Motor drive device

Abstract

In one embodiment, this motor drive device comprises a cover member that covers a high-voltage unit, and a fixing mechanism that fixes the cover member in a closed state. This motor drive device comprises: a mechanism drive circuit for driving the fixing mechanism; and a state acquisition unit that acquires information relating to the operating state of an electric motor. This motor drive device comprises a circuit control unit that controls the mechanism drive circuit. The mechanism drive circuit includes a switch member that conducts or cuts off electricity from a control power supply. The circuit control unit controls the operation of the switch member on the basis of the information relating to the operating state.

Description

Motor drive device

[0007]

[0001] The present disclosure relates to a motor drive device.

[0002] In machines such as machine tools and robots, an electric motor for driving a constituent member and an amplifier for supplying electricity to the electric motor are arranged. There are various types of amplifiers. For example, an amplifier that performs frequency conversion of three-phase alternating current of a power source and supplies electricity to an electric motor is known. In this amplifier, it is known that direct current electricity is generated from three-phase alternating current electricity by a rectifier, and the direct current electricity is converted into alternating current electricity having a desired frequency and amplitude by an inverter.

[0003] A circuit portion through which direct current electricity flows between the rectifier and the inverter is referred to as a DC link portion. A capacitor having a large capacitance is connected to the positive side circuit and the negative side circuit of the DC link portion. The capacitor has a function of suppressing fluctuations in the voltage of the DC link portion.

[0004] Since the DC link portion has a high voltage, it is not preferable for an operator to come into contact with the DC link portion. In the prior art, a protective cover for covering an electrical component is arranged on the electrical component connected to the DC link portion of the amplifier. And a warning light or the like indicating that the voltage of the DC link portion is high can be arranged on the surface of the amplifier. For example, the warning light can be lit until the voltage drops to a safe voltage even if an operator touches it. Or the high voltage can be displayed in characters on the surface of the amplifier.

[0005] Japanese Patent Laid-Open No. 6-98403, Japanese Patent Laid-Open No. 6-83130, Japanese Patent Laid-Open No. 2010-68696

[0006] Even if the amplifier has a function of displaying the voltage of the DC link portion, if the display such as a warning light is overlooked, there is a possibility that an operator may open the protective cover and touch the electrical component connected to the DC link portion.

[0007] Furthermore, because the capacitors in the amplifier's DC link section have a large capacitance, it takes time for them to discharge after the amplifier's AC power supply is cut off. For example, when the amplifier is stopped, the DC link section may maintain a high voltage for several minutes to several tens of minutes. However, when the amplifier is stopped, the function that displays the voltage of the DC link section may stop working. This leaves open the possibility that an operator might open the protective cover and touch the electrical components connected to the DC link section.

[0008] The motor drive device of this disclosure includes a cover member that covers a high-voltage section and a fixing mechanism that fixes the cover member in a closed state. The motor drive device includes a mechanism drive circuit for driving the fixing mechanism and a state acquisition unit that acquires information regarding the operating state of the motor. The motor drive device includes a circuit control unit that controls the mechanism drive circuit. The mechanism drive circuit includes a switch member that conducts or interrupts electricity from a control power supply. The circuit control unit controls the operation of the switch member based on information regarding the operating state.

[0009] Other motor drive devices of this disclosure include a cover member that covers a high-voltage section and a first fixing mechanism that fixes the cover member in a closed state. The motor drive device includes a first mechanism drive circuit for driving the first fixing mechanism. The high-voltage section is the DC link section of an amplifier that supplies electricity to drive the motor, or a member connected to the DC link section. The first mechanism drive circuit is supplied with electricity from the DC link section.

[0010] This is a block diagram of the machine in the embodiment. This is the motor drive circuit built into the amplifier in the embodiment. This is a front view of the amplifier in the embodiment. This is a side view of the amplifier in the embodiment. This is the mechanism drive circuit in the first embodiment. This is the mechanism drive circuit in the second embodiment. This is the mechanism drive circuit in the third embodiment. This is one of the mechanism drive circuits in the fourth embodiment. This is a side view of the other amplifier in the fifth embodiment.

[0011] (First Embodiment) Referring to Figures 1 to 5, a motor drive device and a machine equipped with a motor drive device in the first embodiment will be described. The machine in this embodiment is a machine that performs any task, such as a robot or a machine tool.

[0012] The machine 7 comprises a machine body 1 and a machine control device 2 that controls the machine body 1. The machine body 1 includes an electric motor 11 that drives its components. For example, if the machine is a multi-joint robot, the electric motor 11 rotates an arm or the like.

[0013] Furthermore, the machine body 1 is equipped with a state detector 12 for detecting the operating state of the electric motor 11. Examples of sensors that can be used as the state detector 12 include an encoder for detecting the rotational speed of the electric motor 11, a temperature sensor for detecting the temperature of the electric motor 11, a torque sensor for detecting the torque output by the electric motor 11, a current sensor for detecting the current value supplied to the electric motor, and a vibration sensor for detecting vibrations of the electric motor.

[0014] In this embodiment, the machine control device 2 functions as a motor drive device. The machine 7 in this embodiment is numerically controlled. The machine control device 2 includes an arithmetic processing unit 28 (computer) having a CPU (Central Processing Unit) as a processor. The arithmetic processing unit 28 has RAM (Random Access Memory) and ROM (Read Only Memory), etc., connected to the CPU via a bus. Note that the processor of the arithmetic processing unit is not limited to a CPU, but may also be an FPGA (field-programmable gate array) and ASIC (application-specific integrated circuit), etc.

[0015] The arithmetic processing unit 28 includes a storage unit 21 that stores information related to the machine 7. The storage unit 21 can be made of a non-temporary storage medium capable of storing information. For example, the storage unit 21 can be made of a storage medium such as a volatile memory, a non-volatile memory, a magnetic storage medium, or an optical storage medium.

[0016] The arithmetic processing unit 28 receives an operation program 38 that has been prepared in advance to perform the operation of the machine body 1. Alternatively, the machine control device 2 may generate the operation program 38. The operation program 38 is stored in the storage unit 21.

[0017] The arithmetic processing unit 28 includes an operation control unit 22 that controls the operation of the machine body 1. Based on the operation program 38, the operation control unit 22 sends operation commands to the amplifier 3 to drive the electric motor 11.

[0018] The machine control device 2 includes an amplifier 3 that supplies electricity to the electric motor 11. In this embodiment, the amplifier 3 is a servo amplifier that controls the electric motor 11 based on its rotational position. The amplifier 3 includes an electric motor drive circuit 31 for driving the electric motor 11. The electric motor drive circuit 31 is built into the main body 61 of the amplifier 3. The electric motor drive circuit 31 includes an electrical circuit that supplies electricity to the electric motor 11. The electric motor drive circuit 31 supplies electricity to the electric motor 11 based on operation commands from the operation control unit 22.

[0019] The amplifier 3 includes a fixing mechanism that secures a cover member covering the high-voltage section of the amplifier 3 in a closed state. The amplifier 3 includes a mechanism drive circuit 32 for driving the fixing mechanism. The mechanism drive circuit 32 includes a switch member 33 that conducts or interrupts electricity from the power supply section. The mechanism drive circuit 32 supplies electricity to the fixing mechanism based on operation commands from the operation control unit 22.

[0020] The operation control unit 22 corresponds to a processor that operates according to the operation program 38. The operation control unit 22 is configured to be able to read information stored in the storage unit 21. The processor reads the operation program 38 and functions as the operation control unit 22 by executing the control defined in the operation program 38.

[0021] The arithmetic processing unit 28 includes a monitoring unit 24 that monitors the operating state of the electric motor 11 and controls the mechanism drive circuit 32. The monitoring unit 24 includes a state acquisition unit 25 that acquires information regarding the operating state of the electric motor 11. The state acquisition unit 25 acquires information regarding the operating state of the machine body 1, for example, from a state detector 12 located on the machine body 1. The monitoring unit 24 includes a circuit control unit 26 that controls the mechanism drive circuit 32 based on the information regarding the operating state. The monitoring unit 24, the state acquisition unit 25, and the circuit control unit 26 correspond to processors that operate according to a predetermined program. The processor functions as each unit by reading the program and executing the control defined in the program.

[0022] The arithmetic processing unit 28 includes an input unit 37 for inputting information about the machine 7. The input unit 37 is composed of input components such as a keyboard and a dial. The arithmetic processing unit 28 also includes a display unit 36 ​​for displaying information about the machine 7. The display unit 36 ​​can be composed of any display panel, such as a liquid crystal display panel or an organic EL (Electro-Luminescence) display panel.

[0023] Figure 2 shows the motor drive circuit of the amplifier in this embodiment. The motor drive circuit 31 in this embodiment has the function of changing the frequency and amplitude of the AC power supply 40 in response to an operation command from the operation control unit 22. The AC power supply 40 is a high-voltage power supply that supplies power to the motor drive circuit. The motor drive circuit 31 includes a rectifier 41, an inverter 42, and a DC link unit 43. The rectifier 41 converts the AC current from the AC power supply 40 into a DC current. Examples of rectifiers 41 include diode rectifiers and PWM (Pulse Width Modulation) switching control type rectifiers. The inverter 42 converts the DC current from the rectifier 41 into an AC current having a desired frequency and amplitude based on the operation command.

[0024] The inverter 42 includes a main circuit that generates a three-phase alternating current from a direct current. The main circuit is a bridge circuit that includes a plurality of power elements 51. In this embodiment, a three-phase alternating current is generated and supplied to the motor 11. The main circuit in this embodiment includes six power elements 51. The power elements 51 can include power semiconductor devices such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), or IPMs (Intelligent Power Modules).

[0025] The motor drive circuit 31 includes a processor 56 that sends operation commands to each power element 51 of the inverter 42's main circuit. Any processor can be used as the processor 56 that controls the main circuit, such as an MCU (Micro Controller Unit), LSI (Large Scale Integration), or CPU (Central Processing Unit). Based on the operation commands from the operation control unit 22, the processor 56 sends pulse width modulation control switching commands to the main circuit. That is, the processor 56 sends commands to drive each power element 51.

[0026] The electrical circuit portion between the rectifier 41 and the inverter 42 is called the DC link section 43. The DC link section 43 is the circuit portion that electrically connects the DC output side of the rectifier 41 and the DC input side of the inverter 42. One or more capacitors 52 are arranged in the DC link section 43. The capacitors 52 are connected to a positive potential circuit and a negative potential circuit. The capacitors 52 have the function of suppressing oscillations in the DC current output from the rectifier 41. Alternatively, they can prevent the motor 11 from failing due to a sudden drop in the voltage supplied to the motor 11 during a power outage, etc. Electrolytic capacitors or film capacitors can be used as the capacitors 52.

[0027] The DC link section 43 experiences a high voltage during the operation of the motor 11. For example, the DC link section has a voltage of 350V to 750V. When the motor 11 stops, the supply of DC current from the rectifier 41 is stopped. However, because the capacitance of the capacitor 52 is large, it takes time for the capacitor 52 to discharge. It takes time for the voltage of the DC link section 43 to decrease. The high-voltage section is a part that has a potential that cannot be touched by an operator. In this embodiment, the high-voltage section is the DC link section or a component connected to the DC link section. In particular, the high-voltage section corresponds to a component with the same potential as the DC link section.

[0028] Figure 3 shows a front view of the amplifier in this embodiment. Figure 4 shows a side view of the amplifier in this embodiment. Referring to Figures 3 and 4, the amplifier 3 includes a main body 61 and a cover member 62 as a covering member. The main body 61 in this embodiment has a rectifier 41, a DC link unit 43, and an inverter 42, etc., arranged inside. In this example, a connecting member 53 electrically connected to the DC link unit 43 is arranged on the front of the main body 61. The connecting member 53 includes terminals 53a and 53b that are at the same potential as the DC link unit 43. Terminal 53a is, for example, the positive terminal, and terminal 53b is, for example, the negative terminal.

[0029] Terminals 53a and 53b maintain a high voltage while supplying electricity to the motor 11. In this embodiment, the connecting member 53, including terminals 53a and 53b, corresponds to the high-voltage section. The cover member 62 functions as a cover member that covers the high-voltage section to prevent workers from touching it. In this embodiment, the cover member 62 is formed to rotate as shown by arrow 97. By rotating the cover member 62, the connecting member 53 is exposed, allowing workers to perform work on the connecting member 53.

[0030] In this embodiment, a locking portion 62a is formed to secure the cover member 62 with a small force when the cover member 62 is closed. The locking portion 62a is formed to catch on, for example, a projection formed on the main body portion 61. The locking portion 62a is designed so that it can be released with a small force from the operator.

[0031] The amplifier 3 of this embodiment is equipped with a fixing mechanism that secures the cover member 62 in a closed state so that it cannot be opened by an operator. The fixing mechanism includes an electromagnet 55 and an opposing member 54 made of a magnetic material. The opposing member 54 can be made of an iron plate or a magnet. In this embodiment, the electromagnet 55 is fixed to the main body 61. The opposing member 54 is fixed to the cover member 62. The electromagnet 55 and the opposing member 54 are positioned to be close to each other and facing each other when the cover member 62 is closed. Alternatively, the electromagnet and the opposing member may be positioned to be in contact with each other when the cover member is closed.

[0032] When current flows through the coil 81 of the electromagnet 55, the opposing member 54 is attracted to the electromagnet 55, and the cover member 62 is fixed in the closed position. Note that one of the electromagnet 55 and the opposing member 54 can be located in the main body of the amplifier, and the other can be located in the cover member. For this reason, the electromagnet may be located in the cover member and the opposing member may be located in the main body of the amplifier.

[0033] Figure 5 shows the mechanism drive circuit in this embodiment. The mechanism drive circuit 71 corresponds to the mechanism drive circuit 32 in Figure 1. The mechanism drive circuit 71 is supplied with electricity from the control power supply 68. The control power supply 68 is a DC power supply for driving the control device included in the machine control device 2. The control power supply is a low-voltage power supply. For example, a DC power supply of 50V or less, such as 12V, 24V, or 48V, is used as the control power supply 68.

[0034] The control power supply can be supplied, for example, from the AC power supply 40 via a rectifier different from the rectifier 41, as shown in Figure 2. Alternatively, the control power supply can include a storage battery and a charger for charging the storage battery. By using a storage battery as the control power supply, electricity can be supplied to the control device even if the external AC power supply is lost.

[0035] The electromagnet 55 of the stationary mechanism in this embodiment includes a coil 81 wound around an iron core. The mechanism drive circuit 71 also includes the coil 81. The mechanism drive circuit 71 supplies electricity to the coil 81 or cuts off the supply of electricity to the coil 81.

[0036] The mechanism drive circuit 71 includes a switch member 33 (see Figure 1) for supplying and cutting off electricity from the control power supply 68. In this embodiment, a normally open (a) contact relay 84 is provided as the switch member 33. The relay 84 is configured such that when electricity is supplied to it, the contacts come into contact and conduction is achieved. That is, when a specific signal is input, electricity is supplied from the control power supply 68 to the coil 81, and the cover member 62 is fixed in the closed state by the magnetic force of the electromagnet 55.

[0037] The switch member in this embodiment is a contact relay in which the electrodes are driven mechanically, but it is not limited to this form. The switch member may also be a contactless relay that includes semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors).

[0038] The mechanism drive circuit 71 of this embodiment includes a Zener diode 82. The Zener diode 82 is connected in parallel with the coil 81. The Zener diode 82 prevents a voltage higher than a predetermined voltage from being applied to the coil 81. Also, when the supply of electricity to the coil 81 stops and the voltage drops, a back electromotive force is generated in the coil 81. In this case, the Zener diode 82 is designed to allow electricity to flow and discharge.

[0039] The mechanism drive circuit 71 of this embodiment includes a thermistor 83 connected in series with the coil 81. The thermistor 83 has the characteristic that its resistance increases as the temperature rises. The thermistor 83 has the function of preventing too much current from flowing through the coil 81.

[0040] Referring to Figures 1 and 5, the status acquisition unit 25 of the monitoring unit 24 acquires information regarding the operating state of the electric motor 11. In this embodiment, the status acquisition unit 25 acquires information regarding the operation of the electric motor 11. For example, it acquires operating variables such as the temperature, current value, or rotational speed of the electric motor 11 from the status detector 12. The status acquisition unit 25 then determines that there is an abnormal operating state when the operating state variables of the electric motor 11 deviate from a predetermined determination range. The display unit 36 ​​can display an alarm.

[0041] Furthermore, the operating status of the electric motor 11 includes information about the operation of the amplifier 3. For example, the operation control unit 22 may not send the correct operation command, causing the amplifier 3 to operate in a way different from the desired operation. This includes a state in which the amplifier 3 is malfunctioning. For example, this could occur if the power supply to the processor acting as the operation control unit 22 fails, or if there is an abnormality in communication with another processor, resulting in the sending of an incorrect operation command to the amplifier 3. When the amplifier malfunctions, the DC link voltage may become higher than the normal voltage.

[0042] The circuit control unit 26 controls the mechanism drive circuit 71 based on information regarding the operation of the electric motor 11 acquired by the state acquisition unit 25. The circuit control unit 26 controls the mechanism drive circuit 71 when the operation information of the electric motor 11 deviates from a predetermined determination range. For example, the circuit control unit 26 controls the mechanism drive circuit 71 based on alarm information regarding the operation of the electric motor.

[0043] The circuit control unit 26 of the present embodiment controls the operation of the relay 84 as a switch member of the mechanism drive circuit 71. When alarm information regarding the operation of the electric motor 11 is transmitted, the circuit control unit 26 can energize the relay 84 to bring the movable contact and the fixed contact into contact. When electricity is supplied to the coil 81, due to the action of the electromagnet 55, the opposing member 54 of the cover member 62 is attracted to the electromagnet 55, and the operator can be fixed so as not to open the cover member 62. In this way, the circuit control unit 26 can control the relay 84 so that the cover member 62 is fixed by the fixing mechanism when the alarm information is transmitted.

[0044] The high-voltage part of the present embodiment is a member connected to the DC link part 43 of the motor drive circuit 31, but is not limited to this form. The fixing mechanism and the mechanism drive circuit of the present embodiment can be applied to a cover member that covers a member that becomes a high voltage to such an extent that it is prohibited for an operator to touch. For example, referring to FIG. 2, there are cases where terminals are arranged in a circuit to which three-phase alternating current is supplied to the electric motor 11. Since such terminals become high voltage, a cover member that covers the terminals can be arranged. And the fixing mechanism and the mechanism drive circuit in the present embodiment can be applied.

[0045] In the motor drive device according to the present embodiment, when the operating state of the electric motor reaches a predetermined state, the coil of the mechanism drive circuit is energized, the fixing mechanism is driven, and the cover member is fixed. For this reason, the operator cannot open the cover member. It is possible to prevent the operator from opening the cover member and contacting the high-voltage part. For example, when a high voltage is applied to the high-voltage part immediately after the electric motor has stopped normally, it is possible to prevent the operator from contacting the high-voltage part. Or, it is possible to detect that the amplifier is being driven and fix the cover member in a fixed state.

[0046] When the voltage applied to the high-voltage section becomes low, the circuit control unit 26 can change the state of the relay 84 from a state where the movable contact and the fixed contact are in contact to a separated state. That is, the supply of electricity to the coil 81 can be stopped. The operator can then open the cover member 62. For example, after the alarm is released, the contacts of the relay 84 can be separated after a predetermined period of time has elapsed. Alternatively, a voltage sensor for detecting the voltage of the DC link section can be arranged, and when the voltage of the DC link section becomes less than a predetermined determination value, the contacts of the relay 84 can be separated. For example, when the voltage of the DC link section 43 becomes less than the control voltage, the circuit control unit 26 can release the fixing of the cover member 62.

[0047] Although the fixing mechanism in the present embodiment is formed such that the opposing member is attracted by the electromagnet and the covering member is fixed, it is not limited to this form. Any concept in which the covering member is fixed by the action of the electromagnet can be adopted. For example, a locking member whose orientation changes by the electromagnet can be arranged. And a mechanical mechanism may be formed such that the orientation of the locking member changes due to the magnetic force of the electromagnet and the cover member is fixed.

[0048] The amplifier of the present embodiment is a servo amplifier that controls the rotational position of the electric motor, but is not limited to this form, and the present invention can be applied to any amplifier for driving an electric motor.

[0049] Although the monitoring unit of the present embodiment is arranged in the arithmetic processing device, it is not limited to this form. A processor and a storage unit that function as the monitoring unit may be arranged inside the amplifier.

[0050] (Second Embodiment) Referring to FIG. 6, the motor drive device in the second embodiment will be described. In the motor drive device of the present embodiment, the structure of the amplifier including the fixing mechanism and the covering member is the same as that of the motor drive device in the first embodiment (refer to FIGS. 3 and 4). That is, by the action of the electromagnet 55, the cover member 62 can be fixed or released.

[0051] Figure 6 shows the mechanism drive circuit in this embodiment. In this embodiment, the mechanism drive circuit 72 corresponds to the mechanism drive circuit 32 in Figure 1. Referring to Figures 2 and 6, the mechanism drive circuit 72 in this embodiment includes a coil 81, a Zener diode 82, and a thermistor 83, just as in the mechanism drive circuit 71 in the first embodiment (see Figure 5). In the mechanism drive circuit 72, the electricity stored in the DC link section 43 is used as the electricity to excite the coil 81. In other words, the power source for the mechanism drive circuit 72 is the DC link section 43.

[0052] In the mechanism drive circuit 72, a resistor 85 is placed in parallel with the coil 81. Additionally, a resistor 86 is placed in the electrical circuit that directs the potential of the DC link section 43 from the positive side circuit to the coil 81. The resistor 86 is connected in series with the coil 81. The DC voltage of the DC link section 43 is, for example, between 350V and 750V, which is a high voltage. Therefore, resistors 85 and 86 are placed to ensure that the voltage applied to the coil 81 is a predetermined low voltage.

[0053] The resistance value R1 of resistor 86 is set to be greater than the resistance value R0 of resistor 85. The resistance values ​​R0 and R1 are set so that a voltage below a predetermined voltage is applied to coil 81. For example, resistors 85 and 86 are configured so that a voltage of 50 volts or less is applied to coil 81.

[0054] When the electric motor 11 is being driven, the DC link section 43 is at a high voltage. Current flows through the coil 81, driving the electromagnet 55. Then, due to the action of the fixing mechanism, the cover member 62 is fixed in the closed position.

[0055] When the control unit 22 issues a command to stop the amplifier 3, the power supply from the rectifier 41 is cut off. Due to the action of the capacitor 52, the voltage in the DC link section 43 gradually drops from a high voltage state. For this reason, immediately after the amplifier 3 stops, the DC link section 43 is at a high voltage, causing a large current to flow through the coil 81. The cover member 62 is then fixed in the closed state by the fixing mechanism. This prevents the operator from opening the cover member 62 and coming into contact with the high-voltage section.

[0056] As the electricity stored in the capacitor 52 gradually discharges after the amplifier 3 is stopped, the voltage across the DC link section 43 gradually decreases. That is, the voltage supplied to the mechanism drive circuit 72 decreases. The current flowing through the coil 81 also decreases, and the magnetic force of the electromagnet 55 decreases. When the voltage across the DC link section 43 falls below a predetermined voltage, the operator can open the cover member 62. In other words, the fixing mechanism that secures the cover member 62 is effectively released.

[0057] In this embodiment, it is preferable that the electromagnet 55 and the opposing member 54 are formed so that the cover member 62 cannot be opened until the voltage of the DC link section 43 drops to a level that is safe for an operator to touch. For example, it is preferable that the cover member 62 can be kept fixed until the voltage of the DC link section 43 falls below the voltage of the control power supply. For example, the electromagnet 55 can be formed so that an operator can open the cover member 62 when the current value I obtained by dividing the voltage VDC of the DC link section 43 by the resistance value R1 is less than a predetermined current determination value Ith.

[0058] In the mechanism drive circuit 72 of this embodiment, the cover member 62 can be fixed in the closed position until the DC link section 43 reaches a voltage that is safe for an operator to touch. Furthermore, the cover member 62 can be fixed in the closed position while the motor is running. For example, this can occur when the motor 11 stops normally, when the motor 11 makes an emergency stop due to the activation of an alarm, or when the power supply from the AC power source 40 is stopped. In such cases as well, the cover member 62 can be fixed in the closed position so that an operator cannot open the cover member 62 until the DC link section 43 reaches a voltage that is safe.

[0059] Furthermore, after the amplifier 3 stops, the electricity stored in the DC link section 43 is consumed by flowing through resistors 85 and 86. This allows the voltage of the DC link section 43 to be quickly reduced. Moreover, in the mechanism drive circuit 72 of this embodiment, a switch component such as a relay and a monitoring unit of the arithmetic processing unit are unnecessary, and the cover member can be fixed by utilizing the voltage characteristics of the DC link section.

[0060] Other configurations, operations, and effects are the same as those of the motor drive device in the first embodiment, so they will not be described again here.

[0061] (Third Embodiment) Referring to Figure 7, a motor drive device in a third embodiment will be described. In the motor drive device of this embodiment, the structure of the amplifier, including the fixing mechanism and the cover member, is the same as that of the motor drive device of the first embodiment (see Figures 3 and 4). That is, the cover member 62 can be fixed or released by the action of the electromagnet 55.

[0062] Figure 7 shows the mechanism drive circuit in this embodiment. In this embodiment, the mechanism drive circuit 73 corresponds to the mechanism drive circuit 32 in Figure 1. In the mechanism drive circuit 73, electricity is supplied from the DC link section 43, similar to the mechanism drive circuit 72 in the second embodiment. The mechanism drive circuit 73 in this embodiment differs from the second embodiment in that a switch member 33 (see Figure 1) is provided for supplying and stopping electricity from the DC link section 43. The switch member 33 is located in the electricity supply circuit to which electricity is supplied from the DC link section 43.

[0063] In this embodiment, a normally closed (b) contact relay 87 is provided as the switch member 33. The b-contact relay 87 is configured such that when power is supplied, the contacts separate and interrupt the power supply circuit, and when power is stopped, the contacts make contact and connect the power supply circuit. The relay 87 in this embodiment is connected to the control power supply 68. That is, when power is supplied from the control power supply 68, the power supply from the DC link section 43 is interrupted. When the power supply from the control power supply 68 is stopped, power is supplied from the DC link section 43.

[0064] In this embodiment, the motor drive device does not supply electricity to the coil 81 because the power supply circuit is shut off during periods when electricity is supplied by the control power supply 68. Therefore, during periods when electricity is supplied from the control power supply 68, such as during the operation of the electric motor 11, power consumption by the resistors 86 and 85 can be suppressed. In other words, it is possible to suppress the increase in power consumption and heat generation caused by electricity flowing through the resistors 85 and 86 during the operation of the electric motor 11. When the power supply to the machine control device 2 is shut off, electricity is supplied to the coil 81 from the DC link section 43 by the action of the relay 87. The cover member 62 can be fixed in the closed state until the voltage of the DC link section 43 becomes sufficiently low.

[0065] Other configurations, operations, and effects are the same as those of the motor drive device in the second embodiment, so they will not be described again here.

[0066] (Fourth Embodiment) Referring to Figure 8, a motor drive device in the fourth embodiment will be described. In the motor drive device of this embodiment, the structure of the amplifier, including the fixing mechanism and the cover member, is the same as that of the motor drive device of the first embodiment (see Figures 3 and 4). That is, the cover member 62 can be fixed or released by the action of the electromagnet 55.

[0067] Figure 8 shows the mechanism drive circuit of this embodiment. The motor drive device in this embodiment includes the mechanism drive circuit 73 (see Figure 7) from the third embodiment as the first mechanism drive circuit. The motor drive device includes the fixing mechanism from the third embodiment as the first fixing mechanism. The motor drive device in this embodiment includes the mechanism drive circuit 74 shown in Figure 8 as the second mechanism drive circuit. The motor drive device also includes a fixing mechanism including an electromagnet driven by the mechanism drive circuit 74 as the second fixing mechanism. The mechanism drive circuit 73 from the third embodiment and the mechanism drive circuit 74 shown in Figure 8 correspond to the mechanism drive circuit 32 in Figure 1.

[0068] The mechanism drive circuit 74 is a circuit in which the relay 84 is not arranged in the mechanism drive circuit 71 in the first embodiment (see Figure 5). When electricity is supplied from the control power supply 68, the mechanism drive circuit 74 allows electricity to flow through the coil 81 to fix the cover member 62 in a closed state. When electricity is not supplied from the control power supply 68, the mechanism drive circuit 74 opens the cover member 62.

[0069] In this embodiment, the respective mechanism drive circuits 71 and 74 are formed independently. Two electromagnets are arranged to correspond to each fixing mechanism. The two electromagnets are positioned to face the opposing member when the cover member 62 is closed. The cover member 62 is fixed in place by the magnetic force of either electromagnet so that an operator cannot open the cover member 62. Note that the electromagnet has one core, and the coils of the mechanism drive circuits 71 and 74 may be wound around this single core.

[0070] In the third embodiment, during the period when electricity is supplied from the control power supply 68, no electricity flows through the coil 81 of the mechanism drive circuit 73, and the cover member 62 remains unfixed. In this embodiment, by arranging a mechanism drive circuit 74 in addition to the mechanism drive circuit 73, electricity can be supplied from the control power supply 68 to the coil 81 of the mechanism drive circuit 74, thereby fixing the cover member 62 in a closed state.

[0071] For this reason, during the operation period of the electric motor 11, the cover member 62 can be fixed in the closed state while avoiding power consumption by the resistors 85 and 86 in the mechanism drive circuit 73. Thus, in this embodiment, the cover member 62 can be fixed in the closed state from the time the electric motor 11 is running until the amplifier stops and the voltage of the DC link section 43 drops to a safe voltage.

[0072] Next, the second mechanism drive circuit of this embodiment is not limited to the mechanism drive circuit 74 shown in Figure 8. The second mechanism drive circuit may also be the mechanism drive circuit 71 in the first embodiment (see Figure 2). Furthermore, it may also include a monitoring unit 24 that includes the state acquisition unit 25 and the circuit control unit 26 in the first embodiment. The fixing mechanism in the first embodiment corresponds to the second fixing mechanism. In this case as well, two electromagnets can be arranged to correspond to each fixing mechanism. The state acquisition unit 25 can determine whether or not electricity is being supplied from the control power supply 68. The circuit control unit 26 can control the mechanism drive circuit 71 to fix the cover member 62 in a closed state during the period when electricity is being supplied from the control power supply 68.

[0073] By including the mechanism drive circuit 71 in the first embodiment in addition to the mechanism drive circuit 73 shown in Figure 7, the motor drive device can fix the cover member 62 in a closed state in any operating state while electricity is supplied by the control power supply. For example, the mechanism drive circuit 71 can be controlled so that the cover member 62 is always fixed in a closed state while electricity is supplied by the control power supply 68.

[0074] Other configurations, operations, and effects are the same as those of the motor drive devices in the first and third embodiments, so they will not be described again here.

[0075] (Fifth Embodiment) The motor drive device in the fifth embodiment will be described with reference to Figure 9. The motor drive device of this embodiment differs from the previously described embodiment in the configuration of the high-voltage section and the covering member. In the previously described embodiment, the high-voltage section of the motor drive device is formed to be exposed on the front surface, but it is not limited to this configuration. In the motor drive device of this embodiment, the high-voltage section is configured to be exposed on the rear surface.

[0076] Figure 9 shows a side view of the amplifier in this embodiment. The amplifier 4 includes a main body 63 and a support member 64 that supports the main body 63. Electrodes 66a and 66b for supplying electricity to other electrical devices are arranged on the front surface of the support member 64. Electrodes 65a and 65b, which serve as high-voltage sections connected to the DC link section, are formed on the rear surface of the main body 63. The main body 63 is formed to slide along the surface of the support member 64, as shown by arrow 98. This configuration allows the main body 63 to be removed from the support member 64 when it is being repaired. Each electrode 65a and 65b is formed to contact electrodes 66a and 66b. In this embodiment, the support member 64 functions as a cover member that covers the electrodes 65a and 65b, which are the high-voltage sections.

[0077] The fixing mechanism for securing the support member 64 in the closed position includes a locking member 67 rotatably supported by the support member 64. The fixing mechanism includes an electromagnet for driving the locking member 67 (not shown). The locking member 67 is formed to rotate by the action of the electromagnet. By rotating in the direction indicated by arrow 99, the locking member 67 locks into a recess formed in the main body 63. The locking member 67 is formed to secure the main body 63 in the closed position. The mechanism drive circuit includes the coil of the electromagnet and is formed to drive the fixing mechanism.

[0078] Thus, even when the high-voltage section is exposed on the back of the amplifier's main body, a covering member can be positioned to prevent the operator from touching the high-voltage section. Furthermore, the mechanism drive circuit in the aforementioned embodiment can be used to fix the covering member in a closed position or to release the fixation. The structure of this embodiment can also be applied when the high-voltage section is exposed on the bottom or side of the amplifier's main body, or when the high-voltage section is hidden by the main body.

[0079] The amplifier shown in Figure 9 illustrates an example where electricity is supplied from the main body of the amplifier to other devices, but the configuration is not limited to this. For example, the rectifier and inverter of the amplifier may be formed as separate devices. In this case, electrodes for supplying DC electricity to the inverter can be formed on the main body and support member of the rectifier. Similarly, electrodes for receiving DC electricity from the rectifier can be formed on the main body and support member of the inverter. Even in a motor drive device equipped with such a rectifier and inverter, the fixed mechanism and mechanism drive circuit of this embodiment can be employed.

[0080] Other configurations, operations, and effects are the same as those of the motor drive devices in the first to fourth embodiments, so they will not be described again here.

[0081] As described above, according to at least one embodiment, a motor drive device can be provided that fixes a covering member covering a high-voltage section in a closed state.

[0082] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0083] The following additional information is disclosed regarding the above embodiments and modifications.

[0084] (Note 1) A motor drive device comprising: a cover member that covers a high-voltage section; a fixing mechanism that fixes the cover member in a closed state; a mechanism drive circuit for driving the fixing mechanism; a state acquisition unit that acquires information regarding the operating state of the motor; and a circuit control unit that controls the mechanism drive circuit, wherein the mechanism drive circuit includes a switch member that conducts or interrupts electricity from a control power supply, and the circuit control unit controls the operation of the switch member based on information regarding the operating state.

[0085] (Note 2) The motor drive device as described in Note 1, wherein the information regarding the operating status includes alarm information regarding the operation of the motor, and the circuit control unit controls the switch member so that the cover member is fixed by the fixing mechanism when alarm information is transmitted.

[0086] (Note 3) The motor drive device according to Note 1 or 2, wherein the fixing mechanism includes an electromagnet and an opposing member formed of a magnetic material, the mechanism drive circuit includes a coil for the electromagnet, the opposing member is positioned to face the electromagnet when the cover member is closed, and when current flows through the coil for the electromagnet due to the operation of the switch member, the opposing member is attracted to the electromagnet and the cover member is fixed.

[0087] (Note 4) The motor drive device according to any one of Notes 1 to 3, wherein the high-voltage section is the DC link section of the amplifier that supplies electricity to drive the motor, or a component connected to the DC link section.

[0088] (Note 5) A motor drive device comprising: a covering member that covers a high voltage section; a first fixing mechanism that fixes the covering member in a closed state; and a first mechanism drive circuit for driving the first fixing mechanism, wherein the high voltage section is the DC link section of an amplifier that supplies electricity to drive the motor or a member connected to the DC link section, and the first mechanism drive circuit is supplied with electricity from the DC link section.

[0089] (Note 6) The motor drive device according to Note 5, wherein the first fixing mechanism includes an electromagnet, the first mechanism drive circuit includes a coil for the electromagnet, and the first fixing mechanism is configured such that the covering member is fixed when current flows through the coil for the electromagnet.

[0090] (Note 7) A motor drive device as described in Note 5 or 6, wherein when the motor amplifier stops, electricity is supplied from the DC link section to the first mechanism drive circuit and the cover member is fixed in the closed state by the first fixing mechanism, and when the voltage of the DC link section drops after the motor amplifier stops, the voltage supplied to the first mechanism drive circuit drops and the fixing of the cover member by the first fixing mechanism is released.

[0091] (Note 8) The motor drive device according to Note 5 or 6, wherein the first mechanism drive circuit includes a switch member arranged in an electrical supply circuit from which electricity is supplied from a DC link to an electromagnet, the switch member includes a relay that is supplied with electricity from a control power source, and the relay is configured to shut off the electrical supply circuit when electricity is supplied from the control power source and to conduct electricity in the electrical supply circuit when the supply of electricity from the control power source is stopped.

[0092] (Note 9) The motor drive device according to Note 8, comprising a second fixing mechanism for fixing the cover member in a closed state, and a second mechanism drive circuit for driving the second fixing mechanism, wherein the second mechanism drive circuit is configured to fix the cover member in a closed state during the period when electricity is supplied from the control power supply.

[0093] (Note 10) The motor drive device according to Note 8, comprising: a second fixing mechanism for fixing a cover member in a closed state; a second mechanism drive circuit for driving the second fixing mechanism; a circuit control unit for controlling the second mechanism drive circuit; and a state acquisition unit for acquiring information relating to the operating state of the motor, wherein the state acquisition unit determines whether or not electricity is supplied from a control power supply, and the circuit control unit controls the second mechanism drive circuit to fix the cover member in a closed state during the period when electricity is supplied from the control power supply.

[0094] 2 Mechanical control unit 3,4 Amplifier 11 Electric motor 12 State detector 25 State acquisition unit 26 Circuit control unit 28 Arithmetic processing unit 31 Electric motor drive circuit 32 Mechanism drive circuit 33 Switch member 40 AC power supply 41 Rectifier 42 Inverter 43 DC link unit 52 Capacitor 53a, 53b Terminal 53 Connecting member 54 Opposing member 55 Electromagnet 56 Processor 62 Cover member 64 Support member 65a, 65b Electrode 66a, 66b Electrode 67 Locking member 68 Control power supply 71-74 Mechanism drive circuit 81 Coil 84, 87 Relay

Claims

1. A motor drive device comprising: a cover member that covers a high-voltage section; a fixing mechanism that fixes the cover member in a closed state; a mechanism drive circuit for driving the fixing mechanism; a state acquisition unit that acquires information regarding the operating state of the motor; and a circuit control unit that controls the mechanism drive circuit, wherein the mechanism drive circuit includes a switch member that conducts or interrupts electricity from a control power supply, and the circuit control unit controls the operation of the switch member based on information regarding the operating state.

2. The motor drive device according to claim 1, wherein the information relating to the operating state includes alarm information relating to the operation of the electric motor, and the circuit control unit controls the switch member so that the cover member is fixed by the fixing mechanism when the alarm information is transmitted.

3. The motor drive device according to claim 1 or 2, wherein the fixing mechanism includes an electromagnet and an opposing member formed of a magnetic material, the mechanism drive circuit includes a coil for the electromagnet, the opposing member is positioned to face the electromagnet when the cover member is closed, and when the switch member operates and current flows through the coil for the electromagnet, the opposing member is attracted to the electromagnet and the cover member is fixed.

4. The motor drive device according to any one of claims 1 to 3, wherein the high-voltage section is the DC link section of an amplifier that supplies electricity to drive the motor, or a member connected to the DC link section.

5. A motor drive device comprising: a covering member that covers a high voltage section; a first fixing mechanism for fixing the covering member in a closed state; and a first mechanism drive circuit for driving the first fixing mechanism, wherein the high voltage section is a DC link section of an amplifier that supplies electricity to drive a motor or a member connected to a DC link section, and the first mechanism drive circuit is supplied with electricity from the DC link section.

6. The motor drive device according to claim 5, wherein the first fixing mechanism includes an electromagnet, the first mechanism drive circuit includes a coil for the electromagnet, and the first fixing mechanism is configured such that the covering member is fixed when current flows through the coil for the electromagnet.

7. The motor drive device according to claim 5 or 6, wherein when the motor amplifier stops, electricity is supplied from the DC link section to the first mechanism drive circuit and the cover member is fixed in a closed state by the first fixing mechanism, and when the voltage of the DC link section drops after the motor amplifier stops, the voltage supplied to the first mechanism drive circuit drops and the fixing of the cover member by the first fixing mechanism is released.

8. The motor drive device according to claim 5 or 6, wherein the first mechanism drive circuit includes a switch member arranged in an electrical supply circuit from which electricity is supplied from a DC link to an electromagnet, the switch member includes a relay that is supplied with electricity from a control power source, and the relay is configured to shut off the electrical supply circuit when electricity is supplied from the control power source and to conduct electricity in the electrical supply circuit when the supply of electricity from the control power source is stopped.

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