A motor-side overvoltage suppression device for a PWM inverter drive

Abstract

The application relates to the field of power distribution circuit devices and discloses a motor side overvoltage suppression device driven by a PWM converter, which comprises a single-phase overvoltage suppression module and a low-pass filtering module integrated in a shell unit. The single-phase overvoltage suppression module comprises a rectifying unit, a thin-film capacitor unit and a power resistor unit, constitutes a transient clamping network and is connected in parallel between a long cable and a power receiving terminal wiring node, and is used for clamping differential mode and common mode pulse overvoltage in a direct-current bus voltage range. The low-pass filtering module comprises a three-phase resistance-capacitance filtering unit composed of a non-inductive resistor and a fixed capacitor, and is used for limiting common mode harmonics and restraining a common mode voltage peak value. The application can in-situ accommodate power receiving terminal transient waveform reflection superposition, effectively suppress differential mode and common mode overvoltage, weaken induced shaft voltage and shaft current, and guarantee long-period stable operation of a motor system.

Description

Technical Field

[0001] This invention relates to the field of power distribution circuit device technology, and in particular to an overvoltage suppression device for a motor driven by a PWM converter. Background Technology

[0002] In high-power power conversion and distribution control architecture, the inverter-stage switching devices modulate the output voltage pulse train with high-frequency switching action to achieve efficient power transmission. The voltage pulse with a rising edge of 1μs is transmitted to the terminal equipment node of the power distribution network along the long-distance power transmission cable. Due to the complex distributed high-frequency electromagnetic network formed by the large-capacity copper conductor and the insulating medium, the pulse energy excites a strong waveform positive reflection superposition phenomenon at the impedance mismatch terminal connection node.

[0003] In field conditions such as wind power generation systems or high-voltage, high-capacity transmission trunk lines, there are long-distance transmission cables ranging from 30m to 100m between the converter and the receiving end such as the generator junction box. Due to external constraints such as tower height, number of parallel windings, and variable laying spacing, the physical distribution parameters of the cable exhibit large-scale random fluctuations, leading to complex transient slippage in the characteristic impedance response characteristics at the end of the channel, which can easily deteriorate the electrical insulation of the terminal nodes. Traditional strategies involve connecting fixed impedance reactors or filter circuits on the converter output side. However, facing the dynamically changing electrical parameters at the transmission end, these static front-end suppression methods have the following shortcomings: 1. The fixed impedance components at the beginning cannot adaptively match the dynamic distribution parameters caused by fluctuations in the field layout of long-distance cables, and high-order reflected standing waves are still generated in large quantities at the terminal nodes; 2. Magnetic energy-absorbing components are prone to irreversible magnetic saturation failure when subjected to high-frequency, high-energy transient impacts, losing their continuous pressure resistance performance; 3. The centralized filters connected in series on the trunk line have serious internal heat accumulation losses, making it difficult to match the cost constraints of non-destructive retrofitting of existing junction box terminals to connect the main power cable in parallel without dismantling.

[0004] Therefore, the technical problem to be solved by this invention is how to isolate the impedance fluctuation disturbance introduced into the terminal filter circuit by the changing distributed parameters of long-distance power cables, and how to stably dissipate the differential mode high-frequency impact energy generated by the coupling of multiple factors under complex working conditions and smoothly limit the transient drift amplitude of common mode ground potential while maintaining the integrity of the main circuit topology of the existing high-voltage high-power distribution network power cables. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A motor-side overvoltage suppression device driven by a PWM converter includes a single-phase overvoltage suppression module, a low-pass filter module, and a modular housing unit. The single-phase overvoltage suppression module includes a rectifier unit, a film capacitor unit, and a power resistor unit, and the turn-on time of the rectifier unit is less than or equal to 100ns. The rectifier unit, the film capacitor unit, and the power resistor unit are connected in parallel through metal wires to form a transient clamping network. The transient clamping network is connected in parallel between the three-phase long cable and the power receiving terminal connection node. Based on the differential mode pulse power fluctuation transmitted by the three-phase long cable, the transient clamping network clamps the reflected superimposed transient differential mode and common mode pulse overvoltage peak within the DC bus voltage setting range. The low-pass filter module includes a three-phase RC filter unit, which is connected in parallel between the single-phase overvoltage suppression module and the power receiving terminal. The three-phase RC filter unit is composed of electrically conductive resistor and capacitor components. The three-phase RC filter unit provides a shunt path based on the high-frequency common-mode harmonic variation of the power receiving terminal, limiting the peak common-mode voltage of the power receiving terminal to no more than 0.5 times the DC bus voltage.

[0006] Preferably, in the single-phase overvoltage suppression module, the capacitance of the film capacitor unit is 5μF to 20μF, and the resistance of the power resistor unit is 3kΩ to 10kΩ. When the transient clamping network is conducting and shunt differential mode pulse power, the real-time heat loss power of the power resistor unit is controlled within 20% to 30% of the rated power of the power resistor unit itself, and the power resistor unit and the film capacitor unit are connected by wires to form a RC discharge energy dissipation network.

[0007] Preferably, in the single-phase overvoltage suppression module, the rectifier unit is forward-biased based on the peak value of the differential mode overvoltage input from the three-phase long cable, and the energy of the differential mode pulse overvoltage is introduced into the thin film capacitor unit, and converted into heat energy by the power resistor unit, so as to reduce the voltage change rate conducted to the receiving terminal connection node.

[0008] Preferably, in the low-pass filter module, the shunt path of the three-phase RC filter unit shunts the high-frequency common-mode harmonic components, and the peak value of the common-mode voltage at the receiving end connection node is stabilized within 0.5 times the DC bus voltage, thereby reducing the ground potential drift amplitude on the terminal grounding side.

[0009] Preferably, in the single-phase overvoltage suppression module, the rectifier unit includes multiple rectifier diodes with the same rated operating voltage; the multiple rectifier diodes are connected in series through internal printed wires to form a single-phase rectification and shunt network.

[0010] Preferably, in the low-pass filter module, the three-phase RC filter unit includes three sets of RC filter branches with identical structures; the three sets of RC filter branches are electrically connected according to a star topology network, and the neutral convergence point of the star topology network is electrically connected to the grounding bolt fixed in the system.

[0011] Preferably, the input and output terminals of the device are respectively provided with a three-phase AC input terminal, a DC clamping connection terminal and a grounding bolt; the three-phase AC input terminal electrically guides the three-phase long cable, the DC clamping connection terminal electrically guides the DC busbar of the converter, and the grounding bolt electrically guides the external grounding wire.

[0012] Preferably, in the low-pass filter module, the resistor component is a non-inductive resistor component, and the capacitor component is a fixed capacitor component.

[0013] Preferably, in the low-pass filter module, the resistor component is a non-inductive resistor component, and the capacitor component is a fixed capacitor component.

[0014] The beneficial effects of this invention are: 1. This device is connected in parallel to the generator side junction box at the end of the power transmission and distribution network. It cuts off the coupling channel of dynamic distributed parameters between the high-frequency filter circuit and the long-distance power transmission cable, blocks the characteristic impedance fluctuation disturbance introduced by the changes in cable length, cable laying method and the number of parallel power cables to the power supply terminal control node, and uses the spatial topology architecture of the parallel terminal to eliminate the reflection and superposition of transient pulse waveforms at the end of the high-voltage power network, maintains the symmetry of the three-phase transient voltage at the power supply and distribution network terminal, ensures that the electrical parameters of each phase of the power transmission system maintain high stability under various operating conditions, and controls the differential mode pulse overvoltage amplitude of the power transmission network terminal bus within the safe insulation limit.

[0015] 2. The single-phase overvoltage suppression circuit uses nanosecond-level ultrafast response rectifier devices, high-frequency thin-film capacitors, and power resistors to form a transient clamping circuit. When the high-power converter operates and generates a microsecond-level waveform leading-edge pulse, the rectifier device turns on instantaneously at the transient voltage edge and opens a low-impedance transient energy shunt channel. The differential-mode pulse energy containing rich high-frequency components is discharged to the high-frequency thin-film capacitor for transient absorption and storage, and the heat dissipation is utilized by the power resistor. This forces the differential-mode transient voltage peak at the end node of the power transmission and distribution network to be stably and smoothly clamped near the DC bus voltage safety threshold, controlling the transient voltage impact to be deeply propagated to the internal electrical windings.

[0016] 3. The low-pass filter circuit provides a low-impedance path for high-frequency common-mode harmonics through the introduction of a three-phase RC absorption network. It forms a synergistic response mechanism with the single-phase overvoltage suppression circuit. Relying on the network characteristics of specific capacitor values, it limits the disordered flow of common-mode high-frequency energy, and stably limits the peak value of the common-mode voltage at the terminal connection node to about half of the DC bus voltage. It also reduces the ground potential drift amplitude on the terminal grounding side, thereby weakening the induced shaft voltage and shaft current excitation factors generated by the evolution of distribution mechanism. Since the entire RC circuit does not rely on magnetic components, it eliminates the hidden danger of magnetic saturation failure and ensures the long-term safe operation of the power transmission terminal system.

[0017] 4. The single-phase overvoltage suppression module integrates a fuse mechanism. When encountering an extreme high-energy overvoltage impact with a pulse leading edge of less than or equal to 10μs and an overload current exceeding the rated value, the fuse can actively disconnect the circuit to achieve overload current protection. This effectively avoids the devastating burnout of the thin-film capacitors and power resistors in the transient clamping network caused by high-energy transient impacts, and significantly improves the device's self-protection capability and the reliability of continuous system operation under extreme abnormal conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the hardware connection topology of the transient clamping and RC filtering circuit of the present invention; Figure 2 This is a flowchart of the control logic for differential-mode pulses and high-frequency common-mode harmonics in this invention. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0022] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0023] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] A motor-side overvoltage suppression device driven by a PWM converter includes a single-phase overvoltage suppression module, a low-pass filter module, and a modular housing unit. The single-phase overvoltage suppression module includes a rectifier unit, a film capacitor unit, and a power resistor unit, and the turn-on time of the rectifier unit is less than or equal to 100ns. The rectifier unit, the film capacitor unit, and the power resistor unit are connected in parallel through metal wires to form a transient clamping network. The transient clamping network is connected in parallel between the three-phase long cable and the power receiving terminal connection node. Based on the differential mode pulse power fluctuation transmitted by the three-phase long cable, the transient clamping network clamps the reflected superimposed transient differential mode and common mode pulse overvoltage peak within the DC bus voltage setting range. The low-pass filter module includes a three-phase RC filter unit, which is connected in parallel between the single-phase overvoltage suppression module and the power receiving terminal. The three-phase RC filter unit is composed of electrically conductive resistor and capacitor components. The three-phase RC filter unit provides a shunt path based on the high-frequency common-mode harmonic variation of the power receiving terminal, limiting the peak common-mode voltage of the power receiving terminal to no more than 0.5 times the DC bus voltage.

[0026] Preferably, in the single-phase overvoltage suppression module, the capacitance of the film capacitor unit is 5μF to 20μF, and the resistance of the power resistor unit is 3kΩ to 10kΩ. When the transient clamping network is conducting and shunt differential mode pulse power, the real-time heat loss power of the power resistor unit is controlled within 20% to 30% of the rated power of the power resistor unit itself, and the power resistor unit and the film capacitor unit are connected by wires to form a RC discharge energy dissipation network.

[0027] Preferably, in the single-phase overvoltage suppression module, the rectifier unit is forward-biased based on the peak value of the differential mode overvoltage input from the three-phase long cable, and the energy of the differential mode pulse overvoltage is introduced into the thin film capacitor unit, and converted into heat energy by the power resistor unit, so as to reduce the voltage change rate conducted to the receiving terminal connection node.

[0028] Preferably, in the low-pass filter module, the shunt path of the three-phase RC filter unit shunts the high-frequency common-mode harmonic components, and the peak value of the common-mode voltage at the receiving end connection node is stabilized within 0.5 times the DC bus voltage, thereby reducing the ground potential drift amplitude on the terminal grounding side.

[0029] Preferably, in the single-phase overvoltage suppression module, the rectifier unit includes multiple rectifier diodes with the same rated operating voltage; the multiple rectifier diodes are connected in series through internal printed wires to form a single-phase rectification and shunt network.

[0030] Preferably, in the low-pass filter module, the three-phase RC filter unit includes three sets of RC filter branches with identical structures; the three sets of RC filter branches are electrically connected according to a star topology network, and the neutral convergence point of the star topology network is electrically connected to the grounding bolt fixed in the system.

[0031] Preferably, the input and output terminals of the device are respectively provided with a three-phase AC input terminal, a DC clamping connection terminal and a grounding bolt; the three-phase AC input terminal electrically guides the three-phase long cable, the DC clamping connection terminal electrically guides the DC busbar of the converter, and the grounding bolt electrically guides the external grounding wire.

[0032] Preferably, in the low-pass filter module, the resistor component is a non-inductive resistor component, and the capacitor component is a fixed capacitor component.

[0033] Preferably, in the single-phase overvoltage suppression module, the rectifier unit is an ultrafast response rectifier device.

[0034] Example 1: This example combines Figures 1 to 2 A description of an overvoltage suppression device for a motor driven by a PWM converter is provided, such as... Figure 1As shown, the device receives differential-mode pulse power fluctuations from a three-phase long cable, thereby introducing an impulse voltage. One impulse voltage is input to a low-pass filter module, and the other is input along the differential-mode pulse power shunt path to a single-phase overvoltage suppression module. The low-pass filter module includes a three-phase RC filter unit, which provides a shunt path to limit common-mode harmonics and constrain common-mode voltage peaks. The three-phase RC filter unit internally consists of resistors and capacitors connected in series. The resistors are non-inductive to eliminate magnetic saturation and potential failure hazards, while the capacitors are fixed capacitors to limit the disordered flow of common-mode energy. The low-pass filter module outputs controlled and stable power to the receiving terminal connection point for generator connection. The machine or motor terminal; the single-phase overvoltage suppression module forms a transient clamping network to locally absorb waveform reflection superposition and clamp differential mode pulse overvoltage within the DC bus set range. The single-phase overvoltage suppression module contains a rectifier unit, a film capacitor unit, and a power resistor unit. The differential mode pulse power shunt path is connected to the rectifier unit and the film capacitor unit respectively. The rectifier unit is turned on to achieve ultra-fast response and together with the film capacitor unit with a capacitance of 5μF to 20μF, it is electrically connected to the grounding bolt through the junction node. The power receiving terminal connection node is connected to the power resistor unit through the connection return, so that the differential mode impact energy is dissipated by the heat of the power resistor unit with a resistance of 3kΩ to 10kΩ.

[0035] like Figure 2 As shown, under the condition of power fluctuation input at the end of the power transmission and distribution network, the entire suppression process carries out two-dimensional detection and control in parallel. On the one hand, when the differential mode pulse overvoltage pulse leading edge is less than or equal to ten microseconds, the system determines whether the overload current value exceeds the rated current value of the fuse. If the determination result is yes, the fuse disconnects the circuit to implement overload current protection. If the determination result is no, the transient clamping network is controlled to conduct forward to absorb waveform reflection superposition locally, thereby prompting the rectifier unit to turn on for ultra-fast response shunting. At this time, the energy is transiently absorbed and stored through the thin film capacitor unit with a capacitance value of five to twenty microfarads, and the resistor is used to store the energy. Power resistors with values ​​of three to ten kiloohms convert energy into heat, ultimately achieving the control objective of clamping the peak differential-mode pulse overvoltage within the DC bus voltage setting range. On the other hand, when a transient ground potential drift caused by a high-frequency common-mode harmonic is detected, a three-phase RC filter unit provides a low-impedance shunt path, prompting the resistor and capacitor components to respond in concert. The three sets of identical filter branches are electrically connected in a star topology network, and the neutral convergence point of the star topology network is electrically connected to the system's fixed grounding bolt. The ultimate control objective is to limit the common-mode voltage peak to no more than 0.5 times the DC bus voltage.

[0036] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A motor-side overvoltage suppression device driven by a PWM converter, characterized in that, Includes a single-phase overvoltage suppression module, a low-pass filter module, and a modular housing unit: The single-phase overvoltage suppression module includes a rectifier unit, a film capacitor unit, and a power resistor unit, and the turn-on time of the rectifier unit is less than or equal to 100ns. The rectifier unit, the film capacitor unit, and the power resistor unit are connected in parallel through metal wires to form a transient clamping network. The transient clamping network is connected in parallel between the three-phase long cable and the power receiving terminal connection node. Based on the differential mode pulse power fluctuation transmitted by the three-phase long cable, the transient clamping network clamps the reflected superimposed transient differential mode and common mode pulse overvoltage peak within the DC bus voltage setting range. The low-pass filter module includes a three-phase RC filter unit, which is connected in parallel between the single-phase overvoltage suppression module and the power receiving terminal. The three-phase RC filter unit is composed of electrically conductive resistor and capacitor components. The three-phase RC filter unit provides a shunt path based on the high-frequency common-mode harmonic variation of the power receiving terminal, limiting the peak common-mode voltage of the power receiving terminal to no more than 0.5 times the DC bus voltage.

2. The overvoltage suppression device for a motor driven by a PWM converter according to claim 1, characterized in that, In the single-phase overvoltage suppression module, the capacitance of the film capacitor unit is 5μF to 20μF, and the resistance of the power resistor unit is 3kΩ to 10kΩ. When the transient clamping network is conducting and shunt differential mode pulse power, the real-time heat loss power of the power resistor unit is controlled within 20% to 30% of the rated power of the power resistor unit itself. The power resistor unit and the film capacitor unit are connected by wires to form a RC discharge energy dissipation network.

3. The overvoltage suppression device for a motor driven by a PWM converter according to claim 1, characterized in that, In the single-phase overvoltage suppression module, the rectifier unit conducts forward based on the peak value of the differential mode overvoltage input from the three-phase long cable, and introduces the energy of the differential mode pulse overvoltage into the thin film capacitor unit, which is then converted into heat energy by the power resistor unit, thereby reducing the voltage change rate conducted to the terminal connection node.

4. The motor-side overvoltage suppression device driven by a PWM converter according to claim 1, characterized in that, In the low-pass filter module, the shunt path of the three-phase RC filter unit shunts the high-frequency common-mode harmonic components, and the peak value of the common-mode voltage at the receiving terminal connection node is stabilized within 0.5 times the DC bus voltage, thus reducing the ground potential drift amplitude on the terminal grounding side.

5. The motor-side overvoltage suppression device driven by a PWM converter according to claim 1, characterized in that, In the single-phase overvoltage suppression module, the rectifier unit includes multiple rectifier diodes with the same rated operating voltage; the multiple rectifier diodes are connected in series through internal printed wires to form a single-phase rectification and shunt network.

6. The motor-side overvoltage suppression device driven by a PWM converter according to claim 1, characterized in that, In the low-pass filter module, the three-phase RC filter unit includes three sets of RC filter branches with identical structures; the three sets of RC filter branches are electrically connected according to a star topology network, and the neutral convergence point of the star topology network is electrically connected to the grounding bolt fixed in the system.

7. The overvoltage suppression device for a motor driven by a PWM converter according to claim 1, characterized in that, The device is equipped with a three-phase AC input terminal, a DC clamping connection terminal, and a grounding bolt at its input and output terminals, respectively. The three-phase AC input terminal electrically guides the three-phase long cable, the DC clamping connection terminal electrically guides the DC busbar of the converter, and the grounding bolt electrically guides the external grounding wire.

8. The motor-side overvoltage suppression device driven by a PWM converter according to claim 1, characterized in that, In the low-pass filter module, the resistor component is a non-inductive resistor component, and the capacitor component is a fixed capacitor component.

9. The overvoltage suppression device for a motor driven by a PWM converter according to claim 1, characterized in that, In the single-phase overvoltage suppression module, the rectifier unit is an ultrafast response rectifier device.

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