CN116388543A - Bus capacitor discharging system, bus capacitor discharging method and frequency converter - Google Patents
Bus capacitor discharging system, bus capacitor discharging method and frequency converter Download PDFInfo
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- CN116388543A CN116388543A CN202310444516.4A CN202310444516A CN116388543A CN 116388543 A CN116388543 A CN 116388543A CN 202310444516 A CN202310444516 A CN 202310444516A CN 116388543 A CN116388543 A CN 116388543A
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- 238000007599 discharging Methods 0.000 title claims description 45
- 238000006243 chemical reaction Methods 0.000 claims abstract description 44
- 230000004044 response Effects 0.000 claims abstract description 38
- 230000001939 inductive effect Effects 0.000 claims abstract description 26
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/322—Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
- B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
- B60L3/0046—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electric energy storage systems, e.g. batteries or capacitors
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Abstract
The present application relates generally to the field of power electronics, and more particularly to a bus capacitor discharge system, a bus capacitor discharge method, and a frequency converter. A bus capacitor discharge system according to one aspect of the present application includes: a power conversion device capacitively coupled to the bus and comprising one or more legs, each of the one or more legs comprising one or more power switching devices and an inductive device; and a control device configured to control one of the one or more legs to be in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus capacitance by forming a discharge loop with the bus capacitance by the leg in the micro-conductive state.
Description
Technical Field
The present application relates generally to the field of power electronics, and more particularly to a bus capacitor discharge system, a bus capacitor discharge method, and a frequency converter.
Background
A high voltage energy storage capacitor, i.e., a bus capacitor, is provided in a power conversion device such as a motor controller or the like. Under some working conditions, in order to ensure high-voltage safety, the voltage on the bus capacitor needs to be reduced below the safety voltage within a specified time. For example, a bus capacitor is provided in a power conversion device of an electric vehicle or a hybrid vehicle. When the vehicle is used or fails, the voltage on the bus capacitor needs to be reduced below the safety voltage within a prescribed time in order to ensure high-voltage safety.
At present, a common bus capacitor discharging method is to add a discharging switch and a discharging resistor or other energy-consuming discharging devices between positive and negative buses. When the bus capacitor needs to be actively discharged, the discharging switch is closed to consume the energy on the bus capacitor through the discharging resistor or other energy-consuming discharging devices. However, in the bus capacitor discharging method, as additional discharging switches and discharging resistors or other energy-consuming discharging devices are added, the energy on the bus capacitor is consumed through the discharging resistors or other energy-consuming discharging devices, so that the cost is high, the energy waste in the discharging process and the possible overheat risk are caused.
Disclosure of Invention
To solve or at least alleviate one or more of the above problems, the following solutions are provided.
According to a first aspect of the present application, there is provided a bus capacitor discharge system comprising: a power conversion device capacitively coupled to the bus and comprising one or more legs, each of the one or more legs comprising one or more power switching devices and an inductive device; and a control device configured to control one of the one or more legs to be in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus capacitance by forming a discharge loop with the bus capacitance by the leg in the micro-conductive state.
The bus capacitor discharge system according to an embodiment of the present application, wherein at least one of the one or more power switching devices in the bridge arm in the micro-conductive state operates in a linear region.
The bus capacitor discharge system according to an embodiment of the present application or any one of the above embodiments, wherein the control device includes: and a gate-stage driving unit configured to perform an amplifying operation and/or an isolating operation on the discharge control signal to generate a driving signal.
The bus capacitor discharge system according to an embodiment of the present application or any one of the above embodiments, wherein the control device includes: an on speed adjustment unit configured to selectively switch the drive signal from a first drive state to a second drive state and transmit the drive signal in the second drive state to the power conversion device.
The bus capacitor discharge system according to an embodiment of the present application or any one of the above embodiments, wherein the control device includes: and a current signal processing unit configured to acquire a voltage across the inductance device in the bridge arm in the micro-conduction state and process the voltage to generate a discharge current value.
The bus capacitor discharge system according to an embodiment of the present application or any one of the above embodiments, wherein the control device includes: a comparing unit configured to compare the discharge current value with a current threshold value and output a valid signal in response to the discharge current value being greater than the current threshold value; a latch unit configured to receive and latch the valid signal; and a turn-off unit configured to bring the bridge arm in the micro-on state into an off state in response to receiving the valid signal from the latch unit, thereby disconnecting the discharge loop to end the discharge operation of the bus capacitance.
The bus capacitor discharging system according to an embodiment of the present application or any one of the embodiments above, wherein the latch unit is further configured to synchronously control the current signal processing unit, so that the discharging current value generated by the current signal processing unit is a current value when the bridge arm in the micro-on state enters an off state.
The bus capacitor discharge system according to an embodiment of the present application or any one of the embodiments above, wherein the discharge control signal is a periodic pulse signal, and the control device is configured to cause one of the one or more bridge legs to be in the micro-conductive state in response to the periodic pulse of the discharge control signal.
The bus capacitor discharge system according to an embodiment of the present application or any one of the above embodiments, wherein the control device includes: a discharge enabling unit configured to control the turn-on speed adjusting unit to switch the driving signal from a first driving state to a second driving state in response to receiving a discharge start signal, and to transmit the driving signal in the second driving state to the power conversion device such that one or more power switching devices in the bridge arm in the micro-conduction state in the power conversion device operate in an on state at a predetermined speed.
The bus capacitor discharge system according to an embodiment of the present application or any one of the above embodiments, wherein the discharge enabling unit is further configured to enable the latch unit in response to receiving a discharge start signal, such that the latch unit controls the turn-off unit to be in an open state.
According to a second aspect of the present application, there is provided a bus capacitor discharging method including: capacitively coupling a power conversion device with a bus bar, the power conversion device comprising one or more legs, each of the one or more legs comprising one or more power switching devices and an inductive device; and controlling one of the one or more bridge arms to be in a micro-conduction state in response to a discharge control signal so as to perform a discharge operation on the bus capacitor by forming a discharge loop with the bus capacitor by the bridge arm in the micro-conduction state.
According to an embodiment of the present application, the bus capacitor discharging method is further configured to operate at least one power switching device of the one or more power switching devices in the bridge arm in the micro-conductive state in a linear region.
The bus capacitor discharging method according to an embodiment of the present application or any one of the above embodiments, wherein the method further includes: acquiring voltages at two ends of the inductance device in the bridge arm in the micro-conduction state and processing the voltages to generate a discharge current value; and comparing the discharge current value with a current threshold value, and in response to the discharge current value being greater than the current threshold value, causing the bridge arm in the micro-conduction state to enter an off state, thereby disconnecting the discharge loop to end the discharge operation of the bus capacitor.
According to a third aspect of the present application, there is provided a frequency converter comprising a busbar capacitive discharge system according to the first aspect of the present application.
The bus capacitor discharging scheme according to one or more embodiments of the present application can realize discharging of the bus capacitor by using the power conversion device in the power conversion equipment, and no additional power resistor or energy consumption discharging device is needed, so that the additional hardware cost of discharging the bus capacitor and the possible overheat risk are avoided. The bus capacitor discharge system according to one or more embodiments of the present invention has the advantages of small volume, low cost and high reliability, and can be widely applied to motor controllers, frequency converters, etc. having various discharge requirements.
Drawings
The foregoing and/or other aspects and advantages of the present application will become more apparent and more readily appreciated from the following description of the various aspects taken in conjunction with the accompanying drawings in which like or similar elements are designated with the same reference numerals. In the drawings:
FIG. 1 illustrates a block diagram of a bus capacitor discharge system in accordance with one or more embodiments of the present application.
Fig. 2 shows a schematic block diagram of a bus capacitor discharge system in accordance with one or more embodiments of the present application.
Fig. 3 shows a schematic block diagram of a bus capacitor discharge system in accordance with one or more embodiments of the present application.
Fig. 4 shows a flow diagram of a bus capacitor discharge method in accordance with one or more embodiments of the present application.
Detailed Description
Example embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings. It should be noted that the following description is for purposes of explanation and illustration, and thus should not be construed as limiting the present application. Those skilled in the art may make electrical, mechanical, logical and structural changes in these embodiments as may be made in the practice without departing from the principles of the present application without departing from the scope thereof. Furthermore, one skilled in the art will appreciate that one or more features of the different embodiments described below may be combined for any particular application scenario or actual need.
Terms such as "comprising" and "including" mean that in addition to having elements and steps that are directly and explicitly recited in the description, the technical solutions of the present application do not exclude the presence of other elements and steps not directly or explicitly recited. The terms such as "first" and "second" do not denote the order of units in terms of time, space, size, etc. but rather are merely used to distinguish one unit from another.
In the following description, numerous specific details are set forth, such as examples of specific components, circuits, and processes, in order to provide a thorough understanding of the present application. The term "coupled" as used herein means directly connected to or through one or more intermediate components or circuits. Furthermore, in the following description and for purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the various aspects of the present application. However, it will be apparent to one skilled in the art that the example implementations may be practiced without these specific details. In other instances, well-known circuits and devices are shown in block diagram form in order not to obscure the present application.
FIG. 1 illustrates a block diagram of a bus capacitor discharge system in accordance with one or more embodiments of the present application.
As shown in fig. 1, the bus capacitor discharge system 100 includes a power conversion device 110 and a control device 120. Power conversion device 110 is coupled to control device 120 and bus capacitor 130, respectively, and includes one or more legs, each of which includes one or more power switching devices and an inductive device. The control device 120 is configured to control one of the one or more legs to be in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus capacitor 130 by forming a discharge loop with the bus capacitor 130 through the leg in the micro-conductive state. Alternatively, the discharge control signal may be a periodic pulse signal or a pulse signal having a fixed pulse width, and the control device 120 may be configured to cause one of the one or more legs to be in a micro-conductive state in response to the pulse of the discharge control signal.
Alternatively, the control device 120 may be configured to take a voltage across the inductive device and process (e.g., rectify, filter, etc.) the voltage to generate a discharge current value, compare the generated discharge current value with a current threshold, and put the bridge arm in a micro-on state into an off state in response to the discharge current value being greater than the current threshold, thereby breaking the discharge loop to end the discharge operation on the bus capacitor 130. Illustratively, the current threshold may be flexibly selected according to the discharge requirements and the functional properties of the power conversion device 110, for example, may be selected to be 50 amps to 100 amps. Alternatively, a current value when the bridge arm in the micro-on state enters the off state may be acquired as the discharge current value. By measuring the discharge current by using the induced voltage on the inductive device, no additional current measuring device is needed, and the hardware cost is further saved.
Alternatively, the power switching device may be implemented as a triode, insulated gate bipolar transistor (insulated gate bipolartransistor, IGBT), metal oxide semiconductor field effect transistor (metal oxide semiconductor field effect transistor, MOSFET), bipolar junction transistor (bipolar junction transistor, BJT), superjunction transistor (super junction transistor, SJT), or the like. Alternatively, the inductive device may be implemented as a parasitic inductance connected in series with one or more power switching devices in one leg. In the context of the present application, the bridge arm being in a micro-conductive state means that at least one power switching device of one or more power switching devices in the bridge arm is operated in a linear region, the remaining power switching devices are operated in a saturation region, and the inductive device is in a conductive state. It should be noted that, the working area of the power switch device includes a saturation area, a linear area and a cut-off area, and the power switch device generally works in the saturation area and the cut-off area to control the on-off of the power switch device; when the power switching device is operating in the linear region, it may correspond to a variable resistance, thus enabling the power switching device itself operating in the linear region to consume energy on the bus capacitor 130.
It should be noted that, the power conversion device 110 shown in fig. 1 is an existing device or component in a frequency converter or a motor controller, and the bus capacitor discharging system according to one or more embodiments of the present application can multiplex the bridge arm in the power conversion device 110 to form a discharging loop with the bus capacitor 130 to perform a discharging operation on the bus capacitor 130, and control the discharging duration by controlling the micro-conduction and the micro-conduction of the bridge arm, so that no additional power resistor or energy-consuming discharging device is needed, and thus the additional hardware cost of discharging the bus capacitor and possible overheat risk are avoided.
The bus capacitor discharge system according to one or more embodiments of the application has the advantages of small volume, low cost and high reliability, and can be widely applied to motor controllers, frequency converters and the like with various discharge requirements.
The circuit configuration and discharge process of the bussed capacitor discharge system in accordance with one or more embodiments of the present application will be described in detail below in conjunction with fig. 2-3.
Fig. 2 shows a schematic block diagram of a bus capacitor discharge system in accordance with one or more embodiments of the present application.
As shown in fig. 2, the bus capacitor discharge system 200 includes a power conversion device 210 and a control device 220. Power conversion device 210 is coupled to bus capacitor 230 and includes one or more legs, each of which includes one or more power switching devices and an inductive device.
In fig. 2, power switching devices S1, S2 and inductance device L1 may constitute one leg, power switching devices S3, S4 and inductance device L3 may constitute one leg, and power switching devices S5, S6 and inductance device L5 may constitute one leg. The control device 220 is configured to control one of the one or more legs to be in a micro-conductive state in response to the discharge control signal to perform a discharge operation on the bus capacitor 230 by forming a discharge loop with the bus capacitor 230 through the leg in the micro-conductive state. Alternatively, the discharge control signal may be a periodic pulse signal or a pulse signal having a fixed pulse width, and the control device 220 may be configured to cause one of the one or more legs to be in a micro-conductive state in response to the pulse of the discharge control signal.
As an example, as shown in fig. 2, the control device 220 may be configured to control the bridge arm constituted by the power switching devices S1, S2 and the inductance device L1 in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus bar capacitance 230 by forming a discharge loop with the bus bar capacitance 230 by the bridge arm constituted by the switching devices S1, S2 and the inductance device L1 in the micro-conductive state. Alternatively, the control device 220 may also be configured to control the bridge arm constituted by the power switching devices S3, S4 and the inductance device L3 to be in a micro-conductive state in response to the discharge control signal to perform a discharge operation on the bus bar capacitance 230 by forming a discharge loop with the bus bar capacitance 230 by the bridge arm constituted by the switching devices S3, S4 and the inductance device L3 being in the micro-conductive state. Alternatively, the control device 220 may also be configured to control the bridge arm constituted by the power switching devices S5, S6 and the inductance device L5 to be in a micro-conductive state in response to the discharge control signal, so as to perform a discharge operation on the bus capacitor 230 by forming a discharge loop with the bus capacitor 230 by the bridge arm constituted by the switching devices S5, S6 and the inductance device L5 being in the micro-conductive state. It will be appreciated that the one or more power switching devices in the leg in the micro-conductive state operate in the linear region, thereby enabling the energy on the bus capacitor 230 to be dissipated through the one or more power switching devices themselves (e.g., power switching device S2) in the leg in the micro-conductive state.
Hereinafter, the bus capacitor discharge system 200 shown in fig. 2 will be further described taking as an example that the bridge arm constituted by the power switching devices S1, S2 and the inductance device L1 is in the micro-conduction state.
As further shown in fig. 2, the power conversion apparatus 210 includes power switching devices S1 to S6 and inductance devices L1, L3, and L5, and the control apparatus 220 includes an active discharge control unit 2201, a gate level driving unit 2202, an on speed adjusting unit 2203, an isolation unit 2204, a discharge enabling unit 2205, a latch unit 2206, a turn-off unit 2207, a current signal processing unit 2208, and a comparing unit 2209. It will be appreciated that the bus capacitor discharge system 200 shown in fig. 2 is implemented in an isolated control method, i.e., the active discharge control unit 2201 is on the low voltage side and the bus capacitor 230 is on the high voltage side.
The active discharge control unit 2201 may be configured to generate a discharge control signal and transmit the generated discharge control signal to the gate-level driving unit 2202. The gate level driving unit 2202 may be configured to amplify and isolate the received discharge control signal to generate and transmit the driving signal to the turn-on speed adjusting unit 2203 and the latch unit 2206 on the high voltage side for controlling the power switching device S2 in the bridge arm in the micro-conductive state in the power conversion apparatus 210 to operate in an on state at a predetermined speed through the turn-on speed adjusting unit 2203 and resetting the latch unit 2206. The active discharge control unit 2201 may be further configured to transmit a discharge start signal to the isolation unit 2204, and the isolation unit 2204 may perform an isolation operation on the received discharge start signal and transmit the isolated discharge start signal to the discharge enable unit 2205 on the high voltage side. The discharge enabling unit 2205 may be configured to control the turn-on speed adjusting unit 2203 to transition the driving signal from the first driving state to the second driving state (e.g., from the high-speed driving state to the low-speed driving state) in response to receiving the isolated discharge start signal, and to transmit the driving signal in the second driving state to the power conversion device 210 such that the power switching device S2 in the bridge arm in the micro-on state in the power conversion device 210 operates in the turn-on state at a predetermined speed. Illustratively, in general, the rate of voltage rise of power switching devices S1-S6 may be 10V/ns and the rate of voltage rise of power switching device S2 may be 0.1V/ns when power switching device S2 is operated in an on state at a predetermined speed. The discharge enabling unit 2205 may be further configured to enable the latch unit 2206 in response to receiving the isolated discharge start signal such that the latch unit 2206 controls the turn-off unit 2207 to be in an open state. The on speed adjusting unit 2203 may be further configured to determine whether the turn-off unit 2207 is in the enabled-on state in response to receiving the driving signal, and wait for the comparison result of the comparing unit 2209 without performing an operation when determining that the turn-off unit 2207 is in the enabled-on state, and otherwise cause the power switching device S2 in the bridge arm in the micro-on state in the power conversion apparatus 210 to operate in the on state at a predetermined speed. Alternatively, when the isolated discharge start signal is not received, the discharge enabling unit 2205 may be configured to control the turn-on speed adjusting unit 2203 to directly transmit the driving signal to one or more power switching devices in the power conversion apparatus 210.
The current signal processing unit 2208 may be configured to obtain a voltage across the inductive device L1 and process (e.g., rectify, filter, etc.) the voltage to generate a discharge current value I. As shown in fig. 2, ls (di/dt) may characterize the voltage V across the inductive device L1, where Ls represents the inductance of the inductive device L1 and di/dt represents the rate of change of the current flowing through the inductive device L1. Illustratively, the current signal processing unit 2208 may calculate the discharge current value I by the following equation (1):
where V denotes a voltage across the inductive device L1, t denotes a duration of operation of the power switching device S2 in an on state at a predetermined speed, ls denotes an inductance of the inductive device L1.
The comparison unit 2209 may be configured to compare the generated discharge current value I with a current threshold value, and generate a valid signal when the discharge current value is greater than the current threshold value, and continue the comparison operation when the discharge current value is less than or equal to the current threshold value. Illustratively, the current threshold may be flexibly selected according to the discharge requirements and the functional properties of the power conversion device 110, for example, may be selected to be 50 amps to 100 amps. By measuring the discharge current by using the induced voltage on the inductive device L1, no additional current measuring means is required, further saving hardware costs. Optionally, the latch unit 2206 may be further configured to synchronously control the current signal processing unit 2208, so that the discharge current value I generated by the current signal processing unit 2208 is a current value when the bridge arm in the micro-on state enters the off state. The valid signal generated by the comparing unit 2209 may trigger the latch unit 2206 to set to output the valid signal to the turn-off unit 2207, and the turn-off unit 2207 may cause the bridge arm in the micro-on state to enter the off state in response to receiving the valid signal, thereby breaking the discharge loop to end the discharge operation of the bus capacitor 230.
Through the above operation, the bus capacitor discharging system 200 completes the discharging current closed-loop control of one switching cycle. When the next pulse of the discharge control signal arrives, the control device 220 may control one of the one or more bridge arms to be in the micro-conductive state again, so as to perform a discharge operation on the bus capacitor 230 by forming a discharge loop with the bus capacitor 230 through the bridge arm in the micro-conductive state, thereby reducing the voltage on the bus capacitor 230 below the safe voltage.
Fig. 3 shows a schematic block diagram of a bus capacitor discharge system in accordance with one or more embodiments of the present application.
As shown in fig. 3, the bus capacitor discharge system 300 includes a power conversion device 310 and a control device 320. Power conversion device 310 is coupled to bus capacitor 330 and includes one or more legs, each of which includes one or more power switching devices and an inductive device.
In fig. 3, power switching devices S1, S2 and inductance device L1 may constitute one leg, power switching devices S3, S4 and inductance device L3 may constitute one leg, and power switching devices S5, S6 and inductance device L5 may constitute one leg. The control device 320 is configured to control one of the one or more legs to be in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus capacitor 330 by forming a discharge loop with the bus capacitor 330. Alternatively, the discharge control signal may be a periodic pulse signal or a pulse signal having a fixed pulse width, and the control device 320 may be configured to cause one of the one or more legs to be in a micro-conductive state in response to the pulse of the discharge control signal.
As an example, as shown in fig. 3, the control device 320 may be configured to control the bridge arm constituted by the power switching devices S1, S2 and the inductance device L1 in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus bar capacitance 330 by forming a discharge loop with the bus bar capacitance 330 by the bridge arm constituted by the switching devices S1, S2 and the inductance device L1 in the micro-conductive state. It will be appreciated that the one or more power switching devices in the leg in the micro-conductive state operate in the linear region, thereby enabling the energy on the bus capacitor 330 to be dissipated through the one or more power switching devices themselves (e.g., power switching device S2) in the leg in the micro-conductive state.
Hereinafter, the bus capacitor discharge system 300 shown in fig. 3 will be further described taking as an example that the bridge arm constituted by the power switching devices S1, S2 and the inductance device L1 is in the micro-conduction state.
As further shown in fig. 3, the power conversion apparatus 310 includes power switching devices S1 to S6 and inductance devices L1, L3, and L5, and the control apparatus 320 includes an active discharge control unit 3201, a gate level driving unit 3202, an on speed adjusting unit 3203, a discharge enabling unit 3204, a latch unit 3205, a turn-off unit 3206, a current signal processing unit 3207, and a comparing unit 3208. It will be appreciated that the bus capacitor discharge system 300 shown in fig. 3 is implemented in a non-isolated control method, i.e., the active discharge control unit 3201 and the bus capacitor 330 are in the same electrical network.
The active discharge control unit 3201 may be configured to generate a discharge control signal and transmit the generated discharge control signal to the gate-stage driving unit 3202. The gate stage driving unit 3202 may be configured to perform an isolation operation on the received discharge control signal to generate a driving signal and transmit the driving signal to the turn-on speed adjusting unit 3203 and the latch unit 3205 for controlling the turn-on state operation of the power switching device S2 in the bridge arm in the micro-on state in the power conversion apparatus 310 at a predetermined speed and resetting the latch unit 3205 through the turn-on speed adjusting unit 3203. The active discharge control unit 3201 may also be configured to transmit a discharge start signal to the discharge enable unit 3204. The discharge enabling unit 3204 may be configured to control the turn-on speed adjusting unit 3203 to transition the driving signal from the first driving state to the second driving state (e.g., from the high-speed driving state to the low-speed driving state) in response to receiving the discharge start signal, and to transmit the driving signal in the second driving state to the power conversion device 310 such that the power switching device S2 in the bridge arm in the micro-on state in the power conversion device 310 operates in the turn-on state at a predetermined speed. Illustratively, in general, the rate of voltage rise of power switching devices S1-S6 may be 10V/ns and the rate of voltage rise of power switching device S2 may be 0.1V/ns when power switching device S2 is operated in an on state at a predetermined speed. The discharge enabling unit 3204 may be further configured to enable the latch unit 3205 in response to receiving the discharge start signal such that the latch unit 3205 controls the turn-off unit 3206 to be in an open state. The turn-on speed adjusting unit 3203 may be further configured to determine whether the turn-off unit 3206 is in the enabled-on state in response to receiving the driving signal, and wait for the comparison result of the comparing unit 3208 without performing an operation when determining that the turn-off unit 3206 is in the enabled-on state, and otherwise cause the power switching device S2 in the bridge arm in the micro-on state in the power conversion apparatus 310 to operate in the on state at a predetermined speed. Alternatively, when the discharge start signal is not received, the discharge enabling unit 3204 may be configured to control the turn-on speed adjusting unit 3203 to directly transmit the driving signal to one or more power switching devices in the power conversion apparatus 310.
The current signal processing unit 3207 may be configured to obtain a voltage across the inductive device L1 and process (e.g., rectify, filter, etc.) the voltage to generate the discharge current value I. As shown in fig. 3, ls (di/dt) may characterize the voltage V across the inductive device L1, where Ls represents the inductance of the inductive device L1 and di/dt represents the rate of change of the current flowing through the inductive device L1. Illustratively, the current signal processing unit 3207 may calculate the discharge current value I through the above formula (1).
The comparison unit 3208 may be configured to compare the generated discharge current value I with a current threshold value, and generate a valid signal when the discharge current value is greater than the current threshold value, and to continuously perform the comparison operation when the discharge current value is less than or equal to the current threshold value. Illustratively, the current threshold may be flexibly selected according to the discharge requirements and the functional properties of the power conversion device 310, for example, may be selected to be 50 amps to 100 amps. By measuring the discharge current by using the induced voltage on the inductive device L1, no additional current measuring means is required, further saving hardware costs. Alternatively, the latch unit 3205 may be further configured to synchronously control the current signal processing unit 3207, so that the discharge current value I generated by the current signal processing unit 3207 is a current value when the bridge arm in the micro-on state enters the off state. The effective signal generated by the comparing unit 3208 may trigger the latch unit 3205 to set to output the effective signal to the turn-off unit 3206, and the turn-off unit 3206 may cause the bridge arm in the micro-on state to enter the off state in response to receiving the effective signal, thereby breaking the discharge loop to end the discharge operation of the bus capacitor 330.
Through the above operation, the bus capacitor discharging system 300 completes the discharging current closed-loop control of one switching cycle. When the next pulse of the discharge control signal arrives, the control device 320 may control one of the one or more bridge arms to be in the micro-conductive state again, so as to perform a discharge operation on the bus capacitor 330 by forming a discharge loop with the bus capacitor 330 by the bridge arm in the micro-conductive state, thereby reducing the voltage on the bus capacitor 330 below the safe voltage.
Fig. 4 shows a flow diagram of a bus capacitor discharge method in accordance with one or more embodiments of the present application. The various steps shown in fig. 4 may be implemented by means of the bus capacitor discharge system described in fig. 1-3 above.
As shown in fig. 4, in step S410, a power conversion device is capacitively coupled to a bus bar, the power conversion device including one or more legs, each of the one or more legs including one or more power switching devices and an inductive device.
In step S420, one of the one or more bridge arms is controlled to be in a micro-conductive state in response to the discharge control signal, so as to perform a discharge operation on the bus capacitor by forming a discharge loop with the bus capacitor through the bridge arm in the micro-conductive state. Optionally, at least one of the one or more power switching devices in the leg in the micro-conductive state operates in the linear region.
In step S430, a voltage across an inductive device in a bridge arm in a micro-conductive state is obtained and processed to generate a discharge current value, and the discharge current value and a current threshold are compared, and the bridge arm in the micro-conductive state is brought into an off state in response to the discharge current value being greater than the current threshold, thereby disconnecting a discharge loop to end the discharge operation of a bus capacitor.
According to the bus capacitor discharging method, the power conversion device in the power conversion equipment can be utilized to realize discharging of the bus capacitor, no additional power resistor or energy consumption discharging device is needed, and therefore additional hardware cost of discharging of the bus capacitor and possible overheat risks are avoided. The bus capacitor discharging method according to one or more embodiments of the invention has the advantages of small volume, low cost and high reliability, and can be widely applied to motor controllers, frequency converters and the like with various discharging requirements.
In addition, the present application may also be embodied as a frequency converter including a bus capacitor discharge system according to an aspect of the present application.
The embodiments and examples set forth herein are presented to best explain the embodiments in accordance with the application and its particular application and to thereby enable those skilled in the art to make and use the application. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. The description as set forth is not intended to cover various aspects of the application or to limit the application to the precise form disclosed.
Claims (10)
1. A bus capacitor discharge system, comprising:
a power conversion device capacitively coupled to the bus and comprising one or more legs, each of the one or more legs comprising one or more power switching devices and an inductive device; and
a control device configured to control one of the one or more legs to be in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus capacitance by forming a discharge loop with the bus capacitance by the leg in the micro-conductive state.
2. The bus capacitor discharge system of claim 1, wherein at least one of the one or more power switching devices in the leg in the micro-conductive state operates in a linear region.
3. The bus capacitor discharge system of claim 1, wherein the control means comprises:
a gate stage driving unit configured to perform an amplifying operation and/or an isolating operation on the discharge control signal to generate a driving signal,
wherein the control device comprises:
an on speed adjusting unit configured to selectively switch the driving signal from a first driving state to a second driving state and transmit the driving signal in the second driving state to the power conversion device,
wherein the control device comprises:
a current signal processing unit configured to acquire a voltage across the inductance device in the bridge arm in the micro-conduction state and process the voltage to generate a discharge current value,
wherein the control device comprises:
a comparing unit configured to compare the discharge current value with a current threshold value and output a valid signal in response to the discharge current value being greater than the current threshold value;
a latch unit configured to receive and latch the valid signal; and
and a turn-off unit configured to bring the bridge arm in the micro-on state into an off state in response to receiving the valid signal from the latch unit, thereby disconnecting the discharge loop to end the discharge operation of the bus capacitance.
4. The bus capacitor discharge system according to claim 3, wherein the latch unit is further configured to synchronously control the current signal processing unit such that the discharge current value generated by the current signal processing unit is a current value when the bridge arm in the micro-on state enters an off state.
5. The buss capacitor discharge system of claim 1, wherein the discharge control signal is a periodic pulse signal, the control device configured to cause one of the one or more legs to be in the micro-conductive state in response to the periodic pulse of the discharge control signal.
6. The bus capacitor discharge system of claim 3, wherein said control means comprises:
a discharge enabling unit configured to control the turn-on speed adjusting unit to switch the driving signal from a first driving state to a second driving state in response to receiving a discharge start signal, and to transmit the driving signal in the second driving state to the power conversion device such that one or more power switching devices in the bridge arm in the micro-conduction state in the power conversion device are operated in an on state at a predetermined speed,
wherein the discharge enabling unit is further configured to enable the latch unit in response to receiving the discharge start signal such that the latch unit controls the turn-off unit to be in an open state.
7. A bus capacitor discharging method, characterized in that the bus capacitor discharging method comprises:
capacitively coupling a power conversion device with a bus bar, the power conversion device comprising one or more legs, each of the one or more legs comprising one or more power switching devices and an inductive device; and
one of the one or more legs is controlled to be in a micro-conductive state in response to a discharge control signal to perform a discharge operation on the bus capacitor by forming a discharge loop with the bus capacitor by the leg in the micro-conductive state.
8. The bus capacitor discharge method of claim 7, wherein at least one of the one or more power switching devices in the leg in the micro-conductive state operates in a linear region.
9. The bus capacitor discharge method of claim 7, wherein the method further comprises:
acquiring voltages at two ends of the inductance device in the bridge arm in the micro-conduction state and processing the voltages to generate a discharge current value; and
comparing the discharge current value with a current threshold value, and in response to the discharge current value being greater than the current threshold value, causing the bridge arm in the micro-conduction state to enter an off state, thereby opening the discharge loop to end the discharge operation of the bus capacitor.
10. A frequency converter, the frequency converter comprising:
the bus capacitor discharge system of any one of claims 1-6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310444516.4A CN116388543A (en) | 2023-04-23 | 2023-04-23 | Bus capacitor discharging system, bus capacitor discharging method and frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310444516.4A CN116388543A (en) | 2023-04-23 | 2023-04-23 | Bus capacitor discharging system, bus capacitor discharging method and frequency converter |
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| Publication Number | Publication Date |
|---|---|
| CN116388543A true CN116388543A (en) | 2023-07-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202310444516.4A Pending CN116388543A (en) | 2023-04-23 | 2023-04-23 | Bus capacitor discharging system, bus capacitor discharging method and frequency converter |
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| Country | Link |
|---|---|
| CN (1) | CN116388543A (en) |
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- 2023-04-23 CN CN202310444516.4A patent/CN116388543A/en active Pending
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