JP2011217474A - Motor control device and method for detecting failure of the sasme - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate failure detection in a dynamic brake circuit.SOLUTION: A motor control device includes a first failure detection circuit that outputs a first monitoring signal, a switch for failure detection, a second failure detection circuit that outputs a second monitoring signal, and a control circuit portion that uses the first monitoring signal and the second monitoring signal as input. The first failure detection circuit and the second failure detection circuit each include a photocoupler. The photocoupler converts a minute failure detection current into a first monitoring signal and a second monitoring signal for failure detection.

Description

  The present invention relates to a motor control device that drives a servo motor with an inverter and detects a failure of a dynamic brake circuit of the servo motor, and a failure detection method thereof.

  For example, a servo amplifier (motor control device) that drives and controls an AC servo motor is generally used to prevent the movable part from moving freely when the servo amplifier is not energized or when operation is not permitted (including emergency stop). Dynamic brake circuit is included.

  If the dynamic brake circuit breaks down when the motor is emergency stopped due to some abnormality, the motor cannot be braked normally, and the braking time until the motor stops increases. As a result, the mechanical device driven by the motor may be damaged.

  Thus, the dynamic brake function is important, and maintenance and inspection of the dynamic brake circuit is necessary. For example, the operation of the dynamic brake circuit disclosed in Patent Document 1 will be described with reference to FIG.

  FIG. 15 is a configuration diagram of a motor control device 900 disclosed in Patent Document 1. The motor control device 900 includes a three-phase power source 1, a converter unit 2, a smoothing capacitor 3, an inverter unit 21, a dynamic brake circuit 23, a contactor 25, a motor 20, a position detector 24, a current detection means (detection circuit) 19, and a control circuit. Unit 26 and an inverter control circuit unit 27.

  The dynamic brake circuit 23 includes a braking resistor 18, a relay 17, and a three-phase full-wave rectifier circuit 22 including rectifier diodes 11-16. In the normal operation of the motor 20, the relay 17 is on the SVON side and the three-phase full-wave rectifier circuit 22 is in an open state. When the motor 20 is stopped due to the occurrence of an abnormality, the relay 17 is connected to the DB side and the dynamic brake circuit 23 is turned on. At that time, the induced voltage generated by the motor 20 rotating by inertial force is converted into a DC voltage by the three-phase full-wave rectifier circuit 22, and the DC voltage is consumed as thermal energy by the braking resistor 18. Is braked.

  A failure detection method for the dynamic brake circuit 23 will be briefly described. If the motor 20 is being driven, the operation is stopped. First, the inverter unit 21 is turned off, and the motor 20 is disconnected from the dynamic brake circuit 23 by the contactor 25. Next, the relay 17 is closed to the DB side, and the dynamic brake circuit 23 is turned on.

  In this state, one semiconductor switching element that does not form a pair with any one of the semiconductor switching elements 5, 7, and 9 of the upper arm of the inverter unit 21 and the upper arm of the semiconductor switching elements 6, 8, and 10 of the lower arm is operated. As a result, a looping current flows in the circuit indicated by ← in FIG. That is, the upper arm semiconductor switching element (5, 7, 9) → rectifier diode (12, 14, 16) → braking resistor 18 → relay 17 → rectifier diode (11, 13, 15) → Current flows through the loop of the semiconductor switching element of the lower arm (one of the upper switching arm of 6, 8, 10 which does not form a pair).

  That is, the conventional failure detection method of the dynamic brake circuit 23 is configured to detect a voltage drop generated at both ends of the braking resistor 18 by flowing a direct current from the converter unit 2 in the current path (loop) of the dynamic brake circuit 23. It was done by detecting at 19.

JP 2009-142115 A

  In the conventional method, a high-voltage power supply for driving the motor is used for failure detection. Therefore, if the switching element is short-circuited, a large current flows from the high-voltage power supply and damage is increased.

  The present invention has been made in view of such problems, and provides a motor control device that can easily detect a failure even with a low applied voltage and a small failure detection current value, and a failure detection method thereof. The purpose is to provide.

  The motor control device according to the present invention is a motor control device including a rectifier circuit, a dynamic brake circuit, an inverter unit, and an inverter control unit, wherein the first failure detection circuit, the failure detection switch, and the second failure A detection circuit and a control circuit unit are provided. The first failure detection circuit is connected between the positive power source of the drive power source inverter and the positive power source of the inverter drive power source, and outputs a first monitoring signal. The failure detection switch is connected to one terminal of the rectifier circuit and the negative power source of the drive power source inverter. The second failure detection circuit is connected between the other terminal of the rectifier circuit and the positive power supply of the inverter drive power supply, and outputs a second monitoring signal. The control circuit unit controls the operation of the inverter control unit using the control logic power supply as a power source, and outputs a control signal for controlling ON / OFF of the relay and the failure detection switch, and outputs the first monitoring signal and the second monitoring signal. As input.

  According to the motor control device of the present invention, since the first failure detection circuit, the failure detection switch, and the second failure detection circuit are provided, the applied voltage is low and the current value for failure detection is small. However, the failure of the dynamic brake circuit and the inverter unit of the motor control device can be easily detected.

The figure which shows the function structural example of the motor control apparatus 100 of this invention. The figure which shows the operation | movement flow of the failure detection method of the dynamic brake circuit 23 and the inverter part 21. FIG. The figure which shows the failure detection mode of a relay and a rectifier diode. The figure which shows the operation | movement at the time of failure detection mode OP1. The figure which shows the operation | movement at the time of failure detection mode OP3. The figure which shows operation | movement at the time of failure detection mode OP9 (when the rectifier diode 16 is short-circuit failure). The figure which shows the operation | movement at the time of failure detection mode OP6. The figure which shows operation | movement at the time of failure detection mode OP12 (when the rectifier diode 15 is short-circuit failure). The figure which shows the failure detection mode of the inverter part 21 (switching element). The figure which shows the electric current path | route at the time of failure detection mode OP18. The figure which shows the electric current path | route at the time of failure detection mode OP21. The figure which shows the operation | movement flow which isolates the failure of the switching elements 5-10. The figure which shows the mode which confirms motor connection. The figure which shows the other Example of a 1st failure detection circuit. The figure which shows the function structure of the motor control apparatus 900 disclosed by patent document 1. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals are given to the same components in a plurality of drawings, and the description will not be repeated.

  FIG. 1 shows a functional configuration example of a motor control device 100 of the present invention. The motor control device 100 is new to the motor control device 900 described in the prior art in that it includes a first failure detection circuit 30, a failure detection switch 40, and a second failure detection circuit 50. In addition, the control circuit 90 outputs a control signal for controlling ON / OFF of the failure detection switch 40, the first monitoring signal output from the first failure detection circuit 30 and the second failure detection circuit 50, and the first monitoring signal. 2 It is new in that the monitoring signal is used as an input signal, but is the same in that the control circuit unit 26 and the inverter circuit 21 of the motor control device 900 are controlled. The inverter control unit 60 is also the same as the conventional inverter control circuit unit 27 in that it generates a signal for controlling the motor 20 by PWM (Pulse Width Modulation).

  The dynamic brake circuit 23, the drive power supply converter 2, and the smoothing capacitor 3 are also the same as the motor control device 900, as is clear from the reference numerals. The drive power converter 2 is the same as the converter unit 2 of the motor control device 900. Further, the inverter driving power supply 70 and the control logic power supply 80 are simply omitted in the motor control device 900, and are conventionally necessary functional components. In the description of the present invention, the braking resistor 18 is referred to as a braking resistor 18, and the three-phase full-wave rectifier circuit 22 in the dynamic brake circuit 23 is referred to as a rectifier circuit 22.

  The power source of the motor control device 100 is such that the three-phase AC power source 1 is connected to the primary side of the drive power converter 2 via a leakage breaker 81 (hereinafter referred to as ELB) and an electromagnetic contactor 82 (hereinafter referred to as MC). Connected to. A single phase of the three-phase AC power supply 1 is connected to the primary side of the control power converter 28. The inverter drive power supply 70 and the control logic power supply 80 are insulated power supplies that are insulated from the power supply of the control power supply converter 28, and the inverter drive power supply 70 and the control logic power supply 80 are also insulated from each other. The positive power supply of the inverter drive power supply 70 outputs + Vp, and the negative power supply is connected to the power ground (PG). The positive power supply of the control logic power supply 80 outputs + Vcc, and the negative power supply is connected to the signal ground (SG). Each output U phase, V phase, and W phase of the inverter circuit 21 is connected to the motor 20. A rectangular symbol described between the motor control device 100, the motor 20, and the three-phase AC power source 1 is a connection component such as a terminal or a connector.

  The diode 9d connected in parallel to the switching element 9 functions to absorb the counter electromotive voltage generated by the motor 20. The diode is connected to other switching elements in parallel, but the reference numerals are omitted because the notation is complicated.

  In the first failure detection circuit 30, the primary side is between the positive power source (+ Vp) of the converter 2 for driving power source and the positive power source (+ Vp) of the inverter driving power source 70, and the positive side is the positive power source (+ Vcc) of the control logic power source 80. The first monitoring signal is output to the control circuit unit 90 by being connected to the power source (SG). The failure detection switch 40 is connected between the anode terminals of the rectifier diodes 11, 13, and 15 constituting the rectifier circuit 22 and the negative power source of the drive power source converter 2, and ON / OFF of the switch is controlled by the control circuit unit 90. Is done. The failure detection switch 40 is constituted by, for example, a relay or a semiconductor element.

  In the second failure detection circuit 50, the primary side is between the cathode terminals of the rectifier diodes 12, 14, 16 constituting the rectifier circuit 22 and the positive power supply (+ Vp) of the inverter drive power supply 70, and the secondary side is the control logic power supply 80. Are connected between a positive power source (+ Vcc) and a negative power source (SG), and output a second monitoring signal to the control circuit unit 90.

  With the above configuration, the motor control device 100 can easily detect the failure of the inverter unit 21 and the dynamic brake circuit 23 even when the applied voltage is low and the current value is small for failure detection. Next, the specific configurations of the first failure detection circuit 30 and the second failure detection circuit 50 are shown, and the operation of the embodiment will be described in more detail.

[First failure detection circuit]
The first failure detection circuit 30 is connected to the photocoupler 32, the reverse voltage prevention diode 34 connected in series to the primary side of the photocoupler 32, the current limiting resistor 33, and the secondary side of the photocoupler 32. And a load resistor 31. The anode terminal of the photodiode 32 a on the primary side of the photocoupler 32 is connected to the positive power supply (+ Vp) of the inverter drive power supply 70. The cathode terminal of the photodiode 32 a is connected to the anode terminal of the reverse voltage prevention diode 34 through the current limiting resistor 33. The cathode terminal of the reverse voltage preventing diode 34 is connected to the positive power source of the drive power source converter 2. An emitter terminal of a secondary side switching transistor (hereinafter referred to as a switching Tr) 32b of the photocoupler 32 is connected to a negative power source (SG) of a control logic power source. The collector terminal of the switching Tr 32b is connected to the positive power supply (+ Vcc) of the control logic power supply 80 via the load resistor 31, and the secondary output of the photocoupler 32 is used as a first monitoring signal for detecting a failure. The first monitoring signal is input to the control circuit unit 90.

[Second failure detection circuit]
The configuration of the second failure detection circuit 50 is the same as that of the first failure detection circuit 30, and includes a photocoupler 52, a reverse voltage prevention diode 54, a current limiting resistor 53, and a load resistor 51. The anode terminal of the photodiode 52 a on the primary side of the photocoupler 52 is connected to the positive power supply (+ Vp) of the inverter drive power supply 70. The cathode terminal of the photodiode 52 a is connected to the anode terminal of the reverse voltage prevention diode 54 through the current limiting resistor 53. The cathode terminal of the reverse voltage prevention diode 54 is connected to the cathode terminals of the rectifier diodes 12, 14, and 16 constituting the rectifier circuit 22 and the relay 17. The emitter terminal of the secondary switching Tr 52 b of the photocoupler 52 is connected to the negative power supply (SG) of the control logic power supply 80. The collector terminal of the switching Tr 52b is connected to the positive power supply (+ Vcc) of the control logic power supply 80 via the load resistor 51, and the secondary output of the photocoupler 52 is used as a second monitoring signal for detecting a failure. The second monitoring signal is input to the control circuit unit 90.

  The control circuit unit 90 receives the first monitoring signal and the second monitoring signal and outputs a control signal for controlling ON / OFF of the relay 17 and the failure detection switch 40. The control circuit unit 90 controls ON / OFF of the relay 17 and the failure detection switch 40, the first monitoring signal output from the first failure detection circuit 30, and the second monitoring output from the second failure detection circuit 52. By monitoring the signal, failure detection of the dynamic brake circuit 23 and the inverter circuit 21 is performed. Next, a failure detection method of the functional configuration example of FIG. 1 will be described.

(Failure detection method)
When the motor control device 100 detects a failure, the drive power converter 2 is not supplied with power from the three-phase AC power supply 1, and the control power converter 28 needs to be supplied with the three-phase AC power supply 1. This state can be set, for example, by turning on ELB 81 and turning off MC 82. Hereinafter, the steps of the operation flow of FIG. 2 will be described.

[Voltage confirmation process]
In the voltage confirmation process (step S10), the motor control device 100 confirms whether the inverter drive power supply 70 and the control logic power supply 80 are generating a predetermined voltage by a voltage detection unit (not shown). The voltage detection result of the voltage detection means may be input to the control circuit unit 90, for example, to determine whether it is acceptable or not, and displayed on, for example, an LED, and the operator may be left to determine whether or not to proceed to the subsequent confirmation process. .

[Initial condition confirmation process]
In the initial state confirmation process (step S90), the control circuit unit 90 turns off all the switching elements 5 to 10 constituting the inverter unit 21 and turns off the relay 17 and the failure detection switch 40. This failure detection mode is a mode for confirming the initial state, and is called, for example, OP0. FIG. 3 shows the state of the relay 17, the failure detection switch 40 and each switching element in OP <b> 0 and OP <b> 1 to 14 described later, and the states of the first and second monitoring signals in the normal state. In FIG. 3, “x” means OFF of the relay 17, the failure detection switch 40 and each switching element, and “◯” means ON.

  In OP0, the relay 17, the failure detection switch 40, and each switching element are set to the OFF state. If there is no short circuit failure in the inverter unit 21 and the dynamic brake circuit 23, no current flows through the first failure detection circuit 30 and the second failure detection circuit 50. Therefore, the first monitoring signal is Hi (+ Vcc), and the second monitoring signal is Hi (+ Vcc). The control circuit unit 90 confirms that the initial state of the motor control device 100, that is, the subsequent steps can be performed when the first and second monitoring signals are both Hi when set to OP0 (step S90).

[Motor connection confirmation process]
In the motor connection confirmation process (step S91), the subsequent process is branched depending on the presence or absence of the motor 20, so the connection of the motor 20 is confirmed. This is because, when the motor 20 is connected, there is a failure detection mode that cannot be detected as will be described later because a current flows through the winding of the motor 20.

  Whether or not the motor 20 is connected to the motor control device 100 is confirmed by passing a current through each winding (between U-V, U-W, and V-W). FIG. 13 shows a failure detection mode in the motor connection confirmation process. By setting the failure detection mode to OP31, the switching elements 5 (U-phase upper arm) and 8 (V-phase lower arm) are turned on. When the motor 20 is connected, when the switching elements 5 (U-phase upper arm) and 8 (V-phase lower arm) are turned ON, the first failure detection circuit 30 is supplied from the positive power supply (+ Vp) of the inverter drive power supply 70. Current to the negative power source of the inverter drive power source 70 via the primary side of the inverter, the switching element 5 (U-phase upper arm), the U winding and V winding of the motor 20, and the switching element 8 (V-phase lower arm). Flows, and the first monitoring signal becomes Lo. When the motor 20 is not connected, no current flows, so the first monitoring signal becomes Hi.

  Since OP32 turns ON switching element 6 (U-phase lower arm) and switching element 7 (V-phase upper arm), the direction of current flowing through the U winding and V winding when motor 20 is connected Is in the opposite direction.

  In the same way, OP33 and OP34 confirm the U winding and W winding, and OP35 and OP36 confirm the V winding and W winding. In this way, it is possible to confirm the presence or absence of the motor 20 by passing a current through each winding of the motor 20. The presence / absence of the motor 20 can be given in advance to the control circuit unit 90 as a signal from the outside, for example. If an abnormality is detected in OP31 to OP36, there is an abnormality in the winding of the motor 20, so it is confirmed whether or not the motor winding is normal in this failure detection mode (OP31 to 36). You can also.

  When the motor 20 is connected, OP3-14 of the rectifier circuit conduction confirmation process (step S93) cannot be performed because of the current flowing through the motor 20. In this case, as shown in FIG. 2, after the motor connection confirmation process (step S91), the process proceeds to “ant”, and the relay operation confirmation process (step S92 ′) and the switching element conduction confirmation process (step S94 ′) are performed. Here, “′” is for distinguishing from the case where the motor 20 is “no”, and the operations of Step S92 ′ and Step S92, and Step S94 ′ and Step S94 are exactly the same. Therefore, it is omitted in the following description. When the motor 20 is not connected, as shown in FIG. 2, after the motor connection confirmation process (step S91), it progresses to "No".

  Even when the motor 20 is connected, a contactor (not shown) (see 25 in FIG. 15) is provided between the motor control device 100 and the motor 20, and the motor 20 is connected to the motor control device before failure detection starts. The process without the motor may be performed by separating from 100. Further, instead of disconnecting the motor 20 before detecting the failure, when the motor connection is confirmed in the motor connection confirmation process (step S91), the motor 20 is automatically disconnected, and the failure detection flow is executed to execute the process without the motor. May be.

[Relay operation confirmation process]
In the relay operation confirmation process (step S92), the operations of the relay 17 and the braking resistor 18 are confirmed. First, the failure detection mode is set to OP1. OP1 is a state in which only the failure detection switch 40 is turned on. FIG. 4 shows the operation of the motor control device 100 in the state of OP1. The fact that the failure detection switch 40 is ON is expressed by painting the contact piece black.

  In OP1, if the relay 17 is normally OFF, no current flows through the second failure detection circuit 50. Therefore, the second monitoring signal is Hi. That is, it can be confirmed that the relay 17 is OFF. The first failure detection circuit 30 remains Hi regardless of whether the relay 17 is OFF. The control circuit unit 90 confirms that the relay 17 is turned off when the second monitoring signal in OP1 is Hi.

  When the relay 17 is turned ON at OP2, since the negative power source of the inverter driving power source 70 is at a common potential with the power ground (PG) of the converter 2 for driving power source, the photo power is supplied from the positive power source (+ Vp) of the inverter driving power source 70. A current flows to the negative power source of the inverter drive power source 70 via the diode 52a, the current limiting resistor 53, the reverse voltage prevention diode 54, the relay 17, the braking resistor 18, and the failure detection switch 40. When a current flows to the primary side of the photocoupler 52, a current flows to the load resistor 51 on the secondary side of the photocoupler 52, so the second monitoring signal becomes Lo. The control circuit unit 90 confirms the ON state of the relay 17 and the conduction of the braking resistor 18 by OP2.

  As described above, the photocoupler 52 of the second failure detection circuit 50 according to the embodiment efficiently converts a small current change on the primary side into a large voltage change of the second monitoring signal. The primary current is sufficient on the order of several mA necessary for the photodiode 52a to emit light. In addition, the second failure detection circuit 50 realizes signal transmission between the inverter drive power supply 70 and the control logic power supply 80 that are insulated from each other with a simple configuration. This effect is the same in the first failure detection circuit 30.

[Rectification circuit continuity confirmation process]
In the rectifier circuit conduction confirmation process (step S93), the conduction of the rectifier diodes 11 to 16 constituting the rectifier circuit 22 is individually confirmed (step S93). The control circuit unit 90 sets the failure detection mode to OP3. OP3 turns on the switching element 5 (U-phase upper arm), the relay 17, and the failure detection switch 40. FIG. 5 shows a current path in the state of OP3. The ON state of the switching element 5 (U-phase upper arm) is indicated by enclosing the switching element 5 with a circle.

  In OP3, a current flows through the first failure detection circuit 30. The current from the positive power supply (+ Vp) of the inverter drive power supply 70, the photodiode 32a of the photocoupler 32, the current limiting resistor 33, the reverse voltage prevention diode 34, the switching element 5 (U-phase upper arm), the rectifier diode 16, The current flows through the relay 17, the braking resistor 18, and the failure detection switch 40 to the power ground (PG) that is the negative power source of the drive power source converter 2. As a result, the first monitoring signal becomes Lo. The current path is represented by a thick broken line in FIG. In OP3, a current also flows through the second failure detection circuit 50. The path is from the positive power supply (+ Vp) of the inverter drive power supply 70 to the photodiode 52a of the photocoupler 52, the current limiting resistor 53, the reverse voltage prevention diode 54, the relay 17, the braking resistor 18, and the failure detection switch 40. The power ground (PG) that is the negative power source of the drive power converter 2 is routed through. Therefore, the second monitoring signal is also Lo. The control circuit unit 90 confirms that the first monitoring signal at OP3 is Lo, so that the rectifier diode 16 is in a conductive state and no open failure has occurred. When the first monitoring signal remains Hi, there is a possibility that the switching element 5 may have an open failure in addition to the open failure of the rectifier diode 16. Since it can be determined in step S94), if the switching element 5 is normal in the switching element conduction confirmation process, it is determined that the rectifier diode 16 is faulty.

  Since only the failure detection mode of OP3 cannot detect the case where the rectifier diode 16 is short-circuited, it is confirmed at OP9 that the rectifier diode 16 is not short-circuited. FIG. 6 shows the operation when the rectifier diode 16 is short-circuited.

  Since OP9 turns on only the switching element 6 (U-phase lower arm), if the rectifier diode 16 is normal, its reverse current is about several μA. However, if the rectifier diode 16 has a short-circuit failure due to some abnormality (including an event in which the reverse current increases), from the positive power supply (+ Vp) of the inverter drive power supply 70 to which the second failure detection circuit 50 is connected, the photo A current flows to the power ground (PG) through the diode 52b, the current limiting resistor 53, the reverse voltage prevention diode 54, the short-circuited position of the rectifier diode 16, and the switching element 6 (U-phase lower arm). As a result, the second monitoring signal becomes Lo. The control circuit unit 90 detects that the rectifier diode 16 is short-circuited when the second monitoring signal is Lo in OP9.

  In this way, it is possible to confirm whether or not the rectifier diode 16 is operating normally by the combination of OP3 and OP9 in the failure detection mode. Similarly, the operation state of the rectifier diode 14 can be confirmed by OP4 and OP10, and the rectifier diode 12 can be confirmed by OP5 and OP11. As shown in FIG. 3, the relay 17 and the failure detection switch 40 of OP3 to OP5 are both in the ON state, and the position of the switching element in which the upper arm is turned ON depends on the position of the rectifier diode to be checked, and U and V And W are different. The corresponding relays OP9 to OP11 and the failure detection switch 40 are both OFF and common, and the positions of the switching elements that turn on the lower arm are different. In this way, the idea is the same except that the position of the switching element to be turned on is different. Therefore, the description showing the current paths of OP3, OP4, and OP5, and OP9, OP10, and OP11 is omitted.

As for the rectifier diodes 11, 13, and 15, it is confirmed that each rectifier diode is in a conductive state at OP6 to OP8, and it is confirmed at OP12 to OP14 that each rectifier diode is not short-circuited.
In OP6, the relay 17 and the switching element 6 (U-phase lower arm) are turned on.

  FIG. 7 shows a current path in the state of OP6. In OP6, from the positive power supply (+ Vp) of the inverter drive power supply 70 in the second failure detection circuit 50, the photodiode 52a, the current limiting resistor 53, the reverse voltage prevention diode 54, the relay 17, the braking resistor 18, the rectifier diode 15, A current flows to the negative power supply of the inverter drive power supply 70 via the switching element 6 (U-phase lower arm). If the rectifier diode 15 is operating normally, only the second monitoring signal becomes Lo. When the second monitoring signal becomes abnormal, there is a possibility that the switching element 6 may have an open failure in addition to the open failure of the rectifier diode 15. Since it can be determined in step S94), if the switching element 6 is normal in the switching element conduction confirmation process, it is determined that the rectifier diode 15 has failed.

  In OP12, a short circuit failure of the rectifier diode 15 is detected. FIG. 8 shows a current path in a state of OP12 when the rectifier diode 15 is short-circuited. In OP12, the failure detection switch 40 and the switching element 5 (U-phase upper arm) are turned ON. As a result, from the positive power supply (+ Vp) of the inverter drive power supply 70, the primary side of the first failure detection circuit 30, the switching element 5 (U-phase upper arm), the short-circuited position of the rectifier diode 15, the failure detection switch 40 , Current flows through. As a result, if the rectifier diode 15 is short-circuited, only the first monitoring signal becomes Lo. The state of the rectifier diode 13 is confirmed in OP7 and OP13, and the state of the rectifier diode 11 is confirmed in OP8 and OP14. These operations are the same except that the positions of the switching elements to be turned on are different.

[Switching element conduction confirmation process]
In the switching element operation confirmation process (step S94), it is confirmed whether the operation of the switching elements constituting the inverter unit 21 is normal. FIG. 9 shows the ON / OFF state of each switching element in the failure detection mode of the switching element conduction confirmation process (step S94). Since OP21 to 23 are the same operations as OP6 to 8 in the rectifier circuit conduction confirmation process (step S93), they can be omitted.

  First, the operation confirmation of the switching elements 5 and 6 will be described. In principle, the confirmation process proceeds in the order of the numbers of OP. Hereinafter, OP15, 18, and 21 for confirming the operation of the switching elements 5 and 6 will be described. In OP15, only the switching element 5 (U-phase upper arm) is turned on. In this case, since no current flows anywhere, the first monitoring signal is Hi and the second monitoring signal is Hi. Thereby, it is confirmed that the switching element 6 (U-phase lower arm) is turned off. In OP18, since the switching element 6 (U-phase lower arm) paired with the switching element 5 (U-phase upper arm) is turned on, the positive failure power of the inverter drive power supply (+ Vp) is applied to the first failure detection circuit 30. A current flows to the negative power source of the inverter drive power source via the primary side, the switching element 5 (U-phase upper arm), and the switching element 6 (U-phase lower arm). Therefore, it is confirmed that the switching element 5 (U-phase upper arm) is turned on when the first monitoring signal becomes Lo. FIG. 10 shows the operation in the failure detection mode OP18.

  In the failure detection mode OP21, the switching element 5 (U-phase upper arm) is turned off and the relay 17 is turned on while the switching element 6 (U-phase lower arm) is turned on. FIG. 11 shows a current path in the state of OP21. In OP21, from the positive power supply (+ Vp) of the inverter drive power supply 7 in the second failure detection circuit 50, via the relay 17, the rectifier diode 15 (U-phase upper arm), and the switching element 6 (U-phase lower arm). Thus, a current flows through the negative power supply of the inverter drive power supply 7. Further, since the switching element 5 (U-phase upper arm) is OFF, no current flows through the first failure detection circuit 30. As a result, the second monitoring signal is Lo and the first monitoring signal is Hi, and the ON state of the switching element 6 and the OFF state of the switching element 5 can be confirmed.

  Thus, the operation of the switching elements 5 (U-phase upper arm) and 6 (U-phase lower arm) constituting the U-phase upper arm and lower arm can be confirmed by the combination of OP15, OP18 and OP21. . Based on the same idea, the operation of the switching elements 7 (V-phase upper arm) and 8 (V-phase lower arm) can be confirmed by a combination of OP16, OP19 and OP22. Similarly, the operation of the switching elements 9 (W-phase upper arm) and 10 (W-phase lower arm) can be confirmed by a combination of OP17, OP20 and OP23.

  FIG. 12 shows a simple method for detecting an open failure of the switching elements (5 to 10) of the inverter unit 21. OP18 is a failure detection mode in which switching elements 5 (U-phase upper arm) and 6 (U-phase lower arm) are turned on. OP19 is a failure detection mode in which the switching elements 7 (V-phase upper arm) and 8 (V-phase lower arm) are turned on. OP20 is a failure detection mode in which switching elements 9 (W-phase upper arm) and 10 (W-phase lower arm) are turned on. When OP18 is normal, the first monitoring signal is Lo and the second monitoring signal is Hi.

  When the switching element 5 (U-phase upper arm) or the switching element 6 (U-phase lower arm) has an open failure, OP18 becomes abnormal. Next, the switching element 5 (U-phase upper arm) is turned OFF at OP21. If the failure mode is normal, the switching element 6 (U-phase lower arm) is normal, and in this case, the switching element 5 (U-phase upper arm) is faulty. When OP21 is also abnormal, it is a failure of the switching element 6 (U-phase lower arm). The operations in OP19 and 22 for detecting a failure of the switching elements 7 and 8 and OP20 and 23 for detecting a failure of the switching elements 9 and 10 are the same in concept, except that the switching elements to be turned off are different.

  In the case where the motor 20 is connected (step S94 ′), when it is determined that all are normal in the confirmation of OP15 to OP17, the switching elements 6, 8, and 10 are determined to be normal. If any one of the switching elements 6, 8, and 10 has a short circuit failure, the results of OP15 to 17 are all abnormal, and it is determined that any one has a short circuit failure. In OP18-20, the open failure of the switching element 5 or 6, the open failure of the switching element 7 or 8, and the open failure of the switching element 9 or 10 are detected. Then, when it is determined that all of them are normal in the confirmation of OP21 to 23, from the result of the first monitoring signal, there is no short circuit failure of the switching elements 5, 7, 9 and from the result of the second monitoring signal, the switching element 6, It is confirmed that there are no 8, 10 open failures.

  As described above, according to the motor control device 100 of the present invention, the state of each element of the dynamic brake circuit 23 and the inverter unit 21 can be easily confirmed, and the presence or absence of the connection of the motor 20 is also easily detected. I can do it.

  In the configuration of the first failure detection circuit 34 described above, there are cases where it takes time to set the failure detection mode depending on the state of charge of the smoothing capacitor 3. That is, failure detection cannot be performed unless the smoothing capacitor 3 can be charged with the positive voltage (+ Vp) of the inverter drive power supply 70. Accordingly, FIG. 14 shows a first failure detection circuit 30 'that can shorten the charging time.

  The first failure detection circuit 30 ′ includes a current limiting resistor 33 and a smoothing capacitor charging resistor 35 connected in parallel to the photocoupler 32. By making the resistance value of the smoothing capacitor charging resistor 35 smaller than that of the current limiting resistor, the charging time of the smoothing capacitor 3 can be shortened.

  In addition, the motor control apparatus 100 shown in FIG. 1 is not limited to the structural example. For example, the arrangement relationship between the current limiting resistors 33 and 53 and the reverse voltage prevention diode in the first and second failure detection circuits 30 and 50 is not limited to the configuration shown in FIG.

  In the above description, the number representing the failure mode has no special meaning. The order is also an example, and it is possible to freely change the order of these failure detection modes and set the failure detection process in an arbitrary combination. Further, the ON / OFF combinations of the switching elements may be used in the same way, and other combinations may be used.

Claims (5)

A rectifier circuit that rectifies the induced voltage of the motor, a dynamic brake circuit including a relay and a braking resistor connected in series between output terminals of the rectifier circuit, and an inverter unit that generates a motor drive signal from the converter for the drive power source; In the motor control device comprising the inverter unit, and an inverter control unit that controls the inverter drive power source as a power source,
A first failure detection circuit connected between a positive power source of the converter for driving power source and a positive power source of the inverter driving power source and outputting a first monitoring signal;
A failure detection switch connected to one terminal of the rectifier circuit and the negative power source of the converter for driving power source;
A second failure detection circuit connected between the other terminal of the rectifier circuit and a positive power source of the inverter driving power source and outputting a second monitoring signal;
Controls the operation of the inverter control unit using a control logic power supply as a power supply, outputs a control signal for controlling ON / OFF of the relay and the failure detection switch, and inputs the first monitoring signal and the second monitoring signal. A control circuit unit, and
A motor control device comprising: In the motor control device according to claim 1,
The first failure detection circuit includes:
A photocoupler, a reverse voltage prevention diode connected in series to the primary side of the photocoupler, a current limiting resistor, and a load resistor connected to the secondary side of the photocoupler. The reverse voltage prevention diode and the primary side of the photocoupler are connected in series between a positive power supply and the positive power supply of the inverter drive power supply, and one end of the secondary side of the photocoupler is connected to the positive side of the logic control power supply. A motor control device, characterized in that the load resistor connected to a power source is connected, and the other end of the load resistor is used as an output end of the first monitoring signal. In the motor control device according to claim 1 or 2,
The second failure detection circuit is
A photocoupler, a reverse voltage prevention diode connected in series to the primary side of the photocoupler, a current limiting resistor, and a load resistor connected to the secondary side of the photocoupler, the primary of the photocoupler One side is connected in series between a positive power source of the inverter drive power source and a terminal of the rectifier circuit to which the failure detection switch is connected, and one end is connected to the positive side of the control logic power source on the secondary side of the photocoupler. A motor control device, characterized in that the load resistor connected to the terminal is connected, and the other end of the load resistor is used as the output end of the second monitoring signal. In the motor control device according to any one of claims 1 to 3,
The first failure detection circuit includes:
A photocoupler, a reverse voltage prevention diode connected in series to the primary side of the photocoupler, a current limiting resistor, and a load resistor connected to the secondary side of the photocoupler;
And a smoothing capacitor charging resistor having a resistance value smaller than that of the current limiting resistor connected in parallel to the current limiting resistor. A failure detection method for a motor control device according to any one of claims 1 to 4,
A relay operation confirmation process for confirming the operation of the relay in the dynamic brake circuit;
A rectifier circuit conduction confirmation process for confirming the operation of the diode constituting the rectifier circuit;
A switching element conduction confirmation process for confirming the operation of the switching element included in the inverter unit;
A method for detecting a failure of a motor control device including:

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