command value, and the harmonic voltage command value. A magnetic flux calculating means, a magnet temperature estimating means for estimating the motor magnet temperature for the armature interlinkage flux calculation value with reference to a table of motor magnet temperatures for the armature interlinkage magnetic flux, and the estimated motor magnet temperature And an output adjusting means for adjusting the output of the motor.
As described above, in the motor demagnetization protection method using the conventional motor control device in Patent Document 1, when the temperature of the switching element of the inverter or the motor is equal to or lower than the predetermined temperature, the procedure of switching the inverter cut-off current low is taken. .
In the motor demagnetization protection method by the conventional motor control device in Patent Document 2, when the estimated motor magnet temperature exceeds the allowable temperature, the procedure of reducing the motor output, that is, the torque command, has been taken.
Japanese Patent Laid-Open No. 2001-136771 (page 4-7, FIGS. 1 and 2) Japanese Patent Laying-Open No. 2003-235286 (page 3-7, FIGS. 1 and 2)

  In the conventional motor demagnetization protection method using the motor control device, the procedure of reducing the cut-off current value or the torque command value according to the motor temperature is taken. Therefore, when the synchronous motor rotates at high speed, any switching element of the inverter output unit Or, if a short circuit failure occurs in a diode, or if any switching element in the inverter output unit malfunctions and at the same time an element that is paired with the arbitrary switching element is also called, physically between the inverter output circuit and the synchronous motor wiring There is a problem that a closed loop is formed, an excessive circulation current flows, and irreversible demagnetization cannot be prevented. As a result, it is necessary to replace the inverter and the motor at the same time, and there is also a problem that the time and cost for investigating the cause and replacement are large.

FIG. 5 is a current waveform diagram of each phase at the time of an element short-circuit failure in a conventional motor control device. In the figure, when the synchronous motor has a rated rotation and the switching element on the V phase plus side of the inverter output section has a short circuit failure, the current flowing through each winding of the synchronous motor is measured, and the maximum of 950 is applied to the synchronous motor V phase winding. The excessive current [A] flows. Since the rated current of the used synchronous motor is 101 [A], an excessive current exceeding 9 times the rated current flows. The irreversible demagnetization occurs due to the relationship between the characteristics of the magnet of the synchronous motor, the magnet temperature, and the excessive circulating current amount.
The present invention has been made in view of such problems, and when a synchronous motor is rotating at a high speed, when any switching element or diode of the inverter output section is short-circuited, or any switching element of the inverter output section is If a malfunction occurs and at the same time the element that forms a pair of any of the above switching elements is also ignited, a short circuit will occur before an excessive circulating current flows due to the formation of a closed loop between the inverter output circuit and the synchronous motor wiring. The prevention fuse is detected, the gate is driven to short-circuit the three-phase winding of the synchronous motor, and the current corresponding to the three-phase short-circuit is suppressed to prevent irreversible demagnetization of the magnet constituting the synchronous motor. The aim is to provide a motor control device and its motor demagnetization protection method that can prevent the time and cost required for investigation and motor replacement. To.

In order to solve the above problem, the present invention is as follows.
According to the first aspect of the present invention, there is provided a fuse for preventing upper and lower short circuits of a DC bus, a fuse blown detection circuit, a control circuit for performing motor control calculation, and an inverter for supplying electric power to the motor in response to a command from the control circuit In a motor control device that detects whether or not the fuse is blown by the fuse blow detection circuit, based on a detection signal of the fuse blow detection circuit, and a blow determination unit that determines whether or not the fuse is blown, The control circuit includes a command selection unit that selects either a normal operation time command or a fuse blow time command based on the determination of the fusing determination unit.
According to a second aspect of the present invention, the control circuit according to the first aspect of the invention selects the normal operation time command to control the inverter unit when the fuse is not blown, and controls the inverter. When there is a blow, the fuse blow command is selected to control the inverter unit.
According to a third aspect of the invention, the fuse blow command in the first aspect of the invention shorts the three-phase winding of the motor.
According to a fourth aspect of the present invention, the fuse blow command in the first or third aspect of the invention fully closes the upper arm element of the inverter unit and fully opens the lower arm element of the inverter unit. To do.
According to a fifth aspect of the invention, the fuse blow command in the first or third aspect of the invention opens the upper arm element of the inverter part fully and closes the lower arm element of the inverter part fully. To do.
According to a sixth aspect of the present invention, the fuse blow command in the first or third aspect of the invention fully closes the upper arm element of the inverter unit and fully opens the lower arm element of the inverter unit. And a command to fully open the upper arm element of the inverter unit and to fully close the lower arm element of the inverter unit at preset time intervals.
The invention according to claim 7 is a fuse for preventing a vertical short circuit of a DC bus, a fuse blown detection circuit, a control circuit for performing motor control calculation, and an inverter for supplying electric power to a motor in accordance with a command from the control circuit In the motor demagnetization protection method of the motor control device that detects whether or not the fuse is blown by the fuse blow detection circuit, and determines whether or not the fuse is blown based on a detection signal of the fuse blow detection circuit When the fuse is not blown, the normal operation command is selected to control the inverter unit. When the fuse is blown, the fuse blow command is selected to control the inverter unit.
According to an eighth aspect of the present invention, the fuse blow command in the seventh aspect of the invention short-circuits the three-phase winding of the motor.

According to the invention described in claim 1, 2, or 7, when the synchronous motor is rotating at a high speed, when any switching element or diode of the inverter output section is short-circuited, or when any switching of the inverter output section is performed When the element malfunctions, irreversible demagnetization of the magnet constituting the synchronous motor can be prevented, and the time and cost required for investigating the cause and replacing the synchronous motor can be suppressed.
Further, according to the invention of any one of claims 3 to 5 and claim 8, a simple gate drive command suppresses the amount of current flowing into the synchronous motor by instantaneously short-circuiting the three-phase winding of the synchronous motor. The irreversible demagnetization of the magnets constituting the synchronous motor can be prevented, and the time and cost required for investigating the cause and replacing the synchronous motor can be suppressed.
Further, according to the invention described in claim 6, together with the effects of the invention described in claims 3 to 5, it is possible to disperse the heat generation of the switching element due to the current circulating to the inverter output section when the three-phase short circuit occurs. The failure range can be minimized.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing a configuration of a motor control device of the present invention. In the figure, 101 is a three-phase power source, 102 is a converter unit, 103 is a smoothing capacitor unit, 104 is an inverter unit, 105 is a fuse, 106 is a synchronous motor, 107 is a gate drive circuit, 108 is a control circuit, 109 is a fuse blow detection Circuit. T1 to T6 are switching elements such as IGBTs, and D1 to D6 are diodes. Further, 110 is a fusing determination unit, and 111 is a command selection unit.

Here, each component will be described, and the operation when the inverter unit 104 is abnormal will be described.
Converter unit 102 and smoothing capacitor unit 103 convert three-phase power supply 101 into two phases to create a DC bus. Further, it is possible to connect a DC power supply without going through the converter unit 102. The inverter unit 104 includes switching elements T1 to T3 and diodes D1 to D3 corresponding to the U phase, V phase, and W phase of the synchronous motor 106, and a pair of switching elements T4 to T6 and diodes D4 to D6. The winding of the synchronous motor 106 is connected to the inverter unit 104. In order to prevent a power supply short circuit due to an abnormality of the inverter unit 104, a fuse 105 is disposed on the minus side wiring. In addition, fuses can be arranged on the negative side wirings of the U phase, the V phase, and the W phase, respectively.

The control circuit 108 includes an arithmetic circuit such as a CPU, and also includes a fusing determination unit 110 and a command selection unit 111 in arithmetic processing. During normal operation, a voltage command, which is a normal operation command, and an output phase are given to the gate drive circuit 107 via the command selection unit 111 in response to a command from a host device (not shown). The gate drive circuit 107 drives the synchronous motor 106 by applying the voltage to the motor phase as instructed by driving the switching elements T1 to T6 based on the normal operation instruction.
Here, when the fuse 105 is blown due to an abnormality in the inverter unit 104, the fuse blow detection circuit 109 instantaneously detects the blow of the fuse 105 and outputs a detection signal to the control circuit 108. Fusing determination unit 110 determines whether or not fuse 105 is blown based on the detection signal, and outputs the determination result to command selection unit 111. The command selection unit 111 selects a gate block command, which is a command at the time of fusing, based on the determination result in the fusing determination unit 110 and outputs it to the gate drive circuit 107. The gate drive circuit 107 can prevent a power supply short circuit by opening all the switching elements T1 to T6 based on the gate block command.
The abnormality of the inverter unit 104 refers to a case where the switching elements T1 to T6 or the diodes D1 to D6 are short-circuited or a case where the switching elements T1 to T6 malfunction.

FIG. 2 is a diagram illustrating an excessive circulation current path when the inverter unit is abnormal. As an example of the abnormality in the inverter unit 104, a case where the W-phase switching element T3 of the inverter unit 104 has a short circuit failure will be described.
In the figure, when the W-phase switching element T3 has a short-circuit failure, when the switching element T6 that is a pair of the W-phase switching element T3 is closed in the switching operation process, the plus side and minus side of the DC bus are vertically short-circuited, An excessive current flows and the fuse 105 is blown. After the fuse 105 is blown, a direct current flows through the W-phase winding of the synchronous motor 106 via the switching element T3 short-circuited from the positive side of the DC bus, and the inductance of the W-phase winding is reduced. A closed loop is formed in which the direct current flows in a divided manner to the U-phase winding and the V-phase winding, and flows to the plus side of the DC bus via the diodes D1 and D2. As the synchronous motor 106 rotates, an excessive circulating current obtained by superimposing a DC current on an AC current determined by the generated induced voltage and motor impedance continues to flow in the closed loop path while the synchronous motor 106 is rotating. Eventually, irreversible demagnetization occurs due to the relationship between the magnet characteristics of the synchronous motor 106, the magnet temperature, and the amount of excessive circulating current.

FIG. 3 is a flowchart showing a motor demagnetization protection processing procedure in the motor control device of the present invention.
First, as an example of the abnormality in the inverter unit 104 in FIG. 1, it is assumed that the W-phase switching element T3 of the inverter unit 104 has a short circuit failure. When the W-phase switching element T3 is short-circuited and the switching element T6 that is paired with the W-phase switching element T3 is closed during the switching operation, the plus and minus sides of the DC bus are short-circuited up and down, resulting in excessive current. The flow fuse 105 is blown. At this time, the fuse blow detection circuit 109 instantaneously detects the blow of the fuse 105 and outputs a detection signal to the control circuit 108.

Next, a series of processing procedures will be described with reference to FIG.
(Step 301)
Fusing determination unit 110 determines whether or not fuse 105 is blown based on the detection signal, and outputs the determination result to command selection unit 111. If the fuse 105 is blown, the process proceeds to step 303. If the fuse 105 is not blown, the process proceeds to step 302.
(Step 302)
Command selection unit 111 selects a normal operation command based on the determination result in fusing determination unit 110 and proceeds to step 304.
(Step 303)
Command selection unit 111 selects a three-phase short-circuit command, which is a command at the time of fusing, based on the determination result in fusing determination unit 110 and proceeds to one of steps 305 to 307. Proceeding to any one of steps 305 to 307 may be determined in advance for each application, or may be determined as appropriate based on the status signal.
(Step 304)
The command selection unit 111 outputs a voltage command and an output phase, which are normal operation commands, to the gate drive circuit 107, and ends a series of processes.

(Step 305)
The command selection unit 111 selects the three-phase short-circuit command that is pattern 1 and proceeds to step 308. In pattern 1, the upper arm switching elements T1 to T3 are simultaneously closed and the lower arm switching elements T4 to T6 are simultaneously opened.
(Step 306)
The command selection unit 111 selects a three-phase short-circuit command that is pattern 2 and proceeds to step 308. In pattern 2, the upper arm switching elements T1 to T3 are simultaneously opened, and the lower arm switching elements T4 to T6 are simultaneously closed.
(Step 307)
The command selection unit 111 selects a three-phase short-circuit command that is pattern 3 and proceeds to step 308. Pattern 3 repeats pattern 1 and pattern 2 at a predetermined time interval.
(Step 304)
The command selection unit 111 outputs any one voltage command among the patterns 1 to 3 of the three-phase short-circuit command, which is a command at the time of fusing, to the gate drive circuit 107, and ends a series of processing.

  As described above, when an abnormality occurs in the inverter output section when the synchronous motor rotates at high speed, the synchronous motor winding is instantaneously short-circuited to three phases after detecting the blow of the fuse. The amount of current flowing into the synchronous motor before the excessive circulating current flows into the winding can be suppressed to the equivalent of a three-phase short circuit current, and irreversible demagnetization of the magnets constituting the synchronous motor can be prevented. Moreover, by alternately switching the pattern 1 and pattern 2 as shown in pattern 3 to the switching element, heat generation of the switching element due to the current circulating to the inverter output section when three-phase short-circuited can be dispersed. The failure range can be minimized. Further, since the winding of the synchronous motor is a three-phase short circuit, the rotational speed is immediately reduced, and the continuation of the abnormal state can be shortened.

FIG. 4 is a current waveform diagram of each phase when the motor demagnetization protection method is applied in the motor control device of the present invention. As an example of the abnormality in the inverter unit 104 in FIG. 1, if the synchronous motor 106 has a rated rotation and the W-phase switching element T <b> 3 of the inverter unit 104 is short-circuited, the current flowing in each winding of the synchronous motor 106 based on the series of processes in FIG. 3. Is actually measured.
In the figure, when the synchronous motor 106 is rated, each phase current is very small. However, when the W-phase switching element T3 is short-circuited, for example, an excessive abnormal current as shown in FIG. 5 starts to flow. Here, in order to simulate a normal switching operation process, for example, when the V-phase switching element T5 is forcibly closed, the fuse is blown and the series of processes shown in FIG. The current flowing through the W-phase winding is suppressed to a maximum of 300 [A], and a three-phase short-circuit current by a three-phase short-circuit command flows through each phase. Thereafter, the rotational speed of the synchronous motor decreases (not shown), and the irreversible demagnetization of the magnet can be prevented without continuing the abnormal state. Since the rated current of the used synchronous motor was 75.5 [A], it was possible to suppress the current to about 4 times the rated current.
If the three-phase short-circuit command is not used, as shown in FIG. 2, the direct current flows separately to the U-phase winding and the V-phase winding, and flows to the plus side of the DC bus via the diodes D1 and D2. When the synchronous motor 106 is rotated and the synchronous motor 106 rotates, the direct current is superimposed on the alternating current determined by the generated induced voltage and the motor impedance, so that the excessive circulating current continues to flow in the closed loop path while the synchronous motor 106 is rotating. .

It is the schematic which shows the structure of the motor control apparatus of this invention. It is a figure which shows the excessive circulation current path | route at the time of an inverter part abnormality. It is a flowchart which shows the motor demagnetization protection processing procedure in the motor control apparatus of this invention. It is each phase current waveform figure at the time of the motor demagnetization protection method application in the motor control apparatus of this invention. It is each phase current waveform figure at the time of the element short circuit failure in the conventional motor control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Power supply 102 Converter part 103 Smoothing capacitor part 104 Inverter part 105 Fuse 106 Synchronous motor 107 Gate drive circuit 108 Control circuit 109 Fuse blowing detection circuit 110 Fusing judgment part 111 Command selection part S301-S308 Processing step

Claims (8)

A fuse for detecting a short circuit of a DC bus, a fuse blow detection circuit, a control circuit for performing motor control calculation, and an inverter for supplying electric power to the motor in response to a command from the control circuit, the fuse blow detection In a motor control device that detects whether the fuse is blown in a circuit,
Based on a detection signal of the fuse blow detection circuit, a blow determination unit for determining whether or not the fuse is blown,
A motor control device comprising: a command selection unit that selects either a normal operation time command or a fuse blow time command based on the determination of the fusing determination unit. When the control circuit does not blow the fuse, the normal operation command is selected to control the inverter unit,
When the fuse is blown, the motor control device controls the inverter unit by selecting the fuse blow command.   2. The motor control device according to claim 1, wherein the fuse blow command is for short-circuiting the three-phase winding of the motor. 4. The motor control device according to claim 1, wherein the fuse blowing instruction is to fully close the upper arm element of the inverter unit and fully open the lower arm element of the inverter unit. 5.   4. The motor control device according to claim 1, wherein the fuse blow command is for fully opening the upper arm element of the inverter unit and fully closing the lower arm element of the inverter unit. 5. The fuse blowing command is a command to fully close the upper arm element of the inverter unit and to fully open the lower arm element of the inverter unit;
A command to fully open the upper arm element of the inverter unit and to fully close the lower arm element of the inverter unit,
4. The motor control device according to claim 1, wherein the command is executed alternately at predetermined time intervals. A fuse for detecting a short circuit of a DC bus, a fuse blow detection circuit, a control circuit for performing motor control calculation, and an inverter for supplying electric power to the motor in response to a command from the control circuit, the fuse blow detection In a motor demagnetization protection method of a motor control device that detects whether or not the fuse is blown by a circuit,
Based on the detection signal of the fuse blow detection circuit, determine whether or not the fuse is blown,
If the fuse is not blown, select the normal operation command to control the inverter unit,
A motor demagnetization protection method for a motor control device, wherein when the fuse is blown, a fuse blow command is selected to control the inverter unit.   8. The motor demagnetization protection method for a motor control device according to claim 7, wherein the fuse blow command is for short-circuiting the three-phase winding of the motor.

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