WO2023082712A1 - 一种电容检测装置、方法和电机控制设备 - Google Patents

一种电容检测装置、方法和电机控制设备 Download PDF

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WO2023082712A1
WO2023082712A1 PCT/CN2022/108569 CN2022108569W WO2023082712A1 WO 2023082712 A1 WO2023082712 A1 WO 2023082712A1 CN 2022108569 W CN2022108569 W CN 2022108569W WO 2023082712 A1 WO2023082712 A1 WO 2023082712A1
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capacitor
voltage
current
unit
module
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PCT/CN2022/108569
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English (en)
French (fr)
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谭章德
王长恺
区均灌
王岩
郑培杰
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珠海格力电器股份有限公司
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Publication of WO2023082712A1 publication Critical patent/WO2023082712A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2605—Measuring capacitance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/02—General constructional details
    • G01R1/04—Housings; Supporting members; Arrangements of terminals
    • G01R1/0408—Test fixtures or contact fields; Connectors or connecting adaptors; Test clips; Test sockets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines

Definitions

  • the disclosure belongs to the technical field of motor systems, and in particular relates to a capacitance detection device, method and motor control equipment, in particular to a capacitance abnormality detection circuit, method and motor control equipment applied to servo drives (such as servo drives, frequency converters, etc.) .
  • Electrolytic capacitors are used in rectification, filtering and energy storage circuits of servo drives due to the large amount of charge stored per unit volume.
  • the electrolytic capacitor for rectification and filtering affects the stability of the DC bus voltage.
  • the electrolytic capacitor for rectification and filtering is a key component for the control performance of the servo drive system and the long-term reliable operation of the servo drive system.
  • the change of load makes the electrolytic capacitor frequently charge and discharge, and the temperature rise caused by heat loss is an important factor for the failure of the electrolytic capacitor.
  • electrolytic capacitors are one of the devices with a high failure rate.
  • the purpose of this disclosure is to provide a capacitance detection device, method and motor control equipment to solve the problem of capacitance detection in related solutions.
  • a capacitance detection device, method and motor control equipment to solve the problem of capacitance detection in related solutions.
  • the comprehensive fault detection of electrolytic capacitors during the power-on stage of the motor system can help improve the safety of the motor system.
  • the present disclosure provides a capacitance detection device, which can be applied to a motor control device of a motor system;
  • the motor control device includes: a rectifier unit, a bus capacitor unit, an inverter unit, a detection unit, and a control unit;
  • the bus capacitor unit It includes: a capacitance module and a resistance module; the number of the capacitance modules is more than four, and the number of the resistance modules is the same as the number of the capacitance modules; the above four capacitance modules are divided into two capacitance groups, the first The two capacitor modules in the capacitor group are arranged in parallel, the two capacitor modules in the second capacitor group are also arranged in parallel, and the first capacitor group and the second capacitor group are arranged in series; each of the capacitor modules corresponds to one of the capacitor modules The resistance modules are connected in parallel;
  • the capacitance detection device includes: a switch unit; wherein, the switch unit is configured to be in a closed state when the motor control device needs to control the power-on and start-up of the motor system
  • more than four capacitor modules include: a first capacitor module, a second capacitor module, a third capacitor module, and a fourth capacitor module; the first capacitor module and the third capacitor module are connected in series , forming the first capacitor group; the second capacitor module and the fourth capacitor module are connected in series to form the second capacitor group; the detection unit includes: a voltage sampling module and a current sampling module; wherein, the The detection unit detects the voltage at both ends of at least one of the capacitor modules in the four or more capacitor modules, including: the voltage sampling module is arranged between the positive and negative terminals of the bus bar at the output end of the bus bar capacitor unit, configured In order to detect the voltage at both ends of at least one of the capacitive modules in the four or more capacitive modules; the detection unit detects the current flowing through the four or more capacitive modules, including: the current sampling module is arranged on the Between the bus negative terminal of the output terminal of the rectifier bridge and the bus negative terminal of the input terminal of the bus capacitor unit, it is configured to detect the current flowing through more
  • the voltage sampling module includes: a first sampling resistance module, a second sampling resistance module and a third sampling resistance module; wherein, the first sampling resistance module, the second sampling resistance module and The third sampling resistor module is arranged between the positive and negative terminals of the busbar at the output end of the busbar capacitor unit; the common end of the first sampling resistor module and the second sampling resistor module is connected to the first The common end of the capacitance module and the second capacitance module is connected to the common end of the third capacitance module and the fourth capacitance module; the current sampling module includes: a fourth sampling resistance module; the first The four-sampling module is arranged between the bus negative terminal of the output terminal of the rectifier bridge and the bus negative terminal of the input terminal of the bus capacitor unit.
  • the motor control device further includes: a regenerative braking unit; the regenerative braking unit is arranged between the bus capacitor unit and the inverter unit; the voltage sampling module is arranged between the bus capacitor unit and the regenerative braking unit.
  • the switch unit is arranged between the positive DC bus terminal of the output terminal of the rectifier bridge and the positive DC bus terminal of the input terminal of the bus capacitor unit.
  • the motor control device further includes: a current-limited starting unit; and the switch unit is disposed between the rectifier bridge and the current-limited starting unit.
  • the capacitor voltage includes at least one of the following: the DC bus voltage of the output terminal of the bus capacitor unit, the first terminal of the first capacitor group and the second terminal of the first capacitor group The voltage between the first terminal of the second capacitor group and the voltage between the second terminal of the second capacitor group; wherein, the first terminal of the first capacitor group and the first capacitor The voltage between the second terminals of the group is recorded as the first voltage; the voltage between the first terminal of the second capacitor group and the second terminal of the second capacitor group is recorded as the second voltage;
  • the capacitive current includes at least one of the following: the current flowing through the whole of the four current modules, the current flowing through each of the four or more capacitive modules; wherein, flowing through the four described The overall current of the current module is recorded as charging current; the current flowing through the first capacitor module is recorded as the first current; the current flowing through the second capacitor module is recorded as the second current; the current flowing through the third capacitor module , is denoted as the third current; the current flowing through the fourth capacitor module is denoted as the fourth
  • the control unit determines whether the bus capacitor unit is abnormal, including: if the first voltage and the DC bus voltage If they are equal, it is determined that some devices in the second capacitor group have a short-circuit fault; if the second voltage is equal to the DC bus voltage, it is determined that some devices in the first capacitor group have a short-circuit fault.
  • the control unit determines whether the bus capacitor unit is abnormal, and further includes: if the first capacitor group and the During the charging process of the second capacitor bank, the difference between the first voltage and the second voltage exceeds a first preset value; and, after the charging of the first capacitor bank and the second capacitor bank is completed, If the first voltage is equal to the second voltage, it is determined that a capacitor open fault occurs in the first capacitor bank and the second capacitor bank; wherein, when the charging current is equal to the second current and the In the case of the sum of the fourth current, it is determined that a capacitor open circuit fault occurs in the first capacitor bank; in the case that the charging current is equal to the sum of the first current and the third current, it is determined that the second A capacitor open fault has occurred in the capacitor pack.
  • the control unit determines whether the bus capacitor unit is abnormal, and further includes: After the charging of the second capacitor group is completed, if one of the first voltage and the second voltage changes quickly, the other voltage changes slowly; and, after the first voltage and the second voltage reach a new balance If the difference between the first voltage and the second voltage exceeds a second preset value, it is determined that the resistance module in the bus capacitor unit has an open circuit fault or an aging phenomenon.
  • the control unit determines whether the bus capacitor unit is abnormal, and further includes: according to the charging of the capacitor modules in the bus capacitor unit The charging current, capacitor voltage and charging time in the process determine the resistance value of the equivalent series resistance of the capacity of the capacitor module in the bus capacitor unit; based on the correspondence between the set capacity, the set resistance value and the set aging degree relationship, according to the resistance value of the equivalent series resistance of the capacity of the capacitor module in the bus capacitor unit, the aging degree of the capacitor module in the bus capacitor unit is determined.
  • a motor control device including: the above-mentioned capacitance detection device.
  • another aspect of the present disclosure provides a capacitance detection method, including: when the motor control device needs to control the motor system to be powered on and started, the switch unit is in a closed state to Power on the motor control device; when the motor control device controls the motor system to be powered on and started, detect the voltage at both ends of at least one of the capacitor modules among the four or more capacitor modules, and record it as the capacitor voltage ; and detect the current flowing through more than four capacitive modules, which is recorded as capacitive current; according to at least one of the capacitive voltage and the capacitive current, determine whether the bus capacitive unit is abnormal; When the bus capacitance unit is abnormal, a protection signal is issued; according to the protection signal, the switch unit is switched from the closed state to the open state, so that the motor control device is powered off.
  • the capacitor voltage includes at least one of the following: the DC bus voltage of the output terminal of the bus capacitor unit, the first terminal of the first capacitor group and the second terminal of the first capacitor group The voltage between the first terminal of the second capacitor group and the voltage between the second terminal of the second capacitor group; wherein, the first terminal of the first capacitor group and the first capacitor The voltage between the second terminals of the group is recorded as the first voltage; the voltage between the first terminal of the second capacitor group and the second terminal of the second capacitor group is recorded as the second voltage;
  • the capacitive current includes at least one of the following: the current flowing through the whole of the four current modules, the current flowing through each of the four or more capacitive modules; wherein, flowing through the four described The overall current of the current module is recorded as charging current; the current flowing through the first capacitor module is recorded as the first current; the current flowing through the second capacitor module is recorded as the second current; the current flowing through the third capacitor module , is denoted as the third current; the current flowing through the fourth capacitor module is denoted as the fourth
  • determining whether the bus capacitor unit is abnormal includes: if the first voltage is equal to the DC bus voltage, then determining the Some devices in the second capacitor group have a short-circuit fault; if the second voltage is equal to the DC bus voltage, it is determined that some devices in the first capacitor group have a short-circuit fault.
  • determining whether the bus capacitor unit is abnormal further includes: if charging in the first capacitor bank and the second capacitor bank During the process, the difference between the first voltage and the second voltage exceeds the first preset value; and, after the first capacitor bank and the second capacitor bank are charged, if the first If the voltage is equal to the second voltage, it is determined that a capacitor open circuit fault occurs in the first capacitor bank and the second capacitor bank; wherein, when the charging current is equal to the sum of the second current and the fourth current When the charging current is equal to the sum of the first current and the third current, it is determined that a capacitor failure occurs in the second capacitor bank Open circuit fault.
  • determining whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current further includes: after the first capacitor bank and the second capacitor bank are charged, Afterwards, if one of the first voltage and the second voltage changes rapidly, the other voltage changes slowly; and, after the first voltage and the second voltage reach a new balance, if the first voltage If the difference between the first voltage and the second voltage exceeds a second preset value, it is determined that the resistance module in the bus capacitor unit has an open circuit fault or aging phenomenon.
  • determining whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current further includes: according to the charging current of the capacitor module in the bus capacitor unit during the charging process , capacitor voltage and charging time, determine the resistance value of the equivalent series resistance of the capacity of the capacitor module in the bus capacitor unit; based on the corresponding relationship between the set capacity, the set resistance value and the set aging degree, according to the The resistance value of the equivalent series resistance of the capacity of the capacitor modules in the bus capacitor unit determines the aging degree of the capacitor modules in the bus capacitor unit.
  • the main capacitor circuit of the frequency conversion equipment is monitored by the abnormal capacitance detection circuit.
  • Anomaly detection is performed to timely perform fault handling when an abnormality is detected in the main capacitor circuit; thus, comprehensive fault detection of electrolytic capacitors during the power-on phase of the motor system is conducive to improving the safety of the motor system.
  • FIG. 1 is a schematic structural view of an embodiment of a capacitance detection device of the present disclosure
  • Fig. 2 is a schematic structural diagram of an embodiment of a servo driver in a related scheme
  • Fig. 3 is the structural representation of an embodiment of main capacitor circuit
  • Fig. 4 is the structural representation of an embodiment of the short-circuit fault of the main capacitor circuit part of the device
  • Fig. 5 is a schematic structural view of an embodiment of a partial capacitor open circuit fault of the main capacitor circuit
  • Fig. 6 is a structural schematic diagram of an embodiment of the main capacitor circuit part voltage equalizing resistance open circuit fault
  • Fig. 7 is the structural representation of an embodiment of electrolytic capacitor equivalent model
  • Fig. 8 is a structural schematic diagram of an embodiment of the main capacitance circuit considering the equivalent series resistance
  • Fig. 9 is a schematic structural diagram of an embodiment of adding a capacitor abnormality detection circuit
  • Fig. 10 is a schematic diagram of the voltage waveform of the capacitor charging process
  • Figure 11 is a schematic diagram of the charging waveform when part of the capacitor is disconnected
  • Figure 12 is a schematic diagram of the charging waveform when some voltage equalizing resistors are abnormal
  • Figure 13 is a schematic diagram of charging waveforms for capacitor aging detection
  • FIG. 14 is a schematic flow diagram of an embodiment of the capacitance detection method of the present disclosure.
  • Fig. 15 is a schematic flowchart of an embodiment of determining the aging degree of the capacitor modules in the bus capacitor unit in the method of the present disclosure.
  • Some schemes provide a method for identifying failure parameters of electrolytic capacitors in DC converters. By monitoring the ripple current and ripple voltage of electrolytic capacitors, the equivalent series resistance (ESR) is identified to determine whether the capacitors have failed.
  • ESR equivalent series resistance
  • Other solutions can indeed solve the problem of abnormal voltage equalization at both ends of capacitors used in series, and improve the reliability of capacitors during use.
  • the capacitance state monitoring methods in these solutions all use additional hardware circuits, such as capacitive current sensors, voltage sensors, etc., which affect the design of the main circuit.
  • a capacitance detection device is provided. Refer to FIG. 1 for a schematic structural view of an embodiment of the device of the present disclosure.
  • the capacitance detection device may include: the capacitance detection device can be applied to a motor control device of a motor system.
  • the motor control device includes: a rectification unit, a bus capacitor unit, an inverter unit, a detection unit and a control unit.
  • the bus capacitor unit includes: a capacitor module and a resistor module. The number of the capacitor modules is more than four, and the number of the resistor modules is the same as the number of the capacitor modules.
  • the above four capacitor modules are divided into two capacitor groups, the two capacitor modules in the first capacitor group are arranged in parallel, and the two capacitor modules in the second capacitor group are also arranged in parallel, the first capacitor group and the second capacitor group Tandem settings.
  • Each of the capacitive modules is connected in parallel with the corresponding one of the resistive modules.
  • the capacitance detection device includes: a switch unit.
  • the switch unit is configured to be in a closed state when the motor control device needs to control the motor system to be powered on and started, so as to enable the motor control device to be powered on.
  • the detection unit is configured to detect the voltage across at least one of the capacitor modules among the four or more capacitor modules when the motor control device controls the motor system to be powered on and started, which is recorded as a capacitor voltage . And detect the current flowing through more than four capacitive modules, and record it as capacitive current (ie charging current).
  • the control unit is configured to determine whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current. And, when it is determined that the bus capacitor unit is abnormal, a protection signal is sent.
  • the switch unit is further configured to switch from the closed state to the open state according to the protection signal, so that the motor control device is powered off.
  • Servo drives are mainly used in intelligent equipment fields such as industrial robots, CNC machine tools, and automated production line equipment.
  • Fig. 2 is a schematic structural diagram of an embodiment of a servo driver in a related solution.
  • the servo drive is composed of a power module and a control module. Module composition.
  • the function of the power module is to convert the three-phase AC input power frequency power supply into DC voltage, and then convert the DC voltage into a three-phase AC output with controllable frequency and amplitude through the three-phase inverter module.
  • the control module is composed of the main chip, various detection circuits, and control circuits. It controls the work of the power module, realizes energy conversion, outputs three-phase variable-frequency alternating current, and drives the motor to run.
  • the current-limiting starting circuit includes: a circuit composed of a resistor R1 and a switch K1 connected in parallel, and the circuit is arranged between the rectifier bridge and the main capacitor circuit.
  • the main capacitor circuit includes: a capacitor C1 , a capacitor C2 , a capacitor C3 and a capacitor C4 , and a resistor R1 , a resistor R2 , a resistor R3 and a resistor R4.
  • the capacitor C1 and the capacitor C2 are connected in series to form a first capacitor branch
  • the capacitor C3 and the capacitor C4 are connected in series to form a second series branch.
  • the first series branch and the second series branch are connected in parallel.
  • the resistor R1 is connected in parallel with the capacitor C1
  • the resistor R2 is connected in parallel with the capacitor C2
  • the resistor R3 is connected in parallel with the capacitor C3
  • the resistor R4 is connected in parallel with the capacitor C4.
  • the main capacitor circuit is a key circuit module of the servo driver. It is used to filter the output of the rectifier bridge and store energy. It is related to the power of the servo driver. The greater the power, the greater the capacitance required.
  • the voltage of my country's industrial power grid is AC 380V.
  • capacitors are generally used in series. The terminal voltage of the capacitor may be affected by the difference in insulation resistance and capacity of each capacitor connected in series, so that the terminal voltage of each capacitor is not equal, which may cause the voltage on one of the capacitors to rise and cause breakdown.
  • the equalizing resistors with the same resistance value must be selected to be used in parallel, and the resistance value is much smaller than the equivalent insulation resistance of the capacitor.
  • the equalizing resistor is to ensure that the voltages across the capacitors connected in series are equal. Therefore, the main capacitor circuit is composed of capacitors C1-C4, voltage equalizing resistors R1-resistors R4. The number of capacitors and voltage equalizing resistors is determined according to the power capacity of the servo drive. In the example shown in Figure 2, four capacitors are taken as an example.
  • Electrolytic capacitors are made of key components such as anode foil, cathode foil, electrolyte, and oxide film. Long-term use will cause the electrolyte to dry up and the oxide film to deteriorate, which will lead to a decrease in capacity. Damage to the oxide film and insulating paper will lead to short circuit of the capacitor. If the internal lead wire of the electrolytic capacitor is not well riveted to the aluminum foil or is subjected to external force, it may cause poor contact between the aluminum foil and the lead wire, resulting in a capacitor open circuit. Therefore, the main capacitor circuit is one of the modules with a high failure rate in the servo drive, and timely abnormal detection of it can improve the reliability of the system.
  • the voltage detection circuit includes: a voltage division detection circuit composed of a resistor R5 and a resistor R6.
  • the voltage detection circuit is arranged between the main capacitor circuit and the regenerative braking circuit.
  • the regenerative braking circuit includes: a power switch tube.
  • Three-phase inverter module including: inverter bridge.
  • the servo driver in the related scheme generally only detects the main circuit voltage (ie DC bus voltage) U D and current ID to determine whether there is any abnormality in the main circuit of the power module.
  • the output of the rectifier bridge charges the main capacitors (such as capacitors C1 to C4) in the main capacitor circuit through the resistor R7 to limit the charging current of the main capacitors.
  • the main capacitors in the motor system such as electrolytic capacitors, are detected
  • the DC bus voltage U D reaches the preset value
  • the current-limiting starting circuit controls the switch K1 to act, the switch is closed, the resistor R7 is short-circuited, and the servo drive enters the normal working state.
  • the main capacitor circuit is composed of capacitors connected in series and then connected in parallel, some abnormalities in the main capacitor circuit cannot be detected by related solutions, such as a short circuit or open circuit of a certain capacitor, or a short circuit or open circuit of a voltage equalizing resistor, and capacitor aging significantly wait.
  • the scheme of the present disclosure provides an abnormality detection scheme for series capacitors, specifically a capacitance abnormality detection circuit and method for a servo driver. stage, judge whether there are potential safety hazards in the servo drive, and deal with the corresponding faults in time.
  • a capacitor anomaly detection circuit in the servo driver that is, to improve the circuit structure of the servo driver itself, add a few simple devices to the circuit structure of the servo driver itself, and realize the abnormal detection of the main capacitor circuit without affecting The design of the main circuit.
  • the above four capacitive modules include: a first capacitive module, a second capacitive module, a third capacitive module and a fourth capacitive module.
  • the first capacitor module and the third capacitor module are connected in series to form the first capacitor group.
  • the first capacitor module is, for example, capacitor C1
  • the third capacitor module is, for example, capacitor C3.
  • the second capacitor module and the fourth capacitor module are connected in series to form the second capacitor group.
  • the second capacitor module is, for example, capacitor C2
  • the fourth capacitor module is, for example, capacitor C4.
  • the detection unit includes: a voltage sampling module and a current sampling module.
  • the detection unit detects the voltage at both ends of at least one of the capacitor modules in the four or more capacitor modules, including: the voltage sampling module, which is arranged between the positive and negative terminals of the bus bar at the output end of the bus bar capacitor unit , configured to detect the voltage across at least one of the capacitive modules among the four or more capacitive modules.
  • the detection unit detects the current flowing through more than four capacitor modules, including: the current sampling module, which is set at the bus negative terminal of the output terminal of the rectifier bridge and the bus negative terminal of the input terminal of the bus capacitor unit Between, it is configured to detect the current flowing through more than four capacitive modules.
  • the current sampling module which is set at the bus negative terminal of the output terminal of the rectifier bridge and the bus negative terminal of the input terminal of the bus capacitor unit Between, it is configured to detect the current flowing through more than four capacitive modules.
  • FIG. 3 is a schematic structural diagram of an embodiment of the main capacitor circuit in FIG. 2 .
  • the main capacitor circuit consists of the first capacitor group connected in series with the second capacitor group, which is divided into three poles: P, O, and N.
  • P is the positive pole of the DC bus
  • N is the negative pole of the DC bus
  • O is two sets of capacitors. midpoint of .
  • U D U PO + U ON
  • U PO U ON
  • the capacitor charging state since the capacitors are used in series, the charging current flowing through the two sets of capacitors is equal. Without adding additional current sensors and voltage sensors, it is impossible to detect the state of each resistor and each capacitor, but it is possible to detect the state of the first capacitor group or the second capacitor group.
  • the voltage sampling module includes: a first sampling resistor module, a second sampling resistor module and a third sampling resistor module.
  • the first sampling resistor module, the second sampling resistor module and the third sampling resistor module are arranged between the positive and negative terminals of the bus bar at the output end of the bus bar capacitor unit.
  • the first sampling resistor module such as resistor R5.
  • the second sampling resistor module such as resistor R6.
  • the third sampling resistor module such as resistor R9.
  • the common terminal of the first sampling resistance module and the second sampling resistance module is connected to the common terminal of the first capacitance module and the second capacitance module, and is connected to the third capacitance module and the The common terminal of the fourth capacitor module.
  • FIG. 9 is a schematic structural diagram of an embodiment of adding a capacitance abnormality detection circuit.
  • the capacitance detection circuit composed of resistor R5 and resistor R6 in the example shown in Figure 2 add a resistor R9, and connect the connection point of resistor R5 and resistor R6 to the connection between the first capacitor group and the second capacitor group point, so that the voltage of the two sets of capacitors can be detected.
  • the current sampling module includes: a fourth sampling resistor module.
  • the fourth sampling module is arranged between the bus negative terminal of the output terminal of the rectifier bridge and the bus negative terminal of the input terminal of the bus capacitor unit.
  • the overcurrent detection circuit between the main capacitor circuit and the three-phase inverter module in the example shown in Figure 2 is moved between the rectifier bridge and the main capacitor circuit, which expands the circuit function, and can Detect overcurrent, and can detect the charging current at the moment of power-on.
  • the motor control device further includes: a regenerative braking unit, such as a regenerative braking circuit.
  • the regenerative braking unit is arranged between the bus capacitor unit and the inverter unit.
  • the voltage sampling module is arranged between the bus capacitor unit and the regenerative braking unit.
  • the switch unit is arranged between the positive DC bus terminal of the output terminal of the rectifier bridge and the positive DC bus terminal of the input terminal of the bus capacitor unit.
  • a switch K2 is added to the current-limiting starting circuit in the example shown in Figure 2, which can cut off the power supply according to the fault situation and play a protective role.
  • the motor control device further includes: a current limiting starting unit, such as a current limiting starting circuit.
  • the switch unit is arranged between the rectifier bridge and the current-limited starting unit.
  • a switch K2 is connected in series in front of the current-limiting starting circuit, and the power supply can be cut off in time when a short-circuit fault occurs.
  • the current flowing through resistor R8 is equal to I D +I C .
  • the capacitor voltage includes at least one of the following: the DC bus voltage of the output terminal of the bus capacitor unit, the first terminal of the first capacitor group and the second terminal of the first capacitor group The voltage between the first terminal of the second capacitor bank and the second terminal of the second capacitor bank. Wherein, the voltage between the first end of the first capacitor group and the second end of the first capacitor group is recorded as a first voltage. The voltage between the first end of the second capacitor group and the second end of the second capacitor group is recorded as a second voltage.
  • the difference between the DC bus voltage output by the rectifying unit and the node voltage of the series node between the first capacitor group and the second capacitor group is determined as the voltage across the first capacitor group. and determining the node voltage of the series node between the first capacitor group and the second capacitor group as the voltage across the second capacitor group.
  • the capacitive current includes at least one of the following: a current flowing through the entirety of the four current modules, and a current flowing through each of the four or more capacitive modules. Wherein, the current flowing through the entirety of the four current modules is recorded as charging current.
  • the current flowing through the first capacitor module is denoted as the first current.
  • the current flowing through the second capacitor module is denoted as the second current.
  • the current flowing through the third capacitor module is denoted as the third current.
  • the current flowing through the fourth capacitor module is denoted as the fourth current.
  • control unit determines whether the bus capacitor unit is abnormal, including: detecting whether a capacitor module in the bus capacitor unit appears according to the capacitor voltage
  • the short-circuit fault process specifically includes any of the following short-circuit fault situations.
  • the first short-circuit fault situation the control unit is further configured to determine that some devices in the second capacitor group have a short-circuit fault if the first voltage is equal to the DC bus voltage.
  • the second short-circuit fault situation the control unit is further configured to determine that some devices in the first capacitor group have a short-circuit fault if the second voltage is equal to the DC bus voltage.
  • Fig. 4 is a structural schematic diagram of an embodiment of a short-circuit fault of some components of the main capacitor circuit.
  • the main capacitor circuit has a short circuit, as shown in Figure 4.
  • U PO U D is detected in the electrolytic capacitor detection in the motor system, it means that the voltage at point O is pulled to the negative pole of the DC bus, and a device in the second capacitor group is short-circuited.
  • U ON UD is detected in the electrolytic capacitor detection in the motor system, it means that the voltage at point O is pulled to the positive pole of the DC bus, and a device in the first capacitor group is short-circuited.
  • the short-circuit fault of the main capacitor circuit can be judged by detecting whether the voltages U PO , U ON at both ends of the capacitor are equal to the DC bus voltage U D .
  • the power input should be cut off immediately, otherwise, the short-circuit device may cause a safety hazard due to a sharp increase in heat.
  • the voltage is only applied to one set of capacitors, and one set of capacitors will be damaged due to overvoltage.
  • FIG. 10 is a schematic diagram of a voltage waveform during a capacitor charging process. The voltage changes at both ends of the capacitor are shown in Figure 10. Under normal circumstances, the voltage U PO and U ON are similar, and finally stabilized around U D /2. After charging is completed, the switch K2 is closed, the switch K1 is closed, and the servo driver enters the normal working state .
  • control unit determines whether the bus capacitor unit is abnormal, and further includes: detecting whether the bus capacitor unit is abnormal according to the capacitor voltage and the capacitor current.
  • the control unit is further configured to if the difference between the first voltage and the second voltage exceeds a first preset value during the charging process of the first capacitor bank and the second capacitor bank . And, after the charging of the first capacitor group and the second capacitor group is completed, if the first voltage is equal to the second voltage, it is determined that the first capacitor group and the second capacitor group have Capacitor open fault.
  • ic and Ic both represent the charging current of the capacitor. It is customary in this field to express the integral formula in lowercase, indicating that this is a quantity that changes with time, while the uppercase refers to the value at a certain moment. Because in the state shown in Figure 5, this equation is true at any moment, so Ic is used here to represent the capacitor charging current.
  • control unit determines whether the bus capacitor unit is abnormal, and further includes: detecting whether the resistor module in the bus capacitor unit is abnormal according to the capacitor voltage
  • the control unit is further configured to make the first voltage equal to the second voltage during the charging process of the first capacitor bank and the second capacitor bank. After the first capacitor bank and the second capacitor bank are charged, if one of the first voltage and the second voltage changes quickly, the other voltage changes slowly. Moreover, after the first voltage and the second voltage reach a new balance, if the difference between the first voltage and the second voltage exceeds a second preset value, it is determined that in the bus capacitance unit The resistor module has an open circuit fault or aging phenomenon.
  • FIG. 6 is a structural schematic diagram of an embodiment of an open circuit fault of a voltage equalizing resistor in the main capacitor circuit. If there is an open circuit phenomenon such as virtual welding, missing welding or improper connection of the voltage equalizing resistor, as shown in Figure 6.
  • the equalizing resistor mainly affects the voltage distribution after charging, and has little effect on the charging process of the capacitor. During the charging process of the capacitor, the voltages U PO and U ON at both ends of the capacitor are similar. When the charging is finished, the voltage of the capacitor group with voltage equalizing resistor open circuit will rise slowly due to the increase in resistance value, and the voltage of the other group will slowly decrease.
  • the voltage equalizing resistor may have an open circuit.
  • the open circuit of the voltage equalizing resistor which leads to a large difference in the parallel resistance between the first capacitor group and the second capacitor group, it may also be caused by abnormal phenomena such as aging of the resistor, increased resistance, or wrong welding of the resistor.
  • the resistance value of the equalizing resistor is abnormal, that is, the resistance value after the parallel connection of the resistance R1 and the resistance R3 is quite different from the resistance value after the parallel connection of the resistance R2 and the resistance R4.
  • the voltages U PO and U ON at both ends of the capacitor are similar.
  • FIG. 12 is a schematic diagram of charging waveforms when some voltage equalizing resistors are abnormal. If during the charging process, during the period from 0 to T1, it is detected that the voltage rises of the two groups of capacitors are basically the same, and in the stages of T1 to T2, the voltage of one group of capacitors rises slowly, and the voltage of the other group slowly decreases, and finally reaches a stable state, as shown in the figure 12 shown. It indicates that there is a part of the voltage equalizing resistor open circuit fault in the main capacitor circuit or the resistance value of the voltage equalizing resistor is abnormal. When the voltage difference U ⁇ exceeds the preset value, the servo drive will output a voltage equalization abnormal alarm signal, and the user needs to replace the main capacitor module.
  • control unit determines whether the bus capacitor unit is abnormal, and further includes: determining the aging of the capacitor modules in the bus capacitor unit degree process.
  • the control unit is further configured to determine the equivalent series resistance of the capacity of the capacitor modules in the bus capacitor unit according to the charging current, capacitor voltage and charging time of the capacitor modules in the bus capacitor unit during the charging process. Resistance.
  • the control unit is further configured to determine the resistance value of the equivalent series resistance of the capacity of the capacitor module in the bus capacitor unit based on the corresponding relationship between the set capacity, the set resistance value, and the set aging degree. The aging degree of the capacitor modules in the bus capacitor unit.
  • FIG. 7 is a schematic structural diagram of an embodiment of an equivalent model of an electrolytic capacitor.
  • Electrolytic capacitors have an equivalent series resistance (ESR) due to structural features and material properties, as shown in Figure 7.
  • ESR equivalent series resistance
  • the equivalent series resistance affects the charging and discharging time of the capacitor, and the ripple current generates loss on it, and the operating temperature of the capacitor increases.
  • the temperature rise of the electrolytic capacitor can be determined by the ripple current, ESR and thermal resistance. Under the assumption of thermal balance, the temperature rise of the electrolytic capacitor is equal to the heat generated by the power loss on the ESR.
  • the heat generated by the ripple current of the electrolytic capacitor is the main hazard that significantly shortens the service life of the capacitor.
  • the service life of the electrolytic capacitor will be halved.
  • the shortening of the life will no longer be halved for every 10°C increase, but will be shortened sharply. This is because the electrolyte is subjected to the thermal stress of the capacitor core, which increases the ESR of the capacitor by more than 10 times. Instantaneous over-temperature or instantaneous over-current will cause this to happen and damage the capacitor.
  • the capacitance value and the resistance value of ESR are used to characterize the aging degree of electrolytic capacitors. The life judgment standard used in some schemes is that the resistance value of ESR is doubled or the capacitance value is reduced to 80% of the initial value, that is, it has passed the safe use Expect.
  • C is the capacitance of the electrolytic capacitor
  • U C is the voltage across the electrolytic capacitor
  • i C is the charging current of the electrolytic capacitor
  • U DC is the input voltage
  • t is the charging time
  • R is the resistance value of the equivalent series resistance of the electrolytic capacitor.
  • FIG. 8 is a schematic structural diagram of an embodiment of the main capacitor circuit considering the equivalent series resistance.
  • the capacitance of the first capacitor group is the capacitance of the parallel connection of the electrolytic capacitor C1 and the electrolytic capacitor C3, and the equivalent series resistance of the first capacitor group is ESR1 The resistance after parallel connection with ESR3.
  • the same is true for the second capacitor group.
  • the charging currents of the two capacitor banks are equal.
  • the capacity of the electrolytic capacitor and the resistance value of the equivalent series resistance can be calculated by detecting the charging current, the voltage across the capacitor, and the charging time during the charging process of the electrolytic capacitor, so as to judge the aging degree of the electrolytic capacitor.
  • the solution of the present disclosure improves the circuit structure of the servo driver itself, and detects the voltage and charging current state at both ends of the series capacitor during the charging process of the main capacitor of the servo driver and after the charging of the main capacitor is completed. Determine whether the main capacitor circuit is abnormal. If there is no abnormality, enter the normal working state. If there is an abnormality, take corresponding protective measures.
  • the solution of the present disclosure also provides a capacitor aging detection method, which judges the aging degree of the capacitor by comparing the capacitance and the equivalent series resistance value with the initial parameters, and adopts the capacitor charging current, voltage and charging time. Detection method, and calculate the capacitance and equivalent series resistance value according to the basic formula. It solves the problem that the motor system works abnormally due to the aging of the main capacitor circuit.
  • FIG. 13 is a schematic diagram of charging waveforms for capacitor aging detection.
  • the initial capacitance value of the electrolytic capacitor and the initial resistance value of the equivalent series resistance must be determined first.
  • the first capacitor group as an example, firstly, according to the specification parameters of the selected electrolytic capacitors, calculate the capacitance value of the first capacitor group, the resistance value of the equivalent series resistance, the capacitance value of the second capacitor group, and the equivalent series resistance Resistance.
  • two time points t1 and t2 are taken during the capacitor charging process, and the U PO at the two time points can be detected as U 1 and U 2 respectively.
  • the voltages across the capacitor are U Ct1 and U Ct2 .
  • the capacitor charging currents at two moments are I Ct1 and I Ct2 respectively. Substitute the data into formula (1) and formula (2) to get:
  • Equation (7) Substitute Equation (7) into Equation (6), and then calculate U Ct1 according to Equation (4), so as to calculate the resistance value R of the equivalent series resistance and the capacitance value C of the electrolytic capacitor. Then compared with the initial equivalent series resistance R 0 and the initial capacitance C 0 , whether it satisfies the criteria for judging capacitor aging. If the resistance value of the equivalent series resistance of a certain capacitor group is doubled or the capacitance value is reduced to 80% of the initial value, that is, the safe service period has passed, the servo drive will output a capacitor aging warning signal to remind the user to replace the main capacitor module in time.
  • the above embodiments are for the case where two sets of capacitors are used in series.
  • the motor system uses three sets of capacitors in series or more capacitors in series, the same principle can be used to build a circuit to detect abnormal capacitance.
  • the above-mentioned embodiment is based on a servo drive with an AC input of 380V.
  • the disclosed solution is also applicable.
  • the solution disclosed in the present disclosure can be extended to products with a capacitor series structure, such as air conditioner frequency converters, photovoltaic inverters, and motor controllers.
  • the scheme of the present disclosure provides a capacitance abnormality detection circuit and method applied to servo drives, and specifically relates to a capacitance abnormality detection circuit of series capacitors in the field of motor control such as servo drives and frequency converters.
  • a capacitance abnormality detection circuit of series capacitors in the field of motor control such as servo drives and frequency converters.
  • the main capacitance circuit of the frequency conversion equipment is detected by using the capacitance abnormality detection circuit Abnormality detection, in order to carry out fault handling in time when abnormality is detected in the main capacitor circuit. Therefore, by performing comprehensive fault detection on the electrolytic capacitor during the power-on stage of the motor system, it is beneficial to improve the safety of the motor system.
  • the motor control device may include: the capacitance detection device described above.
  • the main capacitance circuit of the frequency conversion equipment is detected by using the capacitance abnormality detection circuit Abnormality detection, in order to carry out fault handling in time when abnormality is detected in the main capacitor circuit.
  • a capacitance detection method corresponding to a motor control device is also provided, as shown in FIG. 14 , a schematic flowchart of an embodiment of the method of the present disclosure.
  • the capacitance detection method may include: step S110 to step S140.
  • step S110 when the motor control device needs to control the motor system to be powered on and started, the switch unit is in a closed state, so that the motor control device is powered on.
  • step S120 when the motor control device controls the motor system to be powered on and started, detect the voltage across at least one capacitor module among the four or more capacitor modules, and record it as a capacitor voltage. And detect the current flowing through more than four capacitive modules, and record it as capacitive current (ie charging current).
  • step S130 according to at least one of the capacitor voltage and the capacitor current, it is determined whether the bus capacitor unit is abnormal. And, when it is determined that the bus capacitor unit is abnormal, a protection signal is issued.
  • step S140 according to the protection signal, the switch unit is switched from the closed state to the open state, so that the motor control device is powered off.
  • the scheme of the present disclosure provides an abnormality detection scheme for series capacitors, specifically a capacitance abnormality detection circuit and method for a servo driver. stage, judge whether there are potential safety hazards in the servo drive, and deal with the corresponding faults in time.
  • a capacitor anomaly detection circuit in the servo driver that is, to improve the circuit structure of the servo driver itself, add a few simple devices to the circuit structure of the servo driver itself, and realize the abnormal detection of the main capacitor circuit without affecting The design of the main circuit.
  • a switch K2 is connected in series in front of the current-limiting starting circuit, and the power supply can be cut off in time when a short-circuit fault occurs.
  • the current flowing through resistor R8 is equal to I D +I C .
  • the capacitor voltage includes at least one of the following: the DC bus voltage of the output terminal of the bus capacitor unit, the first terminal of the first capacitor group and the second terminal of the first capacitor group The voltage between the first terminal of the second capacitor bank and the second terminal of the second capacitor bank. Wherein, the voltage between the first end of the first capacitor group and the second end of the first capacitor group is recorded as the first voltage. The voltage between the first end of the second capacitor group and the second end of the second capacitor group is recorded as a second voltage.
  • the difference between the DC bus voltage output by the rectifying unit and the node voltage of the series node between the first capacitor group and the second capacitor group is determined as the voltage across the first capacitor group. and determining the node voltage of the series node between the first capacitor group and the second capacitor group as the voltage across the second capacitor group.
  • the capacitive current includes at least one of the following: a current flowing through the entirety of the four current modules, and a current flowing through each of the four or more capacitive modules. Wherein, the current flowing through the entirety of the four current modules is recorded as charging current.
  • the current flowing through the first capacitor module is denoted as the first current.
  • the current flowing through the second capacitor module is denoted as the second current.
  • the current flowing through the third capacitor module is denoted as the third current.
  • the current flowing through the fourth capacitor module is denoted as the fourth current.
  • determining whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current includes: detecting whether a short-circuit fault occurs in a capacitor module in the bus capacitor unit according to the capacitor voltage, It specifically includes any of the following short-circuit fault situations.
  • the first short-circuit fault situation if the first voltage is equal to the DC bus voltage, it is determined that some devices in the second capacitor group have a short-circuit fault.
  • the second short-circuit fault situation if the second voltage is equal to the DC bus voltage, it is determined that some devices in the first capacitor group have a short-circuit fault.
  • Fig. 4 is a structural schematic diagram of an embodiment of a short-circuit fault of some components of the main capacitor circuit.
  • the main capacitor circuit has a short circuit, as shown in Figure 4.
  • U PO U D is detected in the electrolytic capacitor detection in the motor system, it means that the voltage at point O is pulled to the negative pole of the DC bus, and a device in the second capacitor group is short-circuited.
  • U ON UD is detected in the electrolytic capacitor detection in the motor system, it means that the voltage at point O is pulled to the positive pole of the DC bus, and a device in the first capacitor group is short-circuited.
  • the short-circuit fault of the main capacitor circuit can be judged by detecting whether the voltages U PO , U ON at both ends of the capacitor are equal to the DC bus voltage U D .
  • the power input should be cut off immediately, otherwise, the short-circuit device may cause a safety hazard due to a sharp increase in heat.
  • the voltage is only applied to one set of capacitors, and one set of capacitors will be damaged due to overvoltage.
  • FIG. 10 is a schematic diagram of a voltage waveform during a capacitor charging process. The voltage changes at both ends of the capacitor are shown in Figure 10. Under normal circumstances, the voltage U PO and U ON are similar, and finally stabilized around U D /2. After charging is completed, the switch K2 is closed, the switch K1 is closed, and the servo driver enters the normal working state .
  • determining whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current further includes: detecting whether a capacitor module in the bus capacitor unit is disconnected according to the capacitor voltage and the capacitor current
  • the fault process specifically includes: if the difference between the first voltage and the second voltage exceeds a first preset value during the charging process of the first capacitor bank and the second capacitor bank. And, after the charging of the first capacitor group and the second capacitor group is completed, if the first voltage is equal to the second voltage, it is determined that the first capacitor group and the second capacitor group have Capacitor open fault.
  • determining whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current further includes: a process of detecting whether an open circuit fault occurs in a resistor module in the bus capacitor unit according to the capacitor voltage , specifically comprising: during the process of charging the first capacitor bank and the second capacitor bank, the first voltage is equal to the second voltage. After the first capacitor bank and the second capacitor bank are charged, if one of the first voltage and the second voltage changes quickly, the other voltage changes slowly. Moreover, after the first voltage and the second voltage reach a new balance, if the difference between the first voltage and the second voltage exceeds a second preset value, it is determined that in the bus capacitance unit The resistor module has an open circuit fault or aging phenomenon.
  • FIG. 6 is a structural schematic diagram of an embodiment of an open circuit fault of a voltage equalizing resistor in the main capacitor circuit. If there is an open circuit phenomenon such as virtual welding, missing welding or improper connection of the voltage equalizing resistor, as shown in Figure 6.
  • the equalizing resistor mainly affects the voltage distribution after charging, and has little effect on the charging process of the capacitor. During the charging process of the capacitor, the voltages U PO and U ON at both ends of the capacitor are similar. When the charging is finished, the voltage of the capacitor group with voltage equalizing resistor open circuit will rise slowly due to the increase in resistance value, and the voltage of the other group will slowly decrease.
  • the voltage equalizing resistor may have an open circuit.
  • the open circuit of the voltage equalizing resistor which leads to a large difference in the parallel resistance between the first capacitor group and the second capacitor group, it may also be caused by abnormal phenomena such as aging of the resistor, increased resistance, or wrong welding of the resistor.
  • the resistance value of the equalizing resistor is abnormal, that is, the resistance value after the parallel connection of the resistance R1 and the resistance R3 is quite different from the resistance value after the parallel connection of the resistance R2 and the resistance R4.
  • the voltages U PO and U ON at both ends of the capacitor are similar.
  • FIG. 12 is a schematic diagram of charging waveforms when some voltage equalizing resistors are abnormal. If during the charging process, during the period from 0 to T1, it is detected that the voltage rises of the two groups of capacitors are basically the same, and in the stages of T1 to T2, the voltage of one group of capacitors rises slowly, and the voltage of the other group slowly decreases, and finally reaches a stable state, as shown in the figure 12 shown. It indicates that there is a part of the voltage equalizing resistor open circuit fault in the main capacitor circuit or the resistance value of the voltage equalizing resistor is abnormal. When the voltage difference U ⁇ exceeds the preset value, the servo drive will output a voltage equalization abnormal alarm signal, and the user needs to replace the main capacitor module.
  • determining whether the bus capacitor unit is abnormal according to at least one of the capacitor voltage and the capacitor current further includes: a process of determining an aging degree of a capacitor module in the bus capacitor unit.
  • Step S201 according to the charging current, capacitor voltage and charging time of the capacitor modules in the bus capacitor unit during charging, determine the resistance value of the equivalent series resistance of the capacity of the capacitor modules in the bus capacitor unit.
  • Step S202 based on the corresponding relationship between the set capacity, the set resistance value and the set aging degree, determine the capacitance in the bus capacitor unit according to the resistance value of the equivalent series resistance of the capacity of the capacitor module in the bus capacitor unit The aging degree of the module.
  • FIG. 7 is a schematic structural diagram of an embodiment of an equivalent model of an electrolytic capacitor.
  • Electrolytic capacitors have an equivalent series resistance (ESR) due to structural features and material properties, as shown in Figure 7.
  • ESR equivalent series resistance
  • the equivalent series resistance affects the charging and discharging time of the capacitor, and the ripple current generates loss on it, and the operating temperature of the capacitor increases.
  • the temperature rise of the electrolytic capacitor can be determined by the ripple current, ESR and thermal resistance. Under the assumption of thermal balance, the temperature rise of the electrolytic capacitor is equal to the heat generated by the power loss on the ESR.
  • the heat generated by the ripple current of the electrolytic capacitor is the main hazard that significantly shortens the service life of the capacitor.
  • the service life of the electrolytic capacitor will be halved.
  • the shortening of the life will no longer be halved for every 10°C increase, but will be shortened sharply. This is because the electrolyte is subjected to the thermal stress of the capacitor core, which increases the ESR of the capacitor by more than 10 times. Instantaneous over-temperature or instantaneous over-current will cause this to happen and damage the capacitor.
  • the capacitance value and the resistance value of ESR are used to characterize the aging degree of electrolytic capacitors. The life judgment standard used in some schemes is that the resistance value of ESR is doubled or the capacitance value is reduced to 80% of the initial value, that is, it has passed the safe use Expect.
  • C is the capacitance of the electrolytic capacitor
  • U C is the voltage across the electrolytic capacitor
  • i C is the charging current of the electrolytic capacitor
  • U DC is the input voltage
  • t is the charging time
  • R is the resistance value of the equivalent series resistance of the electrolytic capacitor.
  • FIG. 8 is a schematic structural diagram of an embodiment of the main capacitor circuit considering the equivalent series resistance.
  • the capacitance of the first capacitor group is the capacitance of the parallel connection of the electrolytic capacitor C1 and the electrolytic capacitor C3, and the equivalent series resistance of the first capacitor group is ESR1 The resistance after parallel connection with ESR3.
  • the same is true for the second capacitor group.
  • the charging currents of the two capacitor banks are equal.
  • the capacity of the electrolytic capacitor and the resistance value of the equivalent series resistance can be calculated by detecting the charging current, the voltage across the capacitor, and the charging time during the charging process of the electrolytic capacitor, so as to judge the aging degree of the electrolytic capacitor.
  • the solution of the present disclosure improves the circuit structure of the servo driver itself, and detects the voltage and charging current state at both ends of the series capacitor during the charging process of the main capacitor of the servo driver and after the charging of the main capacitor is completed. Determine whether the main capacitor circuit is abnormal. If there is no abnormality, enter the normal working state. If there is an abnormality, take corresponding protective measures.
  • the solution of the present disclosure also provides a capacitor aging detection method, which judges the aging degree of the capacitor by comparing the capacitance and the equivalent series resistance value with the initial parameters, and adopts the capacitor charging current, voltage and charging time. Detection method, and calculate the capacitance and equivalent series resistance value according to the basic formula. It solves the problem that the motor system works abnormally due to the aging of the main capacitor circuit.
  • FIG. 13 is a schematic diagram of charging waveforms for capacitor aging detection.
  • the initial capacitance value of the electrolytic capacitor and the initial resistance value of the equivalent series resistance must be determined first.
  • the first capacitor group as an example, firstly, according to the specification parameters of the selected electrolytic capacitors, calculate the capacitance value of the first capacitor group, the resistance value of the equivalent series resistance, the capacitance value of the second capacitor group, and the equivalent series resistance Resistance.
  • two time points t1 and t2 are taken during the capacitor charging process, and the U PO at the two time points can be detected as U 1 and U 2 respectively.
  • the voltages across the capacitor are U Ct1 and U Ct2 .
  • the capacitor charging currents at two moments are I Ct1 and I Ct2 respectively. Substitute the data into formula (1) and formula (2) to get:
  • Equation (7) Substitute Equation (7) into Equation (6), and then calculate U Ct1 according to Equation (4), so as to calculate the resistance value R of the equivalent series resistance and the capacitance value C of the electrolytic capacitor. Then compared with the initial equivalent series resistance R 0 and the initial capacitance C 0 , whether it satisfies the criteria for judging capacitor aging. If the resistance value of the equivalent series resistance of a certain capacitor group is doubled or the capacitance value is reduced to 80% of the initial value, that is, the safe service period has passed, the servo drive will output a capacitor aging warning signal to remind the user to replace the main capacitor module in time.
  • the scheme of the present disclosure provides a capacitance abnormality detection circuit and method applied to servo drives, and specifically relates to a capacitance abnormality detection circuit of series capacitors in the field of motor control such as servo drives and frequency converters.
  • a capacitance abnormality detection circuit of series capacitors in the field of motor control such as servo drives and frequency converters.
  • the main capacitor circuit of the frequency conversion equipment is detected by the abnormal capacitance detection circuit.
  • Abnormality detection is carried out to deal with the fault in time when an abnormality is detected in the main capacitor circuit; by designing a capacitor abnormal circuit in the servo driver, by detecting the voltage change and charging current of the capacitor during the power-on stage, the abnormality of the series capacitor can be realized
  • the detection and corresponding protection processing enhance the reliability of the servo drive, and the parameters can be adjusted according to the selection of capacitors, which increases the scope of application and improves the market competitiveness of the servo drive.

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Abstract

一种电容检测装置、方法和电机控制设备，检测装置包括：开关单元，在电机控制设备需要控制电机系统上电并启动的情况下，处于闭合状态，以使电机控制设备通电；检测单元，在电机控制设备控制电机系统上电并启动的情况下，检测四个以上电容模块中至少一个电容模块两端的电压，记为电容电压；并检测流过四个以上电容模块的电流，记为电容电流；控制单元，根据电容电压和电容电流中的至少之一，确定母线电容单元是否异常；以及在确定母线电容单元异常的情况下，发出保护信号；开关单元还根据保护信号，由闭合状态切换为断开状态。通过在电机系统上电阶段对电解电容进行全面的故障检测，有利于提升电机系统的安全性。

Description

一种电容检测装置、方法和电机控制设备
本公开要求于2021年11月12日提交中国专利局、申请号为202111341288.5、发明名称为“一种电容检测装置、方法和电机控制设备”的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开属于电机系统技术领域，具体涉及一种电容检测装置、方法和电机控制设备，尤其涉及一种应用于伺服驱动器的电容异常检测电路、方法和电机控制设备(如伺服驱动器、变频器等)。
背景技术
伺服驱动器广泛应用于工业机器人、数控机床领域，用户对产品可靠性的要求也越来越高。电解电容因单位体积存储电荷量大，应用于伺服驱动器的整流滤波、储能电路。整流滤波用电解电容影响直流母线电压的稳定性，整流滤波用电解电容是伺服驱动系统的控制性能、以及伺服驱动系统长期可靠运行的关键部件。负载的变化，使得电解电容频繁充放电，热损耗产生的温度上升，是电解电容失效的重要因素。在伺服驱动器中，电解电容是失效率较高的器件之一。
相关方案中，对于电容检测，一般只检测主回路的电压、电流，并没有对电解电容进行全面的故障检测。
上述内容仅用于辅助理解本公开的技术方案，并不代表承认上述内容是现有技术。
发明内容
本公开的目的在于，提供一种电容检测装置、方法和电机控制设备，以解决相关方案中对于电容检测，一般只检测主回路的电压、电流，并未对电解电容进行全面的故障检测，使得电机系统存在安全隐患的问题，达到通过在电机系统上电阶段对电解电容进行全面的故障检测，有利于提升电机系统的安全性的效果。
本公开提供一种电容检测装置，能够应用于电机系统的电机控制设备；所述电机控制设备，包括：整流单元、母线电容单元、逆变单元、检测单元和控 制单元；所述母线电容单元，包括：电容模块和电阻模块；所述电容模块的数量为四个以上，所述电阻模块的数量与所述电容模块的数量相同；四个以上所述电容模块分为两个电容组，第一电容组中的两个电容模块并联设置，第二电容组中的两个电容模块也并联设置，第一电容组和第二电容组串联设置；每个所述电容模块与其相对应的一个所述电阻模块并联；所述电容检测装置，包括：开关单元；其中，所述开关单元，被配置为在所述电机控制设备需要控制所述电机系统上电并启动的情况下，处于闭合状态，以使所述电机控制设备通电；所述检测单元，被配置为在所述电机控制设备控制所述电机系统上电并启动的情况下，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，记为电容电压；并检测流过四个以上所述电容模块的电流，记为电容电流；所述控制单元，被配置为根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常；以及，在确定所述母线电容单元异常的情况下，发出保护信号；所述开关单元，还被配置为根据所述保护信号，由所述闭合状态切换为断开状态，以使所述电机控制设备断电。
在一些实施方式中，四个以上所述电容模块，包括：第一电容模块、第二电容模块、第三电容模块和第四电容模块；所述第一电容模块和所述第三电容模块串联，形成所述第一电容组；所述第二电容模块和所述第四电容模块串联，形成所述第二电容组；所述检测单元，包括：电压采样模块和电流采样模块；其中，所述检测单元，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，包括：所述电压采样模块，设置在所述母线电容单元的输出端的母线正负端之间，被配置为检测四个以上所述电容模块中至少一个所述电容模块两端的电压；所述检测单元，检测流过四个以上所述电容模块的电流，包括：所述电流采样模块，设置在所述整流桥的输出端的母线负端与所述母线电容单元的输入端的母线负端之间，被配置为检测流过四个以上所述电容模块的电流。
在一些实施方式中，所述电压采样模块，包括：第一采样电阻模块、第二采样电阻模块和第三采样电阻模块；其中，所述第一采样电阻模块、所述第二采样电阻模块和所述第三采样电阻模块，设置在所述母线电容单元的输出端的母线正负端之间；所述第一采样电阻模块与所述第二采样电阻模块的公共端，连接至所述第一电容模块和所述第二电容模块的公共端，并连接至所述第三电 容模块和所述第四电容模块的公共端；所述电流采样模块，包括：第四采样电阻模块；所述第四采样模块，设置在所述整流桥的输出端的母线负端与所述母线电容单元的输入端的母线负端之间。
在一些实施方式中，所述电机控制设备，还包括：再生制动单元；所述再生制动单元，设置在所述母线电容单元与所述逆变单元之间；所述电压采样模块，设置在所述母线电容单元与所述再生制动单元之间。
在一些实施方式中，所述开关单元，设置在所述整流桥的输出端的直流母线正端与所述母线电容单元的输入端的直流母线正端之间。
在一些实施方式中，所述电机控制设备，还包括：限流起动单元；所述开关单元，设置在所述整流桥与所述限流起动单元之间。
在一些实施方式中，所述电容电压，包括以下至少之一：所述母线电容单元的输出端的直流母线电压，所述第一电容组的第一端与所述第一电容组的第二端之间的电压，所述第二电容组的第一端与所述第二电容组的第二端之间的电压；其中，将所述第一电容组的第一端与所述第一电容组的第二端之间的电压，记为第一电压；将所述第二电容组的第一端与所述第二电容组的第二端之间的电压，记为第二电压；所述电容电流，包括一下至少之一：流过四个所述电流模块的整体的电流，流过四个以上所述电容模块中每个所述电容模块的电流；其中，流过四个所述电流模块的整体的电流，记为充电电流；流过第一电容模块的电流，记为第一电流；流过第二电容模块的电流，记为第二电流；流过第三电容模块的电流，记为第三电流；流过第四电容模块的电流，记为第四电流。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，包括：若所述第一电压与所述直流母线电压相等，则确定所述第二电容组中有部分器件出现短路故障；若所述第二电压与所述直流母线电压相等，则确定所述第一电容组中有部分器件出现短路故障。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：若在所述第一电容组和所述第二电容组充电的过程中，所述第一电压与所述第二电压的差值超过第一预设值；并且，在所述第一电容组和所述第二电容组充电结束后，若所述第 一电压与所述第二电压相等，则确定所述第一电容组和所述第二电容组出现电容断路故障；其中，在所述充电电流等于所述第二电流与所述第四电流之和的情况下，确定所述第一电容组中出现电容断路故障；在所述充电电流等于所述第一电流与所述第三电流之和的情况下，确定所述第二电容组中出现电容断路故障。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：在所述第一电容组和所述第二电容组充电结束后，若所述第一电压和所述第二电压中一个电压变化快，另一个电压变化慢；并且，待所述第一电压和所述第二电压达到新的平衡后，若所述第一电压和所述第二电压的差值超过第二预设值，则确定所述母线电容单元中的电阻模块出现断路故障或出现老化现象。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：根据所述母线电容单元中电容模块在充电过程中的充电电流、电容电压和充电时间，确定所述母线电容单元中电容模块的容量的等效串联电阻的阻值；基于设定容量、设定阻值与设定老化程度之间的对应关系，根据所述母线电容单元中电容模块的容量的等效串联电阻的阻值确定所述母线电容单元中电容模块的老化程度。
与上述装置相匹配，本公开再一方面提供一种电机控制设备，包括：以上所述的电容检测装置。
与上述电机控制设备相匹配，本公开再一方面提供一种电容检测方法，包括：在所述电机控制设备需要控制所述电机系统上电并启动的情况下，使开关单元处于闭合状态，以使所述电机控制设备通电；在所述电机控制设备控制所述电机系统上电并启动的情况下，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，记为电容电压；并检测流过四个以上所述电容模块的电流，记为电容电流；根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常；以及，在确定所述母线电容单元异常的情况下，发出保护信号；根据所述保护信号，使所述开关单元由所述闭合状态切换为断开状态，以使所述电机控制设备断电。
在一些实施方式中，所述电容电压，包括以下至少之一：所述母线电容单元的输出端的直流母线电压，所述第一电容组的第一端与所述第一电容组的第 二端之间的电压，所述第二电容组的第一端与所述第二电容组的第二端之间的电压；其中，将所述第一电容组的第一端与所述第一电容组的第二端之间的电压，记为第一电压；将所述第二电容组的第一端与所述第二电容组的第二端之间的电压，记为第二电压；所述电容电流，包括一下至少之一：流过四个所述电流模块的整体的电流，流过四个以上所述电容模块中每个所述电容模块的电流；其中，流过四个所述电流模块的整体的电流，记为充电电流；流过第一电容模块的电流，记为第一电流；流过第二电容模块的电流，记为第二电流；流过第三电容模块的电流，记为第三电流；流过第四电容模块的电流，记为第四电流。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，包括：若所述第一电压与所述直流母线电压相等，则确定所述第二电容组中有部分器件出现短路故障；若所述第二电压与所述直流母线电压相等，则确定所述第一电容组中有部分器件出现短路故障。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：若在所述第一电容组和所述第二电容组充电的过程中，所述第一电压与所述第二电压的差值超过第一预设值；并且，在所述第一电容组和所述第二电容组充电结束后，若所述第一电压与所述第二电压相等，则确定所述第一电容组和所述第二电容组出现电容断路故障；其中，在所述充电电流等于所述第二电流与所述第四电流之和的情况下，确定所述第一电容组中出现电容断路故障；在所述充电电流等于所述第一电流与所述第三电流之和的情况下，确定所述第二电容组中出现电容断路故障。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：在所述第一电容组和所述第二电容组充电结束后，若所述第一电压和所述第二电压中一个电压变化快，另一个电压变化慢；并且，待所述第一电压和所述第二电压达到新的平衡后，若所述第一电压和所述第二电压的差值超过第二预设值，则确定所述母线电容单元中的电阻模块出现断路故障或出现老化现象。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：根据所述母线电容单元中电容模块在充电过程中的充电电流、电容电压和充电时间，确定所述母线电容单元中电容 模块的容量的等效串联电阻的阻值；基于设定容量、设定阻值与设定老化程度之间的对应关系，根据所述母线电容单元中电容模块的容量的等效串联电阻的阻值确定所述母线电容单元中电容模块的老化程度。
由此，本公开的方案，通过在电机系统的变频设备(如伺服驱动器、变频器)等中设置电容异常检测电路，在电机系统上电阶段，利用电容异常检测电路对变频设备的主电容电路进行异常检测，以在检测到主电容电路存在异常时及时进行故障处理；从而，通过在电机系统上电阶段对电解电容进行全面的故障检测，有利于提升电机系统的安全性。
本公开的其它特征和优点将在随后的说明书中阐述，并且，部分地从说明书中变得显而易见，或者通过实施本公开而了解。
下面通过附图和实施例，对本公开的技术方案做进一步的详细描述。
附图说明
图1为本公开的电容检测装置的一实施例的结构示意图；
图2为相关方案中伺服驱动器的一实施例的结构示意图；
图3为主电容电路的一实施例的结构示意图；
图4为主电容电路部分器件短路故障的一实施例的结构示意图；
图5为主电容电路部分电容断路故障的一实施例的结构示意图；
图6为主电容电路部分均压电阻断路故障的一实施例的结构示意图；
图7为电解电容等效模型的一实施例的结构示意图；
图8为考虑等效串联电阻的主电容电路的一实施例的结构示意图；
图9为增加电容异常检测电路的的一实施例的结构示意图；
图10为电容充电过程的电压波形示意图；
图11为部分电容断路时的充电波形示意图；
图12为部分均压电阻异常时的充电波形示意图；
图13为电容老化检测的充电波形示意图；
图14为本公开的电容检测方法的一实施例的流程示意图；
图15为本公开的方法中确定所述母线电容单元中电容模块的老化程度的一实施例的流程示意图。
具体实施方式
为使本公开的目的、技术方案和优点更加清楚，下面将结合本公开具体实施例及相应的附图对本公开技术方案进行清楚、完整地描述。显然，所描述的实施例仅是本公开一部分实施例，而不是全部的实施例。基于本公开中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本公开保护的范围。
一些方案提供了一种直流变换器中电解电容失效参数辨识方法，通过监测电解电容的纹波电流、纹波电压，辨识出等效串联电阻(ESR)，从而判断电容是否失效。另一些方案，确实能解决串联使用的电容，电容两端均压异常的问题，提高电容使用过程中的可靠性。但是，这些方案中的电容状态监测方法，都会使用额外的硬件电路，比如电容电流传感器、电压传感器等，影响了主电路设计。
根据本公开的实施例，提供了一种电容检测装置。参见图1所示本公开的装置的一实施例的结构示意图。该电容检测装置可以包括：所述电容检测装置，能够应用于电机系统的电机控制设备。所述电机控制设备，包括：整流单元、母线电容单元、逆变单元、检测单元和控制单元。所述母线电容单元，包括：电容模块和电阻模块。所述电容模块的数量为四个以上，所述电阻模块的数量与所述电容模块的数量相同。四个以上所述电容模块分为两个电容组，第一电容组中的两个电容模块并联设置，第二电容组中的两个电容模块也并联设置，第一电容组和第二电容组串联设置。每个所述电容模块与其相对应的一个所述电阻模块并联。
所述电容检测装置，包括：开关单元。
其中，所述开关单元，被配置为在所述电机控制设备需要控制所述电机系统上电并启动的情况下，处于闭合状态，以使所述电机控制设备通电。
所述检测单元，被配置为在所述电机控制设备控制所述电机系统上电并启动的情况下，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，记为电容电压。并检测流过四个以上所述电容模块的电流，记为电容电流(即充电电流)。
所述控制单元，被配置为根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常。以及，在确定所述母线电容单元异常的 情况下，发出保护信号。
所述开关单元，还被配置为根据所述保护信号，由所述闭合状态切换为断开状态，以使所述电机控制设备断电。
伺服驱动器主要应用于工业机器人、数控机床、自动化产线设备等智能装备领域。图2为相关方案中伺服驱动器的一实施例的结构示意图。如图2所示，伺服驱动器由功率模块和控制模块组成，功率模块则由整流桥、限流起动电路、主电容电路、电容检测电路、再生制动电路、过流检测电路、三相逆变模块组成。功率模块的作用是将三相交流输入工频电源转换成直流电压，再通过三相逆变模块将直流电压转换成频率幅值可控的三相交流输出。控制模块由主芯片和各类检测电路、控制电路组成，控制功率模块的工作，实现能量转换，输出三相变频交流电，驱动电机运行。
在图2所示的例子中，限流起动电路，包括：由电阻R1和开关K1并联构成的电路，该电路设置在整流桥与主电容电路之间。
在图2所示的例子中，主电容电路，包括：电容C1、电容C2、电容C3和电容C4，以及电阻R1、电阻R2、电阻R3、电阻R4。电容C1和电容C2串联形成第一电容支路，电容C3和电容C4串联形成第二串联支路。第一串联支路和第二串联支路并联。电阻R1与电容C1并联，电阻R2与电容C2并联，电阻R3与电容C3并联，电阻R4与电容C4并联。
主电容电路是伺服驱动器的一个关键电路模块，作用是整流桥输出的滤波整型和储能，与伺服驱动器的功率相关，功率越大，需要的电容容量越大。我国工业电网的电压是交流380V，考虑到电容耐压，一般将电容串联使用。电容的端电压可能会受到串联的各个电容在绝缘电阻与容量上差别的影响而不同，使得各个电容端电压不等，这样可能导致其中一个电容上的电压升高而击穿。必须选择具有相同阻值的均压电阻并联使用，且阻值要比电容器的等效绝缘阻抗小得多。均压电阻的作用是保证串联的各个电容两端的电压相等。所以主电容电路由电容C1～电容C4，均压电阻R1～电阻R4组成。电容和均压电阻的数量是根据伺服驱动器功率容量而定的，在图2所示的例子中以四个电容为例。
主电容电路的电容类型，行业内一般选用大容量的铝电解电容，铝电解电容制作工艺简单、单位体积存储电荷量大。电解电容由阳极箔、阴极箔、电解 液、氧化膜等关键部件制作而成。长期使用，会出现电解液干涸、氧化膜劣化等现象，进而导致容量下降。氧化膜、绝缘纸受损，会导致电容短路现象。电解电容内部引出线如果与铝箔铆接不好或受外力作用，可能会导致铝箔与引出线接触不良，造成电容断路现象。所以主电容电路是伺服驱动器中失效率较高的模块之一，对其进行及时的异常检测，可以提高系统的可靠性。
在图2所示的例子中，电压检测电路，包括：由电阻R5和电阻R6构成的分压检测电路。电压检测电路设置在主电容电路与再生制动电路之间。
在图2所示的例子中，再生制动电路，包括：功率开关管。三相逆变模块，包括：逆变桥。
如图2所示，相关方案中的伺服驱动器一般只检测主回路电压(即直流母线电压)U D、电流I D来判断功率模块的主回路是否有器件存在异常。伺服驱动器上电，整流桥的输出通过电阻R7给主电容电路中的主电容(如电容C1至电容C4)充电，限制主电容的充电电流的大小，当电机系统中主电容如电解电容的检测到直流母线电压U D达到预设值时，限流起动电路控制开关K1动作，开关闭合，电阻R7短路，伺服驱动器进入正常工作状态。如果该过程中检测到直流母线电流I D高于过流保护值，则主回路有异常，过流报警。检测到直流母线电压U D高于过压保护值，则过压报警。检测到直流母线电压U D低于欠压保护值，则欠压报警。因为主电容电路是由电容串联后，再并联组成的，所以主电容电路有些异常是相关方案无法检测出来的，如某个电容发生短路或断路，或某个均压电阻短路或断路，电容老化严重等。
本公开的方案，提供了一种串联电容的异常检测方案，具体是一种伺服驱动器的电容异常检测电路及方法，当电解电容串联使用时，实时检测电容两端电压、充电电流，在设备启动阶段，判断伺服驱动器是否存在安全隐患，并及时处理相应的故障。通过在伺服驱动器里设计一个电容异常检测电路，即在伺服驱动器自身的电路结构上进行改进，在伺服驱动器自身的电路结构上，增加简单的几个器件，实现主电容电路的异常检测，不影响主电路的设计。在电机系统上电阶段，检测主电容电路中电容、均压电阻是否存在异常，具体是在电机系统启动阶段，监测伺服驱动器中主电容电路的充电特性，检测电路短路、断路、电容老化等异常现象，并及时进行相应的故障处理。通过在电机系统启动阶段，监测电容的电压变化、以及电容的充电电流情况，判断是否存在异常， 提高伺服驱动器的可靠性，避免电机系统出现安全问题。
在一些实施方式中，四个以上所述电容模块，包括：第一电容模块、第二电容模块、第三电容模块和第四电容模块。
所述第一电容模块和所述第三电容模块串联，形成所述第一电容组。第一电容模块如电容C1，第三电容模块如电容C3。
所述第二电容模块和所述第四电容模块串联，形成所述第二电容组。第二电容模块如电容C2，第四电容模块如电容C4。
所述检测单元，包括：电压采样模块和电流采样模块。
其中，所述检测单元，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，包括：所述电压采样模块，设置在所述母线电容单元的输出端的母线正负端之间，被配置为检测四个以上所述电容模块中至少一个所述电容模块两端的电压。
所述检测单元，检测流过四个以上所述电容模块的电流，包括：所述电流采样模块，设置在所述整流桥的输出端的母线负端与所述母线电容单元的输入端的母线负端之间，被配置为检测流过四个以上所述电容模块的电流。
图3为图2主电容电路的一实施例的结构示意图。如图3所示，主电容电路由第一电容组串联第二电容组组成，分为P、O、N三极，P是直流母线的正极，N是直流母线的负极，O是两组电容的中点。在正常状态下，直流母线电压U D＝U PO+U ON，由于均压电阻的作用，U PO、U ON接近于相等，不考虑误差，可认为U PO＝U ON。在电容充电状态下，由于电容串联使用，流过两组电容的充电电流是相等的。在不增加额外的电流传感器、电压传感器的情况下，没办法检测每个电阻、每个电容的状态，但可以检测第一电容组或第二电容组的状态。
在一些实施方式中，所述电压采样模块，包括：第一采样电阻模块、第二采样电阻模块和第三采样电阻模块。
其中，所述第一采样电阻模块、所述第二采样电阻模块和所述第三采样电阻模块，设置在所述母线电容单元的输出端的母线正负端之间。第一采样电阻模块，如电阻R5。第二采样电阻模块，如电阻R6。第三采样电阻模块，如电阻R9。
所述第一采样电阻模块与所述第二采样电阻模块的公共端，连接至所述第一电容模块和所述第二电容模块的公共端，并连接至所述第三电容模块和所述 第四电容模块的公共端。
图9为增加电容异常检测电路的一实施例的结构示意图。在图2所示的例子中的电阻R5、电阻R6组成的电容检测电路基础上，增加一个电阻R9，并将电阻R5与电阻R6的连接点接到第一电容组与第二电容组的连接点上，从而可以检测两组电容的电压。
所述电流采样模块，包括：第四采样电阻模块。所述第四采样模块，设置在所述整流桥的输出端的母线负端与所述母线电容单元的输入端的母线负端之间。
参见图9所示的例子，将图2所示的例子中主电容电路与三相逆变模块之间的过流检测电路移到整流桥与主电容电路之间，扩展了电路功能，既能检测过流，又能检测上电时刻的充电电流。
在一些实施方式中，所述电机控制设备，还包括：再生制动单元，如再生制动电路。
所述再生制动单元，设置在所述母线电容单元与所述逆变单元之间。所述电压采样模块，设置在所述母线电容单元与所述再生制动单元之间。
在一些实施方式中，所述开关单元，设置在所述整流桥的输出端的直流母线正端与所述母线电容单元的输入端的直流母线正端之间。
图9所示的例子，是在图2所示的例子中的限流起动电路增加一个开关K2，可以根据故障情况切断电源，起保护作用。
在一些实施方式中，所述电机控制设备，还包括：限流起动单元，如限流起动电路。
所述开关单元，设置在所述整流桥与所述限流起动单元之间。
如图9所示，在限流起动电路前面串接一个开关K2，当出现短路故障时，可以及时切断电源。将过流检测电阻R8移到整流桥负极与主电容负极之间，既能检测正常工作时主回路的电流I D，也能检测伺服驱动器上电时刻，主电容的充电电流I C。流过电阻R8的电流等于I D+I C。上电时刻，由于再生制动电路和三相逆变模块都不工作，所以I D＝0。正常工作时，电容充电已完成，达到一个平衡状态，I C很小，流过电阻的电流主要是I D，所以不影响过流检测电路的工作。电容检测电路再增加一个电阻R9，并且电阻R5的一端连接到主电容C1、C2串联的中点上，这样就可以同时检测到直流母线电压U D，串联电容的 中点电压(也是第二电容组两端电压)U ON。从而算出第一电容组两端的电压：U PO＝U D-U ON。这样可以实时检测主电容电路在充电过程中和充电结束后的电压状态。
在一些实施方式中，所述电容电压，包括以下至少之一：所述母线电容单元的输出端的直流母线电压，所述第一电容组的第一端与所述第一电容组的第二端之间的电压，所述第二电容组的第一端与所述第二电容组的第二端之间的电压。其中，将所述第一电容组的第一端与所述第一电容组的第二端之间的电压，记为第一电压。将所述第二电容组的第一端与所述第二电容组的第二端之间的电压，记为第二电压。
将所述整流单元输出的直流母线电压，与所述第一电容组和所述第二电容组之间的串联节点的节点电压之差，确定为所述第一电容组两端的电压。并将所述第一电容组和所述第二电容组之间的串联节点的节点电压，确定为所述第二电容组两端的电压。
所述电容电流，包括一下至少之一：流过四个所述电流模块的整体的电流，流过四个以上所述电容模块中每个所述电容模块的电流。其中，流过四个所述电流模块的整体的电流，记为充电电流。流过第一电容模块的电流，记为第一电流。流过第二电容模块的电流，记为第二电流。流过第三电容模块的电流，记为第三电流。流过第四电容模块的电流，记为第四电流。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，包括：根据电容电压检测母线电容单元中电容模块是否出现短路故障的过程，具体包括以下任一种短路故障情形。
第一种短路故障情形：所述控制单元，具体还被配置为若所述第一电压与所述直流母线电压相等，则确定所述第二电容组中有部分器件出现短路故障。
第二种短路故障情形：所述控制单元，具体还被配置为若所述第二电压与所述直流母线电压相等，则确定所述第一电容组中有部分器件出现短路故障。
图4为主电容电路部分器件短路故障的一实施例的结构示意图。在伺服驱动器初始上电过程中，如果检测到只有一组电容在充电，则说明主电容电路有短路的现象，如图4所示。若电机系统中针对电解电容的检测，检测到U PO＝U D，则说明O点电压被拉到了直流母线的负极，第二电容组有器件短路。若电机系 统中针对电解电容的检测，检测到U ON＝U D，则说明O点电压被拉到了直流母线的正极，第一电容组有器件短路。也就是说，可以通过检测电容两端电压U PO、U ON与直流母线电压U D是否相等来判断主电容电路的短路故障。当出现短路故障时，应立即切断电源输入，否则，短路器件可能会因热量急剧增加而出现安全隐患。电压只加在一组电容上，一组电容会因为过压损坏。
伺服驱动器上电，开关K2闭合，开关K1断开，通过电阻R7限流给主电容电路充电。图10为电容充电过程的电压波形示意图。电容两端电压变化如图10所示，正常情况下，电压U PO、U ON相近，最终稳定在U D/2附近，充电完成后，开关K2闭合，开关K1闭合，伺服驱动器进入正常工作状态。
若充电过程中，检测到只有一组电容在充电，另一组电容电压一直为零，则主电容电路存在短路故障，开关K2断开，切断电源。
在本公开的方案中，通过在伺服驱动器上电时刻检测串联电容中两组电容的电压，判断是否存在某组电容短路的现象，避免伺服驱动器使用的安全隐患。解决了伺服驱动器中串联使用的主电容电路部分器件发生短路故障时，导致安全事故的问题。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：根据电容电压和电容电流检测母线电容单元中电容模块是否出现断路故障的过程，具体参见以下示例性说明。
所述控制单元，具体还被配置为若在所述第一电容组和所述第二电容组充电的过程中，所述第一电压与所述第二电压的差值超过第一预设值。并且，在所述第一电容组和所述第二电容组充电结束后，若所述第一电压与所述第二电压相等，则确定所述第一电容组和所述第二电容组出现电容断路故障。
其中，在所述充电电流等于所述第二电流与所述第四电流之和的情况下，确定所述第一电容组中出现电容断路故障。在所述充电电流等于所述第一电流与所述第三电流之和的情况下，确定所述第二电容组中出现电容断路故障。
图5为主电容电路部分电容断路故障的一实施例的结构示意图。若主电容电路有电容未安装上、虚焊、电容内部引脚连接不良等断路现象，如图5所示。假设第一电容组的电容C1断路，则充电电流只从电容C3流过，再分别流入电容C2和电容C4，此时充电电流I C＝I 2+I 4，此时电容C3的充电电流更大，电 容两端电压上升更快。假设第二电容组的电容C2断路，则充电电流只从电容C4流回整流桥，此时I C＝I 1+I 3，此时电容C4的充电电流更大，电容两端电压上升更快。所以在电容充电过程中，有断路现象的电容组充电更快，两端电压上升更快。在电容充电结束后，电容间的分压主要取决于均压电阻，由于均压电阻相等，所以U PO＝U ON。可以通过检测充电过程中电容两端电压U PO和U ON的差值，及充电结束后电容两端电压是否趋于相等来判断主电容电路的电容断路故障。当出现此故障时，若伺服驱动器继续工作，会因为纹波电流过高，加剧出现断路故障的电容组老化。
其中，i c、I c都是表示电容充电电流，本领域中习惯在积分公式上用小写的来表达，表示这是个随时间变化的量，而大写的是指某一时刻的值。因为在图5所示的状态下，任何时刻这个等式都成立，所以此处采用I c都是表示电容充电电流。
图11为部分电容断路时的充电波形示意图。若充电过程中，时间0～T1阶段，检测到一组电容电压比另一组的大，且越来越大。时间T1～T2阶段，电压上升较快电容组，电压缓慢下降，另一组则缓慢上升，最终稳定在在U D/2附近，如图11所示。说明主电容电路存在部分电容断路的故障，当电压差值U Δ(U Δ＝|U PO-U ON|)超过预设值时，伺服驱动器输出电容断路报警信号，用户需要更换主电容模块。
在本公开的方案中，通过检测伺服驱动器上电时刻，电容的充电特性，电容电压的变化来判断是否存在器件断路的现象，避免伺服驱动器出现异常工作。也解决了伺服驱动器中串联使用的主电容电路部分器件发生断路故障时，导致电机系统工作异常的问题。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：根据电容电压检测母线电容单元中电阻模块是否出现断路故障的过程，具体参见以下示例性说明。
所述控制单元，具体还被配置为在所述第一电容组和所述第二电容组充电的过程中，所述第一电压和所述第二电压相等。在所述第一电容组和所述第二电容组充电结束后，若所述第一电压和所述第二电压中一个电压变化快，另一个电压变化慢。并且，待所述第一电压和所述第二电压达到新的平衡后，若所述第一电压和所述第二电压的差值超过第二预设值，则确定所述母线电容单元 中的电阻模块出现断路故障或出现老化现象。
图6为主电容电路部分均压电阻断路故障的一实施例的结构示意图。若均压电阻出现虚焊、漏焊或连接不当等断路现象，如图6所示。均压电阻主要影响充电结束后的电压分布，对电容的充电过程影响不大。在电容充电过程中，电容两端电压U PO、U ON相近。当充电结束后，有均压电阻断路的电容组由于阻值变大，电压会缓慢上升，另一组则缓慢下降，达到新的平衡后，如果电容两端电压差值较大，则说明均压电阻可能出现了断路的现象。除了均压电阻出现断路，导致第一电容组和第二电容组的并联阻值差距较大外，也可能是由于电阻老化，阻值变大或电阻错焊等异常现象导致的阻值差距。均压电阻阻值出现异常时，即电阻R1、电阻R3并联后的阻值与电阻R2、电阻R4并联后的阻值有较大差异。在电容充电过程中，电容两端电压U PO、U ON相近。当充电结束后，阻值较大的电容组，电压会缓慢上升，另一组则缓慢下降，达到新的平衡后，如果电容两端电压差值较大，则说明均压电阻可能出现了阻值异常的现象。可以通过检测充电结束后，电容两端电压U PO、U ON的变化来判断主电容电路的均压电阻断路故障或阻值异常。当出现此问题，可能会导致分压较大的电容组因过压而损坏的现象。
图12为部分均压电阻异常时的充电波形示意图。若充电过程中，时间0～T1阶段，检测到两组电容电压上升情况基本一致，而在T1～T2阶段，一组电容电压缓慢上升，另一组缓慢下降，最终达一个稳定状态，如图12所示。说明主电容电路存在部分均压电阻断路故障或均压电阻阻值异常。当电压差值U Δ超过预设值时，伺服驱动器输出均压异常报警信号，用户需要更换主电容模块。
在一些实施方式中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：确定所述母线电容单元中电容模块的老化程度的过程。
所述控制单元，具体还被配置为根据所述母线电容单元中电容模块在充电过程中的充电电流、电容电压和充电时间，确定所述母线电容单元中电容模块的容量的等效串联电阻的阻值。
所述控制单元，具体还被配置为基于设定容量、设定阻值与设定老化程度之间的对应关系，根据所述母线电容单元中电容模块的容量的等效串联电阻的阻值确定所述母线电容单元中电容模块的老化程度。
图7为电解电容等效模型的一实施例的结构示意图。电解电容由于结构特点、材料特性，存在等效串联电阻(ESR)，如图7所示。等效串联电阻影响到电容的充放电时间，纹波电流在其上面产生损耗，电容工作温度升高。电解电容的温升可由纹波电流、ESR和热阻的大小决定，在假设热平衡的条件下，电解电容产生的温升就等于ESR上功率损耗产生的热。电解电容纹波电流产生的热，最主要危害就是明显缩短电容的使用寿命。一般温度每升高10℃，电解电容的使用寿命将折半。但是，当电解电容内部核心接近最大允许温度时，寿命的缩短将不再是每升高10℃而折半，而是急剧缩短。这是因为，电解液受到电容芯包的热应力，使电容的ESR增加10倍多。瞬时超温或者瞬时的过电流都会导致这种情况的发生，使电容损坏。一般用电容值和ESR的阻值来表征电解电容的老化程度，一些方案中使用的寿命判定标准是，ESR的阻值增加一倍或电容值降低到初始值的80％，即过了安全使用期。
在电解电容中，有两个基本公式：
C＝(1/U C)∫i C dt       (1)。
R＝(U DC-U C)/i C       (2)。
其中，C是电解电容的电容量，U C是电解电容两端的电压，i C电解电容的充电电流，U DC是输入电压，t是充电时间，R是电解电容等效串联电阻的阻值。
图8为考虑等效串联电阻的主电容电路的一实施例的结构示意图。如图8所示，考虑等效串联电阻的主电容电路，第一电容组的容值是电解电容C1和电解电容C3并联后的容值，第一电容组的等效串联电阻阻值是ESR1和ESR3并联后的阻值。第二电容组同理。两组电容组的充电电流是相等的。可以通过检测电解电容充电过程的充电电流、电容两端电压，充电时间，来计算出电解电容的容量和等效串联电阻阻值，从而判断电解电容的老化程度。
综上所述，本公开的方案在伺服驱动器的自身电路结构上，进行电路的改进，对伺服驱动器的主电容充电过程中和主电容充电结束后串联电容两端电压、充电电流状态检测，来判断主电容电路是否存在异常。若无异常，则进入正常工作状态。有异常，则采取相应的保护措施。
本公开的方案，还提供了一种电容老化检测方法，通过检测电容容量和等效串联电阻阻值，与初始参数的对比来判断电容的老化程度，采取了电容充电电流、电压及充电时间的检测方式，并根据基本公式计算出电容容量和等效串 联电阻阻值。解决了主电容电路因器件老化，导致电机系统工作异常的问题。
图13为电容老化检测的充电波形示意图。在主电容电路充电过程中，检测电容老化程度，要先确定电解电容的初始容值，等效串联电阻的初始阻值。以第一电容组为例说明，首先，根据所选的电解电容的规格参数，计算出第一电容组的容值、等效串联电阻阻值、第二电容组的容值、等效串联电阻阻值。然后，如图13所示，在电容充电过程取两个时间点t1、t2，则两个时刻的U PO可以检测到分别为U 1、U 2。假设电容两端电压为U Ct1、U Ct2。两个时刻的电容充电电流分别I Ct1、I Ct2。将数据代入到公式(1)、公式(2)得：
C＝(1/U Ct1)∫i C dt       (3)。
R＝(U 1-U Ct1)/I Ct1       (4)。
C＝(1/U Ct2)∫i C dt     (5)。
R＝(U 2-U Ct2)/I Ct2       (6)。
通过式(3)和式(5)电流的积分计算出U Ct1、U Ct2的倍数k值，即：
U Ct2＝kU Ct1        (7)。
将式(7)代入式(6)，再根据式(4)计算出U Ct1，从而计算出等效串联电阻阻值R、电解电容容值C。再与初始的等效串联电阻阻值R 0、初始的电容容值C 0相比，是否满足电容老化的判断标准。若某电容组的等效串联电阻的阻值增加一倍或电容值降低到初始值的80％，即过了安全使用期，伺服驱动器输出电容老化预警信号，提醒用户及时更换主电容模块。
上述实施例是针对两组电容串联使用的情况，当电机系统采用三组电容串联或更多的电容串联时，可以采用相同的原理搭建电路，进行电容异常检测。
上述实施例是基于交流输入380V的伺服驱动器讲述方案，对于其他电压等级的产品，如220V输入、480V输入等，如果主电容采用的是电容串联方式，本公开的方案也适用。
本公开的方案可以推广到空调变频器、光伏逆变器、电机控制器等具有电容串联结构的产品上。
本公开的方案，提供一种应用于伺服驱动器的电容异常检测电路及方法，具体是涉及伺服驱动器、变频器等电机控制领域的一种串联电容的电容异常检测电路，在电机系统启动过程中，通过检测主电容电路的充电特性，判断电路是否存在异常，并进行相应的保护措施。这样，通过在电机系统启动阶段，检 测伺服驱动器是否存在安全隐患，以及时进行故障处理，保证电机系统的安全运行。
采用本公开的技术方案，通过在电机系统的变频设备(如伺服驱动器、变频器)等中设置电容异常检测电路，在电机系统上电阶段，利用电容异常检测电路对变频设备的主电容电路进行异常检测，以在检测到主电容电路存在异常时及时进行故障处理。从而，通过在电机系统上电阶段对电解电容进行全面的故障检测，有利于提升电机系统的安全性。
根据本公开的实施例，还提供了对应于电容检测装置的一种电机控制设备。该电机控制设备可以包括：以上所述的电容检测装置。
由于本实施例的电机系统所实现的处理及功能基本相应于前述装置的实施例、原理和实例，故本实施例的描述中未详尽之处，可以参见前述实施例中的相关说明，在此不做赘述。
采用本公开的技术方案，通过在电机系统的变频设备(如伺服驱动器、变频器)等中设置电容异常检测电路，在电机系统上电阶段，利用电容异常检测电路对变频设备的主电容电路进行异常检测，以在检测到主电容电路存在异常时及时进行故障处理。通过在伺服驱动器上电阶段，检测主电容电路的充电特性，识别故障问题，并进行相应的故障处理，确保伺服驱动器在主电容电路正常的状态下，才开始工作，提高伺服驱动器、变频器等电机系统的可靠性。
根据本公开的实施例，还提供了对应于电机控制设备的一种电容检测方法，如图14所示本公开的方法的一实施例的流程示意图。该电容检测方法可以包括：步骤S110至步骤S140。
在步骤S110处，在所述电机控制设备需要控制所述电机系统上电并启动的情况下，使开关单元处于闭合状态，以使所述电机控制设备通电。
在步骤S120处，在所述电机控制设备控制所述电机系统上电并启动的情况下，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，记为电容电压。并检测流过四个以上所述电容模块的电流，记为电容电流(即充电电流)。
在步骤S130处，根据所述电容电压和所述电容电流中的至少之一，确定 所述母线电容单元是否异常。以及，在确定所述母线电容单元异常的情况下，发出保护信号。
在步骤S140处，根据所述保护信号，使所述开关单元由所述闭合状态切换为断开状态，以使所述电机控制设备断电。
本公开的方案，提供了一种串联电容的异常检测方案，具体是一种伺服驱动器的电容异常检测电路及方法，当电解电容串联使用时，实时检测电容两端电压、充电电流，在设备启动阶段，判断伺服驱动器是否存在安全隐患，并及时处理相应的故障。通过在伺服驱动器里设计一个电容异常检测电路，即在伺服驱动器自身的电路结构上进行改进，在伺服驱动器自身的电路结构上，增加简单的几个器件，实现主电容电路的异常检测，不影响主电路的设计。在电机系统上电阶段，检测主电容电路中电容、均压电阻是否存在异常，具体是在电机系统启动阶段，监测伺服驱动器中主电容电路的充电特性，检测电路短路、断路、电容老化等异常现象，并及时进行相应的故障处理。通过在电机系统启动阶段，监测电容的电压变化、以及电容的充电电流情况，判断是否存在异常，提高伺服驱动器的可靠性，避免电机系统出现安全问题。
如图9所示，在限流起动电路前面串接一个开关K2，当出现短路故障时，可以及时切断电源。将过流检测电阻R8移到整流桥负极与主电容负极之间，既能检测正常工作时主回路的电流I D，也能检测伺服驱动器上电时刻，主电容的充电电流I C。流过电阻R8的电流等于I D+I C。上电时刻，由于再生制动电路和三相逆变模块都不工作，所以I D＝0。正常工作时，电容充电已完成，达到一个平衡状态，I C很小，流过电阻的电流主要是I D，所以不影响过流检测电路的工作。电容检测电路再增加一个电阻R9，并且电阻R5的一端连接到主电容C1、C2串联的中点上，这样就可以同时检测到直流母线电压U D，串联电容的中点电压(也是第二电容组两端电压)U ON。从而算出第一电容组两端的电压：U PO＝U D-U ON。这样可以实时检测主电容电路在充电过程中和充电结束后的电压状态。
在一些实施方式中，所述电容电压，包括以下至少之一：所述母线电容单元的输出端的直流母线电压，所述第一电容组的第一端与所述第一电容组的第二端之间的电压，所述第二电容组的第一端与所述第二电容组的第二端之间的电压。其中，将所述第一电容组的第一端与所述第一电容组的第二端之间的电 压，记为第一电压。将所述第二电容组的第一端与所述第二电容组的第二端之间的电压，记为第二电压。
将所述整流单元输出的直流母线电压，与所述第一电容组和所述第二电容组之间的串联节点的节点电压之差，确定为所述第一电容组两端的电压。并将所述第一电容组和所述第二电容组之间的串联节点的节点电压，确定为所述第二电容组两端的电压。
所述电容电流，包括一下至少之一：流过四个所述电流模块的整体的电流，流过四个以上所述电容模块中每个所述电容模块的电流。其中，流过四个所述电流模块的整体的电流，记为充电电流。流过第一电容模块的电流，记为第一电流。流过第二电容模块的电流，记为第二电流。流过第三电容模块的电流，记为第三电流。流过第四电容模块的电流，记为第四电流。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，包括：根据电容电压检测母线电容单元中电容模块是否出现短路故障的过程，具体包括以下任一种短路故障情形。
第一种短路故障情形：若所述第一电压与所述直流母线电压相等，则确定所述第二电容组中有部分器件出现短路故障。
第二种短路故障情形：若所述第二电压与所述直流母线电压相等，则确定所述第一电容组中有部分器件出现短路故障。
图4为主电容电路部分器件短路故障的一实施例的结构示意图。在伺服驱动器初始上电过程中，如果检测到只有一组电容在充电，则说明主电容电路有短路的现象，如图4所示。若电机系统中针对电解电容的检测，检测到U PO＝U D，则说明O点电压被拉到了直流母线的负极，第二电容组有器件短路。若电机系统中针对电解电容的检测，检测到U ON＝U D，则说明O点电压被拉到了直流母线的正极，第一电容组有器件短路。也就是说，可以通过检测电容两端电压U PO、U ON与直流母线电压U D是否相等来判断主电容电路的短路故障。当出现短路故障时，应立即切断电源输入，否则，短路器件可能会因热量急剧增加而出现安全隐患。电压只加在一组电容上，一组电容会因为过压损坏。
伺服驱动器上电，开关K2闭合，开关K1断开，通过电阻R7限流给主电容电路充电。图10为电容充电过程的电压波形示意图。电容两端电压变化如图10所示，正常情况下，电压U PO、U ON相近，最终稳定在U D/2附近，充电 完成后，开关K2闭合，开关K1闭合，伺服驱动器进入正常工作状态。
若充电过程中，检测到只有一组电容在充电，另一组电容电压一直为零，则主电容电路存在短路故障，开关K2断开，切断电源。
在本公开的方案中，通过在伺服驱动器上电时刻检测串联电容中两组电容的电压，判断是否存在某组电容短路的现象，避免伺服驱动器使用的安全隐患。解决了伺服驱动器中串联使用的主电容电路部分器件发生短路故障时，导致安全事故的问题。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：根据电容电压和电容电流检测母线电容单元中电容模块是否出现断路故障的过程，具体包括：若在所述第一电容组和所述第二电容组充电的过程中，所述第一电压与所述第二电压的差值超过第一预设值。并且，在所述第一电容组和所述第二电容组充电结束后，若所述第一电压与所述第二电压相等，则确定所述第一电容组和所述第二电容组出现电容断路故障。
其中，在所述充电电流等于所述第二电流与所述第四电流之和的情况下，确定所述第一电容组中出现电容断路故障。在所述充电电流等于所述第一电流与所述第三电流之和的情况下，确定所述第二电容组中出现电容断路故障。
图5为主电容电路部分电容断路故障的一实施例的结构示意图。若主电容电路有电容未安装上、虚焊、电容内部引脚连接不良等断路现象，如图5所示。假设第一电容组的电容C1断路，则充电电流只从电容C3流过，再分别流入电容C2和电容C4，此时充电电流I C＝I 2+I 4，此时电容C3的充电电流更大，电容两端电压上升更快。假设第二电容组的电容C2断路，则充电电流只从电容C4流回整流桥，此时I C＝I 1+I 3，此时电容C4的充电电流更大，电容两端电压上升更快。所以在电容充电过程中，有断路现象的电容组充电更快，两端电压上升更快。在电容充电结束后，电容间的分压主要取决于均压电阻，由于均压电阻相等，所以U PO＝U ON。可以通过检测充电过程中电容两端电压U PO和U ON的差值，及充电结束后电容两端电压是否趋于相等来判断主电容电路的电容断路故障。当出现此故障时，若伺服驱动器继续工作，会因为纹波电流过高，加剧出现断路故障的电容组老化。
图11为部分电容断路时的充电波形示意图。若充电过程中，时间0～T1阶 段，检测到一组电容电压比另一组的大，且越来越大。时间T1～T2阶段，电压上升较快电容组，电压缓慢下降，另一组则缓慢上升，最终稳定在在U D/2附近，如图11所示。说明主电容电路存在部分电容断路的故障，当电压差值U Δ(U Δ＝|U PO-U ON|)超过预设值时，伺服驱动器输出电容断路报警信号，用户需要更换主电容模块。
在本公开的方案中，通过检测伺服驱动器上电时刻，电容的充电特性，电容电压的变化来判断是否存在器件断路的现象，避免伺服驱动器出现异常工作。也解决了伺服驱动器中串联使用的主电容电路部分器件发生断路故障时，导致电机系统工作异常的问题。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：根据电容电压检测母线电容单元中电阻模块是否出现断路故障的过程，具体包括：在所述第一电容组和所述第二电容组充电的过程中，所述第一电压和所述第二电压相等。在所述第一电容组和所述第二电容组充电结束后，若所述第一电压和所述第二电压中一个电压变化快，另一个电压变化慢。并且，待所述第一电压和所述第二电压达到新的平衡后，若所述第一电压和所述第二电压的差值超过第二预设值，则确定所述母线电容单元中的电阻模块出现断路故障或出现老化现象。
图6为主电容电路部分均压电阻断路故障的一实施例的结构示意图。若均压电阻出现虚焊、漏焊或连接不当等断路现象，如图6所示。均压电阻主要影响充电结束后的电压分布，对电容的充电过程影响不大。在电容充电过程中，电容两端电压U PO、U ON相近。当充电结束后，有均压电阻断路的电容组由于阻值变大，电压会缓慢上升，另一组则缓慢下降，达到新的平衡后，如果电容两端电压差值较大，则说明均压电阻可能出现了断路的现象。除了均压电阻出现断路，导致第一电容组和第二电容组的并联阻值差距较大外，也可能是由于电阻老化，阻值变大或电阻错焊等异常现象导致的阻值差距。均压电阻阻值出现异常时，即电阻R1、电阻R3并联后的阻值与电阻R2、电阻R4并联后的阻值有较大差异。在电容充电过程中，电容两端电压U PO、U ON相近。当充电结束后，阻值较大的电容组，电压会缓慢上升，另一组则缓慢下降，达到新的平衡后，如果电容两端电压差值较大，则说明均压电阻可能出现了阻值异常的现象。可以通过检测充电结束后，电容两端电压U PO、U ON的变化来判断主电容 电路的均压电阻断路故障或阻值异常。当出现此问题，可能会导致分压较大的电容组因过压而损坏的现象。
图12为部分均压电阻异常时的充电波形示意图。若充电过程中，时间0～T1阶段，检测到两组电容电压上升情况基本一致，而在T1～T2阶段，一组电容电压缓慢上升，另一组缓慢下降，最终达一个稳定状态，如图12所示。说明主电容电路存在部分均压电阻断路故障或均压电阻阻值异常。当电压差值U Δ超过预设值时，伺服驱动器输出均压异常报警信号，用户需要更换主电容模块。
在一些实施方式中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：确定所述母线电容单元中电容模块的老化程度的过程。
下面结合图15所示本公开的方法中确定所述母线电容单元中电容模块的老化程度的一实施例流程示意图，进一步说明确定所述母线电容单元中电容模块的老化程度的具体过程，包括：步骤S201和步骤S202。
步骤S201，根据所述母线电容单元中电容模块在充电过程中的充电电流、电容电压和充电时间，确定所述母线电容单元中电容模块的容量的等效串联电阻的阻值。
步骤S202，基于设定容量、设定阻值与设定老化程度之间的对应关系，根据所述母线电容单元中电容模块的容量的等效串联电阻的阻值确定所述母线电容单元中电容模块的老化程度。
图7为电解电容等效模型的一实施例的结构示意图。电解电容由于结构特点、材料特性，存在等效串联电阻(ESR)，如图7所示。等效串联电阻影响到电容的充放电时间，纹波电流在其上面产生损耗，电容工作温度升高。电解电容的温升可由纹波电流、ESR和热阻的大小决定，在假设热平衡的条件下，电解电容产生的温升就等于ESR上功率损耗产生的热。电解电容纹波电流产生的热，最主要危害就是明显缩短电容的使用寿命。一般温度每升高10℃，电解电容的使用寿命将折半。但是，当电解电容内部核心接近最大允许温度时，寿命的缩短将不再是每升高10℃而折半，而是急剧缩短。这是因为，电解液受到电容芯包的热应力，使电容的ESR增加10倍多。瞬时超温或者瞬时的过电流都会导致这种情况的发生，使电容损坏。一般用电容值和ESR的阻值来表征电解电容的老化程度，一些方案中使用的寿命判定标准是，ESR的阻值增加 一倍或电容值降低到初始值的80％，即过了安全使用期。
在电解电容中，有两个基本公式：
C＝(1/U C)∫i C dt        (1)。
R＝(U DC-U C)/i C        (2)。
其中，C是电解电容的电容量，U C是电解电容两端的电压，i C电解电容的充电电流，U DC是输入电压，t是充电时间，R是电解电容等效串联电阻的阻值。
图8为考虑等效串联电阻的主电容电路的一实施例的结构示意图。如图8所示，考虑等效串联电阻的主电容电路，第一电容组的容值是电解电容C1和电解电容C3并联后的容值，第一电容组的等效串联电阻阻值是ESR1和ESR3并联后的阻值。第二电容组同理。两组电容组的充电电流是相等的。可以通过检测电解电容充电过程的充电电流、电容两端电压，充电时间，来计算出电解电容的容量和等效串联电阻阻值，从而判断电解电容的老化程度。
综上所述，本公开的方案在伺服驱动器的自身电路结构上，进行电路的改进，对伺服驱动器的主电容充电过程中和主电容充电结束后串联电容两端电压、充电电流状态检测，来判断主电容电路是否存在异常。若无异常，则进入正常工作状态。有异常，则采取相应的保护措施。
本公开的方案，还提供了一种电容老化检测方法，通过检测电容容量和等效串联电阻阻值，与初始参数的对比来判断电容的老化程度，采取了电容充电电流、电压及充电时间的检测方式，并根据基本公式计算出电容容量和等效串联电阻阻值。解决了主电容电路因器件老化，导致电机系统工作异常的问题。
图13为电容老化检测的充电波形示意图。在主电容电路充电过程中，检测电容老化程度，要先确定电解电容的初始容值，等效串联电阻的初始阻值。以第一电容组为例说明，首先，根据所选的电解电容的规格参数，计算出第一电容组的容值、等效串联电阻阻值、第二电容组的容值、等效串联电阻阻值。然后，如图13所示，在电容充电过程取两个时间点t1、t2，则两个时刻的U PO可以检测到分别为U 1、U 2。假设电容两端电压为U Ct1、U Ct2。两个时刻的电容充电电流分别I Ct1、I Ct2。将数据代入到公式(1)、公式(2)得：
C＝(1/U Ct1)∫i C dt       (3)。
R＝(U 1-U Ct1)/I Ct1      (4)。
C＝(1/U Ct2)∫i C dt      (5)。
R＝(U 2-U Ct2)/I Ct2        (6)。
通过式(3)和式(5)电流的积分计算出U Ct1、U Ct2的倍数k值，即：
U Ct2＝kU Ct1       (7)。
将式(7)代入式(6)，再根据式(4)计算出U Ct1，从而计算出等效串联电阻阻值R、电解电容容值C。再与初始的等效串联电阻阻值R 0、初始的电容容值C 0相比，是否满足电容老化的判断标准。若某电容组的等效串联电阻的阻值增加一倍或电容值降低到初始值的80％，即过了安全使用期，伺服驱动器输出电容老化预警信号，提醒用户及时更换主电容模块。
本公开的方案，提供一种应用于伺服驱动器的电容异常检测电路及方法，具体是涉及伺服驱动器、变频器等电机控制领域的一种串联电容的电容异常检测电路，在电机系统启动过程中，通过检测主电容电路的充电特性，判断电路是否存在异常，并进行相应的保护措施。这样，通过在电机系统启动阶段，检测伺服驱动器是否存在安全隐患，以及时进行故障处理，保证电机系统的安全运行。
由于本实施例的方法所实现的处理及功能基本相应于前述电机系统的实施例、原理和实例，故本实施例的描述中未详尽之处，可以参见前述实施例中的相关说明，在此不做赘述。
采用本实施例的技术方案，通过在电机系统的变频设备(如伺服驱动器、变频器)等中设置电容异常检测电路，在电机系统上电阶段，利用电容异常检测电路对变频设备的主电容电路进行异常检测，以在检测到主电容电路存在异常时及时进行故障处理；通过在伺服驱动器里设计一个电容异常电路，通过在上电阶段，检测电容的电压变化，充电电流，实现串联电容的异常检测及相应的保护处理，增强了伺服驱动器的可靠性，可根据电容的选型调节参数，增加适用范围，提升了伺服驱动器的市场竞争力。
综上，本领域技术人员容易理解的是，在不冲突的前提下，上述各有利方式可以自由地组合、叠加。
以上所述仅为本公开的实施例而已，并不用于限制本公开，对于本领域的技术人员来说，本公开可以有各种更改和变化。凡在本公开的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本公开的权利要求范围之内。

Claims (18)

  1. 一种电容检测装置，所述电容检测装置，能够应用于电机系统的电机控制设备；所述电机控制设备，包括：整流单元、母线电容单元、逆变单元、检测单元和控制单元；所述母线电容单元，包括：电容模块和电阻模块；所述电容模块的数量为四个以上，所述电阻模块的数量与所述电容模块的数量相同；四个以上所述电容模块分为两个电容组，第一电容组中的两个电容模块并联设置，第二电容组中的两个电容模块也并联设置，第一电容组和第二电容组串联设置；每个所述电容模块与其相对应的一个所述电阻模块并联；
    所述电容检测装置，包括：开关单元；其中，
    所述开关单元，被配置为在所述电机控制设备需要控制所述电机系统上电并启动的情况下，处于闭合状态，以使所述电机控制设备通电；
    所述检测单元，被配置为在所述电机控制设备控制所述电机系统上电并启动的情况下，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，记为电容电压；并检测流过四个以上所述电容模块的电流，记为电容电流；
    所述控制单元，被配置为根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常；以及，在确定所述母线电容单元异常的情况下，发出保护信号；
    所述开关单元，还被配置为根据所述保护信号，由所述闭合状态切换为断开状态，以使所述电机控制设备断电。
  2. 根据权利要求1所述的电容检测装置，其中，四个以上所述电容模块，包括：第一电容模块、第二电容模块、第三电容模块和第四电容模块；
    所述第一电容模块和所述第三电容模块串联，形成所述第一电容组；
    所述第二电容模块和所述第四电容模块串联，形成所述第二电容组；
    所述检测单元，包括：电压采样模块和电流采样模块；其中，
    所述检测单元，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，包括：
    所述电压采样模块，设置在所述母线电容单元的输出端的母线正负端之间，被配置为检测四个以上所述电容模块中至少一个所述电容模块两端的电压；
    所述检测单元，检测流过四个以上所述电容模块的电流，包括：
    所述电流采样模块，设置在所述整流桥的输出端的母线负端与所述母线电容单元的输入端的母线负端之间，被配置为检测流过四个以上所述电容模块的电流。
  3. 根据权利要求2所述的电容检测装置，其中，所述电压采样模块，包括：第一采样电阻模块、第二采样电阻模块和第三采样电阻模块；
    其中，所述第一采样电阻模块、所述第二采样电阻模块和所述第三采样电阻模块，设置在所述母线电容单元的输出端的母线正负端之间；
    所述第一采样电阻模块与所述第二采样电阻模块的公共端，连接至所述第一电容模块和所述第二电容模块的公共端，并连接至所述第三电容模块和所述第四电容模块的公共端；
    所述电流采样模块，包括：第四采样电阻模块；所述第四采样模块，设置在所述整流桥的输出端的母线负端与所述母线电容单元的输入端的母线负端之间。
  4. 根据权利要求3所述的电容检测装置，其中，所述电机控制设备，还包括：再生制动单元；
    所述再生制动单元，设置在所述母线电容单元与所述逆变单元之间；所述电压采样模块，设置在所述母线电容单元与所述再生制动单元之间。
  5. 根据权利要求1所述的电容检测装置，其中，所述开关单元，设置在所述整流桥的输出端的直流母线正端与所述母线电容单元的输入端的直流母线正端之间。
  6. 根据权利要求5所述的电容检测装置，其中，所述电机控制设备，还包括：限流起动单元；
    所述开关单元，设置在所述整流桥与所述限流起动单元之间。
  7. 根据权利要求1至6中任一项所述的电容检测装置，其中，所述电容电压，包括以下至少之一：
    所述母线电容单元的输出端的直流母线电压，所述第一电容组的第一端与所述第一电容组的第二端之间的电压，所述第二电容组的第一端与所述第二电容组的第二端之间的电压；其中，将所述第一电容组的第一端与所述第一电容组的第二端之间的电压，记为第一电压；将所述第二电容组的第一端与所述第 二电容组的第二端之间的电压，记为第二电压；
    所述电容电流，包括一下至少之一：流过四个所述电流模块的整体的电流，流过四个以上所述电容模块中每个所述电容模块的电流；其中，
    流过四个所述电流模块的整体的电流，记为充电电流；流过第一电容模块的电流，记为第一电流；流过第二电容模块的电流，记为第二电流；流过第三电容模块的电流，记为第三电流；流过第四电容模块的电流，记为第四电流。
  8. 根据权利要求7所述的电容检测装置，其中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，包括：
    若所述第一电压与所述直流母线电压相等，则确定所述第二电容组中有部分器件出现短路故障；
    若所述第二电压与所述直流母线电压相等，则确定所述第一电容组中有部分器件出现短路故障。
  9. 根据权利要求7所述的电容检测装置，其中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：
    若在所述第一电容组和所述第二电容组充电的过程中，所述第一电压与所述第二电压的差值超过第一预设值；并且，在所述第一电容组和所述第二电容组充电结束后，若所述第一电压与所述第二电压相等，则确定所述第一电容组和所述第二电容组出现电容断路故障；
    其中，在所述充电电流等于所述第二电流与所述第四电流之和的情况下，确定所述第一电容组中出现电容断路故障；在所述充电电流等于所述第一电流与所述第三电流之和的情况下，确定所述第二电容组中出现电容断路故障。
  10. 根据权利要求7所述的电容检测装置，其中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：
    在所述第一电容组和所述第二电容组充电结束后，若所述第一电压和所述第二电压中一个电压变化快，另一个电压变化慢；并且，待所述第一电压和所述第二电压达到新的平衡后，若所述第一电压和所述第二电压的差值超过第二预设值，则确定所述母线电容单元中的电阻模块出现断路故障或出现老化现 象。
  11. 根据权利要求7所述的电容检测装置，其中，所述控制单元，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：
    根据所述母线电容单元中电容模块在充电过程中的充电电流、电容电压和充电时间，确定所述母线电容单元中电容模块的容量的等效串联电阻的阻值；
    基于设定容量、设定阻值与设定老化程度之间的对应关系，根据所述母线电容单元中电容模块的容量的等效串联电阻的阻值确定所述母线电容单元中电容模块的老化程度。
  12. 一种电机控制设备，包括：如权利要求1至11中任一项所述的电容检测装置。
  13. 一种如权利要求12所述的电机控制设备中电容检测方法，包括：
    在所述电机控制设备需要控制所述电机系统上电并启动的情况下，使开关单元处于闭合状态，以使所述电机控制设备通电；
    在所述电机控制设备控制所述电机系统上电并启动的情况下，检测四个以上所述电容模块中至少一个所述电容模块两端的电压，记为电容电压；并检测流过四个以上所述电容模块的电流，记为电容电流；
    根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常；以及，在确定所述母线电容单元异常的情况下，发出保护信号；
    根据所述保护信号，使所述开关单元由所述闭合状态切换为断开状态，以使所述电机控制设备断电。
  14. 根据权利要求13所述的电容检测方法，其中，所述电容电压，包括以下至少之一：
    所述母线电容单元的输出端的直流母线电压，所述第一电容组的第一端与所述第一电容组的第二端之间的电压，所述第二电容组的第一端与所述第二电容组的第二端之间的电压；其中，将所述第一电容组的第一端与所述第一电容组的第二端之间的电压，记为第一电压；将所述第二电容组的第一端与所述第二电容组的第二端之间的电压，记为第二电压；
    所述电容电流，包括一下至少之一：流过四个所述电流模块的整体的电流，流过四个以上所述电容模块中每个所述电容模块的电流；其中，
    流过四个所述电流模块的整体的电流，记为充电电流；流过第一电容模块的电流，记为第一电流；流过第二电容模块的电流，记为第二电流；流过第三电容模块的电流，记为第三电流；流过第四电容模块的电流，记为第四电流。
  15. 根据权利要求14所述的电容检测方法，其中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，包括：
    若所述第一电压与所述直流母线电压相等，则确定所述第二电容组中有部分器件出现短路故障；
    若所述第二电压与所述直流母线电压相等，则确定所述第一电容组中有部分器件出现短路故障。
  16. 根据权利要求14所述的电容检测方法，其中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：
    若在所述第一电容组和所述第二电容组充电的过程中，所述第一电压与所述第二电压的差值超过第一预设值；并且，在所述第一电容组和所述第二电容组充电结束后，若所述第一电压与所述第二电压相等，则确定所述第一电容组和所述第二电容组出现电容断路故障；
    其中，在所述充电电流等于所述第二电流与所述第四电流之和的情况下，确定所述第一电容组中出现电容断路故障；在所述充电电流等于所述第一电流与所述第三电流之和的情况下，确定所述第二电容组中出现电容断路故障。
  17. 根据权利要求14所述的电容检测方法，其中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：
    在所述第一电容组和所述第二电容组充电结束后，若所述第一电压和所述第二电压中一个电压变化快，另一个电压变化慢；并且，待所述第一电压和所述第二电压达到新的平衡后，若所述第一电压和所述第二电压的差值超过第二预设值，则确定所述母线电容单元中的电阻模块出现断路故障或出现老化现象。
  18. 根据权利要求14所述的电容检测方法，其中，根据所述电容电压和所述电容电流中的至少之一，确定所述母线电容单元是否异常，还包括：
    根据所述母线电容单元中电容模块在充电过程中的充电电流、电容电压和充电时间，确定所述母线电容单元中电容模块的容量的等效串联电阻的阻值；
    基于设定容量、设定阻值与设定老化程度之间的对应关系，根据所述母线 电容单元中电容模块的容量的等效串联电阻的阻值确定所述母线电容单元中电容模块的老化程度。
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