Motor control device

Abstract

By standardizing the power supply and detection unit for detecting the resistance value of insulation resistance and detecting open circuits in DB resistance, this motor control device reduces the number of parts and lowers manufacturing costs. [Solution] The motor control device 100 includes a first switch SW1 that can turn off the power supply from the first power supply unit 200 to the motor M via the motor power line, a second power supply unit 10, an insulation resistance value detection path P1 connected from the second power supply unit 10 to the motor M and the motor power line L1 via a second switch SW2, a DB resistance open circuit detection path P2 provided in parallel with the insulation resistance value detection path P1 and connected from the second power supply unit 10 to the motor power line L1 via an open circuit detection adjustment resistor R3 and a third switch SW3, a DB resistor connected between the motor power line L1 and the second power supply unit 10 and placed in a common return path P3 for the insulation resistance value detection path P1 and the DB resistance open circuit detection path P2, and a current detection unit 20 that detects the current flowing through the DB resistor Rdb.

Description

[Technical Field]

[0001] This invention relates to a motor control device. [Background technology]

[0002] Patent Document 1 discloses a motor control device comprising a monitoring circuit for detecting failures in the dynamic brake circuit (DB circuit), such as a break in the dynamic brake resistor (DB resistor), and a failure detection circuit for determining the failure of the DB circuit. The motor control device outputs a monitoring signal from the monitoring circuit, and if the failure detection circuit determines that the monitoring signal is different from the normal state, it detects a failure in the DB circuit.

[0003] Patent Document 2 discloses a motor control device equipped with an insulation resistance calculation unit that calculates the resistance value of the insulation resistance of a motor. This motor control device prevents secondary damage to the semiconductor switching elements of the inverter and insulation degradation of the motor by calculating the resistance value of the insulation resistance with high accuracy. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2011-135750 [Patent Document 2] Japanese Patent Publication No. 2021-18163 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, in order to realize a motor control device that can detect the resistance value of the motor's insulation resistance and also detect a fault in the DB circuit, it was necessary to provide dedicated circuits for each. This presented the challenge of making the motor control device large.

[0006] Therefore, the present disclosure aims to provide a motor control device that reduces the number of parts and lowers manufacturing costs by standardizing the power supply and detection unit for detecting the resistance value of the insulation resistance and the open circuit of the DB resistance. [Means for solving the problem]

[0007] A motor control device relating to one aspect of this disclosure is A first switch that can turn off the power supply from the first power supply unit to the motor via the motor power line, The second power supply unit, An insulation resistance value detection path connected from the second power supply unit to the motor and motor power line via the second switch, A DB resistance wire break detection path is provided in parallel with the insulation resistance value detection path and connected to the motor power line via a wire break detection adjustment resistor and a third switch from the second power supply unit, A DB resistor is connected between the motor power line and the second power supply unit and is located in a common return path for the insulation resistance value detection path and the DB resistor open circuit detection path, The system includes a current detection unit for detecting the current flowing through the DB resistor, With the first switch in the off position, the second switch is turned on and the third switch is turned off, and the resistance value of the insulation resistance of the motor is detected based on the voltage value of the current detected by the current detection unit. With the first switch in the off position, the second switch is turned off and the third switch is turned on, and the open circuit of the DB resistor is detected based on the voltage value of the current detected by the current detection unit. [Effects of the Invention]

[0008] According to this disclosure, by standardizing the power supply and detection unit for detecting the resistance value of the insulation resistance and the open circuit detection of the DB resistance, it is possible to provide a motor control device that reduces the number of parts and lowers manufacturing costs. [Brief explanation of the drawing]

[0009] [Figure 1] This is a circuit diagram of a motor control device according to the first embodiment of the present disclosure. [Figure 2] This is a circuit diagram of a motor control device according to a second embodiment of the present disclosure. [Figure 3] This is a circuit diagram of a motor control device according to a third embodiment of the present disclosure. [Figure 4] This is a circuit diagram of a motor control device according to the fourth embodiment of this disclosure. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described below with reference to the drawings. For the sake of clarity, the description of components having the same reference numeral as those already described in the description of the embodiments will be omitted. Furthermore, the dimensions of the components shown in these drawings may differ from the actual dimensions of the components for the sake of clarity.

[0011] <First Embodiment> [Circuit Configuration] Figure 1 is a circuit diagram of a motor control device 100 according to the first embodiment. As shown in Figure 1, the motor control device 100 includes a power converter 300, a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a DC power supply 10, an insulation resistance value detection path P1, a DB resistance open circuit detection path P2, a feedback path P3, a DB resistance Rdb, and a current detection unit 20.

[0012] The power converter 300 has an AC power supply 200 connected to its input side via a first switch SW1, and a motor M connected to its output side. The AC power supply 200 is, for example, a three-phase AC power supply. The power converter 300 includes a rectifier circuit 400 composed of diodes D1 to D6, and an inverter circuit 500 composed of a smoothing capacitor C1 and transistors Tr1 to Tr6 having freewheeling diodes Df1 to Df6. The power converter 300 converts the AC power from the AC power supply 200 into power and outputs it to the motor M. The smoothing capacitor C1 connects the rectifier circuit 400 and the inverter circuit 500 to the positive busbar ML. +and the negative busbar ML - is connected therebetween. The positive busbar ML + and the negative busbar ML - may each be connected with a grounding capacitor C2, C3 respectively.

[0013] The DB resistor Rdb is a resistor for operating dynamic braking on the motor M and is disposed on the motor power line L1. The motor power line L1 is a path connecting the power conversion device 300 and the motor M, for example, a path of the V phase. During the normal operation of the motor control device 100, the first switch SW1 and the fourth switch SW4 are in the on state and no current flows through the DB resistor Rdb. During an emergency stop or the like of the motor control device 100, the first switch SW1 and the fourth switch SW4 are turned off, and the power of the operating motor M flows through the DB resistor Rdb. Thereby, the rotational energy of the motor M is converted into the thermal energy of the DB resistor Rdb to stop the rotation of the motor M.

[0014] The first switch SW1 is, for example, an electromagnetic contactor and is disposed between the AC power supply 200 and the power conversion device 300 to control the power supply from the AC power supply 200 to the power conversion device 300. When the first switch SW1 is in the off state, DC power is output from the DC power supply 10 to a path passing through the insulation resistance value detection path P1 and the feedback path P3, or a path passing through the DB resistor disconnection detection path P2 and the feedback path P3.

[0015] The insulation resistance value detection path P1 is a path connected from the DC power supply 10 to the motor M and the motor power line L1 via the second switch SW2. The DB resistor disconnection detection path P2 is provided in parallel with the insulation resistance value detection path P1 and is a path connected from the DC power supply 10 to the motor power line L1 via the disconnection detection adjustment resistor R3 and the third switch SW3. The feedback path P3 is connected between the motor power line L1 and the DC power supply 10 and is a common path for the insulation resistance value detection path P1 and the DB resistor disconnection detection path P2. The DB resistor Rdb is disposed in the feedback path P3. Therefore, the motor control device 100 constitutes a single-phase short-circuit dynamic brake.

[0016] The second switch SW2 and the third switch SW3 are located in the insulation resistance value detection path P1 and the DB resistance open circuit detection path P2, respectively. Furthermore, the second switch SW2 and the third switch SW3 are mutually controlled on / off by the processor 22 of the current detection unit 20. Therefore, the DC power supply 10 energizes only one of the insulation resistance value detection path P1 and the DB resistance open circuit detection path P2.

[0017] The current detection unit 20 is located in the feedback path P3 and detects the current flowing through the DB resistor Rdb by detecting the current flowing through the detection resistor R1. The current detection unit 20 consists of an isolation amplifier 21, a processor 22, a detection resistor R1, and a voltage divider resistor R2. The isolation amplifier 21 and the detection resistor R1 are connected in parallel, and the detection resistor R1 and the voltage divider resistor R2 are connected in series in the feedback path P3. The processor 22 is connected to the isolation amplifier 21.

[0018] The isolated amplifier 21 detects the current flowing through its internal resistance, calculates the current flowing through the detection resistor R1, and calculates the potential difference ΔV between the terminals of the detection resistor R1. The isolated amplifier 21 performs AD conversion on the calculated potential difference ΔV and outputs the AD conversion value to the processor 22. Because the input and output of the isolated amplifier 21 are electrically isolated, the potential difference ΔV can be calculated with high accuracy without being affected by common-mode noise.

[0019] The detection resistor R1 and the voltage divider resistor R2 are connected in series with the DB resistor Rdb. The voltage divider resistor R2 adjusts the potential difference across the detection resistor R1.

[0020] The processor 22 is, for example, a CPU, which takes in the AD conversion value output from the isolation amplifier 21 and detects the resistance value of the isolation resistance RM of the motor M and the open circuit of the DB resistance Rdb from the AD conversion value.

[0021] [Operation Mode] As described above, during normal operation of the motor control device 100, the first switch SW1 and the fourth switch SW4 are in the ON state, and the second switch SW2 and the third switch SW3 are in the OFF state. During normal operation, power output from the AC power supply 200 is supplied to the motor M via the power converter 300.

[0022] When the motor control device 100 is stopped in an emergency, the fourth switch SW4 is turned off, and power from the operating motor M flows through the DB resistor Rdb. This converts the rotational energy of the motor M into thermal energy in the DB resistor Rdb, stopping the rotation of the motor M.

[0023] Furthermore, the motor control device 100 has two operating modes: an insulation resistance detection mode for detecting the resistance value of the insulation resistance RM of the motor M, and a DB resistance disconnection detection mode for detecting a disconnection in the DB resistance Rdb. In the insulation resistance detection mode, the device informs the user that the insulation resistance RM is NG if its resistance value is less than a predetermined value. In the DB resistance disconnection detection mode, the device informs the user that the DB resistance Rdb is NG if its resistance value is less than a predetermined value. The user can input a predetermined signal to the processor 22 via an input interface (not shown), which will allow the processor 22 to execute the insulation resistance detection mode and the insulation resistance detection mode.

[0024] In insulation resistance detection mode, the second switch SW2 is ON, while the first switch SW1, third switch SW3, and fourth switch SW4 are OFF. Therefore, the insulation resistance detection path P1 and the feedback path P3 are energized by the DC power supply 10.

[0025] In insulation resistance detection mode, the processor 22 calculates the resistance value of the insulation resistance RM using the following formula. Hereinafter, the resistance value of the insulation resistance RM is defined as rm, the DC voltage of the DC power supply 10 is defined as Vdc, the resistance value of the detection resistor R1 is defined as r1, the resistance value of the voltage divider resistor R2 is defined as r2, the resistance value of the DB resistor Rdb is defined as rdb, and the potential difference between the terminals of the detection resistor R1 is defined as ΔV. (Formula 1) rm = Vdc × r1 / ΔV - (r1 + r2 + rdb)

[0026] The DC voltage Vdc of the DC power supply 10, the resistance value r1 of the detection resistor R1, the resistance value r2 of the voltage divider resistor R2, and the resistance value rdb of the DB resistor Rdb are stored in the memory unit (not shown) of the processor 22.

[0027] In DB resistance open circuit detection mode, the third switch SW3 is ON, and the first switch SW1, second switch SW2, and fourth switch SW4 are OFF. Therefore, the DC power supply 10 energizes the DB resistance open circuit detection path P2 and the feedback path P3.

[0028] In DB resistor open circuit detection mode, the processor 22 determines that the DB resistor Rdb is open if the potential difference ΔV between the terminals of the detection resistor R1 is less than a predetermined value (e.g., 0V).

[0029] In summary, with the first switch SW1 in the off position, the processor 22 turns on the second switch SW2 and turns off the third switch, and detects the resistance value of the insulation resistance RM of the motor M based on the voltage value of the current detected by the current detection unit 20. Also, with the first switch SW1 in the off position, the processor 22 turns off the second switch SW2 and turns on the third switch SW3, and detects an open circuit in the DB resistance Rdb based on the voltage value of the current detected by the current detection unit 20.

[0030] Thus, a common DC power supply 10 and current detection unit 20 are used in two operating modes with different purposes, such as the insulation resistance value detection mode and the DB resistance open circuit detection mode. In other words, by making the feedback path P3, which includes the DC power supply 10 and the current detection unit 20, a common path connected to the detection path for the resistance value of the insulation resistance RM and the detection path for the open circuit of the DB resistance Rdb, the DC power supply 10 and the current detection unit 20 can be standardized. As a result, the number of parts in the motor control device 100 can be reduced, and manufacturing costs can be lowered.

[0031] Furthermore, the processor 22 controls the second switch SW2 and the third switch SW3 to acquire the AD conversion value, which is the output value of the isolation amplifier 21, and detects the resistance value of the isolation resistor RM or an open circuit in the DB resistor Rdb based on the voltage value across the detection resistor R1.

[0032] In this way, the processor 22 controls the second switch SW2 and the third switch SW3 based on the insulation resistance value detection mode and the DB resistance open circuit detection mode to acquire the AD conversion value of the isolation amplifier 21, thereby enabling the common use of the DC power supply 10 and the current detection unit 20 as described above.

[0033] Furthermore, the DC voltage of the DC power supply 10 is set to a value smaller than the DC voltage across the smoothing capacitor C1. This is to prevent a reduction in the detection accuracy of the insulation resistor RM and the detection accuracy of the open circuit of the DB resistor Rdb, which would occur if a portion of the DC current output from the DC power supply 10 were to pass through the freewheeling diodes Df1 to Df3 of the inverter circuit 500 instead of the feedback path P3.

[0034] Furthermore, a resistor R3 for adjusting the disconnection detection is provided in the DB resistance disconnection detection path P2. The resistance value of the disconnection detection adjustment resistor R3 is equivalent to the resistance value of the insulation resistance RM. Therefore, the combined resistance value RA1 of the insulation resistance value detection path P1 and the feedback path P3 (sum of insulation resistance RM, DB resistance Rdb, detection resistance R1, and voltage divider resistance R2), and the combined resistance value RA2 of the DB resistance disconnection detection path P2 and the feedback path P3 (sum of disconnection detection adjustment resistor R3, DB resistance Rdb, detection resistance R1, and voltage divider resistance R2) are approximately the same. Therefore, in the insulation resistance value detection mode and the DB resistance disconnection detection mode, if the resistance value of insulation resistance RM is normal and the DB resistance Rdb is not disconnected, the current flowing through the internal resistance of the isolation amplifier 21 is approximately the same. Consequently, in the DB resistance disconnection detection mode, it is possible to detect a disconnection in the DB resistance Rdb without changing the gain of the isolation amplifier 21.

[0035] <Second Embodiment> Figure 2 is a circuit diagram of the motor control device 600 according to the second embodiment. In the following description of the second embodiment, only the differences from the motor control device 100 according to the first embodiment shown in Figure 1 will be explained, and the same parts will not be described.

[0036] As shown in Figure 2, in the motor control device 600 according to the second embodiment, a rectifier circuit 30 consisting of diodes D7 to D12 is provided between the motor power line L1, the DB resistor Rdb, and the fourth switch SW4. The rectifier circuit 30 is connected to the U-phase path, the V-phase path, and the W-phase path that connect the power converter 300 and the motor M. Therefore, the rectifier circuit 30, the DB resistor Rdb, and the fourth switch SW4 constitute a three-phase short-circuit dynamic brake.

[0037] In this configuration, multiple phases of the motor power line L1 are short-circuited to a single DB resistor Rdb via a rectifier circuit 30, thereby activating the dynamic brakes of multiple phases. This configuration allows for both detection of a disconnection in the DB resistor Rdb and detection of its insulation resistance value using a single DB resistor disconnection detection path P2. If multiple phases of the motor power line L1 were to be short-circuited to multiple DB resistors, the phases of the motor power line L1 other than the V phase would not be energized by the DC power supply 10. Therefore, the DB resistors short-circuited from the phases other than the V phase of the motor power line L1 would not be energized, and it would not be possible to detect a disconnection in those DB resistors.

[0038] <Third and Fourth Embodiments> Figure 3 is a circuit diagram of the motor control device 700 according to the third embodiment. Figure 4 is a circuit diagram of the motor control device 800 according to the fourth embodiment. Hereinafter, in the third embodiment, only the differences from the motor control device 100 according to the first embodiment shown in Figure 1 will be described, and the same parts will not be described. Similarly, in the fourth embodiment, only the differences from the motor control device 600 according to the second embodiment shown in Figure 2 will be described, and the same parts will not be described.

[0039] As shown in FIG. 3, in the motor control device 700 according to the third embodiment, a feedback path P3 is connected to the DC power supply 10 via the negative bus bar ML that connects the rectifier circuit 400 and the inverter circuit 500. - Further, a fifth switch SW5 is provided between the DC power supply 10, the insulation resistance value detection path P1, and the DB resistance disconnection detection path P2. Therefore, it is possible to switch so as to short-circuit the path passing through the insulation resistance value detection path P1 and the feedback path P3 or the path passing through the DB resistance disconnection detection path P2 and the feedback path P3 without passing through the DC power supply 10.

[0040] Thus, by providing a part of the feedback path P3 via the negative bus bar ML and the fifth switch SW5, when shifting to the insulation resistance value detection mode or the DB resistance disconnection detection mode, the charge on the bus bar ML side of the grounding capacitor C3 can be discharged. Therefore, since the potential of the negative bus bar ML becomes 0V, the potential difference ΔV across both ends of the detection resistor R1 becomes large during the insulation resistance value detection mode or the DB resistance disconnection detection mode, and the detection accuracy of the resistance value of the insulation resistance RM and the detection accuracy of the disconnection of the DB resistance Rdb can be improved. - Also, as shown in FIG. 4, in the motor control device 800 according to the fourth embodiment, similarly to the motor control device 700 according to the third embodiment, the feedback path P3 is connected to the DC power supply 10 via the negative bus bar ML that connects the rectifier circuit 400 and the inverter circuit 500. - Further, a fifth switch SW5 is provided between the DC power supply 10, the insulation resistance value detection path P1, and the DB resistance disconnection detection path P2. Therefore, when shifting to the insulation resistance value detection mode or the DB resistance disconnection detection mode, the charge on the bus bar ML side of the grounding capacitor C3 can be discharged. Therefore, during the insulation resistance value detection mode or the DB resistance disconnection detection mode, the potential of the negative bus bar ML becomes 0V, the potential difference ΔV across both ends of the detection resistor R1 becomes large, and the detection accuracy of the resistance value of the insulation resistance RM and the detection accuracy of the disconnection of the DB resistance Rdb can be improved. -

[0041] - - - ​​​​​

[0042] While embodiments of this disclosure have been described above, it goes without saying that the technical scope of this disclosure should not be interpreted restrictively by the description of these embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications to the embodiments are possible within the scope of the invention described in the claims. The technical scope of this disclosure should be determined based on the scope of the invention described in the claims and the scope of its equivalents. [Explanation of Symbols]

[0043] 10:DC power supply 20: Current detection unit 21: Isolation Amplifier 22: Processor 30: Rectifier circuit 100, 600, 700, 800: Motor control device 200: AC power supply 300: Power converter 400: Rectifier circuit 500: Inverter circuit R1: Detection resistance R2: Voltage divider resistor R3: Resistor for detecting and adjusting broken wires. Rdb:DB resistance SW1: Switch 1 SW2: Second Switch SW3: Third Switch SW4: Switch 4 P1: Insulation resistance value detection path P2: DB resistance break detection path P3: Return Route

Claims

1. A first switch that can turn off the power supply from the first power supply unit to the motor via the motor power line, The second power supply unit, An insulation resistance value detection path connected from the second power supply unit to the motor and the motor power line via the second switch, A DB resistance wire break detection path is provided in parallel with the insulation resistance value detection path and connected to the motor power line via a wire break detection adjustment resistor and a third switch from the second power supply unit, A DB resistor is connected between the motor power line and the second power supply unit and is located in a common return path for the insulation resistance value detection path and the DB resistor open circuit detection path, The system includes a current detection unit for detecting the current flowing through the DB resistor, With the first switch in the off position, the second switch is turned on and the third switch is turned off, and the resistance value of the insulation resistance of the motor is detected based on the voltage value of the current detected by the current detection unit. With the first switch in the off position, the second switch is turned off and the third switch is turned on, and based on the voltage value of the current detected by the current detection unit, an open circuit in the DB resistor is detected. Motor control device.

2. The current detection unit comprises a detection resistor, an isolation amplifier, and a processor. The processor controls the second and third switches to acquire the output value of the isolation amplifier and detects the resistance value of the isolation resistor or the open circuit of the DB resistor based on the voltage value across the detection resistor. The motor control device according to claim 1.

3. The motor's dynamic brake is activated by short-circuiting multiple phases of the motor power line of the motor to the DB resistor via a rectifier circuit. The motor control device according to claim 1.

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