CN216016437U - Short-circuit protection circuit of resonant converter, resonant converter and energy storage equipment - Google Patents
Short-circuit protection circuit of resonant converter, resonant converter and energy storage equipment Download PDFInfo
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Abstract
The utility model relates to a short-circuit protection circuit, a resonant converter and an energy storage device, wherein the short-circuit protection circuit comprises: the state acquisition circuit is used for acquiring a zone bit signal of the starting state of the resonant converter; the current sampling circuit is used for collecting the output current of the resonant converter; the voltage sampling circuit is used for collecting the output voltage of the resonant converter; the first comparison circuit is used for outputting a first comparison result when the output current is greater than the current protection threshold value; the second comparison circuit is used for outputting a second comparison result when the output voltage is smaller than the voltage protection threshold value; and the control circuit is used for outputting a turn-off signal to the resonant converter according to the zone bit signal, the first comparison result and the second comparison result, and the turn-off signal is used for controlling the resonant converter to stop outputting. The short-circuit protection circuit can avoid the situation of misjudgment caused by directly adopting the first comparison result and the second comparison result for judgment, and can improve the working stability of equipment.
Description
Technical Field
The application belongs to the technical field of energy storage, and particularly relates to a short-circuit protection circuit of a resonant converter, the resonant converter and energy storage equipment.
Background
The resonant converter is used for converting direct current into alternating current square wave voltage or current through the chopper circuit, then the alternating current square wave voltage or current is added at two ends of the resonant network to generate high-frequency resonance, and the resonant voltage or current is converted into direct current voltage or current after rectification and filtering, so that direct current-direct current conversion (DC-DC) is realized. The resonant converter needs to be short-circuit protected to ensure the reliability of the devices used in the circuit. The traditional short-circuit protection circuit directly compares the sampled current with the threshold current to be used as a judgment basis for judging whether short-circuit protection is needed, and the scheme is easy to misjudge, so that the resonant converter is easy to start short-circuit protection under normal conditions and cannot work normally.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems, the short-circuit protection circuit capable of improving the working stability of the resonant converter is provided.
A short-circuit protection circuit for a resonant converter, comprising: the state acquisition circuit is used for acquiring a zone bit signal of the starting state of the resonant converter; the current sampling circuit is connected to the output end of the resonant converter and is used for collecting the output current of the resonant converter; the voltage sampling circuit is connected to the output end of the resonant converter and used for collecting the output voltage of the resonant converter; a first comparison circuit, a first input terminal of which is connected with the current sampling circuit to receive the output current; the second input end of the first comparison circuit is used for receiving a current protection threshold value; the first comparison circuit is used for outputting a first comparison result when the output current is greater than the current protection threshold value; a second comparison circuit, a first input terminal of the second comparison circuit being connected to the voltage sampling circuit to receive the output voltage; a second input end of the second comparison circuit is used for receiving a voltage protection threshold value; the second comparison circuit is used for outputting a second comparison result when the output voltage is smaller than the voltage protection threshold value; the control circuit is respectively connected with the state acquisition circuit, the first comparison circuit and the second comparison circuit; the control circuit is used for outputting a turn-off signal to the resonant converter according to the zone bit signal, the first comparison result and the second comparison result, and the turn-off signal is used for controlling the resonant converter to stop outputting.
According to the short-circuit protection circuit of the resonant converter, in the short-circuit protection process, short-circuit protection control can be performed according to the collected flag bit signal of the starting state of the resonant converter, the first comparison result of the first comparison circuit and the second comparison result of the second comparison circuit, the situation of misjudgment caused by directly adopting the first comparison result and the second comparison result for judgment can be avoided, and the working stability of the resonant converter can be improved.
In one embodiment, the first comparison circuit comprises a first operational amplifier, wherein a non-inverting input terminal of the first operational amplifier is connected with a first input terminal of the first comparison circuit; the inverting input end of the first operational amplifier is connected with the second input end of the first comparison circuit; the output end of the first operational amplifier is connected with the output end of the first comparison circuit; and/or the second comparison circuit comprises a second operational amplifier, wherein the non-inverting input end of the second operational amplifier is connected with the second input end of the second comparison circuit; the inverting input end of the second operational amplifier is connected with the first input end of the second comparison circuit; and the output end of the second operational amplifier is connected with the output end of the second comparison circuit.
In one embodiment, the control circuit is specifically configured to: when the flag bit signal is in a first state and the first comparison result and the second comparison result are received at the same time, outputting the turn-off signal to the resonant converter; the first state is indicative of a start-up incomplete state of the resonant converter; when the flag bit signal is in a second state and the first comparison result or the second comparison result is received, outputting the turn-off signal to the resonant converter; the second state characterizes a start-up complete state of the resonant converter.
In one embodiment, the control circuit comprises a NOR gate, a NAND gate and a switching unit; two input ends of the NAND gate are respectively connected with the output ends of the first operational amplifier and the second operational amplifier, and the output end of the NAND gate is connected with the first input end of the switching unit; two input ends of the nor gate are respectively connected with output ends of the first operational amplifier and the second operational amplifier, and an output end of the nor gate is connected with a second input end of the switching unit; the controlled end of the switching unit is also connected with the state acquisition circuit, and the switching unit is used for outputting the turn-off signal according to the input of the second input end when the zone bit signal is in the first state and outputting the turn-off signal according to the input of the first input end when the zone bit signal is in the second state.
In one embodiment, the method further comprises the following steps: the first timing circuit is used for metering the duration of the first comparison result; and a second timing circuit for measuring the duration of the second comparison result; the control circuit is used for outputting the turn-off signal to the resonant converter according to the zone bit signal, the first comparison result and the second comparison result when the duration measured by the first timing circuit and the duration measured by the second timing circuit reach a preset time threshold.
In one embodiment, the preset time threshold is between 400 microseconds and 600 microseconds; and/or the current protection threshold is 25 amps and the voltage protection threshold is 25 volts.
A resonant converter comprising a resonant conversion circuit and a short-circuit protection circuit as described in any of the previous embodiments.
In one embodiment, the device further comprises a feedback control circuit; the feedback control circuit comprises a voltage outer ring, a current inner ring and a pulse modulation circuit, wherein the voltage outer ring is used for generating a current ring given signal according to the deviation between a target output voltage and the output voltage, and the current inner ring is used for generating a corresponding control quantity according to the deviation between the current ring given signal and the output current; the pulse modulation circuit is used for generating a corresponding pulse signal to the control circuit according to the control quantity; and the control circuit is used for controlling the resonance conversion circuit to work according to the driving signal when the turn-off signal is not generated.
In one embodiment, the device further comprises an overcurrent protection circuit; a first input end of the overcurrent protection circuit is used for receiving a sampling current, and a second input end of the overcurrent protection circuit is used for receiving a current threshold corresponding to the sampling current; the overcurrent protection circuit is used for outputting an overcurrent signal to the control circuit when the sampling current is greater than the current threshold; the control circuit is also used for generating the turn-off signal according to the overcurrent signal; the sampling current is a direct current bus current of the resonant conversion circuit, a resonant current or a current before filtering of the output current.
An energy storage device comprising a resonant converter as claimed in any preceding embodiment.
Drawings
Fig. 1 is a circuit diagram of a resonant conversion circuit of a resonant converter in an embodiment.
Fig. 2 is a circuit block diagram of a short-circuit protection circuit of a resonant converter in an embodiment.
Fig. 3 is a circuit block diagram of a short-circuit protection circuit of a resonant converter in another embodiment.
Fig. 4 is a circuit diagram of a control circuit in an embodiment.
Fig. 5 is a circuit diagram of the resonant converter in the first embodiment.
Fig. 6 is a circuit diagram of a resonant converter in a second embodiment.
Fig. 7 is a circuit diagram of a resonant converter in a third embodiment.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
The resonant converter is used for converting direct current into alternating current square wave voltage or current through the chopper circuit, then the alternating current square wave voltage or current is added at two ends of the resonant network to generate high-frequency resonance, and the resonant voltage or current is converted into direct current voltage or current after rectification and filtering, so that voltage conversion (DC-DC) between direct current and direct current is realized. Resonant converters are used in an increasing number of DC-DC conversion scenarios, since they enable soft switching, effectively reduce switching losses and allow high frequency operation. Resonant converters include many types, and are described herein by way of example as LLC converters.
Fig. 1 is a circuit schematic diagram of a resonant conversion circuit of a resonant converter (LLC converter) in an embodiment. Resonant conversion circuits are mainly used to implement DC-DC conversion, which needs to be operated under the control of an associated control circuit. The resonant conversion circuit includes a switching circuit 110, a resonant circuit 120, a transformer Tr, a rectification circuit 130, and a filter circuit 140. The switch circuit 110 is a full bridge circuit, i.e., is composed of four MOS transistors (Q1 to Q4) to convert the dc voltage on the dc bus into ac voltage. The switching circuit 110 may also be a half-bridge circuit. The resonant circuit 120 includes a resonant inductor LrAnd a resonance capacitor CrResonant inductance LrAnd a resonance capacitor CrConnected in series between the middle points A, B of the two arms of the full bridge circuit and located in the transformer TrOn the primary winding side of the transformer. Transformer TrThe secondary winding of the transformer is connected to a rectifying circuit 130, and the other end of the rectifying circuit 130 is connected to a filter circuit 140. The rectifying circuit 130 may also be a full bridge circuit or a half bridge circuit, and the rectifying circuit 130 in fig. 1 is a full bridge circuit, and includes 4 MOS transistors (Q5 to Q8). The middle point D, E of the two arms of the full bridge circuit is connected to the transformer TrAcross the secondary winding. The filter circuit 140 may include at least one capacitor C connected in parallel to the output terminalo. The resonant conversion circuit can realize voltage conversion between DC and DC, and the voltage conversion can be voltage boosting or voltage reduction.
In FIG. 1, CdcRepresenting the DC bus capacitance, VdcRepresenting the input dc bus voltage. RLRepresents the load, R1Representing the sampling resistance, VoRepresenting the output voltage of the resonant converter, IoRepresenting the output current of the resonant converter. Each MOS transistor is connected in parallel with a corresponding diode and a corresponding capacitor, for example, the MOS transistor Q1 is connected in parallel with a diode Q1 and a capacitor C1, the diode Q1 and the capacitor C1 may be parasitic diodes and parasitic capacitors of the MOS transistor Q1, or may be capacitors and diodes independently added at two ends of the MOS transistor. In this embodiment, each MOS transistor is an NMOS transistor, and each MOS transistor can be turned on under the control of a high level and turned off under the control of a low level.
The present application provides a short-circuit protection circuit 150 for short-circuit protection of a resonant converter. The structural block diagram of the protection circuit is shown in fig. 2, and includes a state acquisition circuit 210, a current sampling circuit 220, a voltage sampling circuit 230, a first comparison circuit 240, a second comparison circuit 250, and a control circuit 260.
The state acquisition circuit 210 is used for acquiring a flag bit signal Lab of the starting state of the resonant converter. The flag bit signal Lab is used for representing whether the resonant converter is started completely. In this case, the flag signal Lab includes two states, wherein the first state indicates that the start of the resonant converter is not completed, and the second state indicates that the start of the resonant converter is completed. Specifically, the flag bit signal Lab may be a level signal, and two corresponding states are represented by a high level signal and a low level signal, where the high level signal represents that the start is completed, and the low level signal represents that the start is not completed. Therefore, whether the resonant converter is started up can be confirmed by the flag signal Lab.
The current sampling circuit 220 is connected to the output terminal of the resonant converter, i.e. the output terminal of the resonant conversion circuit, and is used for collecting the output current I of the resonant convertero. The current sampling circuit 220 may be implemented using current sampling techniques commonly used in the art, such as resistive sampling, and is not limited to a particular implementation.
The voltage sampling circuit 230 is connected to the output terminal of the resonant converter, i.e. the output terminal of the resonant conversion circuit, and is used for collecting the output voltage V of the resonant convertero. The voltage sampling circuit 230 may also be implemented using voltage sampling techniques commonly used in the art, and is not limited to a particular implementation.
The first comparison circuit 240 includes a first input terminal IN1 and a second input terminal IN 2. The first input terminal IN1 is connected to the output terminal of the current sampling circuit 220 for receiving the sampled output current Io. The second input terminal IN2 is used for receiving the current protection threshold I1. Current protection thresholdI1The critical current when a short circuit occurs or the maximum current that can be allowed by the resonant converter. The first comparison circuit 240 is used for outputting the current IoGreater than the current protection threshold I1Then, the first comparison result COM1 is output.
The second comparing circuit 250 includes a first input terminal IN3 and a second input terminal IN 4. The first input terminal IN3 is connected to the output terminal of the voltage sampling circuit 230 for receiving the sampled output voltage Vo. Second input terminal IN4Then for receiving the voltage protection threshold V1. Voltage protection threshold V1The critical voltage when a short circuit occurs or the minimum voltage required for the resonant converter to operate properly. The second comparator circuit 250 is used for outputting the voltage VoLess than a voltage protection threshold V1Then, the second comparison result COM2 is output.
The control circuit 260 is connected to the state acquisition circuit 210, the first comparison circuit 240, and the second comparison circuit 250, respectively. The control circuit 260 is configured to determine whether a short circuit occurs according to the flag bit signal Lab, the first comparison result COM1, and the second comparison result COM2, and further output a turn-off signal to the resonant converter after the short circuit is determined to occur. The turn-off signal is used for controlling the resonant converter to stop outputting.
In the short-circuit protection process, the short-circuit protection control is performed according to the collected flag bit signal Lab of the starting state of the resonant converter, the first comparison result COM1 of the first comparison circuit 240 and the second comparison result COM2 of the second comparison circuit 250, so that the occurrence of misjudgment caused by directly adopting the first comparison result COM1 and the second comparison result COM2 for judgment can be avoided, the working stability of the resonant converter and the reliability of products can be improved, and the short-circuit protection circuit has the advantage of high detection speed.
Specifically, the control circuit 260 outputs a shutdown signal to the resonant converter when the flag signal Lab is in the first state and the first comparison result COM1 and the second comparison result COM2 are received at the same time, and outputs a shutdown signal to the resonant converter when the flag signal Lab is in the second state and the first comparison result COM1 or the second comparison result COM2 are received. That is to say, when the resonant converter is not started, only when the output current is greater than the current protection threshold and the output voltage is less than the voltage protection threshold, the short-circuit protection is determined to be needed, so that the problem that the whole resonant converter cannot be started normally due to the fact that the short-circuit protection condition is triggered because the output voltage is too low in the normal starting process can be avoided. When the resonant converter is started, the short circuit is determined to occur as long as one of the current or the voltage is met, and short-circuit protection is needed, so that the output is timely and effectively turned off, the whole circuit is protected, and the reliable operation of the whole circuit is ensured.
In one embodiment, the first comparison circuit 240 includes a first operational amplifier U1, as shown in fig. 3. The non-inverting input terminal of the first operational amplifier U1 is connected to the first input terminal IN1 of the first comparison circuit 240; the inverting input terminal of the first operational amplifier U1 is connected to the second input terminal IN2 of the first comparison circuit 240; the output of the first operational amplifier U1 is connected to the output of the first comparison circuit 240. Therefore, the first operational amplifier U1 can calculate the deviation between the two input signals and output the current IoGreater than the current protection threshold I1Then, the first comparison result COM1 is output. That is, in the present embodiment, the first comparison result COM1 is a high level signal.
The second comparison circuit 250 includes a second operational amplifier U2. The non-inverting input of the second operational amplifier U2 is connected to the second input IN4 of the second comparator circuit 250; the inverting input of the second operational amplifier U2 is connected to the first input IN3 of the second comparator circuit 250; the output of the second operational amplifier U2 is connected to the output of the second comparator circuit 250. Therefore, the second operational amplifier U2 can calculate the deviation between the two input signals and output the voltage VoLess than a voltage protection threshold V1Then, the second comparison result COM2 is output. That is, in the present embodiment, the second comparison result COM2 is also a high level signal. In other embodiments, it may be necessary to change the inputs of the first operational amplifier U1 and the second operational amplifier U2 when the corresponding first comparison result COM1 and the second comparison result C are obtainedOM2 can be both low level signals, or one high level signal and one low level signal. In this embodiment, both the first comparison result COM1 and the second comparison result COM2 are high level signals.
In one embodiment, the control circuit 260 may adopt the circuit structure shown in fig. 4. Specifically, the control circuit 260 includes a nor gate 262, a nand gate 264, and a switching unit 266. Two input terminals of the nor gate 262 are respectively connected to the output terminals of the first comparing circuit 240 and the second comparing circuit 250, and an output terminal of the nor gate 262 is connected to the first input terminal S1 of the switching unit 266. Two inputs of the nand-gate 264 are respectively connected to the outputs of the first and second comparing circuits 240 and 250, and the output of the nand-gate 264 is connected to the second input S2 of the switching unit 266. The controlled end of the switching unit 266 is connected to the state acquisition circuit 210. The switching unit 266 is used for outputting a shutdown signal according to the input and the output of the second input terminal S2 when the flag bit signal Lab is in the first state, and outputting the shutdown signal according to the input and the output of the first input terminal S1 when the flag bit signal Lab is in the second state.
In this embodiment, the first comparison result COM1 and the second comparison result COM2 are both high level signals, so the nand gate 262 outputs the off signal of the low level signal when receiving the first comparison result COM1 and the second comparison result COM2 at the same time, otherwise both output the high level signal, while the nor gate 262 outputs the off signal of the low level signal when receiving any one of the first comparison result COM1 and the second comparison result COM2, and outputs the high level signal only when not receiving the first comparison result COM1 and the second comparison result COM2 at the same time. The switching unit 266 can switch the connection between the output and the output according to the flag bit signal Lab output by the state acquisition circuit 210, so as to output a shutdown signal according to the corresponding input terminal. Specifically, when the flag bit signal Lab is in the first state, that is, in the low level state, the switching unit 266 connects the second input terminal S2 thereof with the output terminal So, and outputs the low level signal input from the second input terminal S2 to the resonant converter as the off signal; when the flag signal is in the second state, i.e., in the high level state, the switching unit 266 connects its first input terminal S1 with the output terminal So, and outputs the low level input from the first input terminal S1 to the resonant converter as the off signal. The turn-off signal is used to turn off and control the MOS transistor in the switching circuit 110 in the resonant conversion circuit, so that the entire resonant converter stops outputting.
It is understood that in other embodiments, different control circuits may be selected to realize the output of the shutdown signal according to the settings of the first comparison circuit 240 and the second comparison circuit 250, and the present invention is not limited to the above embodiments.
In other embodiments, the short-circuit protection circuit further includes a first timing circuit 270 and a second timing circuit 280, as shown in fig. 3. The first timing circuit 270 is used for measuring the duration of the first comparison result COM1, and the second timing circuit 280 is used for measuring the duration of the second comparison result COM 1. The control circuit 260 outputs a short signal to the resonant converter according to the flag bit signal Lab, the first comparison result COM1 and the second comparison result COM2 only when the duration of the first comparison result COM1 and the second comparison result COM2 reaches the time threshold. By monitoring the maintaining time of the first comparison result COM1 and the second comparison result COM2, false alarm caused by surge pulse can be avoided, and the stability and reliability of the whole circuit are improved.
Optionally, the preset time threshold is 400 microseconds to 600 microseconds, for example, 500 microseconds.
Optionally, the current protection threshold is 25 amps and the voltage protection threshold is 25 volts.
The present application further provides a resonant converter including the circuit shown in fig. 1 and the short-circuit protection circuit according to any of the foregoing embodiments, and further including a feedback control circuit 160, as shown in fig. 5. Feedback control circuit 160 includes a voltage outer loop 310, a current inner loop 320, and a pulse modulation circuit 330. The voltage outer loop 310 is used for outputting a voltage V according to a target output voltagerefAnd an output voltage VoThe deviation between them generates a current loop given signal, and the current inner loop 320 is used to generate the output current I according to the current loop given signal and the output current IoThe deviation between the two generates a corresponding control quantity; pulse modulation circuit 330For generating a corresponding pulse signal to the control circuit 260 according to the control quantity. The control circuit 260 is configured to control the resonant converter to operate according to the driving signal when the shutdown signal is not generated, so as to stabilize the output of the resonant converter.
Specifically, the voltage outer loop 310 includes a first adder 312, a PI regulator 314, and a limiter 316. The positive input terminal of the first adder 312 is used for receiving the target output voltage VrefThe negative input terminal of the first adder 312 is used for inputting the output voltage VoThe first adder 312 calculates a deviation between the two inputs, outputs the deviation to the PI regulator 314, performs PI (proportional integral) regulation, and generates a corresponding control quantity to the limiter 316 for limiting, so as to obtain a current loop given signal.
The current inner ring 320 may have the same structure as the voltage outer ring, or may have a structure as shown in fig. 5. Referring to fig. 5, the current inner loop 320 includes a second adder 321, a PI regulator 322, a PR regulator (proportional resonant regulator) 323, a third adder 324, and a limiter 325. The positive input end of the second adder 321 is configured to receive a current loop given signal, the negative input end of the second adder 321 is configured to input an output current Io, and the second adder 321 calculates a difference between the two inputs and outputs the difference to the PI regulator 322 and the PR regulator 323 for corresponding processing. The PI regulator 322 performs PI regulation on the deviation to generate a corresponding control quantity to one of the input terminals of the third adder 324. The PR adjuster 323 is used for PR adjusting the deviation input by the second adder 321 to generate a corresponding control quantity to another input terminal of the third adder 324. The third adder 325 is used for summing the two input control quantities and outputting the sum to the limiter 325 for limiting to obtain the final control quantity.
The pulse modulation circuit 330 is used for generating a corresponding pulse signal to the control circuit 260 according to the control quantity. The pulse modulation circuit 330 may adopt a PWM modulation circuit or a PFM modulation circuit, in this embodiment, the pulse modulation circuit 330 includes both the PWM modulation circuit and the PFM modulation circuit, so that after the pulse frequency and the amplitude are adjusted, a corresponding pulse signal is generated to the control circuit 260. The control circuit 260 may generate a driving signal for controlling each MOS transistor (Q1 to Q4) in the switch circuit 110 according to the pulse signal, and the driving signal may adjust duty ratios of the MOS transistors (Q1 to Q4), thereby implementing adjustment of the output.
In another embodiment, the resonant converter further comprises an overcurrent protection circuit 170. A first input of the over-current protection circuit 170 is for receiving a sampled current, and a second input of the over-current protection circuit 170 is for receiving a current threshold I corresponding to the sampled currentlimit. The over-current protection circuit 170 is used for detecting the sampling current greater than the current threshold IlimitThen, the over-current signal Disable is output to the control circuit 260. The control circuit 260 is further configured to generate a shutdown signal according to the over-current signal Disable, so as to shut down the output of the resonant converter.
The overcurrent protection circuit 170 includes an operational amplifier U3. The non-inverting input end of the operational amplifier U3 is connected to the first input end of the over-current protection circuit 170, the inverting input end of the operational amplifier U3 is connected to the second input end of the over-current protection circuit 170, and the output end of the operational amplifier U3 is connected to the output end of the over-current protection circuit 170. The operational amplifier U3 is used for sampling the current larger than the current threshold IlimitTime, output over-current signal Disable。
The overcurrent protection circuit 170 may be disposed at different positions as required, and as shown in fig. 5, the sampling current is a dc bus current I at the input side of the resonant converterbusAt this time, the current threshold value IlimitAlso the over-current protection threshold corresponding to that position. The overcurrent protection circuit 170 has a transformer TrThe primary side MOS tube has the function of preventing direct connection.
In other embodiments, the sampling current may be a resonant current i of the resonant converterrAs shown in fig. 6, the resonant current ir can participate in the control, and the flexibility is greater, and a current transformer is needed. The sampling current can also be the current i before the output current of the resonant converter is filteredsecAs shown in fig. 7, a current transformer is not needed, and resistance sampling can be directly performed, so that the cost is low.
The present application further provides an energy storage device comprising a resonant converter as in any of the previous embodiments. The resonant converter is used for converting an input direct-current power supply into a voltage required by the energy storage device and then supplying power to a battery pack in the energy storage device, or converting the voltage of the battery pack in the energy storage device into a target voltage and then outputting the target voltage to a post-stage circuit.
By arranging the short-circuit protection circuit, the operation stability and the reliability of the energy storage device can be improved.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (10)
1. A short-circuit protection circuit for a resonant converter, comprising:
the state acquisition circuit is used for acquiring a zone bit signal of the starting state of the resonant converter;
the current sampling circuit is connected to the output end of the resonant converter and is used for collecting the output current of the resonant converter;
the voltage sampling circuit is connected to the output end of the resonant converter and used for collecting the output voltage of the resonant converter;
a first comparison circuit, a first input terminal of which is connected with the current sampling circuit to receive the output current; the second input end of the first comparison circuit is used for receiving a current protection threshold value; the first comparison circuit is used for outputting a first comparison result when the output current is greater than the current protection threshold value;
a second comparison circuit, a first input terminal of the second comparison circuit being connected to the voltage sampling circuit to receive the output voltage; a second input end of the second comparison circuit is used for receiving a voltage protection threshold value; the second comparison circuit is used for outputting a second comparison result when the output voltage is smaller than the voltage protection threshold value; and
the control circuit is respectively connected with the state acquisition circuit, the first comparison circuit and the second comparison circuit; the control circuit is used for outputting a turn-off signal to the resonant converter according to the zone bit signal, the first comparison result and the second comparison result, and the turn-off signal is used for controlling the resonant converter to stop outputting.
2. The short-circuit protection circuit of claim 1, wherein the first comparison circuit comprises a first operational amplifier, a non-inverting input of the first operational amplifier being connected to a first input of the first comparison circuit; the inverting input end of the first operational amplifier is connected with the second input end of the first comparison circuit; the output end of the first operational amplifier is connected with the output end of the first comparison circuit; and/or
The second comparison circuit comprises a second operational amplifier, and the non-inverting input end of the second operational amplifier is connected with the second input end of the second comparison circuit; the inverting input end of the second operational amplifier is connected with the first input end of the second comparison circuit; and the output end of the second operational amplifier is connected with the output end of the second comparison circuit.
3. The short-circuit protection circuit of claim 1, wherein the control circuit is specifically configured to:
when the flag bit signal is in a first state and the first comparison result and the second comparison result are received at the same time, outputting the turn-off signal to the resonant converter; the first state is indicative of a start-up incomplete state of the resonant converter;
when the flag bit signal is in a second state and the first comparison result or the second comparison result is received, outputting the turn-off signal to the resonant converter; the second state characterizes a start-up complete state of the resonant converter.
4. The short-circuit protection circuit according to claim 3, wherein the control circuit comprises a NOR gate, a NAND gate, and a switching unit; two input ends of the NAND gate are respectively connected with the output ends of the first operational amplifier and the second operational amplifier, and the output end of the NAND gate is connected with the first input end of the switching unit; two input ends of the nor gate are respectively connected with output ends of the first operational amplifier and the second operational amplifier, and an output end of the nor gate is connected with a second input end of the switching unit; the controlled end of the switching unit is also connected with the state acquisition circuit, and the switching unit is used for outputting the turn-off signal according to the input of the second input end when the zone bit signal is in the first state and outputting the turn-off signal according to the input of the first input end when the zone bit signal is in the second state.
5. The short-circuit protection circuit according to claim 1, further comprising:
the first timing circuit is used for metering the duration of the first comparison result; and
the second timing circuit is used for measuring the duration of the second comparison result;
the control circuit is used for outputting the turn-off signal to the resonant converter according to the zone bit signal, the first comparison result and the second comparison result when the duration measured by the first timing circuit and the duration measured by the second timing circuit reach a preset time threshold.
6. The short-circuit protection circuit of claim 5, wherein the preset time threshold is between 400 microseconds and 600 microseconds; and/or
The current protection threshold is 25 amps and the voltage protection threshold is 25 volts.
7. A resonant converter comprising a resonant conversion circuit and a short-circuit protection circuit as claimed in any of claims 1 to 6.
8. The resonant converter of claim 7, further comprising a feedback control circuit; the feedback control circuit comprises a voltage outer ring, a current inner ring and a pulse modulation circuit, wherein the voltage outer ring is used for generating a current ring given signal according to the deviation between a target output voltage and the output voltage, and the current inner ring is used for generating a corresponding control quantity according to the deviation between the current ring given signal and the output current; the pulse modulation circuit is used for generating a corresponding pulse signal to the control circuit according to the control quantity; and the control circuit is used for controlling the resonance conversion circuit to work according to the driving signal when the turn-off signal is not generated.
9. The resonant converter of claim 8, further comprising an over-current protection circuit; a first input end of the overcurrent protection circuit is used for receiving a sampling current, and a second input end of the overcurrent protection circuit is used for receiving a current threshold corresponding to the sampling current; the overcurrent protection circuit is used for outputting an overcurrent signal to the control circuit when the sampling current is greater than the current threshold; the control circuit is also used for generating the turn-off signal according to the overcurrent signal; the sampling current is a direct current bus current of the resonant conversion circuit, a resonant current or a current before filtering of the output current.
10. An energy storage device comprising a resonant converter as claimed in any of claims 7 to 9.
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| CN202121776792.3U CN216016437U (en) | 2021-07-30 | 2021-07-30 | Short-circuit protection circuit of resonant converter, resonant converter and energy storage equipment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115955090A (en) * | 2023-03-13 | 2023-04-11 | 季华实验室 | Control circuit of magnetron high-voltage power supply |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115955090A (en) * | 2023-03-13 | 2023-04-11 | 季华实验室 | Control circuit of magnetron high-voltage power supply |
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