A protection device, method and motor system for an IGBT module in a frequency converter

Abstract

The present invention discloses a protection device, method and motor system for an IGBT module in an inverter. The device includes: a collection unit that collects three-phase currents of the inverter, collects the peak voltage between the collector and emitter of the IGBT module, and collects the bus voltage of the DC power supply; a control unit that determines whether the inverter is operating normally based on at least one of the collected three-phase currents, peak voltage, and bus voltage; and, in the case where the inverter is not operating normally, controls the IGBT module to remain in the off state and issues a control signal to control the IGBT peak voltage suppression unit to suppress the peak voltage between the collector and emitter of the IGBT module. With this solution, when the inverter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off and the peak voltage of the IGBT module is suppressed, avoiding damage to the IGBT module when the inverter is overloaded or a short circuit occurs in the bridge arm of the inverter bridge.

Description

Technical Field

[0001] The present invention belongs to the technical field of frequency converters, and particularly relates to a protection device, method and motor system for an IGBT module in a frequency converter, and more particularly to a fault detection device, method and motor system for an IGBT module in a frequency converter. Background Art

[0002] At the front end of the frequency converter, an industrial alternating current is converted into direct current by a rectifier bridge and supplied to the back end; at the back end of the frequency converter, a controllable inverter bridge composed of IGBT modules can be used to invert the direct current into alternating current and supply it to the motor winding to drive the motor to operate. Among them, the IGBT module will be damaged when the frequency converter is overloaded or a short circuit occurs in the bridge arm of the inverter bridge.

[0003] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The purpose of the present invention is to provide a protection device, method and motor system for an IGBT module in a frequency converter to solve the problem that the IGBT module will be damaged when the frequency converter is overloaded or a short circuit occurs in the bridge arm of the inverter bridge, and achieve the effect of avoiding damage to the IGBT module when the frequency converter is overloaded or a short circuit occurs in the bridge arm of the inverter bridge.

[0005] The present invention provides a protection device for an IGBT module in a frequency converter, including: a collection unit, an IGBT peak voltage suppression unit and a control unit; wherein, the collection unit is configured to collect the three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter when the inverter bridge is working after the frequency converter is powered on; the control unit is configured to determine whether the frequency converter is working normally according to at least one of the collected three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter; and, when the frequency converter is not working normally, control the IGBT module to remain in the off state and initiate a control signal capable of controlling the IGBT peak voltage suppression unit; the IGBT peak voltage suppression unit is configured to suppress the peak voltage between the collector and emitter of the IGBT module under the control of the control signal.

[0006] In some embodiments, the acquisition unit includes: a current acquisition unit, a voltage acquisition unit, and a voltage capture unit; the number of the voltage acquisition units is the same as the number of IGBT modules in the inverter bridge; each of the voltage acquisition units is configured to collect the spike voltage between the collector and the emitter of a corresponding IGBT module when the inverter bridge is operating after the frequency converter is powered on; wherein, the acquisition unit collects the three-phase current of the frequency converter and the spike voltage between the collector and the emitter of the IGBT module, including: the current acquisition unit is configured to collect the three-phase current of the frequency converter; the voltage acquisition unit is configured to collect the spike voltage between the collector and the emitter of the IGBT module; the voltage capture unit is configured to collect the bus voltage of the DC power supply of the frequency converter; correspondingly, the control unit determines whether the frequency converter is operating normally according to at least one of the collected three-phase current of the frequency converter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter, including: if the collected three-phase current of the frequency converter shows that the frequency converter has a normal three-phase current output, and the amplitude of the three-phase current output by the frequency converter becomes larger and exceeds the set current amplitude, it is determined that the frequency converter is overloaded; and, if the spike voltage between the collector and the emitter of the IGBT module exceeds the set voltage threshold, it is determined that the frequency converter is not operating normally, that is, it is determined that the frequency converter is overloaded and not operating normally; or, comparing the collected spike voltage between the collector and the emitter of the IGBT module with the set voltage between the collector and the emitter of the IGBT module; and comparing the bus voltage of the DC power supply of the frequency converter with the set bus voltage; and, if the spike voltage between the collector and the emitter of the IGBT module collected changes suddenly relative to the set voltage between the collector and the emitter of the IGBT module; and, the bus voltage of the DC power supply of the frequency converter drops relative to the set bus voltage, it is determined that the frequency converter is not operating normally, that is, it is determined that the arm of the inverter bridge is short-circuited.

[0007] In some embodiments, the number of the IGBT spike voltage suppression units is the same as the number of IGBT modules in the inverter bridge of the frequency converter; each of the IGBT spike voltage suppression units is specifically arranged between a corresponding IGBT module and the driver board of the IGBT module; the control unit controls the IGBT module to remain in the off state and issues a control signal capable of controlling the IGBT spike voltage suppression unit, including: in the case that the frequency converter is not operating normally, turning off the IGBT module and issuing a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located.

[0008] In some embodiments, each of the IGBT spike voltage suppression units includes a resistance suppression module and a voltage source suppression module. The resistance suppression module is disposed between the output terminal of the driving board of the IGBT module and the gate of the IGBT module. The voltage source suppression module is disposed between the input terminal of the driving board of the IGBT module and the emitter of the IGBT module. Wherein, the IGBT spike voltage suppression unit suppresses the spike voltage between the collector and the emitter of the IGBT module under the control of the control signal, including: the resistance suppression module is configured to suppress the spike voltage between the collector and the emitter of the IGBT module by utilizing its own resistance value; the voltage source suppression module is configured to further suppress the spike voltage between the collector and the emitter of the IGBT module by utilizing the negative voltage source provided by itself when it is connected.

[0009] In some embodiments, the control signal includes a resistance value adjustment signal capable of adjusting the resistance value of the resistance suppression module and a voltage source connection or disconnection signal capable of controlling the connection or disconnection of the voltage source suppression module. Wherein, the control unit issues a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located, including: issuing a resistance value adjustment signal for adjusting the resistance value of the gate resistance suppression module corresponding to the another IGBT module; after the gate resistance suppression module corresponding to the another IGBT module adjusts its resistance value based on the resistance value adjustment signal, determining again whether the spike voltage between the collector and the emitter of the IGBT module turned off on the arm where the another IGBT module is located still exceeds the set voltage threshold; if the spike voltage between the collector and the emitter of the IGBT module turned off on the arm where the another IGBT module is located still exceeds the set voltage threshold, then issuing a voltage source connection signal capable of controlling the connection of the voltage source suppression module corresponding to the another IGBT module.

[0010] In some embodiments, it further includes: the control unit is further configured to, after initiating a control signal capable of controlling the IGBT spike voltage suppression unit, if the situation where the frequency converter does not work properly is that the frequency converter is overloaded, initiate a reminder message of the frequency converter overload to remind the user to adjust the load of the frequency converter to within the rated load range; if the situation where the frequency converter does not work properly is that the arm of the inverter bridge is short-circuited, locate and remove the fault of the short-circuited arm of the inverter bridge; and, when the frequency converter outputs to the bearing controller, transmit the message of the arm short-circuit of the inverter bridge to the bearing controller through the communication channel, so that the bearing controller can start its own protection mechanism in time when it learns of the fault of the inverter bridge.

[0011] In some embodiments, the control unit locates the short-circuited arm of the inverter bridge, including: comparing the spike voltage between the collector and the emitter of the IGBT module collected with the set voltage between the collector and the emitter of this IGBT module to obtain a first voltage residual; and comparing the bus voltage of the DC power supply of the frequency converter with the set bus voltage to obtain a second voltage residual; and processing the first voltage residual and the second voltage residual to realize the location of the short-circuited arm of the inverter bridge.

[0012] Matched with the above device, on the other hand, the present invention provides a motor system, including: the protection device of the IGBT module in the above-mentioned frequency converter.

[0013] Matched with the above motor system, on the other hand, the present invention provides a protection method for the IGBT module in the frequency converter, including: through the acquisition unit, when the inverter bridge works after the frequency converter is powered on, acquire the three-phase current of the frequency converter, acquire the spike voltage between the collector and the emitter of the IGBT module, and acquire the bus voltage of the DC power supply of the frequency converter; through the control unit, determine whether the frequency converter works properly according to at least one of the acquired three-phase current of the frequency converter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter; and, when the frequency converter does not work properly, control the IGBT module to remain in the off state and initiate a control signal capable of controlling the IGBT spike voltage suppression unit; through the IGBT spike voltage suppression unit, under the control of the control signal, suppress the spike voltage between the collector and the emitter of the IGBT module.

[0014] In some embodiments, the acquisition unit includes: a current acquisition unit, a voltage acquisition unit, and a voltage capture unit; the number of the voltage acquisition units is the same as the number of IGBT modules in the inverter bridge; each of the voltage acquisition units is configured to collect the spike voltage between the collector and the emitter of one IGBT module corresponding thereto when the inverter bridge is operating after the frequency converter is powered on; wherein, collecting the three-phase current of the frequency converter and the spike voltage between the collector and the emitter of the IGBT module through the acquisition unit includes: collecting the three-phase current of the frequency converter through the current acquisition unit; collecting the spike voltage between the collector and the emitter of the IGBT module through the voltage acquisition unit; collecting the bus voltage of the DC power supply of the frequency converter through the voltage capture unit; correspondingly, determining whether the frequency converter is operating normally by the control unit according to at least one of the collected three-phase current of the frequency converter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter includes: if the collected three-phase current of the frequency converter shows that the frequency converter has a normal three-phase current output, and the amplitude of the three-phase current output by the frequency converter becomes larger and exceeds the set current amplitude, it is determined that the frequency converter is overloaded; and, if the spike voltage between the collector and the emitter of the IGBT module exceeds the set voltage threshold, it is determined that the frequency converter is not operating normally, that is, it is determined that the frequency converter is overloaded and not operating normally; or, comparing the collected spike voltage between the collector and the emitter of the IGBT module with the set voltage between the collector and the emitter of this IGBT module; and comparing the bus voltage of the DC power supply of the frequency converter with the set bus voltage; and, if the spike voltage between the collector and the emitter of the IGBT module collected changes suddenly relative to the set voltage between the collector and the emitter of this IGBT module; and the bus voltage of the DC power supply of the frequency converter drops relative to the set bus voltage, it is determined that the frequency converter is not operating normally, that is, it is determined that the arm of the inverter bridge is short-circuited.

[0015] In some embodiments, the number of the IGBT spike voltage suppression units is the same as the number of IGBT modules in the inverter bridge of the frequency converter; each of the IGBT spike voltage suppression units is specifically arranged between one IGBT module corresponding thereto and the driver board of this IGBT module; controlling the IGBT module to remain in the off state and initiating a control signal capable of controlling the IGBT spike voltage suppression unit by the control unit includes: when the frequency converter is not operating normally, turning off the IGBT module and initiating a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where this IGBT module is located.

[0016] In some embodiments, each of the IGBT spike voltage suppression units includes a resistor suppression module and a voltage source suppression module. The resistor suppression module is disposed between the output terminal of the driving board of the IGBT module and the gate of the IGBT module. The voltage source suppression module is disposed between the input terminal of the driving board of the IGBT module and the emitter of the IGBT module. Wherein, through the IGBT spike voltage suppression unit, under the control of the control signal, the spike voltage between the collector and the emitter of the IGBT module is suppressed, including: through the resistor suppression module, by utilizing its own resistance value, to suppress the spike voltage between the collector and the emitter of the IGBT module; through the voltage source suppression module, by utilizing the negative voltage source provided by itself when it is connected, to further suppress the spike voltage between the collector and the emitter of the IGBT module.

[0017] In some embodiments, the control signal includes a resistance value adjustment signal capable of adjusting the resistance value of the resistor suppression module, and a voltage source connection or disconnection signal capable of controlling the connection or disconnection of the voltage source suppression module. Wherein, through the control unit, the control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the same arm as the IGBT module includes: initiating a resistance value adjustment signal for adjusting the resistance value of the gate resistance suppression module corresponding to the another IGBT module; after the gate resistance suppression module corresponding to the another IGBT module adjusts its resistance value based on the resistance value adjustment signal, determining again whether the spike voltage between the collector and the emitter of the turned-off IGBT module on the same arm as the another IGBT module still exceeds the set voltage threshold; if the spike voltage between the collector and the emitter of the turned-off IGBT module on the same arm as the another IGBT module still exceeds the set voltage threshold, then initiating a voltage source connection signal capable of controlling the connection of the voltage source suppression module corresponding to the another IGBT module.

[0018] In some embodiments, it further includes: after the control unit issues a control signal capable of controlling the IGBT spike voltage suppression unit, if the abnormal operation of the frequency converter is due to the overload of the frequency converter, a reminder message of the overload of the frequency converter is issued to remind the user to adjust the load of the frequency converter within the rated load range; if the abnormal operation of the frequency converter is due to the short circuit of the arm of the inverter bridge, position and remove the fault of the short-circuited arm of the inverter bridge; and when the frequency converter outputs to the bearing controller, the message of the short circuit of the arm of the inverter bridge is transmitted to the bearing controller through the communication channel, so that the bearing controller can start its own protection mechanism in time when it knows the fault of the inverter bridge.

[0019] In some embodiments, the control unit locates the short-circuited arm of the inverter bridge by: comparing the spike voltage between the collector and the emitter of the IGBT module collected with the set voltage between the collector and the emitter of the IGBT module to obtain a first voltage residual; comparing the bus voltage of the DC power supply of the frequency converter with the set bus voltage to obtain a second voltage residual; and processing the first voltage residual and the second voltage residual to achieve the positioning of the short-circuited arm of the inverter bridge.

[0020] Thus, in the solution of the present invention, by setting an IGBT spike voltage suppression unit at the gate of the IGBT, when the frequency converter is overloaded and the arm of the inverter bridge is short-circuited, the IGBT is turned off, and the IGBT module spike voltage is suppressed by the IGBT spike voltage suppression unit, avoiding damage to the device of the IGBT module when the frequency converter is overloaded or the arm of the inverter bridge is short-circuited.

[0021] Furthermore, in the solution of the present invention, after the suppression measure fails, that is, when the spike voltage exceeds the set threshold, the fault of the IGBT module is quickly detected, the fault is cut off in time, and the system is not allowed to operate with a phase missing, ensuring the safe and reliable operation of the frequency converter system.

[0022] Other features and advantages of the present invention will be described in the following description, and, in part, will be obvious from the description or learned by implementing the present invention.

[0023] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of an embodiment of the protection device for the IGBT module in the frequency converter of the present invention;

[0025] Figure 2 It is a schematic structural diagram of an embodiment of the frequency converter;

[0026] Figure 3 Schematic structural diagram of an embodiment of the power supply control system for an electric motor;

[0027] Figure 4 Schematic structural diagram of a driving structure of an embodiment of an IGBT;

[0028] Figure 5 Schematic structural diagram of an embodiment of an IGBT peak voltage suppression and fault detection system for an inverter bridge;

[0029] Figure 6 Schematic diagram of curves of Ic current, PWM drive signal, and Vce voltage when the peak voltage is 820V without peak voltage suppression;

[0030] Figure 7 Schematic diagram of curves of Ic current, PWM drive signal, and Vce voltage when the peak voltage is 780V with peak voltage suppression;

[0031] Figure 8 Schematic flow diagram of an embodiment of a method for detecting IGBT faults in an inverter;

[0032] Figure 9 Schematic flow diagram of an embodiment of a method for protecting an IGBT module in an inverter of the present invention;

[0033] Figure 10 Schematic flow diagram of an embodiment of the judgment process of whether an inverter is overloaded in the method of the present invention;

[0034] Figure 11 Schematic flow diagram of an embodiment of the judgment process of whether the arm of an inverter bridge is short - circuited in the method of the present invention;

[0035] Figure 12 Schematic flow diagram of an embodiment of a control signal for controlling the IGBT peak voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located in the method of the present invention;

[0036] Figure 13 Schematic flow diagram of an embodiment of locating the short - circuited arm of the inverter bridge in the method of the present invention. Detailed implementation manners

[0037] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0038] According to an embodiment of the present invention, a protection device for an IGBT module in an inverter is provided. Refer to Figure 1 the structural schematic diagram of an embodiment of the device of the present invention as shown. The protection device for the IGBT module in the inverter may include: a collection unit, an IGBT spike voltage suppression unit, and a control unit. The GBT spike voltage suppression unit is disposed between the gate of the IGBT module and the drive board of the IGBT module. The IGBT module includes: an IGBT and a diode connected in parallel between the collector and the emitter of the IGBT.

[0039] Specifically, the collection unit is configured to collect the three-phase current of the inverter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the inverter when the inverter is powered on and the inverter bridge is working.

[0040] Specifically, the control unit is configured to determine whether the inverter is working properly, that is, to determine whether the inverter is overloaded or whether the arm of the inverter bridge is short-circuited, according to at least one of the three-phase current of the inverter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the inverter; and, when the inverter is not working properly, that is, when the inverter is overloaded or the arm of the inverter bridge is short-circuited, control the IGBT module to remain in the off state, and initiate a control signal capable of controlling the IGBT spike voltage suppression unit to control the IGBT spike voltage suppression unit to start, and control the IGBT spike voltage suppression unit to suppress the spike voltage between the collector and the emitter of the IGBT module.

[0041] Wherein, when the inverter is overloaded or the arm of the inverter bridge is short-circuited, the other IGBT module of the arm is controlled not to conduct (that is, when overload and short circuit occur in the upper tube of the arm, the lower tube is always closed).

[0042] Specifically, the IGBT spike voltage suppression unit is configured to suppress the spike voltage between the collector and the emitter of the IGBT module under the control of the control signal.

[0043] Therefore, in view of the problem that the devices will be damaged when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, an IGBT spike voltage suppression unit is set at the gate of the IGBT. When the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off, and the spike voltage of the IGBT module is suppressed through the IGBT spike voltage suppression unit, so as to prevent the IGBT module from being damaged when the frequency converter is overloaded or a short circuit occurs in the inverter bridge.

[0044] In some embodiments, the acquisition unit includes a current acquisition unit, a voltage acquisition unit, and a voltage capture unit. The number of the voltage acquisition units is the same as the number of IGBT modules in the inverter bridge. Each of the voltage acquisition units is configured to acquire the spike voltage between the collector and the emitter of a corresponding IGBT module when the inverter bridge is working after the frequency converter is powered on.

[0045] Wherein, when the inverter bridge is working after the frequency converter is powered on, the acquisition unit acquires the three-phase current of the frequency converter and the spike voltage between the collector and the emitter of the IGBT module, including:

[0046] The current acquisition unit, such as a current sensor, is configured to acquire the three-phase current of the frequency converter.

[0047] The voltage acquisition unit, such as a voltage sensor, is configured to acquire the spike voltage between the collector and the emitter of the IGBT module.

[0048] The voltage capture unit, such as a voltage capture circuit, is configured to acquire the bus voltage of the DC power supply of the frequency converter.

[0049] Correspondingly, the control unit determines whether the frequency converter is working normally, that is, determines whether the frequency converter is overloaded or whether the bridge arm of the inverter bridge is short-circuited, according to at least one of the acquired three-phase current of the frequency converter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter. The judgment process of whether the frequency converter is overloaded may specifically include:

[0050] The control unit is specifically further configured that if the acquired three-phase current of the frequency converter shows that the frequency converter has a normal three-phase current output, and the amplitude of the three-phase current output by the frequency converter becomes larger and exceeds the set current amplitude, it is determined that the frequency converter is overloaded. And,

[0051] The control unit is specifically further configured that in the case of the frequency converter being overloaded, if the acquired spike voltage between the collector and the emitter of the IGBT module exceeds the set voltage threshold, it is determined that the frequency converter is not working normally, that is, it is determined that the frequency converter is overloaded and not working normally.

[0052] Specifically, it is detected by a current sensor that the frequency converter has a normal three-phase current output, and the amplitude increases and exceeds the set threshold value i lim When this happens, it is determined that the frequency converter is in an overload state. When the peak voltage V of an IGBT in a bridge arm CE exceeds the set voltage threshold, it is necessary to suppress the peak voltage of the IGBT.

[0053] Alternatively, the control unit determines whether the frequency converter is operating normally, that is, determines whether the frequency converter is overloaded or whether the bridge arm of the inverter bridge is short-circuited, based on at least one of the three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter collected. It also includes: the judgment process of whether the bridge arm of the inverter bridge is short-circuited, which may specifically include:

[0054] The control unit is specifically further configured to compare the peak voltage between the collector and emitter of the IGBT module collected with the set voltage between the collector and emitter of this IGBT module; and compare the bus voltage of the DC power supply of the frequency converter with the set bus voltage; and,

[0055] The control unit is specifically further configured to determine that the frequency converter is not operating normally, that is, determine that the bridge arm of the inverter bridge is short-circuited, if the peak voltage between the collector and emitter of the IGBT module collected changes suddenly with respect to the set voltage between the collector and emitter of this IGBT module; and the bus voltage of the DC power supply of the frequency converter drops with respect to the set bus voltage.

[0056] Specifically, when a short circuit occurs in the inverter bridge of the frequency converter, the peak voltage value V between the collector and emitter of the IGBT CE will change suddenly (such as Figure 4 shown as u ce4 ), and the bus voltage U DC will also drop instantaneously.

[0057] In some embodiments, the number of the IGBT peak voltage suppression units is the same as the number of IGBT modules in the inverter bridge of the frequency converter. Each of the IGBT peak voltage suppression units is specifically disposed between a corresponding IGBT module and the driver board of this IGBT module. Specifically, there are IGBT peak voltage suppression units and fault detection and processing units on all three bridge arms of the inverter bridge.

[0058] The control unit, when the frequency converter is not working properly, that is, when the frequency converter is overloaded or a short circuit occurs in the bridge arm of the inverter bridge, controls the IGBT module to remain in the off state and issues a control signal capable of controlling the IGBT spike voltage suppression unit, including: The control unit is specifically further configured to, when the frequency converter is not working properly, turn off the IGBT module and issue a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the bridge arm where the IGBT module is located.

[0059] Thus, by turning off the IGBT when the frequency converter is overloaded and a short circuit occurs in the inverter bridge arm, it can be ensured that non-faulty IGBTs are not damaged, enhancing the reliability of the frequency converter system. Among them, when the IGBT module is turned off, that is, when the gate of the faulty IGBT is turned off, there is a spike voltage between the collector and emitter of the faulty IGBT. Due to the large current flowing through the branch, the spike voltage is also large, and it is necessary to suppress the influence of the spike voltage between the collector and emitter of the faulty IGBT on the non-faulty IGBT; therefore, the spike voltage of the IGBT module can be suppressed through the IGBT spike voltage suppression unit to ensure that the non-faulty IGBT will not be damaged when the faulty IGBT is turned off.

[0060] In some embodiments, each of the IGBT spike voltage suppression units includes: a resistor suppression module (such as adjustable resistor R G ) and a voltage source suppression module (such as voltage source V neg ). The resistor suppression module is disposed between the output terminal of the drive board of the IGBT module and the gate of the IGBT module. The voltage source suppression module is disposed between the input terminal of the drive board of the IGBT module and the emitter of the IGBT module.

[0061] Among them, the IGBT spike voltage suppression unit suppresses the spike voltage between the collector and emitter of the IGBT module under the control of the control signal, including:

[0062] The resistor suppression module is configured to suppress the spike voltage between the collector and emitter of the IGBT module by utilizing its own resistance value.

[0063] Specifically, an adjustable resistor R G is added to the gate of the IGBT, and the adjustable resistor R G is used to limit the voltage spike when the switching tube (i.e., IGBT) is turned on. For example, a first adjustable resistor R G1 is added to the gate of the first switching tube Q1, and a fourth adjustable resistor R G4 is added to the gate of the fourth switching tube Q4, and so on.

[0064] The voltage source suppression module is configured to further suppress the spike voltage between the collector and the emitter of the IGBT module by using the negative voltage source provided by itself when it is connected.

[0065] Specifically, the inverter bridge in the frequency converter is composed of 6 IGBTs, and a voltage source V is added between the gate of each IGBT and the drive board. neg , such as the first IGBT Q 1 A first voltage source V is added between the gate of and its drive board. neg1 , the second IGBT Q 2 A second voltage source V is added between the gate of and its drive board. neg2 . Figure 4 Only the voltage source of one IGBT, the main control board fault detection device, etc. are drawn in, and the voltage spike suppression and fault detection of the other 5 IGBTs are not drawn.

[0066] Among them, when the frequency converter is overloaded and the spike voltage V CE of an IGBT in a bridge arm exceeds the set voltage threshold, if the adjustable resistor R G can control it within the threshold u lim range, then there is no need to connect the gate voltage source of another IGBT to the circuit. At this time, the fault detection module is not started. If adjusting the gate adjustable resistor R G of the IGBT cannot suppress the spike voltage within the threshold u lim range, connect the voltage source V neg . After connection, the gate voltage V GE is lifted, which can resist the spike voltage impact when turning off the IGBT.

[0067] Thus, when the frequency converter is overloaded or the IGBT is short-circuited, the voltage source is connected to the system, and then the voltage spike is suppressed to ensure that the IGBTs in the non-faulty phases are not damaged.

[0068] In some embodiments, the control signal includes: a resistance value adjustment signal capable of adjusting the resistance value of the resistance suppression module, and a voltage source connection or disconnection signal capable of controlling the connection or disconnection of the voltage source suppression module. Specifically, the control of the connection or disconnection of the voltage source suppression module can be controlled by a switch module such as a relay provided in the circuit where the voltage source suppression module is located.

[0069] Among them, the control signal initiated by the control unit to control the IGBT spike voltage suppression unit corresponding to another IGBT module on the bridge arm where the IGBT module is located includes:

[0070] The control unit is specifically further configured to, when the spike voltage between the collector and the emitter of an IGBT module collected by the collection unit mutates relative to the set voltage between the collector and the emitter of this IGBT module, turn off this IGBT module, and initiate a resistance adjustment signal for adjusting the resistance of the gate resistance suppression module corresponding to the other IGBT module, so as to suppress the spike voltage between the collector and the emitter of the other IGBT module by adjusting the resistance of this gate resistance suppression module.

[0071] Specifically, when the frequency converter is overloaded, the spike voltage V of the first transistor in the bridge arm CE will exceed the set threshold. If the adjustable resistor R is adjusted G and it can be controlled within the threshold range, then there is no need to connect the gate voltage source of the other transistor to the circuit. If the adjustable resistor R is adjusted G and it can no longer be controlled within the threshold range, then connect the gate voltage source of the other transistor to the circuit to increase the IGBT gate limit voltage V GE to prevent the other IGBT in the bridge arm from being triggered and conducting when it conducts, resulting in a failure.

[0072] The control unit is specifically further configured to, after the gate resistance suppression module corresponding to the other IGBT module adjusts its resistance based on the resistance adjustment signal, determine again whether the spike voltage between the collector and the emitter of the IGBT module turned off on the bridge arm where the other IGBT module is located still exceeds the set voltage threshold.

[0073] The control unit is specifically further configured to, if the spike voltage between the collector and the emitter of the IGBT module turned off on the bridge arm where the other IGBT module is located still exceeds the set voltage threshold, initiate a voltage source connection signal capable of controlling the access of the voltage source suppression module corresponding to the other IGBT module, so as to further suppress the spike voltage between the collector and the emitter of the other IGBT module by accessing this voltage source suppression module.

[0074] Specifically, when the spike voltage exceeds the set threshold, the instantaneous voltage value detected can be captured by a voltage sensor, and the voltage analyzer is immediately started for fault analysis and processing. When a short circuit occurs in the inverter bridge, by adjusting the adjustable resistor R G the spike voltage V can no longer be controlled CE , then connect the voltage source to the circuit to increase the IGBT gate limit voltage V GE, prevent another IGBT of the bridge arm from being triggered into conduction during its conduction, resulting in a fault. Among them, there is a voltage source at the gate of the IGBT to prevent the IGBTs of the same bridge arm from causing another IGBT to conduct when turned on. This voltage source is controlled by the inter-board relay KA1. When the spike voltage is within the threshold range, this voltage source can be cut off, which can minimize the switching loss while ensuring reliability. After using a negative voltage source at the gate of the IGBT, the spike voltage generated at the turn-off moment of the IGBT can be suppressed, ensuring the reliability of turn-off.

[0075] Of course, if the spike voltage between the collector and emitter of an IGBT module that is turned off on the bridge arm where another IGBT module is located does not exceed the set threshold, there is no need to connect the voltage source suppression module corresponding to the other IGBT module.

[0076] Specifically, when the frequency converter is operating normally (the frequency converter is not overloaded and the inverter bridge is not short-circuited), adjust the resistance value of the adjustable resistor R G so that the spike voltage of the IGBT is within a reasonable threshold range. Then, for the other IGBT of that bridge arm, there is no need to connect the voltage source to the circuit, which can reduce the circuit loss.

[0077] In some embodiments, it further includes: a process of fault handling when a bridge arm short-circuit fault occurs in the inverter bridge.

[0078] The control unit is further configured to, after initiating a control signal capable of controlling the IGBT spike voltage suppression unit, specifically after initiating a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the bridge arm where this IGBT module is located, if the situation where the frequency converter is not operating normally is that the frequency converter is overloaded, initiate a reminder message for the frequency converter overload to remind the user to adjust the load of the frequency converter to within the rated load range. Specifically, the overload information can be fed back to the customer to let the customer adjust the load of the unit within the rated range.

[0079] Or, the control unit is specifically further configured to, after initiating a control signal capable of controlling the IGBT spike voltage suppression unit, specifically after initiating a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the bridge arm where this IGBT module is located, if the situation where the frequency converter is not operating normally is that the bridge arm of the inverter bridge is short-circuited, locate and cut off the fault of the short-circuited bridge arm of the inverter bridge, and then the frequency converter can be powered on again; and, when the frequency converter outputs to the bearing controller, transmit the message of the bridge arm short-circuit of the inverter bridge to the bearing controller through the communication channel, so that the bearing controller can start its own protection mechanism in time when it learns of the inverter bridge fault.

[0080] Specifically, a fault detection and fault handling circuit is added to the main control board. A voltage capture circuit is added to one side of the bus capacitor C, i.e., the DC output terminal of the bus voltage, which can obtain the peak voltage between the DC bus DC+ and DC- in real time, so as to judge whether the bus voltage is within the working range of the bearing switching power supply through a voltage analyzer. When a short circuit occurs in the inverter bridge of the frequency converter, the peak voltage value V between the collector and emitter of the IGBT CE will mutate, and the bus voltage U DC will also be instantaneously pulled down and fall out of the voltage range of the DC-DC switching power supply that supplies power to the bearing controller. The instantaneous lack of input of the switching power supply will cause abnormal output, resulting in abnormal operation of the bearing controller, and further leading to abnormal bearing suspension. In the light case, the floating shaft accuracy of the bearing is poor. In the severe case, the shaft will touch the shaft while still rotating, or even smash the shaft, which are not allowed. After applying V neg to the IGBT gate, regardless of whether the actual value of V GE exceeds the set value, as long as a short circuit occurs in the bridge arm, then, it is necessary to enter the fault handling.

[0081] On the one hand, the frequency converter detects the voltage value u ce4 of the IGBT. When this value exceeds the set value, the detected voltage value is processed by a voltage analyzer and compared with the data in the inverter bridge topology analyzer. The residual value can represent the deviation rate, and the residual is transmitted to the fault identifier to locate which IGBT has a short circuit, so as to handle the fault, transmit the fault signal to the main control DSP, the main control displays short circuit protection, cuts off the circuit, and stops for inspection; after troubleshooting, power on again.

[0082] On the other hand, when the voltage capture circuit detects abnormal bus voltage, it gives a fault judgment through a voltage analyzer. After determining the fault, the fault is sent to the fault responder of the bearing controller through the CAN communication by the fault generator. The bearing controller receives the fault and responds, and feeds back the fault to the main control MCU. The main program of the MCU immediately issues an instruction to activate the standby power supply to ensure the normal power supply of the bearing controller, and the shaft suspension is stable before the motor stops rotating. When the motor stops rotating, the shaft normally drops. Wait for the frequency converter to troubleshoot the fault. After troubleshooting, power on again.

[0083] Thus, by quickly detecting faults and timely cutting off the fault source when the peak voltage suppression measure fails, the frequency converter system can be prevented from running with a phase loss, ensuring the safe and reliable operation of the frequency converter system. In this way, after the IGBT peak voltage suppression unit fails, the frequency converter system performs fault identification and fault diagnosis, quickly adjusts the settings of the frequency converter system or cuts off the fault source to ensure the reliability of the frequency converter system.

[0084] In some embodiments, the control unit locates the short-circuited bridge arm of the inverter bridge, including:

[0085] The control unit is specifically further configured to compare the peak voltage between the collector and the emitter of the IGBT module collected with the set voltage between the collector and the emitter of the IGBT module to obtain a first voltage residual; and compare the bus voltage of the DC power supply of the frequency converter with the set bus voltage to obtain a second voltage residual. And,

[0086] The control unit is specifically further configured to process the first voltage residual and the second voltage residual to locate the short - circuited bridge arm of the inverter bridge.

[0087] Thus, when a short - circuit occurs in the inverter bridge, the voltage of the short - circuited phase drops to zero instantaneously, and the current increases rapidly. A voltage sensor is used to capture the voltage change, and the voltage value V of the IGBT at this time is analyzed through a voltage analyzer CE and the bus voltage. By comparing with the set normal value, there is a residual. Analyzing and processing the residual can realize the identification and location of the fault, so as to further process the fault.

[0088] Verified by a large number of tests, adopting the technical solution of the present invention, by setting a protection resistor and a protection voltage source at the gate of the IGBT, when the frequency converter is overloaded and a bridge arm short - circuit occurs in the inverter bridge, the IGBT is turned off, and the peak voltage of the IGBT module is suppressed by the protection resistor and the protection voltage source, avoiding damage to the device of the IGBT module when the frequency converter is overloaded or a bridge arm short - circuit occurs in the inverter bridge.

[0089] According to an embodiment of the present invention, there is also provided a motor system corresponding to the protection device of the IGBT module in the frequency converter. The motor system may include: the protection device of the IGBT module in the frequency converter described above.

[0090] With the rapid development of the semiconductor industry, the cost of the IGBT module has been gradually reduced. Replacing the expensive IPM (Intelligent Power Module) with it has become the first choice of frequency converter developers.

[0091] Figure 2 It is a schematic structural diagram of an embodiment of the frequency converter. As Figure 2 shown, the frequency converter includes: a rectifier bridge, an inverter bridge, an inductor, a capacitor, a resistor and a switch. The AC power supply is input to the input end of the rectifier bridge. The first end of the output end of the rectifier bridge is output to the first end of the input end of the inverter bridge after passing through the inductor; the second end of the output end of the rectifier bridge is output to the second end of the input end of the inverter bridge after passing through the resistor. The output end of the inverter bridge is output to the motor. The switch is connected in parallel at both ends of the resistor, and the capacitor is connected in parallel between the first end and the second end of the input end of the inverter bridge. Figure 2The alternating current on the input side of the shown frequency converter is three-phase 380V alternating current, which is rectified into direct current by a full-bridge rectifier bridge, and then inverted into alternating current by a full-bridge inverter bridge to supply the motor to run.

[0092] In Figure 2 In the shown example, in a diode frequency converter, an uncontrolled rectifier bridge composed of diode modules is usually adopted to convert industrial alternating current into direct current for supply to the backend, and the backend can be a controllable inverter bridge composed of IGBT modules to invert the direct current into alternating current for supply to the motor windings to drive the motor to run.

[0093] In Figure 2 In the shown example, after replacing the IPM with an IGBT module, there will be fault problems such as overload and short circuit in the IGBT module.

[0094] Specifically, since reliable IGBT protection measures are integrated in the IPM, during the operation of the frequency converter, the IPM hardly fails under harsh conditions such as overload, overcurrent, and overvoltage. However, the IGBT module is different. When the frequency converter is overloaded or a short circuit occurs in the bridge arm of the inverter bridge, if the IGBT is to be turned off, the generated voltage spike is very high, and at this time the IGBT is very easy to be damaged. The branch where the damaged IGBT is located is in an open state. However, after the open circuit fault occurs, the system can often still operate with a phase loss for a period of time. If the fault source is not cut off in time, it will cause the non-fault IGBT to have overcurrent, overheat, and insulation damage, and even affect the system paralysis, resulting in huge economic losses.

[0095] In addition, commercial variable-frequency air-conditioning systems are usually used in large places such as buildings and factories. Due to the large volume of the frequency converter system, it is generally placed on the roof or in the underground warehouse, and the environment is harsh. The system is very easy to be overloaded. When operating under overload, if the load cannot be adjusted in time, the frequency converter will operate overloaded.

[0096] In some embodiments, the solution of the present invention provides a fault detection solution for the IGBT module in the frequency converter, which can solve the problem of device damage when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge. When the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off, and the spike voltage of the IGBT module is suppressed; and, after the suppression measure fails, that is, when the spike voltage exceeds the set threshold, the fault of the IGBT module is quickly detected, the fault is cut off in time, and the system is not allowed to operate with a phase loss, ensuring the safe and reliable operation of the frequency converter system.

[0097] Specifically, in the solution of the present invention, when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off, which can ensure that the non-fault IGBT is not damaged due to being affected, enhancing the reliability of the frequency converter system. Among them, when the IGBT module is turned off, that is, when the gate of the faulty IGBT is turned off, there is a spike voltage between the collector and emitter of the faulty IGBT. Because the current flowing through the branch is large, the spike voltage is also large, and it is necessary to suppress the influence of the spike voltage between the collector and emitter of the faulty IGBT on the non-faulty IGBT; therefore, the spike voltage of the IGBT module can be suppressed through the IGBT spike voltage suppression unit to ensure that the non-faulty IGBT will not be damaged when the faulty IGBT is turned off.

[0098] Specifically, in the solution of the present invention, in the case where the spike voltage suppression measure fails, the fault can be quickly detected and the fault source can be cut off in time, so that the frequency converter system does not operate with a phase loss, ensuring the safe and reliable operation of the frequency converter system. In this way, after the IGBT spike voltage suppression unit fails, the frequency converter system performs fault identification and fault diagnosis, and quickly adjusts the settings of the frequency converter system or cuts off the fault source to ensure the reliability of the frequency converter system.

[0099] The following combines Figures 3 to 8 the example shown below to exemplarily illustrate the specific implementation process of the solution of the present invention.

[0100] Figure 3 is a schematic structural diagram of an embodiment of the power supply control system for a motor. As Figure 3 shown, the power supply control system for a motor includes: a rectifier bridge, a DC reactor L, a bus capacitor C, a charging resistor R, a contactor K, a first DC-DC power supply, a main control board, a drive board, an inverter bridge, a second DC-DC power supply, a bearing controller, and a bearing load.

[0101] Among them, the input end of the rectifier bridge can input three-phase alternating current. The first end of the output end of the rectifier bridge is output to the first end of the input end of the inverter bridge after passing through the DC reactor L, and the second end of the output end of the rectifier bridge is output to the second end of the input end of the inverter bridge after passing through the charging resistor R. The contactor K is connected in parallel with the charging resistor R. The first end of the bus capacitor C is connected to the end of the DC reactor L far from the rectifier bridge, and the second end of the bus capacitor C is connected to the end of the charging resistor R far from the rectifier bridge. The output end of the bus capacitor C is output to the inverter bridge after passing through the first DC-DC power supply, the main control board, and the drive board. The output end of the bus capacitor C is also output to the bearing load after passing through the second DC-DC power supply and the bearing controller.

[0102] In Figure 3In the power supply control system of the motor shown, the inductor between the rectifier bridge and the inverter bridge is the DC reactor L. The rectifier bridge is composed of 6 diodes and is an uncontrolled rectifier, which does not require a main control board or a drive board; the inverter bridge is composed of 6 IGBTs to form 3 full-bridge arms, and the main control board and the drive board control it. When the frequency converter is just powered on, the contactor K is disconnected, and the bus charges the capacitor C through the charging resistor R. When the bus capacitor C is fully charged, the contactor K closes, bypassing the charging resistor R, and the motor runs.

[0103] Figure 4 It is a schematic diagram of the drive structure of an embodiment of the IGBT, which can show the gate drive principle of the IGBT. In the example as Figure 4 shown, the pulse modulator of the IGBT can Figure 3 isolate and transform the front-end control signal and the back-end drive signal of the drive board in the example shown. The pulse modulator of the IGBT outputs corresponding level signals by detecting the edge jump of the control signal, thereby controlling the opening and closing of the gate of the IGBT.

[0104] Figure 5 It is a schematic diagram of the structure of an embodiment of the IGBT spike voltage suppression and fault detection system for the inverter bridge. In the IGBT spike voltage suppression and fault detection system for the inverter bridge as Figure 5 shown, the inverter bridge in the frequency converter is composed of 6 IGBTs, and a voltage source V neg is added between the gate of each IGBT and the drive board, such as a first voltage source V 1 is added between the gate of the first IGBT Q neg1 and its drive board, and a second voltage source V 2 is added between the gate of the second IGBT Q neg2 and its drive board. Figure 5 Only the voltage source of one IGBT and the main control board fault detection and other devices are drawn in, and the voltage spike suppression and fault detection of the other 5 IGBTs are not drawn. When the frequency converter is overloaded or the IGBT has a short circuit, the voltage source is connected to the system, and then the voltage spike is suppressed to ensure that the IGBTs of the non-faulty phases are not damaged.

[0105] Among them, there is a voltage source at the gate of the IGBT to prevent the other IGBT from conducting when the IGBTs in the same bridge arm are turned on. This voltage source is controlled by the inter-board relay KA1. When the spike voltage is within the threshold range, this voltage source is cut off, which can minimize the switching loss while ensuring reliability. After using a negative voltage source at the gate of the IGBT, the spike voltage generated at the moment when the IGBT is turned off can be suppressed, ensuring the reliability of the turn-off. When the spike voltage exceeds the threshold, the instantaneous voltage value detected can be captured by the voltage sensor, and the voltage analyzer is immediately started for fault analysis and processing.

[0106] In Figure 5 In the example shown, an adjustable resistor R is added to the gate of the IGBT G , the adjustable resistor R G is used to limit the voltage spike when the switching device (i.e., IGBT) is turned on. For example, a first adjustable resistor R G1 is added to the gate of the first switching device Q1, and a fourth adjustable resistor R G4 is added to the gate of the fourth switching device Q4, and so on.

[0107] In Figure 5 the example shown, a fault detection and fault handling circuit is added to the main control board. A voltage capture circuit is added to one side of the bus capacitor C, that is, the DC output terminal of the bus voltage, to obtain the spike voltage between the DC bus DC+ and DC- in real time, so as to judge whether the bus voltage is within the operating range of the bearing switching power supply through a voltage analyzer.

[0108] As Figure 4 shown, for the IGBT itself, based on the coupling between the gate G and the collector C, a very high spike voltage will be generated between the gate G and the collector C during the IGBT turn-off period. As Figure 5 shown, 6 IGBTs are used to form 3 arms of an inverter bridge. When the upper transistor Q1 (Q3 / Q5) of each arm is conducting, a changing dV / dt is generated, and this voltage will pass through the lower transistor Q4 (Q6 / Q2). The current will cause a voltage difference across the gate resistor of the lower transistor. If the voltage exceeds the IGBT gate drive threshold, it will cause the lower transistor to conduct, and there will be a risk of shoot-through. This mis-conduction will cause the IGBT to be damaged, and thus the system will malfunction.

[0109] When a gate voltage source V neg is added, the IGBT gate limiting voltage V GE is increased as follows:

[0110] V GE =(R d +R G )*I CG +V neg .

[0111] In the formula, V GE is the gate voltage of the IGBT, R d is the driving resistor, R G is the gate resistor, I CG is the conduction current of the IGBT, and V neg is the externally connected voltage source.

[0112] Figure 6It is a schematic diagram of the curves of the Ic current, PWM drive signal, and Vce voltage when the IGBT is turned off and the peak voltage is 820V without peak voltage suppression. Figure 7 It is a schematic diagram of the curves of the Ic current, PWM drive signal, and Vce voltage when the IGBT is turned off and the peak voltage is 780V with peak voltage suppression. Figure 8 Implementation flowchart of the IGBT fault detection method in the frequency converter.

[0113] Figure 6 In it, when there is no peak voltage suppression, the gate turn-on signal PWM signal of the upper IGBT changes from "1" to "0", and the upper IGBT turns off. At this time, the peak voltage of the Vce voltage is 820V. Figure 7 In it, when there is peak voltage suppression, the gate turn-on signal PWM signal of the upper IGBT changes from "1" to "0", and the upper IGBT turns off. At this time, the peak voltage of the Vce voltage is 780V.

[0114] In some embodiments, as Figure 8 shown, when the frequency converter is working normally (the frequency converter is not overloaded and the inverter bridge is not short-circuited), adjust the resistance value of the adjustable resistor R G so that the peak voltage of the IGBT is within a reasonable threshold range. Then, the other IGBT of that bridge arm does not need to connect the voltage source to the circuit, which can reduce the circuit loss.

[0115] When the frequency converter is working abnormally, it is divided into two cases: the frequency converter is overloaded or the inverter bridge is short-circuited, and the specific methods of fault protection processing are exemplarily described.

[0116] The first specific method of fault protection processing:

[0117] When the frequency converter is overloaded, the peak voltage V CE of one tube in the bridge arm will exceed the set threshold. If it can be controlled within the threshold range by adjusting the adjustable resistor R G , then it is not necessary to connect the gate voltage source of the other tube to the circuit. If it can no longer be controlled within the threshold range by adjusting the adjustable resistor R G , then connect the gate voltage source of the other tube to the circuit to increase the IGBT gate limit voltage V GE , preventing the other IGBT in the bridge arm from being triggered to conduct when it is conducting and causing a fault.

[0118] The second specific method of fault protection processing: When the inverter bridge is short-circuited, if the peak voltage V G cannot be controlled by adjusting the adjustable resistor R CE , then connect the voltage source to the circuit to increase the IGBT gate limit voltage V GE , preventing the other IGBT in the bridge arm from being triggered to conduct when it is conducting and causing a fault.

[0119] In some embodiments, as Figure 5 shown, when the frequency converter operates abnormally, where the abnormality refers to overload of the frequency converter and short circuit of the bridge arm, the voltage source needs to be connected to the circuit.

[0120] The detection method for the first type of fault:

[0121] When the frequency converter is overloaded, it is detected by the current sensor that the frequency converter outputs normal three-phase currents, and the amplitudes increase and exceed the set threshold i lim at this time, it is determined that the frequency converter is in an overloaded state. When the peak voltage V CE of an IGBT in a bridge arm exceeds the set voltage threshold, if the adjustable resistor R G can control it within the threshold u lim range, then there is no need to connect the gate voltage source of another IGBT to the circuit. At this time, the fault detection module is not started either. If adjusting the gate adjustable resistor R G of the IGBT cannot suppress the peak voltage within the threshold u lim range, connect the voltage source V neg After connection, the gate voltage V GE is lifted, which can resist the peak voltage impact when turning off the IGBT. Also, the overload information can be fed back to the customer to let the customer adjust the load of the unit within the rated range.

[0122] The detection method for the second type of fault:

[0123] When a short circuit occurs in the inverter bridge, the voltage of the short-circuited phase drops to zero instantaneously, and the current increases rapidly. The voltage sensor is used to capture the voltage change, and the voltage analyzer analyzes the voltage value V CE of the IGBT and the bus voltage at this time. There is a residual difference compared with the set normal value, and the residual difference is analyzed and processed to realize the identification and location of the fault, so as to further process the fault.

[0124] Among them, analyzing and processing the residual difference may include: there is a Vce threshold set in the voltage analyzer, which is a given calibration value. When there is a deviation between the captured voltage and this value, there will be a residual voltage. The residual voltage is amplified, and the fault is identified according to the residual voltage, so as to start the fault processing program.

[0125] In some embodiments, in the solution of the present invention, the frequency converter is used on a magnetic levitation centrifugal unit. The difference between a magnetic levitation centrifugal machine and an ordinary frequency conversion centrifugal machine is that in addition to using a magnetic levitation motor for the motor, the shaft of the magnetic levitation motor must be suspended during motor operation, that is, the bearing controller is required to suspend the shaft.

[0126] When a short circuit occurs in the inverter bridge of the frequency converter, the peak voltage value V between the collector and emitter of the IGBT CE will mutate (as shown in Figure 5 u ce4 ), and the bus voltage U DC will also drop instantaneously and fall out of the voltage range of the DC-DC switching power supply that powers the bearing controller. Without input to the switching power supply instantaneously, the output will be abnormal, resulting in abnormal operation of the bearing controller, and further leading to abnormal bearing suspension. In the light case, the floating shaft accuracy of the bearing is poor; in the severe case, the shaft will touch the shaft while still rotating, or even smash the shaft, which are all not allowed.

[0127] After applying V neg to the gate of the IGBT, regardless of whether the actual value of V GE exceeds the set value, as long as a short circuit occurs in the bridge arm, then, it is necessary to enter the fault handling.

[0128] On the one hand, the frequency converter detects the voltage value u ce4 of the IGBT. When this value exceeds the set value, the detected voltage value is processed by the voltage analyzer and compared with the data in the inverter bridge topology analyzer. The residual value can represent the deviation rate, and the residual is passed to the fault identifier to locate which IGBT has a short circuit, so as to handle the fault, send the fault signal to the main control DSP, the main control displays short circuit protection, cuts off the circuit, and stops for inspection; after troubleshooting, power on again.

[0129] On the other hand, when the voltage capture circuit detects abnormal bus voltage, it gives a fault judgment through the voltage analyzer. After determining the fault, the fault is sent to the fault responder of the bearing controller through the fault generator via CAN communication. The bearing controller receives the fault and responds, and feeds back the fault to the main control MCU. The main program of the MCU immediately issues an instruction to activate the standby power supply to ensure normal power supply to the bearing controller, and the shaft suspension is stable before the motor stops rotating. When the motor stops rotating, the shaft drops normally. Wait for the frequency converter to troubleshoot the fault. After troubleshooting, power on again.

[0130] In the above embodiment, Figure 5 only the fault detection device of one bridge arm (Q1 and Q4) is drawn. Actually, each of the three bridge arms of the inverter bridge has an IGBT peak voltage suppression unit and a fault detection and processing unit.

[0131] In some embodiments, the same function can also be achieved by improving the algorithm and adding an external single-pole double-throw switch.

[0132] Specifically, the 6 IGBTs are controlled by separate switches, and the gate of the IGBT will not be out of control due to the delay of the mutual switch signals or the failure of the contacts. For a single-pole double-throw switch, one coil has two contacts. When the coil is out of control, the switch state will not change.

[0133] Since the processing and functions implemented by the motor system of this embodiment basically correspond to the embodiments, principles, and examples of the device shown in the foregoing Figure 1 For the parts not described in detail in the description of this embodiment, reference can be made to the relevant descriptions in the foregoing embodiments and will not be elaborated herein.

[0134] Through a large number of experimental verifications, by adopting the technical solution of the present invention, when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off, which can ensure that the non-fault IGBT is not damaged due to being affected, enhancing the reliability of the frequency converter system; through the IGBT peak voltage suppression unit, the peak voltage of the IGBT module is suppressed to ensure that the non-fault IGBT will not be damaged when the fault IGBT is turned off.

[0135] According to an embodiment of the present invention, there is also provided a protection method for an IGBT module in a frequency converter corresponding to the motor system, as Figure 9 shown in the flowchart of an embodiment of the method of the present invention. The protection method for the IGBT module in the frequency converter may include: step S110 to step S130.

[0136] In step S110, through the acquisition unit, when the inverter bridge is working after the frequency converter is powered on, the three-phase current of the frequency converter is acquired, the peak voltage between the collector and emitter of the IGBT module is acquired, and the bus voltage of the DC power supply of the frequency converter is acquired.

[0137] In step S120, through the control unit, according to at least one of the acquired three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter, it is determined whether the frequency converter is working normally, that is, it is determined whether the frequency converter is overloaded or whether the bridge arm of the inverter bridge is short-circuited; and, when the frequency converter is not working normally, that is, when the frequency converter is overloaded or the bridge arm of the inverter bridge is short-circuited, the IGBT module is controlled to remain in the off state, and a control signal capable of controlling the IGBT peak voltage suppression unit is initiated to control the IGBT peak voltage suppression unit to start, and the IGBT peak voltage suppression unit is controlled to suppress the peak voltage between the collector and emitter of the IGBT module.

[0138] In step S130, through the IGBT peak voltage suppression unit, under the control of the control signal, the peak voltage between the collector and emitter of the IGBT module is suppressed.

[0139] Therefore, to address the problem that device damage may occur during frequency converter overload and arm short - circuit in the inverter bridge, an IGBT spike voltage suppression unit is set at the gate of the IGBT. When the frequency converter is overloaded and an arm short - circuit occurs in the inverter bridge, the IGBT is turned off, and the IGBT spike voltage suppression unit suppresses the spike voltage of the IGBT module, avoiding damage to the device when the IGBT module is damaged due to frequency converter overload or arm short - circuit in the inverter bridge.

[0140] In some embodiments, the acquisition unit includes: a current acquisition unit, a voltage acquisition unit, and a voltage capture unit. The number of the voltage acquisition units is the same as the number of IGBT modules in the inverter bridge. Each voltage acquisition unit is configured to collect the spike voltage between the collector and the emitter of a corresponding IGBT module when the inverter bridge is operating after the frequency converter is powered on.

[0141] Among them, in step S110, through the acquisition unit, when the inverter bridge is operating after the frequency converter is powered on, collecting the three - phase current of the frequency converter and the spike voltage between the collector and the emitter of the IGBT module includes:

[0142] Collect the three - phase current of the frequency converter through a current acquisition unit, such as a current sensor.

[0143] Collect the spike voltage between the collector and the emitter of the IGBT module through a voltage acquisition unit, such as a voltage sensor.

[0144] Collect the bus voltage of the DC power supply of the frequency converter through a voltage capture unit, such as a voltage capture circuit.

[0145] Correspondingly, through the control unit, determining whether the frequency converter is operating normally, that is, determining whether the frequency converter is overloaded or whether the arm of the inverter bridge is short - circuited, based on at least one of the collected three - phase current of the frequency converter, the spike voltage between the collector and the emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter, includes: the judgment process of whether the frequency converter is overloaded.

[0146] The following combines Figure 10 A schematic flowchart of an embodiment of the judgment process of whether the frequency converter is overloaded in the method of the present invention shown, further illustrating the specific process of the judgment process of whether the frequency converter is overloaded, may include: step S210 and step S220.

[0147] Step S210, if the three - phase current of the frequency converter collected shows that the frequency converter has a normal three - phase current output, and the amplitude of the three - phase current output by the frequency converter becomes larger and exceeds the set current amplitude, then it is determined that the frequency converter is overloaded. And,

[0148] Step S220, in the case of the frequency converter being overloaded, if the peak voltage between the collector and emitter of the IGBT module collected exceeds the set voltage threshold, it is determined that the frequency converter is not working properly, that is, it is determined that the frequency converter is overloaded and not working properly.

[0149] Specifically, it is detected by a current sensor that the frequency converter has a normal three-phase current output, and the amplitude becomes larger and exceeds the set threshold i lim When, it is determined that the frequency converter is in an overloaded state. When the peak voltage V CE of an IGBT in a bridge arm exceeds the set voltage threshold, the peak voltage of the IGBT needs to be suppressed.

[0150] Alternatively, through a control unit, according to at least one of the three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter collected, it is determined whether the frequency converter is working properly, that is, it is determined whether the frequency converter is overloaded or whether the bridge arm of the inverter bridge is short-circuited. It further includes: the judgment process of whether the bridge arm of the inverter bridge is short-circuited.

[0151] Next, in conjunction with Figure 11 a schematic flowchart of an embodiment of the judgment process of whether the bridge arm of the inverter bridge is short-circuited in the method of the present invention shown, the specific process of the judgment process of whether the bridge arm of the inverter bridge is short-circuited is further described, which may include: step S310 and step S320.

[0152] Step S310, compare the peak voltage between the collector and emitter of the IGBT module collected with the set voltage between the collector and emitter of this IGBT module; and compare the bus voltage of the DC power supply of the frequency converter with the set bus voltage. And,

[0153] Step S320, if the peak voltage between the collector and emitter of the IGBT module collected changes suddenly with respect to the set voltage between the collector and emitter of this IGBT module; and the bus voltage of the DC power supply of the frequency converter drops with respect to the set bus voltage, it is determined that the frequency converter is not working properly, that is, it is determined that the bridge arm of the inverter bridge is short-circuited.

[0154] Specifically, when a short circuit occurs in the inverter bridge of the frequency converter, the peak voltage value V CE between the collector and emitter of the IGBT will change suddenly (as Figure 4 shown by u ce4 ), and the bus voltage U DC will also drop instantaneously.

[0155] In some embodiments, the number of IGBT spike voltage suppression units is the same as the number of IGBT modules in the inverter bridge of the frequency converter. Each IGBT spike voltage suppression unit is specifically arranged between a corresponding IGBT module and the drive board of the IGBT module. Specifically, each of the three arms of the inverter bridge is provided with an IGBT spike voltage suppression unit and a fault detection and processing unit.

[0156] In step S120, through the control unit, when the frequency converter is not working properly, that is, when the frequency converter is overloaded or the arm of the inverter bridge is short-circuited, the IGBT module is controlled to remain in the off state, and a control signal capable of controlling the IGBT spike voltage suppression unit is initiated, including: when the frequency converter is not working properly, turning off the IGBT module and initiating a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located.

[0157] Thus, by turning off the IGBT when the frequency converter is overloaded and the arm of the inverter bridge is short-circuited, it can be ensured that the non-faulty IGBTs are not damaged, enhancing the reliability of the frequency converter system. Among them, when the IGBT module is turned off, that is, when the gate of the faulty IGBT is turned off, there is a spike voltage between the collector and emitter of the faulty IGBT. Due to the large current flowing through the branch, the spike voltage is also large, and it is necessary to suppress the influence of the spike voltage between the collector and emitter of the faulty IGBT on the non-faulty IGBTs. Therefore, the spike voltage of the IGBT module can be suppressed by the IGBT spike voltage suppression unit to ensure that the non-faulty IGBTs are not damaged when the faulty IGBT is turned off.

[0158] In some embodiments, each IGBT spike voltage suppression unit includes: a resistor suppression module (such as adjustable resistor R G ) and a voltage source suppression module (such as voltage source V neg ). The resistor suppression module is arranged between the output end of the drive board of the IGBT module and the gate of the IGBT module. The voltage source suppression module is arranged between the input end of the drive board of the IGBT module and the emitter of the IGBT module.

[0159] Among them, in step S130, through the IGBT spike voltage suppression unit, under the control of the control signal, the spike voltage between the collector and emitter of the IGBT module is suppressed, including:

[0160] Through the resistor suppression module, by utilizing its own resistance value, the spike voltage between the collector and emitter of the IGBT module is suppressed.

[0161] Specifically, an adjustable resistor R is added to the gate of the IGBT. G The adjustable resistor R G is used to limit the voltage spike when the switching device (i.e., the IGBT) is turned on. For example, a first adjustable resistor R is added to the gate of the first switching transistor Q1. G1 A fourth adjustable resistor R is added to the gate of the fourth switching transistor Q4. G4 And so on.

[0162] Through the voltage source suppression module, when it is connected by itself, by using the negative voltage source provided by itself, the spike voltage between the collector and the emitter of the IGBT module is further suppressed.

[0163] Specifically, the inverter bridge in the frequency converter is composed of 6 IGBTs. A voltage source V is added between the gate of each IGBT and the drive board. neg For example, between the gate of the first IGBT Q 1 and its drive board, a first voltage source V is added. neg1 Between the gate of the second IGBT Q 2 and its drive board, a second voltage source V is added. neg2 . Figure 4 Only the voltage source of one IGBT and the method for detecting the failure of the main control board are drawn in the figure, and the voltage spike suppression and failure detection of the other 5 IGBTs are not drawn.

[0164] Among them, when the frequency converter is overloaded and the spike voltage V CE of an IGBT in a bridge arm exceeds the set voltage threshold, if the adjustable resistor R G can control it within the threshold u lim range, then there is no need to connect the gate voltage source of another IGBT to the circuit. At this time, the failure detection module is not started. If adjusting the gate adjustable resistor R G of the IGBT cannot suppress the spike voltage within the threshold u lim range, the voltage source V neg is connected. After connection, the gate voltage V GE is lifted, which can resist the spike voltage impact when turning off the IGBT.

[0165] Thus, when the frequency converter is overloaded or the IGBT has a short circuit, the voltage source is connected to the system, and then the voltage spike is suppressed to ensure that the IGBTs in the non-faulty phases are not damaged.

[0166] In some embodiments, the control signal includes: a resistance adjustment signal capable of adjusting the resistance value of the resistance suppression module, and a voltage source access or cut-off signal capable of controlling the access or cut-off of the voltage source suppression module. Specifically, the control of the access or cut-off of the voltage source suppression module can be controlled by a switch module such as a relay provided in the circuit where the voltage source suppression module is located.

[0167] Among them, the specific process of initiating a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located through a control unit can be referred to the following exemplary description.

[0168] The following combines Figure 12 a schematic flowchart of an embodiment of a control signal for initiating control of the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located in the method of the present invention shown, and further illustrates the specific process of the control signal for initiating control of the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located, which may include: step S410 to step S430.

[0169] Step S410, when the spike voltage between the collector and emitter of an IGBT module collected by the acquisition unit mutates relative to the set voltage between the collector and emitter of this IGBT module, turn off this IGBT module, and initiate a resistance adjustment signal for adjusting the resistance value of the gate resistance suppression module corresponding to the other IGBT module, so as to suppress the spike voltage between the collector and emitter of the other IGBT module by adjusting the resistance value of this gate resistance suppression module.

[0170] Specifically, when the frequency converter is overloaded, the spike voltage V CE of one tube in the arm will exceed the set threshold. If it can be controlled within the threshold range by adjusting the adjustable resistor R G , then there is no need to connect the gate voltage source of the other tube to the circuit. If it can no longer be controlled within the threshold range by adjusting the adjustable resistor R G , then connect the gate voltage source of the other tube to the circuit to increase the IGBT gate limit voltage V GE , and prevent the other IGBT in the arm from being triggered and conducting when it conducts, resulting in a failure.

[0171] Step S420: After the gate resistance suppression module corresponding to the other IGBT module adjusts the resistance based on the resistance adjustment signal, determine again whether the spike voltage between the collector and emitter of the IGBT module that is turned off on the arm where the other IGBT module is located still exceeds the set voltage threshold.

[0172] Step S430: If the spike voltage between the collector and emitter of the IGBT module that is turned off on the arm where the other IGBT module is located still exceeds the set voltage threshold, initiate a voltage source access signal that can control the access of the voltage source suppression module corresponding to the other IGBT module, so as to further suppress the spike voltage between the collector and emitter of the other IGBT module by accessing this voltage source suppression module.

[0173] Specifically, when the spike voltage exceeds the set threshold, the instantaneous voltage value detected can be captured by a voltage sensor, and the voltage analyzer is immediately started for fault analysis and processing. When an inverter bridge short circuit occurs, by adjusting the adjustable resistor R G it is no longer possible to control the spike voltage V CE , then the voltage source is connected to the circuit to increase the IGBT gate limit voltage V GE . This prevents the other IGBT on the arm from being triggered into conduction when it conducts, resulting in a fault. Among them, there is a voltage source at the gate of the IGBT to prevent the IGBT on the same arm from causing the other IGBT to conduct when it is turned on. This voltage source is controlled by the inter-board relay KA1. When the spike voltage is within the threshold range, this voltage source is cut off, which can minimize the switching loss while ensuring reliability. After using a negative voltage source at the gate of the IGBT, the spike voltage generated at the moment of IGBT turn-off can be suppressed, ensuring the reliability of turn-off.

[0174] Of course, if the spike voltage between the collector and emitter of an IGBT module that is turned off on the arm where the other IGBT module is located does not exceed the set threshold, there is no need to access the voltage source suppression module corresponding to the other IGBT module.

[0175] Specifically, when the frequency converter is working normally (the frequency converter is not overloaded and the inverter bridge is not short-circuited), adjust the resistance value of the adjustable resistor R G so that the spike voltage of the IGBT is within a reasonable threshold range, then the other IGBT on that arm does not need to connect the voltage source to the circuit, which can reduce the circuit loss.

[0176] In some embodiments, it further includes: a process of fault handling when a bridge arm short circuit fault occurs in the inverter bridge. Specifically, it may include:

[0177] After the control unit issues a control signal capable of controlling the IGBT spike voltage suppression unit, specifically, after issuing a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located, if the abnormal operation of the frequency converter is that the frequency converter is overloaded, a reminder message for the overload of the frequency converter is issued to remind the user to adjust the load of the frequency converter within the rated load range. Specifically, the overload information can be fed back to the customer to enable the customer to adjust the load of the unit within the rated range.

[0178] Alternatively, the control unit is specifically further configured to, after issuing a control signal capable of controlling the IGBT spike voltage suppression unit, specifically, after issuing a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located, if the abnormal operation of the frequency converter is that the arm of the inverter bridge is short-circuited, locate and remove the fault of the short-circuited arm of the inverter bridge, and then enable the frequency converter to be powered on again. And, when the frequency converter outputs to the bearing controller, the message of the short circuit of the arm of the inverter bridge is transmitted to the bearing controller through the communication channel, so that the bearing controller can start its own protection mechanism in time when it knows the fault of the inverter bridge.

[0179] Specifically, a fault detection and fault handling circuit is added to the main control board. A voltage capture circuit is added to one side of the bus capacitor C, that is, the DC output terminal of the bus voltage, to obtain the spike voltage between the DC bus DC+ and DC- in real time, so as to judge whether the bus voltage is within the working range of the bearing switching power supply through a voltage analyzer. When a short circuit occurs in the inverter bridge of the frequency converter, the spike voltage value V between the collector and emitter of the IGBT CE will mutate, and the bus voltage U DC will also be instantaneously pulled down and fall out of the voltage range of the DC-DC switching power supply that supplies power to the bearing controller. The instantaneous lack of input of the switching power supply will cause abnormal output, resulting in abnormal operation of the bearing controller, and further abnormal bearing suspension. In the light case, the floating shaft accuracy of the bearing is poor. In the heavy case, the shaft will touch the shaft while rotating, or even smash the shaft, which are not allowed. After applying V neg to the gate of the IGBT, regardless of whether the actual value of V GE exceeds the set value, as long as a short circuit occurs in the arm, fault handling must be entered.

[0180] On the one hand, the frequency converter detects the voltage value u of the IGBT ce4, this value exceeds the set value. After the detected voltage value is processed by the voltage analyzer, it is compared with the data in the inverter bridge topology analyzer. The residual value can represent the deviation rate. The residual is transmitted to the fault identifier to locate which IGBT has a short circuit, so as to handle the fault. The fault signal is transmitted to the main control DSP, and the main control displays short-circuit protection, cuts off the circuit, and stops for inspection; after troubleshooting, power on again.

[0181] On the other hand, when the voltage capture circuit detects abnormal bus voltage, it gives a fault judgment through the voltage analyzer. After determining the fault, the fault is sent to the fault responder of the bearing controller through the CAN communication by the fault generator. The bearing controller receives the fault and responds, and feeds back the fault to the main control MCU. The main program of the MCU immediately issues an instruction to activate the standby power supply to ensure normal power supply to the bearing controller. Before the motor stops rotating, the shaft suspension is stable. The motor stops rotating and the shaft drops normally. Wait for the frequency converter to troubleshoot the fault. After troubleshooting, power on again.

[0182] Thus, by quickly detecting faults and cutting off the fault source in time when the spike voltage suppression measures fail, the frequency converter system can be prevented from running with a phase loss, ensuring the safe and reliable operation of the frequency converter system. In this way, after the IGBT spike voltage suppression unit fails, the frequency converter system performs fault identification and fault diagnosis, and quickly adjusts the settings of the frequency converter system or cuts off the fault source to ensure the reliability of the frequency converter system.

[0183] In some embodiments, the specific process of positioning the short-circuited bridge arm of the inverter bridge through the control unit can be referred to the following exemplary description.

[0184] The following combines Figure 13 The schematic flowchart of an embodiment of the method for positioning the short-circuited bridge arm of the inverter bridge in the present invention shown in the figure further illustrates the specific process of positioning the short-circuited bridge arm of the inverter bridge, which may include: step S510 and step S520.

[0185] Step S510, compare the spike voltage between the collector and emitter of the IGBT module collected with the set voltage between the collector and emitter of the IGBT module to obtain the first voltage residual; and compare the bus voltage of the DC power supply of the frequency converter with the set bus voltage to obtain the second voltage residual. And,

[0186] Step S520, process the first voltage residual and the second voltage residual to realize the positioning of the short-circuited bridge arm of the inverter bridge.

[0187] Thus, when a short circuit occurs in the inverter bridge, the voltage of the short-circuited phase drops to zero instantaneously and the current increases rapidly. Use a voltage sensor to capture the voltage change and analyze the voltage value V of the IGBT at this time through a voltage analyzer.CE There are residuals when comparing the phase current and the bus voltage with the set normal values. Analyze and process the residuals to achieve the identification and location of faults, and then further process the faults.

[0188] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the foregoing motor system, for the details not described in the description of this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments, and details will not be repeated here.

[0189] Verified by a large number of tests, with the technical solution of this embodiment, when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off and the spike voltage of the IGBT module is suppressed; and, after the suppression measure fails, that is, when the spike voltage exceeds the set threshold, quickly detect the fault of the IGBT module, cut off the fault in time, and prevent the system from running with a phase missing, ensuring the safe and reliable operation of the frequency converter system.

[0190] In summary, it is easy for those skilled in the art to understand that, on the premise of no conflict, the above advantageous ways can be freely combined and superimposed.

[0191] The above are only the embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A protection device for an IGBT module in a frequency converter, characterized in that, it includes: a collection unit, an IGBT peak voltage suppression unit, and a control unit; wherein, the collection unit is configured to collect the three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter when the inverter bridge is working after the frequency converter is powered on; the control unit is configured to determine whether the frequency converter is working normally according to at least one of the collected three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter; and, when the frequency converter is not working normally, control the IGBT module to remain in the off state and initiate a control signal capable of controlling the IGBT peak voltage suppression unit; the IGBT peak voltage suppression unit is configured to suppress the peak voltage between the collector and emitter of the IGBT module under the control of the control signal; by setting an IGBT peak voltage suppression unit at the gate of the IGBT, when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, the IGBT is turned off, and the IGBT peak voltage suppression unit is used to suppress the peak voltage of the IGBT module; after the suppression measure fails, that is, when the peak voltage exceeds the set threshold, quickly detect the fault of the IGBT module, cut off the fault in time, and prevent the system from running with a phase missing.

2. The protection device for an IGBT module in a frequency converter according to claim 1, characterized in that, the collection unit includes: a current collection unit, a voltage collection unit, and a voltage capture unit; the number of the voltage collection units is the same as the number of IGBT modules in the inverter bridge; each of the voltage collection units is configured to collect the peak voltage between the collector and emitter of a corresponding IGBT module when the inverter bridge is working after the frequency converter is powered on; wherein, the collection unit collects the three-phase current of the frequency converter and the peak voltage between the collector and emitter of the IGBT module, including: the current collection unit is configured to collect the three-phase current of the frequency converter; the voltage collection unit is configured to collect the peak voltage between the collector and emitter of the IGBT module; the voltage capture unit is configured to collect the bus voltage of the DC power supply of the frequency converter; Correspondingly, the control unit determines whether the frequency converter is working normally according to at least one of the collected three-phase current of the frequency converter, the peak voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter, including: If the collected three-phase current of the frequency converter shows that the frequency converter has a normal three-phase current output, and the amplitude of the three-phase current output by the frequency converter becomes larger and exceeds the set current amplitude, it is determined that the frequency converter is overloaded; and, If the peak voltage between the collector and the emitter of the IGBT module collected exceeds the set voltage threshold, it is determined that the frequency converter is not working properly, that is, it is determined that the frequency converter is overloaded and not working properly; Or, Compare the peak voltage between the collector and the emitter of the IGBT module collected with the set voltage between the collector and the emitter of this IGBT module; and compare the bus voltage of the DC power supply of the frequency converter with the set bus voltage; and, If the peak voltage between the collector and the emitter of the IGBT module collected changes suddenly with respect to the set voltage between the collector and the emitter of this IGBT module; and the bus voltage of the DC power supply of the frequency converter drops with respect to the set bus voltage, it is determined that the frequency converter is not working properly, that is, it is determined that the arm of the inverter bridge is short-circuited.

3. The protection device for the IGBT module in the frequency converter according to claim 2, characterized in that, The number of the IGBT peak voltage suppression units is the same as the number of IGBT modules in the inverter bridge of the frequency converter; each of the IGBT peak voltage suppression units is specifically arranged between a corresponding IGBT module and the drive board of this IGBT module; The control unit controls the IGBT module to remain in the off state and issues a control signal capable of controlling the IGBT peak voltage suppression unit, including: In the case where the frequency converter is not working properly, turn off the IGBT module and issue a control signal for controlling the IGBT peak voltage suppression unit corresponding to another IGBT module on the arm where this IGBT module is located.

4. The protection device for the IGBT module in the frequency converter according to claim 3, characterized in that, Each of the IGBT peak voltage suppression units includes: a resistor suppression module and a voltage source suppression module; the resistor suppression module is arranged between the output end of the drive board of the IGBT module and the gate of the IGBT module; the voltage source suppression module is arranged between the input end of the drive board of the IGBT module and the emitter of the IGBT module; Among them, the IGBT peak voltage suppression unit suppresses the peak voltage between the collector and the emitter of the IGBT module under the control of the control signal, including: The resistor suppression module is configured to suppress the peak voltage between the collector and the emitter of the IGBT module by using its own resistance value; The voltage source suppression module is configured to further suppress the peak voltage between the collector and the emitter of the IGBT module by using the negative voltage source provided by itself when it is connected.

5. The protection device for the IGBT module in the frequency converter according to claim 4, characterized in that, The control signal includes: a resistance value adjustment signal capable of adjusting the resistance value of the resistor suppression module, and a voltage source connection or disconnection signal capable of controlling the connection or disconnection of the voltage source suppression module; Among them, the control unit issues a control signal for controlling the IGBT spike voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located, including: Issuing a resistance adjustment signal for adjusting the resistance of the gate resistance suppression module corresponding to the other IGBT module; After the resistance of the gate resistance suppression module corresponding to the other IGBT module is adjusted based on the resistance adjustment signal, determining again whether the spike voltage between the collector and the emitter of the turned-off IGBT module on the arm where the other IGBT module is located still exceeds the set voltage threshold; If the spike voltage between the collector and the emitter of the turned-off IGBT module on the arm where the other IGBT module is located still exceeds the set voltage threshold, issuing a voltage source access signal capable of controlling the access of the voltage source suppression module corresponding to the other IGBT module.

6. The protection device for the IGBT module in the frequency converter according to any one of claims 1 to 5, characterized in that, further comprising: The control unit is further configured to, after issuing a control signal capable of controlling the IGBT spike voltage suppression unit, if the situation where the frequency converter does not work properly is that the frequency converter is overloaded, issue a reminder message of the overload of the frequency converter to remind the user to adjust the load of the frequency converter to within the rated load range; if the situation where the frequency converter does not work properly is that the arm of the inverter bridge is short-circuited, locate and remove the fault of the short-circuited arm of the inverter bridge; and, when the frequency converter outputs to the bearing controller, transmit the message of the short-circuit of the arm of the inverter bridge to the bearing controller through the communication channel, so that the bearing controller can start its own protection mechanism in time when it knows the fault of the inverter bridge.

7. The protection device for the IGBT module in the frequency converter according to claim 6, characterized in that, The control unit locates the short-circuited arm of the inverter bridge, including: Comparing the spike voltage between the collector and the emitter of the IGBT module collected with the set voltage between the collector and the emitter of the IGBT module to obtain a first voltage residual; and comparing the bus voltage of the DC power supply of the frequency converter with the set bus voltage to obtain a second voltage residual; and, Processing the first voltage residual and the second voltage residual to realize the location of the short-circuited arm of the inverter bridge.

8. An electric motor system, characterized in that, comprising: The protection device for the IGBT module in the frequency converter according to any one of claims 1 to 7.

9. A method for protecting an IGBT module in a frequency converter, characterized in that, comprising: Through the acquisition unit, when the inverter bridge works after the frequency converter is powered on, acquiring the three-phase current of the frequency converter, acquiring the spike voltage between the collector and the emitter of the IGBT module, and acquiring the bus voltage of the DC power supply of the frequency converter; Through a control unit, determine whether the frequency converter is operating normally based on at least one of the three-phase current of the frequency converter, the spike voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter; and, when the frequency converter is not operating normally, control the IGBT module to remain in the off state and initiate a control signal capable of controlling the IGBT spike voltage suppression unit; Through the IGBT spike voltage suppression unit, suppress the spike voltage between the collector and emitter of the IGBT module under the control of the control signal; by setting the IGBT spike voltage suppression unit at the gate of the IGBT, when the frequency converter is overloaded and a short circuit occurs in the bridge arm of the inverter bridge, turn off the IGBT, and suppress the spike voltage of the IGBT module through the IGBT spike voltage suppression unit; after the suppression measure fails, that is, when the spike voltage exceeds the set threshold, quickly detect the failure of the IGBT module and cut off the fault in time to prevent the system from running with a phase missing.

10. The protection method for the IGBT module in the frequency converter according to claim 9, characterized in that, The acquisition unit includes: a current acquisition unit, a voltage acquisition unit, and a voltage capture unit; the number of the voltage acquisition units is the same as the number of IGBT modules in the inverter bridge; each of the voltage acquisition units is configured to acquire the spike voltage between the collector and emitter of one corresponding IGBT module when the inverter bridge is operating after the frequency converter is powered on; wherein, through the acquisition unit, acquiring the three-phase current of the frequency converter and acquiring the spike voltage between the collector and emitter of the IGBT module includes: Acquiring the three-phase current of the frequency converter through the current acquisition unit; Acquiring the spike voltage between the collector and emitter of the IGBT module through the voltage acquisition unit; Acquiring the bus voltage of the DC power supply of the frequency converter through the voltage capture unit; Correspondingly, through the control unit, determining whether the frequency converter is operating normally based on at least one of the three-phase current of the frequency converter, the spike voltage between the collector and emitter of the IGBT module, and the bus voltage of the DC power supply of the frequency converter includes: If the three-phase current of the frequency converter acquired shows that the frequency converter has a normal three-phase current output, and the amplitude of the three-phase current output by the frequency converter becomes larger and exceeds the set current amplitude, it is determined that the frequency converter is overloaded; and, If the spike voltage between the collector and emitter of the IGBT module acquired exceeds the set voltage threshold, it is determined that the frequency converter is not operating normally, that is, it is determined that the frequency converter is overloaded and not operating normally; Or, Compare the acquired spike voltage between the collector and emitter of the IGBT module with the set voltage between the collector and emitter of this IGBT module; and compare the bus voltage of the DC power supply of the frequency converter with the set bus voltage; and, If the peak voltage between the collector and emitter of the IGBT module collected undergoes a mutation relative to the set voltage between the collector and emitter of the IGBT module; and the bus voltage of the DC power supply of the frequency converter drops relative to the set bus voltage, it is determined that the frequency converter is not operating properly, that is, it is determined that there is a short circuit in the arm of the inverter bridge.

11. The protection method for the IGBT module in the frequency converter according to claim 10, characterized in that the number of the IGBT peak voltage suppression units is the same as the number of IGBT modules in the inverter bridge of the frequency converter; each of the IGBT peak voltage suppression units is specifically arranged between a corresponding IGBT module and the drive board of the IGBT module; through the control unit, controlling the IGBT module to remain in the off state and initiating a control signal capable of controlling the IGBT peak voltage suppression unit, including: in the case where the frequency converter is not operating properly, turning off the IGBT module and initiating a control signal for controlling the IGBT peak voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located.

12. The protection method for the IGBT module in the frequency converter according to claim 11, characterized in that each of the IGBT peak voltage suppression units includes: a resistance suppression module and a voltage source suppression module; the resistance suppression module is arranged between the output terminal of the drive board of the IGBT module and the gate of the IGBT module; the voltage source suppression module is arranged between the input terminal of the drive board of the IGBT module and the emitter of the IGBT module; wherein, through the IGBT peak voltage suppression unit, under the control of the control signal, suppressing the peak voltage between the collector and emitter of the IGBT module includes: through the resistance suppression module, by utilizing its own resistance value, realizing the suppression of the peak voltage between the collector and emitter of the IGBT module; through the voltage source suppression module, by utilizing the negative voltage source provided by itself when it is connected, realizing the further suppression of the peak voltage between the collector and emitter of the IGBT module.

13. The protection method for the IGBT module in the frequency converter according to claim 12, characterized in that the control signal includes: a resistance value adjustment signal capable of adjusting the resistance value of the resistance suppression module, and a voltage source connection or disconnection signal capable of controlling the connection or disconnection of the voltage source suppression module; wherein, through the control unit, initiating a control signal for controlling the IGBT peak voltage suppression unit corresponding to another IGBT module on the arm where the IGBT module is located includes: initiating a resistance value adjustment signal for adjusting the resistance value of the gate resistance suppression module corresponding to the another IGBT module; After the gate resistance suppression module corresponding to the other IGBT module adjusts the resistance based on the resistance adjustment signal, it is determined again whether the peak voltage between the collector and the emitter of the IGBT module that is turned off on the arm where the other IGBT module is located still exceeds the set voltage threshold; If the peak voltage between the collector and the emitter of the IGBT module that is turned off on the arm where the other IGBT module is located still exceeds the set voltage threshold, a voltage source access signal that can control the access of the voltage source suppression module corresponding to the other IGBT module is initiated.

14. The protection method for the IGBT module in the frequency converter according to any one of claims 9 to 13, characterized in that, further comprising: Through the control unit, after initiating a control signal that can control the IGBT peak voltage suppression unit, If the abnormal working condition of the frequency converter is that the frequency converter is overloaded, a reminder message of the overload of the frequency converter is initiated to remind the user to adjust the load of the frequency converter within the rated load range; If the abnormal working condition of the frequency converter is that the arm of the inverter bridge is short-circuited, the short-circuited arm of the inverter bridge is located and the fault is removed; and, when the frequency converter outputs to the bearing controller, the message of the short circuit of the arm of the inverter bridge is transmitted to the bearing controller through the communication channel, so that the bearing controller can start its own protection mechanism in time when it knows the fault of the inverter bridge.

15. The protection method for the IGBT module in the frequency converter according to claim 14, characterized in that, Through the control unit, locating the short-circuited arm of the inverter bridge includes: Comparing the peak voltage between the collector and the emitter of the IGBT module collected with the set voltage between the collector and the emitter of this IGBT module to obtain a first voltage residual; and comparing the bus voltage of the DC power supply of the frequency converter with the set bus voltage to obtain a second voltage residual; and, Processing the first voltage residual and the second voltage residual to realize the location of the short-circuited arm of the inverter bridge.

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