CN218162211U - Discharge control circuit and inverter device - Google Patents
Discharge control circuit and inverter device Download PDFInfo
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- CN218162211U CN218162211U CN202222407852.5U CN202222407852U CN218162211U CN 218162211 U CN218162211 U CN 218162211U CN 202222407852 U CN202222407852 U CN 202222407852U CN 218162211 U CN218162211 U CN 218162211U
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Abstract
The embodiment of the application provides a discharge control circuit and an inverter, wherein the discharge control circuit comprises a direct-current bus capacitor, a first resistance module, a capacitor module, a direct-current power supply, a relay, a switch tube and a diode; the relay comprises a first contact, a second contact, a third contact and a coil; the positive electrode of the direct current bus capacitor is connected with the first end of the first resistor module, the second end of the first resistor module is connected with the first end of the switch tube, and the second end of the switch tube, the negative electrode of the direct current bus capacitor, the first end of the coil, the negative electrode of the capacitor module and the negative electrode of the direct current power supply are grounded; the second end of the coil is connected with the anode of the direct-current power supply and the anode of the diode, the cathode of the diode is connected with the anode of the capacitor module and the first contact, and the third contact is communicated with the third end of the switch tube. The embodiment of the application can reduce energy consumption.
Description
Technical Field
The application relates to the technical field of electronics, concretely relates to discharge control circuit and inverter.
Background
In the existing energy conversion equipment such as a frequency converter and an inverter, a direct current bus capacitor is generally arranged. In order to meet the requirement that the direct-current bus capacitor can discharge in time after the equipment is stopped, a fixed discharge resistor is generally connected to the direct-current bus capacitor in parallel, so that the loss is continuously generated in the running process of the equipment, heat is brought to the equipment, and the energy consumption is higher.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a discharge control circuit and an inverter device, which can reduce energy consumption.
A first aspect of an embodiment of the present application provides a discharge control circuit, including a dc bus capacitor, a first resistance module, a capacitor module, a dc power supply, a relay, a switching tube, and a diode; the relay comprises a first contact, a second contact, a third contact and a coil;
the positive electrode of the direct current bus capacitor is connected with the first end of the first resistor module, the second end of the first resistor module is connected with the first end of the switch tube, and the second end of the switch tube, the negative electrode of the direct current bus capacitor, the first end of the coil, the negative electrode of the capacitor module and the negative electrode of the direct current power supply are grounded; the second end of the coil is connected with the anode of the direct-current power supply and the anode of the diode, the cathode of the diode is connected with the anode of the capacitor module and the first contact, and the third contact is communicated with the third end of the switch tube.
Optionally, when the positive electrode of the dc bus capacitor is powered on, the dc power supply is powered on, the coil is powered on, the first contact and the second contact are connected, the switching tube is disconnected, the first resistor module is disconnected from the dc bus capacitor, and the dc power supply charges the capacitor module through the diode;
under the condition that the positive electrode of the direct-current bus capacitor is powered off, the direct-current power supply is powered off, the coil is powered off, the first contact is communicated with the third contact, the switch tube is conducted, the capacitor module discharges electricity, and the direct-current bus capacitor discharges electricity through the first resistor module.
Optionally, the discharge control circuit includes a dc conversion circuit, the positive electrode of the dc bus capacitor is connected to the positive input end of the dc conversion circuit, and the positive output end of the dc conversion circuit is connected to the positive electrode of the dc power supply.
Optionally, the first resistance module includes one resistance or at least two resistances; in the case where the first resistance module includes at least two resistances, the at least two resistances included in the first resistance module are connected in series or in parallel.
Optionally, the capacitance module includes one capacitance or at least two capacitances; in case the capacitance module comprises at least two capacitances, the at least two capacitances are connected in parallel.
Optionally, the discharge control circuit further includes a second resistor module, a first end of the second resistor module is connected to the third contact, and a second end of the second resistor module is connected to the third end of the switching tube;
the second resistance module comprises one resistance or at least two resistances; in the case that the second resistance module includes at least two resistances, the at least two resistances included in the second resistance module are connected in series or in parallel.
Optionally, the discharge control circuit further includes a third resistor module, a first end of the third resistor module is connected to the third end of the switching tube, and a second end of the third resistor module is grounded;
the third resistance module comprises one resistance or at least two resistances; in the case that the third resistance module includes at least two resistances, the third resistance module includes at least two resistances connected in series or in parallel.
Optionally, the capacitance value of the capacitance module satisfies the following formula:
C2>(R1*C1*lnB)/[(R2+R3)*lnA]；
A＝(1+R2/R3)*Voff/Vdc；B＝Vsave/Vbus；
wherein C2 is a capacitance value of the capacitor module, C1 is a capacitance value of the dc bus capacitor, R1 is a resistance value of the first resistor module, R2 is a resistance value of the second resistor module, R3 is a resistance value of the third resistor module, voff is a cut-off voltage of the switching tube, vdc is a voltage after the dc power supply is powered on, vbus is a voltage before the dc bus capacitor is powered off, vsave is a safe voltage corresponding to the dc bus capacitor, voff < Vdc, and Vsave < Vbus.
Optionally, the switch tube includes an active switch device, and the active switch device includes any one of a metal-oxide semiconductor field effect transistor MOSFET, an insulated gate bipolar transistor IGBT, and a triode.
A second aspect of an embodiment of the present application provides an inverter device, including the discharge control circuit, the new energy power generation module, and the inverter unit described in the first aspect; the output positive electrode of the new energy power generation module is connected with the positive electrode of a direct-current bus capacitor in the discharge control circuit and the positive electrode of the inversion unit, and the output negative electrode of the new energy power generation module is connected with the negative electrode of the direct-current bus capacitor in the discharge control circuit and the negative electrode of the inversion unit; the new energy power generation module is used for outputting direct-current voltage.
The embodiment of the application designs a discharge control circuit, which comprises a direct current bus capacitor, a first resistance module, a capacitor module, a direct current power supply, a relay, a switch tube and a diode; the relay comprises a first contact, a second contact, a third contact and a coil; the positive electrode of the direct current bus capacitor is connected with the first end of the first resistor module, the second end of the first resistor module is connected with the first end of the switch tube, and the second end of the switch tube, the negative electrode of the direct current bus capacitor, the first end of the coil, the negative electrode of the capacitor module and the negative electrode of the direct current power supply are grounded; the second end of the coil is connected with the anode of the direct-current power supply and the anode of the diode, the cathode of the diode is connected with the anode of the capacitor module and the first contact, and the third contact is communicated with the third end of the switch tube.
Under the condition that the positive electrode of the direct current bus capacitor is electrified, on one hand, the switch tube can be controlled to be disconnected with the capacitor module through the direct current power supply and the relay, so that the control switch tube is disconnected, the first resistor module is disconnected with the direct current bus capacitor, the direct current bus capacitor is not allowed to discharge through the first resistor module, and the energy consumption can be reduced.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of a conventional connection method between a DC bus capacitor and a discharge resistor;
fig. 2 is a schematic structural diagram of a discharge control circuit according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of another discharge control circuit provided in an embodiment of the present application;
fig. 4 is a schematic structural diagram of another discharge control circuit provided in an embodiment of the present application;
fig. 5 is a schematic structural diagram of an inverter according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms "first," "second," and the like in the description and claims of the present application and in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may alternatively include other steps or elements not expressly listed or inherent to such process, system, article, or apparatus.
Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
In the current energy conversion equipment such as frequency converters and inverters, a direct current bus capacitor is generally arranged. In order to meet the requirement that the direct current bus capacitor can discharge in time after the equipment is stopped, a fixed discharge resistor is generally connected in parallel to the direct current bus capacitor. As shown in fig. 1, a dc bus capacitor C is connected in parallel with a discharge resistor R. After the energy conversion equipment is shut down, the positive electrode of the direct-current bus capacitor C1 is disconnected with the direct-current high voltage, and the direct-current bus capacitor C can discharge through the discharge resistor R. In the engineering of the work of the energy conversion equipment, the positive electrode of the direct-current bus capacitor C is connected with direct-current high voltage, and at the moment, the direct-current bus capacitor C can still discharge through the discharge resistor R. It can be seen that the design of fig. 1 results in continuous losses during operation of the plant, which brings about a higher energy consumption of the plant.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a discharge control circuit according to an embodiment of the present disclosure. As shown in fig. 2, the discharge control circuit includes a dc bus capacitor C1, a first resistor module R1, a capacitor module C2, a dc power supply, a relay K1, a switch tube Q1, and a diode D1; the relay K1 comprises a first contact 1, a second contact 2, a third contact 3 and a coil L1;
the positive electrode of the direct current bus capacitor C1 is connected to the first end of the first resistor module R1, the second end of the first resistor module R1 is connected to the first end of the switch tube Q1, and the second end of the switch tube Q1, the negative electrode of the direct current bus capacitor C1, the first end of the coil L1, the negative electrode of the capacitor module C2 and the negative electrode of the direct current power supply are grounded; the second end of the coil L1 is connected with the anode of the direct-current power supply and the anode of the diode D1, the cathode of the diode D1 is connected with the anode of the capacitor module C2 and the first contact 1, and the third contact 3 is communicated with the third end of the switch tube Q1.
In this embodiment, the positive electrode of the dc bus capacitor C1 may be connected to a dc high voltage. For example, the positive electrode of the dc bus capacitor C1 may be connected to the dc high voltage output by the new energy power generation module. The new energy power generation module can comprise a photovoltaic module or a wind power generation module. For example, a photovoltaic module may convert solar energy to a 600V dc high voltage output.
The power generation of the new energy power generation module has periodicity. For example, in the daytime, the photovoltaic module starts to work and starts to generate electricity; after sunset at night, the photovoltaic module stops working and stops generating electricity. For another example, when wind exists, the wind power generation assembly starts to work to generate power; and when no wind exists, the wind power generation assembly stops working and stops generating power.
When the new energy power generation module works, the new energy power generation module can output direct-current high voltage, and when the new energy power generation module stops working, the new energy power generation module cannot output direct-current high voltage.
The relay K1 is a normally closed relay, and under the condition that the relay K1 is not electrified, the first contact 1 is communicated with the third contact 3, and at the moment, the capacitor module C2 is disconnected with the third end of the switch tube Q1. When the relay is electrified, the first contact 1 and the second contact 2 are communicated, and at the moment, the capacitor module C2 is connected with the third end of the switch tube Q1.
The dc power supply may be a low voltage dc power supply. The direct current power supply can take power from the output end (such as DC + and DC-) of the new energy power generation module in fig. 2. And the new energy power generation module and the direct-current power supply can perform direct-current voltage conversion through a direct-current conversion circuit. For example, the dc power supply may be a 12V power supply, the new energy power generation module may output a 600V dc voltage, and the dc conversion circuit may convert the 600V dc voltage into a 12V dc voltage.
The first resistance module R1 may include at least one resistance. The capacitance module C2 may include at least one capacitance.
In the embodiment of the application, under the condition that the anode of the dc bus capacitor is powered on, on one hand, the switching tube can be controlled to be disconnected with the capacitor module through the dc power supply and the relay, so as to control the switching tube to be disconnected, the first resistor module is disconnected with the dc bus capacitor, the dc bus capacitor is not allowed to discharge through the first resistor module, and energy consumption can be reduced.
Optionally, when the positive electrode of the dc bus capacitor C1 is powered on, the dc power supply is powered on, the coil L1 is powered on, the first contact 1 is communicated with the second contact 2, the switching tube Q1 is disconnected, the first resistor module R1 is disconnected from the dc bus capacitor C1, and the dc power supply charges the capacitor module C2 through the diode D1;
under the condition that the positive electrode of the direct-current bus capacitor C1 is powered off, the direct-current power supply is powered off, the coil L1 is powered off, the first contact 1 is communicated with the third contact 3, the switch tube Q1 is conducted, the capacitor module C2 discharges electricity, and the direct-current bus capacitor C1 discharges electricity through the first resistor module R1.
When the positive electrode of the dc bus capacitor C1 is powered on, the dc power supply charges the capacitor module C2 through the diode D1, and the voltage across the capacitor module C2 gradually increases from 0 to Vdc across the dc power supply (ignoring the on-voltage of the diode D1). When the positive electrode of the dc bus capacitor C1 is powered down, the capacitor module C2 discharges, and the voltage across the capacitor module C2 gradually decreases from Vdc to 0.
After the positive electrode of the direct current bus capacitor C1 is electrified, the switching tube Q1 continuously keeps the off state. After the positive electrode of the direct-current bus capacitor C1 is powered off, the switching tube Q1 just starts to keep the on state, after the voltage of the capacitor module C2 is reduced to the cut-off voltage of the switching tube Q1, the switching tube Q1 is in the off state, and until the positive electrode of the direct-current bus capacitor C1 is powered on next time, the switching tube Q1 keeps the off state. In the process of powering on and powering off the positive electrode of the direct current bus capacitor C1, the switch tube Q1 is in a conducting state only in a period of time after the positive electrode of the direct current bus capacitor C1 is powered off, the conducting time is relatively short, the switch tube Q1 cannot be continuously conducted after being powered off, the loss of the switch tube Q1 is reduced, and the safety can be improved. The switching tube Q1 can be kept in a disconnected state after the anode of the direct current bus capacitor C1 is electrified next time, the situation that the switching tube Q1 is still conducted after the direct current power supply is electrified slowly cannot occur, and then the direct current bus capacitor C1 can be immediately cut off to discharge to the first resistance module R1 after the anode of the direct current bus capacitor C1 is electrified, so that energy consumption is reduced.
In this application embodiment, when the positive pole of direct current bus capacitor C1 was gone up, can guarantee that first resistance module R1 and direct current bus capacitor C1 can be at once and last the disconnection, can reduce the energy consumption, and direct current power supply charges to capacitor module C2 through diode D1 simultaneously. When the positive electrode of the direct current bus capacitor C1 is powered down, the capacitor module C2 can provide the on-state voltage of the switching tube Q1, so that the direct current bus capacitor C1 discharges through the first resistor module R1.
After the dc bus capacitor C1 is powered down, the time required for the voltage of the capacitor module C2 to drop from the voltage before the power down to the cut-off voltage of the switching tube Q1 is less than the time required for the voltage of the dc bus capacitor C1 to drop from the voltage before the power down to the safe voltage. By setting the capacitance value of the capacitor module C2, the time required for the capacitor module C2 to decrease from the voltage before the capacitor module C2 is powered down to the cut-off voltage of the switching tube Q1 is less than the time required for the voltage of the dc bus capacitor C1 to decrease from the voltage before the power down to the safe voltage. Before direct current bus capacitor C1 discharges to safe voltage, switching tube Q1 can continuously switch on, improves the security that direct current bus capacitor C1 discharged.
The voltage before the capacitor module C2 is powered down is the voltage across the capacitor module C2 when the positive electrode of the dc bus capacitor C1 is powered down immediately. The voltage before the direct current bus capacitor C1 is powered down is the voltage across the direct current bus capacitor C1 when the positive electrode of the direct current bus capacitor C1 is just powered down.
Optionally, the switching tube Q1 includes an active switching device, and the active switching device includes any one of a metal-oxide-semiconductor field-effect transistor (MOSFET), an Insulated Gate Bipolar Transistor (IGBT), and a triode. The third terminal of the switching tube Q1 may correspond to a gate of a MOSFET or a gate of an IGBT or a base of a transistor. The first end and the second end of the switching tube Q1 may correspond to a drain electrode and a source electrode of the MOSFET, the first end and the second end of the switching tube Q1 may correspond to a collector electrode and an emitter electrode of the IGBT, and the first end and the second end of the switching tube Q1 may correspond to a collector electrode and an emitter electrode of the triode.
Referring to fig. 3, fig. 3 is a schematic structural diagram of another discharge control circuit according to an embodiment of the present disclosure. As shown in fig. 3, the discharge control circuit further includes a dc converter circuit, wherein the positive electrode of the dc bus capacitor C1 is connected to the positive input terminal of the dc converter circuit, and the positive output terminal of the dc converter circuit is connected to the positive electrode of the dc power supply.
In this embodiment of the application, the dc conversion circuit may be a switching power supply circuit, and the dc conversion circuit may include a starting resistor, an MOS transistor, a transformer, a capacitor, and the like, and in order to reduce loss, the starting resistor is selected to be relatively large, so the starting adjustment of the dc conversion circuit is relatively slow, and the starting time (the time until the output voltage reaches 90% Vdc when the switch of the dc conversion circuit is turned on, where Vdc is a stable voltage after the dc power supply is powered on, such as 12V mentioned above) is relatively long. For example, the start-up time of the dc power supply may take 20 seconds during the power-up process.
Because the direct-current power supply is electrified for a long time, under the condition that the direct-current power supply is just electrified, the current flowing through the coil L1 of the relay K1 is low, the first contact 1 and the third contact 3 are still connected at the moment, and the direct-current power supply and the relay K1 cannot control the switching tube Q1 and the capacitor module C2 to be immediately disconnected when the direct-current power supply is just electrified. When the direct-current power supply is just powered on, the voltage of the capacitor module C2 starts to rise from 0 and is lower than the cut-off voltage of the switch tube Q1, even if the switch tube Q1 and the capacitor module C2 are not immediately disconnected, the switch tube Q1 still can keep the disconnected state, the first resistor module R1 is disconnected with the direct-current bus capacitor C1, the direct-current bus capacitor C1 is not allowed to discharge through the first resistor module R1, and energy consumption can be reduced.
Optionally, when the positive electrode of the dc bus capacitor C1 is powered on, a time required for the voltage of the capacitor module C2 to rise from 0 to the cut-off voltage of the switching tube Q1 is longer than a time required for the current of the coil L1 of the relay K1 to rise from 0 to a current threshold. The current threshold is the minimum current required for the relay K1 to go from normally closed to normally open.
In the embodiment of the application, the time required for the voltage of the capacitor module C2 to rise from 0 to the cut-off voltage of the switching tube Q1 is longer than the time required for the current of the coil L1 of the relay K1 to rise from 0 to the current threshold, so that the switching tube Q1 is always kept in the off state after the positive electrode of the direct current bus capacitor C1 is electrified, the direct current bus capacitor C1 is not allowed to discharge through the first resistor module R1, and the energy consumption is reduced.
Optionally, the first resistor module R1 includes one resistor or at least two resistors; in the case that the first resistance module R1 includes at least two resistances, the at least two resistances included in the first resistance module R1 are connected in series or in parallel.
The embodiment of the application provides a specific structure of a first resistor module R1. When the first resistor module R1 includes at least two resistors, the at least two resistors may be connected in series or in parallel, or may be connected in series and then in parallel (for example, 5 resistors are connected in parallel to form 3 paths, and the number of the resistors in each path is 2, and 1, respectively). The embodiments of the present application are not limited.
Optionally, the resistance of the first resistor module R1 may be adjusted, and when at least two resistors are connected in parallel (each resistor is connected in parallel), a switch (for example, a single-pole single-throw switch) may be added to each resistor, and the switch on or off of each resistor is selected, so as to adjust the resistance of the first resistor module R1, and further adjust the discharging speed of the dc bus capacitor C1. For example, when the first resistor module R1 includes at least two resistors, each resistor may be connected in series with a switch, and the at least two resistors may be connected in parallel.
Optionally, the capacitance module C2 includes one capacitance or at least two capacitances; in case the capacitive module C2 comprises at least two capacitances, the at least two capacitances are connected in parallel.
The capacitor module C2 of the embodiment of the present application may include one capacitor, or may include at least two capacitors. Under the condition that includes two at least electric capacities, parallelly connected two electric capacities, can promote capacitor module C2's electric capacity, under the anodal circumstances of unloading of direct current bus electric capacity C1, let capacitor module C2 as far as possible long let switch tube Q1 be in the state that switches on to can guarantee direct current bus electric capacity C1 can improve direct current bus electric capacity C1's the effect of discharging through the abundant discharge of first resistance module R1.
Optionally, the discharge control circuit further includes a second resistor module R2, a first end of the second resistor module R2 is connected to the third contact 3, and a second end of the second resistor module R2 is connected to the third end of the switching tube Q1;
the second resistance module R2 comprises one resistance or at least two resistances; in the case where the second resistance module R2 includes at least two resistances, the at least two resistances included in the second resistance module R2 are connected in series or in parallel.
The embodiment of the application provides a specific structure of a second resistor module R2. When the second resistance module R2 includes at least two resistances, the at least two resistances may be connected in series, or may be connected in parallel, or may be connected in series and then connected in parallel. The embodiments of the present application are not limited.
The second resistor module R2 is provided to limit the current flowing through the switch Q1. For example, if the switching tube Q1 is a transistor, the second resistor module R2 is connected to the base of the transistor (the third end of the switching tube Q1), so that the current flowing through the transistor can be limited, and the transistor can be prevented from being damaged due to an excessive current.
Optionally, the discharge control circuit further includes a third resistor module R3, a first end of the third resistor module R3 is connected to the third end of the switching tube Q1, and a second end of the third resistor module R3 is grounded;
the third resistance module R3 comprises one resistance or at least two resistances; in the case where the third resistance module R3 includes at least two resistances, the at least two resistances included in the third resistance module R3 are connected in series or in parallel.
The third resistor module R3 is arranged, the capacitor module C2 can discharge through the second resistor module R2 and the third resistor module R3, and the discharge speed of the capacitor module C2 can be controlled by setting the resistance values of the second resistor module R2 and the third resistor module R3.
The embodiment of the application provides a specific structure of a third resistor module R3. When the third resistor module R3 includes at least two resistors, the at least two resistors may be connected in series, may also be connected in parallel, and may be connected in parallel after being connected in series. The embodiments of the present application are not limited.
Referring to fig. 4, fig. 4 is a schematic structural diagram of another discharge control circuit according to an embodiment of the present disclosure. As shown in fig. 4, the discharge control circuit includes a dc bus capacitor C1, a first resistor module R1, a second resistor module R2, a third resistor module R3, a capacitor module C2, a dc power supply, a relay K1, a switching tube Q1, and a diode D1; the relay K1 comprises a first contact 1, a second contact 2, a third contact 3 and a coil L1;
the positive electrode of the direct current bus capacitor C1 is connected to the first end of the first resistor module R1, the second end of the first resistor module R1 is connected to the first end of the switch tube Q1, and the second end of the switch tube Q1, the negative electrode of the direct current bus capacitor C1, the first end of the coil L1, the negative electrode of the capacitor module C2, the second end of the third resistor module R3, and the negative electrode of the direct current power supply are grounded; the second end of the coil L1 is connected with the anode of the direct-current power supply and the anode of the diode D1, the cathode of the diode D1 is connected with the anode of the capacitor module C2 and the first contact 1, the third contact 3 is connected with the first end of the second resistor module R2, and the second end of the second resistor module R2 is connected with the third end of the switch tube Q1 and the first end of the third resistor module R3.
Under the condition that the positive electrode of the direct-current bus capacitor C1 is electrified, the direct-current power supply is electrified, the coil L1 is electrified, the first contact 1 is communicated with the second contact 2, the switch tube Q1 is disconnected, the first resistor module R1 is disconnected with the direct-current bus capacitor C1, and the direct-current power supply charges the capacitor module C2 through the diode D1;
under the condition that the positive electrode of the direct-current bus capacitor C1 is powered down, the direct-current power supply is powered down, the coil L1 is powered down, the first contact 1 is communicated with the third contact 3, the switch tube Q1 is conducted, the capacitor module C2 discharges electricity through the second resistor module R2 and the third resistor module R3, and the direct-current bus capacitor C1 discharges electricity through the first resistor module R1.
After the dc bus capacitor C1 is powered down, the time required for the voltage of the capacitor module C2 to drop from the voltage before the power down to the cut-off voltage of the switching tube Q1 is less than the time required for the voltage of the dc bus capacitor C1 to drop from the voltage before the power down to the safe voltage. Under the condition that the resistance values of the first resistor module R1, the second resistor module R2 and the third resistor module R3 and the capacitance value of the dc bus capacitor C1 are determined, the time required for the capacitor module C2 to decrease from the voltage before the power-down of the capacitor module C2 to the cut-off voltage of the switching tube Q1 can be made shorter than the time required for the voltage of the dc bus capacitor C1 to decrease from the voltage before the power-down to the safe voltage by setting the capacitance value of the capacitor module C2. Before direct current bus capacitor C1 discharges to safe voltage, switch tube Q1 can continuously switch on, improves the security that direct current bus capacitor C1 discharged.
The voltage before the capacitor module C2 is powered down is the voltage across the capacitor module C2 when the positive electrode of the dc bus capacitor C1 is powered down immediately. The voltage before the power-off of the direct current bus capacitor C1 is the voltage across the two ends of the direct current bus capacitor C1 when the positive electrode of the direct current bus capacitor C1 is just powered off.
Optionally, the capacitance value of the capacitance module C2 satisfies the following formula:
C2>(R1*C1*lnB)/[(R2+R3)*lnA]；
A＝(1+R2/R3)*Voff/Vdc；B＝Vsave/Vbus；
wherein C2 is a capacitance value of the capacitor module, C1 is a capacitance value of the dc bus capacitor, R1 is a resistance value of the first resistor module, R2 is a resistance value of the second resistor module, R3 is a resistance value of the third resistor module, voff is a cut-off voltage of the switching tube, vdc is a stable voltage after the dc power supply is powered on, vbus is a voltage before the dc bus capacitor is powered off, vsave is a safe voltage corresponding to the dc bus capacitor, voff < Vdc, and Vsave < Vbus.
In the embodiment of the application, the time from Vdc discharging to (1 + r2/R3) × Voff of the voltage on the capacitor module C2 is set to t1, and the time from Vbus discharging to the designated safe voltage Vsave of the voltage on the dc bus capacitor C1 is set to t2, so that t1> t2 is required.
The derivation of the above formula is described in detail below.
(1+R2/R3)*Voff＝Vdc*e^{-t1/[(R2+R3)*C2]}；
t1＝-(R2+R3)*C2*ln[(1+R2/R3)*Voff/Vdc]＝-(R2+R3)*C2*lnA；
Vsave＝Vbus*e^[-t2/(R1*C1)]；
t2＝-R1*C1*ln(Vsave/Vbus)＝-R1C1*lnB；
If t1> t2, - (R2 + R3) C2lnA > -R1C1lnB;
since lnA <0,lnB are woven into the layers of cloth 0;
then C2> (R1 x C1 x lnB)/[ (R2 + R3) x lnA ].
According to the embodiment of the application, only the capacitance value of C2 needs to be set, and the time required for the capacitor module to be reduced to the cut-off voltage of the switch tube from the voltage before the capacitor module is powered down is less than the time required for the voltage of the direct-current bus capacitor to be reduced to the safe voltage from the voltage before the capacitor module is powered down. Before the direct current bus capacitor discharges to safe voltage, the switch tube can be continuously conducted, and the discharging safety of the direct current bus capacitor is improved.
Referring to fig. 5, fig. 5 is a schematic structural diagram of an inverter according to an embodiment of the present disclosure. As shown in fig. 5, the inverter device includes a discharge control circuit 100, a new energy power generation module 200, and an inverter unit 300; the output positive electrode of the new energy power generation module 200 is connected with the positive electrode of the direct current bus capacitor C1 in the discharge control circuit 100 and the positive electrode of the inverter unit 300, and the output negative electrode of the new energy power generation module 200 is connected with the negative electrode of the direct current bus capacitor C1 in the discharge control circuit 100 and the negative electrode of the inverter unit 300; the new energy power generation module 200 is configured to output a dc voltage. The new energy power generation module 200 may include a photovoltaic module or a wind power generation module.
In this embodiment, the discharge control circuit 100 may be used in an inverter device shown in fig. 5, when the new energy power generation module 200 works, the new energy power generation module may output a direct current voltage (for example, a direct current high voltage), and the inverter unit 300 may convert the direct current voltage into an alternating current voltage, and may access the alternating current voltage to an alternating current power grid. For example, the power can be converted into 220V power for residents to use.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to the related descriptions of other embodiments.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus may be implemented in other manners. For example, the above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one type of division of logical functions, and there may be other divisions when actually implementing, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not implemented.
Claims (10)
1. A discharge control circuit is characterized by comprising a direct current bus capacitor, a first resistance module, a capacitor module, a direct current power supply, a relay, a switch tube and a diode; the relay comprises a first contact, a second contact, a third contact and a coil;
the positive electrode of the direct current bus capacitor is connected with the first end of the first resistor module, the second end of the first resistor module is connected with the first end of the switch tube, and the second end of the switch tube, the negative electrode of the direct current bus capacitor, the first end of the coil, the negative electrode of the capacitor module and the negative electrode of the direct current power supply are grounded; the second end of the coil is connected with the anode of the direct-current power supply and the anode of the diode, the cathode of the diode is connected with the anode of the capacitor module and the first contact, and the third contact is communicated with the third end of the switch tube.
2. The discharge control circuit of claim 1,
under the condition that the anode of the direct current bus capacitor is electrified, the direct current power supply is electrified, the coil is electrified, the first contact and the second contact are communicated, the switch tube is disconnected, the first resistance module is disconnected with the direct current bus capacitor, and the direct current power supply charges the capacitor module through the diode;
under the condition that the positive electrode of the direct-current bus capacitor is powered off, the direct-current power supply is powered off, the coil is powered off, the first contact is communicated with the third contact, the switch tube is conducted, the capacitor module discharges electricity, and the direct-current bus capacitor discharges electricity through the first resistor module.
3. The discharge control circuit of claim 1, wherein the discharge control circuit comprises a dc converter circuit, the positive electrode of the dc bus capacitor is connected to the positive input terminal of the dc converter circuit, and the positive output terminal of the dc converter circuit is connected to the positive electrode of the dc power supply.
4. The discharge control circuit of claim 1, wherein the first resistance module comprises one resistance or at least two resistances; in the case where the first resistance module includes at least two resistances, the at least two resistances included in the first resistance module are connected in series or in parallel.
5. The discharge control circuit of claim 1, wherein the capacitance module comprises one capacitance or at least two capacitances; in case the capacitance module comprises at least two capacitances, the at least two capacitances are connected in parallel.
6. The discharge control circuit of claim 1, further comprising a second resistor module, wherein a first end of the second resistor module is connected to the third contact, and a second end of the second resistor module is connected to the third end of the switch tube;
the second resistance module comprises one resistance or at least two resistances; in the case where the second resistance module includes at least two resistances, the at least two resistances included in the second resistance module are connected in series or in parallel.
7. The discharge control circuit of claim 6, further comprising a third resistor module, wherein a first end of the third resistor module is connected to the third end of the switching tube, and a second end of the third resistor module is grounded;
the third resistance module comprises one resistance or at least two resistances; in the case that the third resistance module includes at least two resistances, the third resistance module includes at least two resistances connected in series or in parallel.
8. The discharge control circuit of claim 7, wherein the capacitance value of the capacitance module satisfies the following equation:
C2>(R1*C1*lnB)/[(R2+R3)*lnA]；
A＝(1+R2/R3)*Voff/Vdc；B＝Vsave/Vbus；
wherein C2 is a capacitance value of the capacitor module, C1 is a capacitance value of the dc bus capacitor, R1 is a resistance value of the first resistor module, R2 is a resistance value of the second resistor module, R3 is a resistance value of the third resistor module, voff is a cut-off voltage of the switching tube, vdc is a stable voltage after the dc power supply is powered on, vbus is a voltage before the dc bus capacitor is powered off, vsave is a safe voltage corresponding to the dc bus capacitor, voff < Vdc, and Vsave < Vbus.
9. The discharge control circuit of any one of claims 1 to 8, wherein the switching tube comprises an active switching device, and the active switching device comprises any one of a metal-oxide semiconductor field effect transistor (MOSFET), an Insulated Gate Bipolar Transistor (IGBT) and a triode.
10. An inverter device, comprising the discharge control circuit according to any one of claims 1 to 9, a new energy power generation module, and an inverter unit; the output positive electrode of the new energy power generation module is connected with the positive electrode of a direct-current bus capacitor in the discharge control circuit and the positive electrode of the inversion unit, and the output negative electrode of the new energy power generation module is connected with the negative electrode of the direct-current bus capacitor in the discharge control circuit and the negative electrode of the inversion unit; the new energy power generation module is used for outputting direct-current voltage.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222407852.5U CN218162211U (en) | 2022-09-09 | 2022-09-09 | Discharge control circuit and inverter device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222407852.5U CN218162211U (en) | 2022-09-09 | 2022-09-09 | Discharge control circuit and inverter device |
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| CN218162211U true CN218162211U (en) | 2022-12-27 |
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