Motor control device and insulation resistance detection method thereof

Abstract

The present invention provides a motor control device and an insulation resistance detection method thereof. The motor control device includes: a second switch capable of grounding a negative busbar; a third switch having one end connected to a second power supply connected to the busbar and the other end capable of being grounded; a current detection unit for detecting the current value between a motor winding and the negative busbar; and an insulation resistance calculation unit for calculating the insulation resistance value of the motor based on the current values detected by the current detection unit when the third switch is opened and when the third switch is closed, respectively, in a state where the power supply is disconnected by the first switch unit and the charge of the grounding capacitor is discharged by turning on the second switch for a predetermined time, as well as the voltage values of the capacitor and the voltage values of the second power supply unit.

Description

Technical Field

[0001] One aspect of the present invention relates to a motor control device and an insulation resistance detection method for the motor control device. Background Art

[0002] Servo motors, such as these, are driven by motor control devices including inverters and are used in machine tools and other applications. In equipment like machine tools that use cutting fluid for machining, the fluid can adhere to the motor. This can cause the fluid to enter the motor and degrade its insulation.

[0003] Furthermore, even when a motor is used in a device other than a machine tool, insulation degradation may occur in the motor if the motor is used for a long period of time or in a harsh operating environment.

[0004] Motor insulation deteriorates gradually, eventually leading to a ground fault. This can cause a ground fault to trip a leakage current switch or damage the motor control device. This can lead to system failure, which can significantly impact factory production lines. Therefore, from a preventive maintenance perspective, a device capable of detecting the insulation resistance of motors is highly desired.

[0005] Such a method for detecting the insulation resistance of a motor is described in, for example, Japanese Patent Application Laid-Open No. 2015-129704. The motor drive device described in Japanese Patent Application Laid-Open No. 2015-129704 includes a rectifier circuit, a power supply unit, an inverter unit, a current detector, a second switch, and an insulation resistance detector.

[0006] The rectifier circuit rectifies the AC voltage supplied from the AC power supply via the first switch into a DC voltage. The power supply unit smoothes the DC voltage rectified by the rectifier circuit using a capacitor. The inverter unit converts the DC voltage smoothed by the power supply unit into an AC voltage through the switching action of the semiconductor switching element. The inverter unit drives the motor using this AC voltage. The current detection unit measures the current value flowing through a resistor, one end of which is connected to the motor coil and the other end is connected to one terminal of the capacitor. The voltage detection unit measures the voltage value across the capacitor. The second switch grounds the other terminal of the capacitor. The insulation resistance detection unit detects the insulation resistance value of the motor, which is the resistance between the motor coil and the ground, using two sets of current and voltage values measured in two states: a state in which the motor is stopped, the first switch is open, and the second switch is open, and a state in which the second switch is closed.

[0007] The technology in Japanese Patent Application Laid-Open No. 2015-129704 uses the voltage across a smoothing capacitor to calculate the motor's insulation resistance from two sets of measurement results. This calculation eliminates the equivalent resistance corresponding to the leakage current of each semiconductor switching element. This eliminates the effect of the leakage current of the semiconductor switching elements.

[0008] According to the circuit configuration described in Japanese Patent Application Laid-Open No. 2015-129704, in the two states described above, with both the first and second switches open, the potential difference between the negative-side busbar of the smoothing capacitor and the ground is 0 V, and no current flows through the insulation resistance of the motor. Therefore, the equivalent resistance corresponding to the leakage current of the semiconductor switching element can be accurately calculated.

[0009] However, in actual motor control devices, a grounding capacitor is often inserted between the negative busbar of the smoothing capacitor and the ground line to mitigate noise. Furthermore, in three-phase AC power supplies, the S phase or neutral point is typically grounded. In this configuration, when applying the motor insulation resistance detection method described in Japanese Patent Application Laid-Open No. 2015-129704, when the first switch is turned on to supply AC power, a potential difference at the frequency of the AC power source is generated by the rectifier circuit between the negative busbar of the smoothing capacitor and the ground line. This potential difference charges the grounding capacitor. Furthermore, when the first switch is turned off to measure the motor insulation resistance, if a voltage remains across the grounding capacitor, the current detection unit will receive not only the leakage current of the semiconductor switching element based on the voltage across the smoothing capacitor, but also the current flowing through the insulation resistance of the motor due to the voltage across the grounding capacitor. Consequently, it is difficult to accurately calculate the equivalent resistance corresponding to the leakage current of the semiconductor switching element. Summary of the Invention

[0010] An object of the present invention is to provide a motor control device having a grounding capacitor inserted between a negative-side bus bar and a ground line, and capable of detecting the insulation resistance of a motor with high accuracy.

[0011] A motor control device according to one embodiment of the present invention includes: a first power supply; a first switch capable of disconnecting power supply from the first power supply; a DC supply unit that outputs power from the first power supply to a bus; a capacitor connected to the bus; a switching element that converts a DC voltage supplied to the bus into an AC voltage, and drives and controls the motor using the AC voltage; a grounding capacitor connected to a negative bus; a second switch capable of grounding the negative bus; a third switch having one end connected to a second power supply connected to the bus and the other end capable of being grounded; a current detection unit that detects a current value between a winding of the motor and the negative bus; and an insulation resistance calculation unit that calculates the insulation resistance value of the motor based on current values detected by the current detection unit when the third switch is opened and when the third switch is closed, respectively, in a state where power supply is disconnected by the first switch and charge in the grounding capacitor is discharged by turning on the second switch for a predetermined time, as well as voltage values of the capacitor and voltage values of the second power supply.

[0012] Another embodiment of the present invention is a method for detecting insulation resistance of a motor control device. The motor control device includes: a first power supply; a first switch capable of disconnecting power supply from the first power supply; a DC supply unit that outputs power from the first power supply to a bus; a capacitor connected to the bus; a switching element that converts a DC voltage supplied to the bus into an AC voltage, and drives and controls the motor using the AC voltage; and a grounding capacitor connected to a negative bus. The method comprises: disconnecting power supply using the first switch; discharging charge in the grounding capacitor by turning on a second switch capable of grounding the negative bus for a predetermined time; opening a third switch of a second power supply unit that has one end connected to the bus and the other end capable of being grounded via a third switch; detecting a first current value between a winding of the motor and the bus connected to the second power supply by a current detection unit; closing the third switch; detecting a second current value between the winding of the motor and the bus connected to the second power supply by the current detection unit; and calculating the insulation resistance value of the motor based on the detected first and second current values, as well as voltage values of the capacitor and the second power supply.

[0013] Other aspects of the present invention will become apparent from the description of the embodiments for carrying out the invention described below.

[0014] According to the aspect of the present invention, the power supply from the first power supply unit is stopped by shutting off the power supply by the first switch unit.

[0015] Furthermore, when calculating the insulation resistance of the motor, the second switch is closed before closing the third switch while the power supply from the first power supply is stopped. This discharges the charge stored in the grounding capacitor connected to the negative busbar to the ground. Consequently, the potential difference between the negative busbar and each ground point is eliminated.

[0016] In this state, when the third switch is open, leakage current flows through the switching element due to the voltage across the capacitor, and the current detection unit detects a first current value. Similarly, when the third switch is closed while power from the first power supply is stopped, the current detection unit detects a second current value. This second current value comprises the first current value and the majority of the current flowing through the motor windings due to the voltage across the second power supply (the remainder is a minute leakage current from the negative-side switching element). By performing calculations based on the two current values detected by the current detection unit—the first and second current values—and the voltage across the capacitor and the voltage across the second power supply, the insulation resistance value of the motor can be calculated with high accuracy.

[0017] In addition, here, the "first switch" includes all switches including circuit breakers. Even if the "first switch" is a terminal or contact that contacts the terminal of a battery or power supply, as long as it has a structure that can disconnect the power supply from the power supply, all are included. In addition, as a "DC supply unit", a power converter that converts AC power into DC power is used. In addition, the component called a "switch" includes the "first switch" mentioned above. The "switch" can be any switch as long as it can stop or flow current. The "switch" also includes mechanical switches, relays, semiconductor switches, etc.

[0018] As described above, according to the aspects of the present invention, it is possible to provide a motor control device that has a grounding capacitor inserted between the negative-side bus bar and the ground line and that can detect the insulation resistance of the motor with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a circuit diagram showing a motor control device according to a first embodiment of the present invention.

[0020] Figure 2 This is a circuit diagram showing a motor control device according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0021] In the following detailed description, for purposes of illustration, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, it will be apparent that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown for simplicity of drawing.

[0022] Figure 1 A first embodiment of the present invention is shown.

[0023] In the following description, “current” may include a current value, “voltage” may include a voltage value, “impedance” may include an impedance value, and “resistance” may include a resistance value. These terms are to be interpreted according to common technical knowledge of those skilled in the art.

[0024] Motor control device C ont1 Includes: rectifier circuit (DC supply unit) S DC 、Including the positive side bus ML + and the negative busbar ML - The bus bar ML, smoothing capacitors (capacitors) C1 and C2, an inverter including semiconductor switching elements TR1 to TR6, and an insulation resistance calculation unit 31 are provided.

[0025] The power is supplied from the three-phase AC power source (first power source) S1 to the motor control device C via the electromagnetic contactor MS as a first switch capable of interrupting the power supply.ont1 Supply three-phase AC voltage. Motor control device C ont1 By using the rectifier circuit (DC supply unit) S DC The three-phase AC voltage is full-wave rectified to generate a DC voltage, and the DC voltage is output to the bus ML.

[0026] The output DC voltage is connected to the positive side of bus ML through bus ML + With the negative side bus ML - The current is smoothed by the smoothing capacitors (capacitors) C1 and C2 between them.

[0027] Smoothed supply to busbar ML + and ML - The DC voltage is supplied to the bus ML connected to the positive side + With the negative side bus ML - The inverter including semiconductor switching elements TR1 to TR6 is connected to the bus ML. + and ML - The AC voltage obtained by inversely converting the DC voltage is used to drive the motor 1.

[0028] Motor control device C ont2 Includes: including the positive side bus ML + and the negative busbar ML - bus ML, smoothing capacitor (capacitor) C2, including semiconductor switching elements TR7 to TR 12 The inverter and the insulation resistance calculation unit 32 are provided.

[0029] From the motor control device C ont1 Rectifier circuit S DC To motor control device C ont2 Supply DC voltage. Motor control device C ont2 The motor 2 is driven by an AC voltage, and the AC voltage is generated by a semiconductor switching element TR7 to TR 12 The inverter performs inverse conversion on the DC voltage supplied to the bus ML.

[0030] Motor control device C ont1 、C ont2 Negative bus ML - To counteract noise, the terminals are grounded via grounding capacitors C3 and C4, respectively.

[0031] Here, on the negative side bus ML - A second switch SW1 is also provided as a grounding switch.

[0032] This embodiment shows a configuration applied to a two-axis drive in which the motor 1 and the motor 2 drive different axes, respectively.

[0033] Motor control device C ont1 The insulation resistance calculation unit 31 includes: a negative bus bar ML provided in the bus bar ML - The DC power supply (second power supply) S2 of the DC power supply unit between the DC power supply unit and the ground line E, the third switch SW2 (third switch), and the DC power supply (second power supply) S2 connected to the negative bus ML - The second switch SW1 and the third switch SW2 are connected to the negative bus ML in this order. - One end of the DC power supply S2 is connected to ML - The other end can be grounded via the third switch SW2. The detection control unit 41 detects the current based on the voltage of the current detection resistor R1. In addition, the detection control unit 41 controls the insulation resistance detection operation and calculates the insulation resistance value.

[0034] Motor control device C ont2 The insulation resistance calculation unit 32 includes a negative bus bar ML in the bus bar ML. - The current detection resistor R2 and the detection control unit (current detection unit) 42 are connected to the winding L of the motor 2. The detection control unit 42 detects the current based on the voltage of the current detection resistor R2. In addition, the detection control unit 42 calculates the insulation resistance value.

[0035] Current detection resistors R1 and R2 only need to be connected to the winding L of one phase of each of the U, V, and W phases of motors 1 and 2. The resistance of winding L of motors 1 and 2 is very small, so current can be detected in any phase.

[0036] The power source used as the DC power source S2 is a power source with a voltage as high as possible within a voltage range lower than the voltage of the smoothing capacitors C1 and C2, and is set so that the potential on the ground line E becomes higher than the negative bus line ML. - A power supply with a high current capacity is used as the DC power supply S2.

[0037] The reason why the voltage of the DC power supply S2 is set lower than the voltage of the smoothing capacitors C1 and C2 is as follows. That is, the reason is to suppress the current from flowing through the insulation resistance R of the motors 1 and 2 during measurement. m1 、R m2 The freewheeling diode D of the semiconductor switching elements TR1 to TR3 and TR7 to TR9 of the upper arm (positive side) of the inverter unit f The current flows in the direction of charging the smoothing capacitors C1 and C2, and the insulation resistance R m1、R m2 The detection accuracy is reduced as a result.

[0038] The motor control device C is described below. ont1 、C ont2 action.

[0039] During normal motor control, the second switch SW1 and the third switch SW2 remain in the off state, and the electromagnetic contactor MS is turned on. Thus, the motor control of each axis is performed through the inverter. During insulation resistance detection, the motor control device C ont1 、C ont2 It operates as follows.

[0040] Stop the motor control operation of all axes and make the semiconductor switching elements TR1 to TR 12 The electromagnetic contactor MS is disconnected. Furthermore, the third switch SW2 remains in the off state, and the second switch SW1 is turned on. During a predetermined time, the charges in the grounding capacitors C3 and C4 are discharged, and the potential difference between the negative bus and the ground is reduced to 0V. Next, the second switch SW1 is turned off, and the DC voltage V of the inverter is measured. PN , the voltage V across the current detection resistor R1 R1A and the voltage V across the current detection resistor R2 R2A .

[0041] Since the voltage of the grounding capacitors C3 and C4 is 0V, the current does not flow from the grounding capacitors C3 and C4 through the insulation resistance R of the motors 1 and 2. m1 、R m2 flows into the measurement circuit.

[0042] The voltage of the smoothing capacitors C1 and C2 is applied to the semiconductor switching elements TR1 to TR2 that constitute the inverter. 12 Therefore, the DC voltage of the inverter V PN The voltage of the smoothing capacitors C1 and C2 is substantially equal. Due to the above voltage, current flows from the semiconductor switching element TR1 to TR4, and current (first current (value)) flows through the current detection resistor R1. Similarly, current flows from the semiconductor switching element TR7 to TR 10 Furthermore, a current (first current (value)) flows through the current detection resistor R2.

[0043] The current flowing from the positive side semiconductor switching element TR1 to TR4 and the current flowing from the semiconductor switching element TR7 to TR 10 The current flowing is the leakage current of the semiconductor switching element. Leakage current flows equally in all phases. By focusing on the phase to which current sensing resistors R1 and R2 are connected, the insulation resistance of the motor can be determined.

[0044] If the equivalent leakage resistance of the semiconductor switching elements TR1 and TR4 is respectively R tr1 , and the semiconductor switching elements TR7, TR 10 The equivalent leakage resistance is R tr2 , then the following equations (1) and (2) hold.

[0045] (V PN -V R1A ) / R tr1 =V R1A / R tr1 +V R1A / R1···(1)

[0046] (V PN -V R2A ) / R tr2 =V R2A / R tr2 +V R2A / R2···(2)

[0047] Next, the third switch SW2 is turned on to supply power to the negative bus ML. - The voltage V of DC power supply S2 is applied between the ground line E and the ground line E. DC In this state, measure the voltage V across the current detection resistor R1. R1B and the voltage V across the current detection resistor R2 R2B . Based on these current detection resistors R1, R2 and voltage V R1B 、V R2B , obtain the current (second current (value)) flowing through the current detection resistors R1 and R2.

[0048] When the insulation of motor 1 is degraded, the voltage of DC power supply S2 passes through the insulation resistance R m1 is applied to the semiconductor switching element TR4. Therefore, current flows through the current detection resistor R1 and the semiconductor switching element TR4.

[0049] Similarly, when the insulation of motor 2 is degraded, the voltage of DC power supply S2 passes through the insulation resistance R m2 Applied to the semiconductor switching element TR 10 Therefore, the current flows through the current detection resistor R2 and the semiconductor switching element TR 10 .

[0050] In addition, the voltage of the smoothing capacitors C1 and C2, that is, the DC voltage V PN The current is applied to the semiconductor switching elements TR1 and TR4. Therefore, the current flows from the semiconductor switching element TR1 to TR4. In addition, the current also flows through the current detection resistor R1.

[0051] Likewise, the current flows from the semiconductor switching element TR7 to the TR 10 In addition, current also flows through the current detection resistor R2.

[0052] The current flowing from the semiconductor switching element TR1 to TR4 and the current flowing from the semiconductor switching element TR7 to TR 10 The current flowing is the leakage current of these semiconductor switching elements. However, the leakage current of these semiconductor switching elements is generally smaller than the current flowing due to the decrease in the insulation resistance of the motor. Therefore, it can be assumed that even with the leakage current, the voltage of smoothing capacitors C1 and C2 will hardly drop.

[0053] At this time, the following equations (3) and (4) hold true.

[0054] (V PN -V R1B ) / R tr1 +(V DC -V R1B ) / R m1 =V R1B / R tr1 +V R1B / R1···(3)

[0055] (V PN -V R2B ) / R tr2 +(V DC -V R2B ) / R m2 =V R2B / R tr2 +V R2B / R2···(4)

[0056] Insulation resistance R of motor 1 m1 By solving the simultaneous equations of the above-mentioned equations (1) and (3), it can be obtained from the following equation (5).

[0057] R m1 =R1(V DC -V R1B )(V PN -2V R1A ) / {(V R1B -V R1A )V PN}···(5)

[0058] In addition, the insulation resistance R of the motor 2 m2 It can be obtained from the following equation (6) by solving the simultaneous equations of the above equations (2) and (4).

[0059] R m2 =R2(V DC -VR2B )(V PN -2V R2A ) / {(V R2B -V R2A )V PN}···(6)

[0060] These calculations are performed by the detection control units 41 and 42. Of course, the voltage V across the current detection resistors R1 and R2 can be detected respectively. R1A 、V R2A To calculate the insulation resistance value R m1 、R m2 In this connection, it is also possible to measure two voltages V multiple times. R1A 、V R2A Calculate the insulation resistance value R by taking the average value of the measured voltage on either side or both sides. m1 、R m2 .

[0061] When using such various average values, the influence of abnormal values caused by noise etc. can be reduced, and a more accurate insulation resistance value R can be obtained. m1 、R m2 .

[0062] And, the calculated insulation resistance value R m1 、R m2 Transmitted as information to the user device. Insulation resistance value R m1 、R m2 The transmission can be done in any way. m1 、R m2 The method can be wired transmission or wireless transmission.

[0063] Get the insulation resistance value R m1 、R m2 Users can determine that insulation resistance is deteriorating when the insulation resistance value is low, and can predict in advance that the motor may be grounded and cause system failure. Therefore, users can take preventive measures such as replacing the motor in advance, thereby preventing such adverse events from occurring.

[0064] To determine whether insulation resistance has deteriorated, an appropriate determination method can be used. Examples of such determination methods include comparison with values known from experiments or experience, comparison with initial values measured and recorded or stored using a normal product when the motor control device was first installed, or comparison with safety standards or other set values.

[0065] Sometimes the insulation resistance R of motors 1 and 2 m1 、R m2Very small, semiconductor switching elements TR1 to TR 12 The semiconductor switching elements TR4 to TR6 and TR 10 ~TR 12 In this case, the current flows from the DC power supply S2 through the insulation deterioration portion of the motors 1 and 2 to the negative side semiconductor switching elements TR4 to TR6 and TR 10 ~TR 12 Here, the current capacity of the DC power supply S2 can be made much smaller than that of the smoothing capacitors C1 and C2. Therefore, the flowing current can be limited to a very small current.

[0066] Therefore, the negative side semiconductor switching elements TR4 to TR6 and TR 10 ~TR 12 The possibility of secondary damage and further insulation degradation of motors 1 and 2 is small.

[0067] In the above embodiment, the embodiment of the present invention is described as being applied to a two-axis motor control device using two motors 1 and 2. The embodiment of the present invention can also be similarly applied to a motor control device having one axis or three or more axes. As shown in the above embodiment, even if the motor control device has three or more axes, the DC power supply S2 only needs to be provided for one axis.

[0068] In the above method, a three-phase AC power supply S1 is used as the first power supply. Alternatively, a single-phase AC power supply may be used instead of a three-phase AC power supply. Furthermore, in the above method, a rectifier circuit is used as the DC supply. Alternatively, a circuit capable of regenerating power, such as a PWM converter, may be used as the DC supply. In this case, measurement is performed with the PWM converter stopped.

[0069] Alternatively, a DC power source such as a battery may be used as the first power source instead of an AC power source. Alternatively, a switch may be used as the first switch instead of an electromagnetic contactor MS. Furthermore, when a battery is installed to supply power to the motor control device, the contacts or terminals electrically connected when the battery is installed can be considered the first switch.

[0070] In addition, in the above-mentioned embodiment, the motor control device C ont1 、C ont2 A three-phase inverter including semiconductor switching elements is used. In the case of driving a single-phase motor, as the motor control device C ont1 、C ont2 A single-phase inverter may also be used. In addition, the inverter method is not limited to the above method, and may be a full-bridge method or a half-bridge method.

[0071] In addition, in the above-described embodiment, the semiconductor switching elements TR1 to TR 12 The gate drive power supply uses a conventional isolated power supply (not shown). Depending on the needs, any gate drive power supply can be selected, such as a bootstrap power supply, a high-voltage IC, or a combination of various other power supplies.

[0072] then, Figure 2 A second embodiment of the present invention is shown.

[0073] Figure 2 The second switch SW1 shown is not an on-off switch, but is configured to be in contact only with the DC bus ML. - A switch for selecting one of the contact a communicating with the second power supply unit S2 and the contact b communicating with the second power supply unit S2.

[0074] The following describes the motor control device C in this case. ont1 、C ont2 action.

[0075] During normal motor control, the second switch SW1 is disconnected from contact b to enable measurement similar to the first embodiment of the present invention. In this state, the second switch SW1 can be in a neutral state or connected to contact a. In this state, the third switch SW2 remains open, the electromagnetic contactor MS is closed, and motor control of each axis is performed via the inverter. In this state, the second switch SW1 remains disconnected from contact b.

[0076] When testing insulation resistance, the motor control device C ont1 、C ont2 It operates as follows.

[0077] Stop the motor control operation of all axes, and make the semiconductor switching elements TR1 to TR 12 The electromagnetic contactor MS is disconnected. The second switch SW1 is switched to the negative bus ML. - The state of the contact a is connected. In addition, by switching the third switch SW2 from off to on, a ground circuit is formed. Then, after a predetermined time, by switching the third switch SW2 from on to off, the ground circuit is cut off. In this state, the DC voltage V PN , the voltage V across the current detection resistor R1 R1A and the voltage V across the current detection resistor R2 R2A .

[0078] Next, the second switch SW1 is switched to the state where the contact b connected to the second power supply S2 is selected. In addition, the third switch SW2 is switched from OFF to ON to form a ground circuit. Next, the negative bus ML -The voltage V of DC power supply S2 is applied between the ground line E and the ground line E. DC In this state, measure the voltage V across the current detection resistor R1. R1B and the voltage V across the current detection resistor R2 R2B . Based on these current detection resistors R1, R2 and voltage V R1B 、V R2B The current (second current (value)) flowing through the current detection resistors R1 and R2 is acquired.

[0079] Other operations and insulation resistance R of motors 1 and 2 m1 、R m2 The measurement and calculation methods are substantially the same as those of the first embodiment of the present invention.

[0080] In the first and second aspects of the present invention, the second and third switches have different structures. These switches may have any structure as long as they have the same technical significance as the second and third switches. These switches may be switches that measure the insulation resistance R of the motors 1 and 2. m1 、R m2 When the charge stored in the grounding capacitors C3 and C4 is discharged, the voltage V DC Current detection is performed by applying the

[0081] The above describes various aspects of the present invention. The technical scope of the present invention is not limited to the contents specifically specified in the description so far, but includes all aspects included in the matters described in the claims. In addition, each term and description does not limit the technical scope of the present invention.

[0082] The detailed description has been presented for purposes of illustration and description. Numerous variations and modifications are possible in light of the above teachings. The detailed description is not intended to be exhaustive or to limit the subject matter described herein. Although the subject matter has been described in terms of specific structural features and / or methodological procedures, it should be understood that the subject matter defined in the claims is not necessarily limited to the specific features or procedures described. Rather, the specific features and procedures described are described as examples of implementing the claims.

Claims

1. A motor control device, characterized in that include: First power supply unit; a first switch capable of disconnecting the power supply from the first power supply unit; a DC supply unit configured to output the power from the first power supply unit to a bus bar; a capacitor connected to the busbar; a switching element for converting a DC voltage supplied to the bus into an AC voltage, and for driving and controlling the motor via the AC voltage; A grounding capacitor connected to the negative busbar; a second switch capable of grounding the negative busbar; a third switch, one end of which is connected to the second power supply connected to the bus bar, and the other end of which is groundable; a current detection unit, configured to detect a current value between the winding of the motor and the negative bus; as well as An insulation resistance calculation unit calculates the insulation resistance value of the motor based on current values detected by the current detection unit when the third switch is opened and when the third switch is closed, respectively, in a state where power supply is disconnected by the first switch and the charge of the grounding capacitor is discharged by turning on the second switch for a predetermined time, as well as voltage values of the capacitor and voltage values of the second power supply.

2. The motor control device according to claim 1, characterized in that: The second power supply is a DC power supply between the bus bar and the third switch. The insulation resistance calculation unit calculates the insulation resistance value of the motor based on the current values detected by the current detection unit when the third switch is open and closed, respectively, as well as the voltage values of the capacitor and the second power supply.

3. The motor control device according to claim 2, wherein: One negative end of the DC power supply is connected to the negative bus bar. The voltage of the DC power supply unit is set to be lower than the voltage of the capacitor.

4. The motor control device according to claim 2 or 3, characterized in that: The second switch and the third switch are connected in series from the negative bus in this order, The second switch is a switch capable of selectively connecting at least the negative-side bus bar and the DC power supply unit to the third switch.

5. A method for detecting insulation resistance of a motor control device, characterized in that: The motor control device includes: a first power supply unit; a first switch capable of disconnecting the power supply from the first power supply unit; a DC supply unit that outputs the power from the first power supply unit to a bus; a capacitor connected to the bus; a switching element that converts the DC voltage supplied to the bus into an AC voltage, and controls the motor drive with the AC voltage; and a grounding capacitor connected to the negative bus. The insulation resistance detection methods of motor control devices include: disconnecting the power supply by using the first switch; discharging the charge of the grounding capacitor by turning on a second switch capable of grounding the negative bus bar for a predetermined time; The third switch of the second power supply unit, one end of which is connected to the bus bar and the other end of which can be grounded via a third switch, is opened, and a first current value between the winding of the motor and the bus bar connected to the second power supply unit is detected by a current detection unit; closing the third switch and detecting, by the current detecting unit, a second current value between the winding of the motor and the bus bar connected to the second power supply unit; and An insulation resistance value of the motor is calculated based on the detected first and second current values, the voltage value of the capacitor, and the voltage value of the second power supply.

6. The insulation resistance detection method of a motor control device according to claim 5, characterized in that: The second power supply unit is the capacitor connected to the bus bar and storing electricity, and the voltage value of the second power supply unit is the voltage value of the capacitor.

7. The method for detecting insulation resistance of a motor control device according to claim 5, wherein: The second power supply is a DC power supply between the bus bar and the third switch. In the step of calculating the insulation resistance value of the motor, the insulation resistance value of the motor is calculated based on the current values detected by the current detection unit when the third switch is open and closed, respectively, and the voltage values of the capacitor and the second power supply unit.

8. The insulation resistance detection method of a motor control device according to claim 7, characterized in that: One negative end of the DC power supply is connected to the negative bus bar. The voltage of the DC power supply unit is set to be lower than the voltage of the capacitor.

9. The insulation resistance detection method of a motor control device according to claim 7 or 8, characterized in that: The second switch and the third switch are connected in series from the negative bus in this order, The second switch is a switch capable of selectively connecting at least the negative-side bus bar and the DC power supply unit to the third switch.

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