CN117748963A - Bidirectional direct current series-parallel relay control device and method and bidirectional direct current series-parallel equipment - Google Patents
Bidirectional direct current series-parallel relay control device and method and bidirectional direct current series-parallel equipment Download PDFInfo
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Abstract
The invention relates to a bidirectional direct current series-parallel relay control device and a bidirectional direct current series-parallel relay control method, which are applied to bidirectional direct current series-parallel equipment. In the invention, the control signal of the relay is sent by the DSP controller, and the switching sequence is adjusted according to the switching state, so that the condition that the relay is turned off and the relay is turned on is ensured not to cause the output anode and the output cathode of the bidirectional direct current power supply network to be directly communicated. And the DSP controller can judge whether relay adhesion occurs or not through detecting and judging the output voltage under different serial-parallel connection conditions, so that stable serial-parallel connection switching of the output of the bidirectional direct current converter is realized. Furthermore, by controlling the switching of the relay, the output voltage range is widened.
Description
Technical Field
The invention relates to the field of new energy, such as an optical storage grid-connected system and a V2G (Vehicle-to-grid) system, in particular to a bidirectional direct current series-parallel relay control device and bidirectional direct current series-parallel equipment.
Background
Energy and environmental problems have become two of the most important issues facing mankind at the present stage. The green and efficient utilization of energy has become the key point of research and application in various countries. The traditional isolated bidirectional direct current conversion topology can not realize soft switching in a wide voltage range, so that the implementation of series-parallel connection of two bidirectional direct current conversion networks by using a relay on the battery side of the bidirectional direct current conversion topology is a better method. However, the relays are not switched at the same time absolutely due to the batch, specification, etc. of the relays. Therefore, in the process of implementing series-parallel connection, devices are easy to burn out due to direct current converter direct connection caused by relay adhesion.
Disclosure of Invention
The invention aims to solve the technical problems of the prior art and provides a bidirectional direct current series-parallel relay control device and bidirectional direct current series-parallel equipment, which can ensure that the series-parallel switching of two bidirectional direct current conversion networks is more reliable and safer.
The technical scheme adopted for solving the technical problems is as follows: constructing a control device of a bidirectional direct current series-parallel relay, which is applied to bidirectional direct current series-parallel equipment; the bidirectional direct current series-parallel connection equipment comprises a first bidirectional direct current power supply network, a second bidirectional direct current power supply network, a first relay, a second relay, a first relay driving circuit and a second relay driving circuit; the first relay and the second relay are respectively connected with the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the first relay driving circuit and the second relay driving circuit respectively drive the first relay and the second relay to be turned off or on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series or in parallel; the bidirectional DC series-parallel relay control device comprises: an output voltage sampling circuit for sampling a total output voltage of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the low-voltage side sampling circuit is used for sampling the single-network output voltage of the second bidirectional direct current power supply network; the DSP controller is used for judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage and generating a first relay control signal, a second relay control signal and an auxiliary power supply control signal based on a charging and discharging mode, a set voltage value and the total output voltage; an auxiliary power supply for charging output capacitances of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the auxiliary power supply control signal; the first relay driving circuit drives the first relay to be turned off or turned on based on the first relay control signal, and the second relay driving circuit drives the second relay to be turned off or turned on based on the second relay control signal.
In the bidirectional direct current series-parallel relay control device, the DSP controller is used for generating a first turn-off signal and a second turn-off signal after starting; the first relay and the second relay are turned off based on the first turn-off signal and the second turn-off signal, respectively, to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series; the DSP controller is further used for generating a charging signal after starting, and the auxiliary power supply charges output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the charging signal; the DSP controller is further used for judging whether the ratio of the total output voltage to the single-network output voltage is out of a first set range or not when the first relay and the second relay are turned off so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, and generating a fault signal indicating that relay adhesion occurs if the ratio of the total output voltage to the single-network output voltage is out of the first set range.
In the bidirectional direct current series-parallel relay control device, the DSP controller is further used for judging whether the set voltage value is larger than a preset value or not in a charging mode, if so, the first turn-off signal and the second turn-off signal are maintained to be output, otherwise, a first turn-on signal, a second turn-on signal and a charging stop signal are output; the auxiliary power supply stops charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the stop charging signal; the first relay and the second relay are respectively conducted based on the first conduction signal and the second conduction signal so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, wherein the second conduction signal is delayed by a set time than the first conduction signal.
In the bidirectional direct current series-parallel relay control device, the DSP controller is further used for judging whether the total output voltage is larger than a preset value or not in a discharging mode, if so, the first turn-off signal and the second turn-off signal are maintained to be output, otherwise, a first turn-on signal, a second turn-on signal and a charging stop signal are output; the auxiliary power supply stops charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the stop charging signal; the first relay and the second relay are respectively conducted based on the first conduction signal and the second conduction signal so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, wherein the second conduction signal is delayed by a set time than the first conduction signal.
In the bidirectional direct current series-parallel relay control device of the present invention, the DSP controller is further configured to determine whether a ratio of the total output voltage to the single-network output voltage is outside a second set range when the first relay and the second relay are turned on to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, and if so, generate a fault signal indicating that relay adhesion occurs.
In the bidirectional direct current series-parallel relay control device, the first setting range is 0.45-0.55, the second setting range is 0.95-1.05, and the preset value is larger than 500V.
The invention solves the technical problem by adopting another technical scheme that a control method of the bidirectional direct current series-parallel relay is constructed and is applied to bidirectional direct current series-parallel equipment; the bidirectional direct current series-parallel connection equipment comprises a first bidirectional direct current power supply network, a second bidirectional direct current power supply network, a first relay, a second relay, a first relay driving circuit and a second relay driving circuit; the first relay and the second relay are respectively connected with the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the first relay driving circuit and the second relay driving circuit respectively drive the first relay and the second relay to be turned off or on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series or in parallel; the control method of the bidirectional direct current series-parallel relay comprises the following steps: controlling the first relay and the second relay to turn off after starting so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series; controlling an auxiliary power supply to charge output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; sampling a total output voltage of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network and a single-network output voltage of the second bidirectional direct current power supply network; judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage; and controlling the charging operation of the auxiliary power supply and the turning-off and turning-on of the first relay and the second relay based on the charging and discharging mode, the set voltage value and the total output voltage.
In the control method of the bidirectional direct current series-parallel relay of the present invention, the judging whether relay adhesion occurs based on the total output voltage and the single network output voltage includes: when the first relay and the second relay are turned off to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, judging whether the proportion of the total output voltage to the single-network output voltage is out of a first set range, and if so, generating a fault signal for indicating relay adhesion; when the first relay and the second relay are conducted so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, judging whether the proportion of the total output voltage to the single-network output voltage is out of a second set range, and if so, generating a fault signal for indicating relay adhesion; the first setting range is 0.45-0.55, and the second setting range is 0.95-1.05.
In the bidirectional dc series-parallel relay control method of the present invention, the controlling the charging operation of the auxiliary power supply and the turning-off and turning-on of the first relay and the second relay based on the charge-discharge mode, the set voltage value, and the total output voltage includes: in a charging mode, judging whether the set voltage value is larger than a preset value or not; if so, judging a series mode, controlling the first relay and the second relay to be turned off so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, otherwise, judging a parallel mode, controlling the auxiliary power supply to stop charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network, and controlling the first relay and the second relay to be turned on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel; in a discharging mode, judging whether the total output voltage is larger than a preset value, if yes, judging a serial mode, controlling the first relay and the second relay to be turned off so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, otherwise judging a parallel mode, controlling the auxiliary power supply to stop charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network, and controlling the first relay and the second relay to be turned on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel; wherein the on-time of the second relay is delayed from the on-time of the first relay by a set time.
The invention solves the technical problem by adopting another technical scheme that a bidirectional direct current series-parallel connection system is constructed, and comprises bidirectional direct current series-parallel connection equipment and a bidirectional direct current series-parallel connection relay control device;
the bidirectional direct current series-parallel connection equipment comprises a first bidirectional direct current power supply network, a second bidirectional direct current power supply network, a first relay, a second relay, a first relay driving circuit and a second relay driving circuit; the first relay and the second relay are respectively connected with the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the first relay driving circuit and the second relay driving circuit respectively drive the first relay and the second relay to be turned off or on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series or in parallel;
the bidirectional direct current series-parallel relay control device comprises an output voltage sampling circuit, a low-voltage side sampling circuit, a DSP controller and an auxiliary power supply; the output voltage sampling circuit is used for sampling the total output voltage of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the low-voltage side sampling circuit is used for sampling the single-network output voltage of the second bidirectional direct current power supply network; the DSP controller is used for judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage, and generating a first relay control signal, a second relay control signal and an auxiliary power supply control signal based on a charging and discharging mode, a set voltage value and the total output voltage; the auxiliary power supply is used for charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the auxiliary power supply control signal;
The first relay driving circuit drives the first relay to be turned off or turned on based on the first relay control signal, and the second relay driving circuit drives the second relay to be turned off or turned on based on the second relay control signal.
In the invention, the control signal of the relay is sent by the DSP controller, and the switching sequence is adjusted according to the switching state, so that the condition that the relay is turned off and the relay is turned on is ensured not to cause the output anode and the output cathode of the bidirectional direct current power supply network to be directly communicated. And the DSP controller can judge whether relay adhesion occurs or not through detecting and judging the output voltage under different serial-parallel connection conditions, so that stable serial-parallel connection switching of the output of the bidirectional direct current converter is realized. Furthermore, by controlling the switching of the relay, the output voltage range is widened.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic block diagram of a bi-directional DC series-parallel relay control device and bi-directional DC series-parallel system of the present invention;
FIG. 2 is a schematic block diagram of a preferred embodiment of the bi-directional DC series-parallel relay control device and bi-directional DC series-parallel system of the present invention;
FIG. 3 is a circuit diagram of a preferred embodiment of the bi-directional DC series-parallel relay control device and bi-directional DC series-parallel system of the present invention;
FIG. 4 is a flow chart of a bi-directional DC series-parallel relay control method of the present invention;
fig. 5 is a flow chart of a preferred embodiment of the bi-directional dc series-parallel relay control method of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The preferred embodiment of the invention relates to a bidirectional direct current series-parallel relay control device which is applied to bidirectional direct current series-parallel equipment. Fig. 1 is a schematic block diagram of a bidirectional dc series-parallel relay control device and a bidirectional dc series-parallel system of the present invention. As shown in fig. 1, the bidirectional direct current series-parallel connection system comprises bidirectional direct current series-parallel connection equipment and a bidirectional direct current series-parallel connection relay control device.
The bidirectional dc series-parallel device includes a bidirectional dc power network 110, a bidirectional dc power network 120, a relay K1, a relay K2, a relay driving circuit 510, and a relay driving circuit 520. The relay K1 and the relay K2 are connected to the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120, respectively. The relay driving circuit 510 and the relay driving circuit 520 respectively drive the relay K1 and the relay K2 to be turned off or on so as to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in series or in parallel.
Here, the bidirectional DC power supply network 110, 120 may be constructed using any bidirectional DC/DC conversion module known in the art. The relay drive 510 and relay drive 520 may be of any suitable switching tube drive configuration. The relay K1 and the relay K2 may be connected in series or in parallel with the bi-directional dc power supply network 110 and the bi-directional dc power supply network 120 by switching off and on the output terminals of the bi-directional dc power supply network 110 and the bi-directional dc power supply network 120, respectively, in any suitable manner. The relays K1 and K2 are commonly used alternating current relays.
The bidirectional dc series-parallel relay control device includes an output voltage sampling circuit 210, a low voltage side sampling circuit 220, a DSP controller 300, and an auxiliary power supply 400. The output voltage sampling circuit 210 is configured to sample the total output voltage of the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120. The low side sampling circuit 220 is configured to sample a single-network output voltage of the bi-directional dc power supply network 120. The DSP controller 300 is configured to determine whether relay adhesion occurs based on the total output voltage and the single-network output voltage, and generate a first relay control signal, a second relay control signal, and an auxiliary power control signal based on a charge-discharge mode, a set voltage value, and the total output voltage. The relay driving circuit 510 drives the relay K1 to be turned off or on based on the first relay control signal, and the relay driving circuit 520 drives the relay K2 to be turned off or on based on the second relay control signal. Here, the first relay control signal may include a first shutdown signal and a second shutdown signal, respectively, and the relay K1 and the relay K2 may be turned off based on the first shutdown signal and the second shutdown signal, respectively, to thereby connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in series. The second relay control signal may include a first conduction signal and a second conduction signal, respectively, and the relay K1 and the relay K2 are turned on based on the first conduction signal and the second conduction signal, respectively, so as to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in parallel. The auxiliary power control signal may include a charge signal and a stop charge signal. The auxiliary power supply 400 charges the output capacitances of the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 based on the charging signal, and stops charging the output capacitances of the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 based on the stop charging signal.
The output voltage sampling circuit 210 and the low-side sampling circuit 220 may employ any sampling resistor and voltage acquisition device known in the art, which fall within the scope of the present invention. The auxiliary power supply 400 may be any suitable power supply module that may be accessed using a relay or switching device and connected in series with a diode to prevent current flow back.
The DSP controller 300 may be constructed using any suitable software, hardware, or combination thereof, so long as it is capable of performing the aforementioned functions. For example, the DSP controller 300 may load a computer program, and determine whether relay adhesion occurs based on the total output voltage and the single-network output voltage when the computer program is run, and generate a first relay control signal, a second relay control signal, and an auxiliary power control signal based on a charge-discharge mode, a set voltage value, and the total output voltage.
Therefore, in the present invention, the control signals of the relays K1 and K2 are sent by the DSP controller 300, and the switching sequence is adjusted according to the switched state, so that it is ensured that there is no state where the relay K1 is turned off and the relay K2 is turned on, so that the output positive pole and the output negative pole of the bidirectional dc power supply network 120 are directly connected. And the DSP controller 300 can determine whether relay adhesion occurs by detecting and determining output voltages under different serial-parallel conditions, thereby realizing stable serial-parallel switching of the output of the bidirectional dc converter. Furthermore, by controlling the switching of the relays K1, K2, the output voltage range is widened.
Fig. 2 is a schematic block diagram of a preferred embodiment of the bi-directional dc-series-parallel relay control device and bi-directional dc-series-parallel system of the present invention. As shown in fig. 2, the bidirectional direct current series-parallel connection system comprises bidirectional direct current series-parallel connection equipment and a bidirectional direct current series-parallel connection relay control device.
The bidirectional dc series-parallel device includes a bidirectional dc power network 110, a bidirectional dc power network 120, a relay K1, a relay K2, a relay driving circuit 510, and a relay driving circuit 520. The relay K1 and the relay K2 are connected to the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120, respectively. The relay driving circuit 510 and the relay driving circuit 520 respectively drive the relay K1 and the relay K2 to be turned off or on so as to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in series or in parallel. The bidirectional dc series-parallel relay control device includes an output voltage sampling circuit 210, a low voltage side sampling circuit 220, a DSP controller 300, and an auxiliary power supply 400. The output voltage sampling circuit 210 is configured to sample the total output voltage of the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120. The low side sampling circuit 220 is configured to sample a single-network output voltage of the bi-directional dc power supply network 120.
As shown in fig. 2, the relays K1 and K2 are double pole double throw switch relays, the common pin is 3 pins, the 4 pins are normally closed pins, and the 5 pins are normally open pins. The input ends of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 are respectively connected with the positive pole and the negative pole of the direct current bus, and the output positive pole of the bidirectional direct current power supply network 110 is connected with the 5 pin of the relay K1. The output cathode of the bidirectional DC power supply network 110 is connected with the 5 pin of the relay K2. The output anode of the bidirectional DC power supply network 120 is connected with 3 pins of the relay K1; the output cathode of the bidirectional DC power supply network 120 is connected with 3 pins of the relay K2. The output voltage sampling circuit 210 is connected between the output positive electrode of the bidirectional dc power supply network 110 and the output negative electrode of the bidirectional dc power supply network 120, and samples the total output voltage between the output positive electrode of the bidirectional dc power supply network 110 and the output negative electrode of the bidirectional dc power supply network 120. The low-side voltage sampling circuit 220 is connected between the output positive pole of the bidirectional dc power supply network 120 and the output negative pole of the bidirectional dc power supply network 120 to sample the single-network output voltage between the two ends of the bidirectional dc power supply network 120. The output of the low-side voltage sampling circuit 220 is connected to the DSP controller 300. The output of the output voltage sampling circuit 210 is connected to the DSP controller 300. The auxiliary power supply 400 is connected to the output positive electrode of the bidirectional dc power supply network 110 and the output negative electrode of the bidirectional dc power supply network 120 via a diode. The DSP controller 300 drives the relays K1, K2 through the relay driving circuits 510, 520, respectively.
Further, when the relays K1 and K2 are both closed, the output negative electrode of the bidirectional dc power supply network 110 is connected to the output negative electrode of the bidirectional dc power supply network 120, the output positive electrode of the bidirectional dc power supply network 110 is connected to the output positive electrode of the bidirectional dc power supply network 120, and the connection relationship between the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 is parallel. When the relays K1 and K2 are both turned off, the output positive electrode of the bidirectional dc power supply network 110 is connected to the output negative electrode of the bidirectional dc power supply network 120, and the connection relationship between the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 is serial.
In a preferred embodiment of the present invention, the DSP controller 300 is configured to generate a first shutdown signal and a second shutdown signal after the start-up; the relay K1 and the relay K2 are turned off based on the first turn-off signal and the second turn-off signal, respectively, to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in series. The DSP controller 300 is further configured to generate a charging signal after the start-up, and the auxiliary power supply 400 charges the output capacitors of the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 based on the charging signal.
The DSP controller 300 is further configured to determine whether the ratio of the total output voltage to the single-network output voltage is outside a first set range when the relay K1 and the relay K2 are turned off to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in series, and if so, generate a fault signal indicating that relay adhesion occurs. For example, the low-side voltage sampling circuit 220 detects whether the single-network output voltage outputted by the bidirectional dc power supply network 120 has an approximately half relationship with the total output voltage detected by the output voltage sampling circuit 210, for example, the ratio is between 0.45 and 0.55. If the proportion is not in the range, the relay adhesion is indicated, and the fault is reported.
The DSP controller 300 is further configured to determine, in the charging mode, whether the set voltage value is greater than a preset value, and if so, maintain outputting the first turn-off signal and the second turn-off signal, and otherwise, output a first turn-on signal, a second turn-on signal, and a stop charging signal. The auxiliary power supply 400 stops charging the output capacitances of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 based on the stop charging signal. The relay K1 and the relay K2 are turned on based on the first conduction signal and the second conduction signal, respectively, to thereby connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in parallel, wherein the second conduction signal is delayed by a set time from the first conduction signal.
Specifically, if the set voltage value is greater than 500V in the charging mode, the bidirectional dc power supply network 110, 120 should be set to the series mode, and the relays K1 and K2 are not operated. If the set voltage is less than 500V, the bi-directional dc power network 110 and 120 should be set in parallel mode, and the relays K1 and K2 need to be switched. If the relays K1 and K2 need to be switched, the auxiliary power supply 400 is turned off, the relay K1 is turned on first, and the relay K2 is turned on after a delay of 20 ms.
The DSP controller 300 is further configured to determine, in a discharging mode, whether the total output voltage is greater than a preset value, and if so, maintain outputting the first turn-off signal and the second turn-off signal, otherwise, output a first turn-on signal, a second turn-on signal, and a stop charging signal; the auxiliary power supply 400 stops charging the output capacitances of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 based on the stop charging signal. The relay K1 and the relay K2 are turned on based on the first conduction signal and the second conduction signal, respectively, to thereby connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in parallel, wherein the second conduction signal is delayed by a set time from the first conduction signal.
Specifically, if in the discharge mode, it is determined whether the total output voltage detected by the output voltage sampling circuit 210 is greater than 500V. If the total output voltage is greater than 500V, then the bi-directional dc power network 110, 120 should be set to series mode, where relays K1 and K2 are not active. If the total output voltage is less than 500V, the bi-directional dc power network 110, 120 should be set to the parallel mode, where relays K1 and K2 need to be switched. If the relays K1 and K2 need to be switched, the auxiliary power supply 400 is turned off, the relay K1 is turned on first, and the relay K2 is turned on after a delay of 20 ms.
The DSP controller 300 is further configured to determine whether the ratio of the total output voltage to the single-network output voltage is outside a second set range when the relay K1 and the relay K2 are turned on to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in parallel, and if so, generate a fault signal indicating that relay adhesion occurs.
For example, the low-side voltage sampling circuit 220 detects whether the single-network output voltage outputted by the bidirectional dc power supply network 120 and the total output voltage detected by the output voltage sampling circuit 210 are in an approximately equal relationship, for example, the ratio is between 0.95 and 1.05, and if not, a fault is reported.
In a preferred embodiment of the present invention, the bi-directional DC power supply network 110 and the bi-directional DC power supply network 120 may be CLLLC circuits, bi-directional active bridge circuits. The output voltage sampling circuit 210 and the low side voltage sampling circuit 220 may employ simple resistor divider sampling circuits. The auxiliary power supply 400 may have a high output impedance, with its anode connected to the cathode of the diode and connected to the output anode of the bi-directional dc power supply network 110 through the diode. For example, the output of the auxiliary power supply 400 may be connected in series with a 1000 ohm resistor to increase its output impedance, followed by a relay to control whether the auxiliary power supply is connected to a bi-directional dc power supply network, followed by a diode to prevent current flow back.
In the bidirectional direct current series-parallel relay control device, the control signals of the relays K1 and K2 are sent by the DSP controller, and the switching sequence is adjusted according to the switching state, so that the condition that the relay K1 is turned off and the relay K2 is turned on is ensured to enable the output anode and the output cathode of the bidirectional direct current power supply network 120 to be directly communicated. When the connection relationship between the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 is switched from parallel connection to series connection, the DSP controller firstly sends out a control signal to turn off the relay K2, and after a short delay (e.g., 20 ms), then sends out a control signal to turn off the relay K1. When the connection relationship between the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 is switched from serial connection to parallel connection, the DSP controller firstly sends out a control signal to turn on the relay K1, and after a short delay (for example, 20 ms), then sends out a control signal to turn on the relay K2; after the DSP controller is started, the two relays K1 and K2 are kept in an off state, namely in a series state; the auxiliary power supply is then controlled to charge the output capacitance of the bi-directional dc power supply network 110 and V2, and is sampled by the low voltage sampling circuit 220 and the output voltage sampling circuit 210 and passed to the DSP controller.
Therefore, the bidirectional direct current series-parallel relay control device realizes stable series-parallel switching of the output of the bidirectional direct current converter; the delay is prolonged by detecting and judging the output voltage under different serial-parallel connection conditions, so that the system is stable or whether the system has faults is judged; by controlling the switching of the relays K1, K2, the output voltage range is widened.
Fig. 3 is a circuit diagram of a preferred embodiment of the bi-directional dc-series-parallel relay control device and bi-directional dc-series-parallel system of the present invention. As shown in fig. 3, the bidirectional direct current series-parallel connection system comprises bidirectional direct current series-parallel connection equipment and a bidirectional direct current series-parallel connection relay control device.
The bidirectional dc series-parallel device includes a bidirectional dc power network 110, a bidirectional dc power network 120, a relay K1, a relay K2, a relay driving circuit 510, and a relay driving circuit 520. The relay K1 and the relay K2 are connected to the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120, respectively. The relay driving circuit 510 and the relay driving circuit 520 respectively drive the relay K1 and the relay K2 to be turned off or on so as to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in series or in parallel. The bidirectional dc series-parallel relay control device includes an output voltage sampling circuit 210, a low voltage side sampling circuit 220, a DSP controller 300, and an auxiliary power supply 400. The output voltage sampling circuit 210 is configured to sample the total output voltage of the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120. The low side sampling circuit 220 is configured to sample a single-network output voltage of the bi-directional dc power supply network 120.
As shown in fig. 2, the relays K1 and K2 are double pole double throw switch relays, the common pin is 3 pins, the 4 pins are normally closed pins, and the 5 pins are normally open pins. The input ends of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 are respectively connected with the positive pole and the negative pole of the direct current bus, and the output positive pole of the bidirectional direct current power supply network 110 is connected with the 5 pin of the relay K1. The output cathode of the bidirectional DC power supply network 110 is connected with the 5 pin of the relay K2. The output anode of the bidirectional DC power supply network 120 is connected with 3 pins of the relay K1; the output cathode of the bidirectional DC power supply network 120 is connected with 3 pins of the relay K2. The output voltage sampling circuit 210 is connected between the output positive electrode of the bidirectional dc power supply network 110 and the output negative electrode of the bidirectional dc power supply network 120, and samples the total output voltage between the output positive electrode of the bidirectional dc power supply network 110 and the output negative electrode of the bidirectional dc power supply network 120. The low-side voltage sampling circuit 220 is connected between the output positive pole of the bidirectional dc power supply network 120 and the output negative pole of the bidirectional dc power supply network 120 to sample the single-network output voltage between the two ends of the bidirectional dc power supply network 120. The output of the low-side voltage sampling circuit 220 is connected to the DSP controller 300. The output of the output voltage sampling circuit 210 is connected to the DSP controller 300. The auxiliary power supply 400 is connected to the output positive electrode of the bidirectional dc power supply network 110 and the output negative electrode of the bidirectional dc power supply network 120 via a diode. The DSP controller 300 drives the relays K1, K2 through the relay driving circuits 510, 520, respectively;
As further shown in fig. 3, the bidirectional dc power supply network 110 includes a transformer T1, a primary side switching tube network formed by switching tubes Q1-Q4 disposed on the primary side of the transformer T1, a resonant network formed by an inductor L1 and a capacitor C4, and an input capacitor C3, and a secondary side switching tube network formed by switching tubes Q5-Q8 disposed on the first secondary side of the transformer T1, a resonant network formed by an inductor L2 and a capacitor C5, and an output capacitor C1. The bidirectional dc power supply network 120 also includes a transformer T1, a primary switching tube network formed by switching tubes Q1-Q4 disposed on a primary side of the transformer T1, a resonant network formed by an inductor L1 and a capacitor C4, and an input capacitor C3, and a secondary switching tube network formed by switching tubes Q9-Q12 disposed on a second secondary side of the transformer T1, a resonant network formed by an inductor L3 and a capacitor C6, and an output capacitor C2.
The output voltage sampling circuit 210 includes resistors R1-R4 and an operational amplifier U1. The low side sampling circuit 220 includes resistors R5-R8 and an op-amp U2. The first end of the op-amp U1 is connected to the output positive electrode of the bidirectional dc power network 110, i.e. the drains of the switching transistors Q5 and Q6, through a resistor R1, and the first end of the op-amp U1 is grounded through a resistor R3. The second end of the operational amplifier U1 is connected with the second end of the operational amplifier U2 through resistors R2 and R6. The resistor R4 is connected between the second end and the output end of the op-amp U1, and the output end of the op-amp U1 is connected with the DSP controller 300. The first end of the operational amplifier U2 is connected to the output positive electrode of the bidirectional dc power network 120, i.e. the drains of the switching transistors Q9 and Q10, through a resistor R5, and the first end of the operational amplifier U2 is grounded through a resistor R7. The resistor R8 is connected between the second end and the output end of the op-amp U2, and the output end of the op-amp U2 is connected with the DSP controller 300. The DSP controller 300 outputs a control signal GPI101 to control the relay control circuit 510, and outputs a control signal GPI102 to control the relay control circuit 520, thereby controlling the relays K1 and K2.
The auxiliary power supply 400 includes a transformer T2, a switching tube Q13 and an input capacitor C6 located on the primary side of the transformer T2, and a diode D1, an output capacitor C7 and a resistor R9 located on the secondary side of the transformer T2. The anode of the diode is connected with one end of the secondary side of the transformer T2, the cathode is connected with the capacitor C1 through the resistor R9, and the other end of the secondary side of the transformer T2 is connected with the capacitor C2, so that the capacitors C1 and C2 are charged when needed.
In the bidirectional direct current series-parallel relay control device, the control signals of the relays K1 and K2 are sent by the DSP controller, and the switching sequence is adjusted according to the switching state, so that the condition that the relay K1 is turned off and the relay K2 is turned on is ensured to enable the output anode and the output cathode of the bidirectional direct current power supply network 120 to be directly communicated. When the connection relationship between the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 is switched from parallel connection to series connection, the DSP controller firstly sends out a control signal to turn off the relay K2, and after a short delay (e.g., 20 ms), then sends out a control signal to turn off the relay K1. When the connection relationship between the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 is switched from serial connection to parallel connection, the DSP controller firstly sends out a control signal to turn on the relay K1, and after a short delay (for example, 20 ms), then sends out a control signal to turn on the relay K2; after the DSP controller is started, the two relays K1 and K2 are kept in an off state, namely in a series state; the auxiliary power supply is then controlled to charge the output capacitance of the bi-directional dc power supply network 110 and V2, and is sampled by the low voltage sampling circuit 220 and the output voltage sampling circuit 210 and passed to the DSP controller. The circuit shown in fig. 3 can be used for accurately and precisely sampling related parameters, so that finer and more accurate control is performed, and the connection relation of the relay can make the relay more difficult to adhere.
The invention also discloses a control method of the bidirectional direct current series-parallel relay, which is suitable for the bidirectional direct current series-parallel equipment shown in figures 1-3. Fig. 4 is a flow chart of a control method of the bidirectional direct current series-parallel relay of the present invention.
As shown in fig. 1-3, the bidirectional dc series-parallel device includes a bidirectional dc power supply network 110, a bidirectional dc power supply network 120, a relay K1, a relay K2, a relay driving circuit 510, and a relay driving circuit 520; the relay K1 and the relay K2 are respectively connected to the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120; the relay driving circuit 510 and the relay driving circuit 520 respectively drive the relay K1 and the relay K2 to be turned off or on so as to connect the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 in series or in parallel.
As shown in fig. 4, the control method of the bidirectional direct current series-parallel relay includes: controlling the relay K1 and the relay K2 to be turned off after starting so as to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in series; controlling the auxiliary power supply 400 to charge the output capacitors of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120; sampling the total output voltage of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 and the single-network output voltage of the bidirectional direct current power supply network 120; judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage; the charging operation of the auxiliary power supply 400 and the turning off and on of the relays K1 and K2 are controlled based on the charge-discharge mode, the set voltage value, and the total output voltage.
Preferably, the determining whether relay adhesion occurs based on the total output voltage and the single-network output voltage includes: when the relay K1 and the relay K2 are turned off to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in series, judging whether the ratio of the total output voltage to the single-network output voltage is out of a first set range, and if so, generating a fault signal indicating that relay adhesion occurs; and/or when the relay K1 and the relay K2 are turned on to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in parallel, judging whether the ratio of the total output voltage to the single-network output voltage is out of a second set range, and if so, generating a fault signal indicating that relay adhesion occurs; the first setting range is 0.45-0.55, and the second setting range is 0.95-1.05.
Preferably, the controlling the charging operation of the auxiliary power supply 400 and the turning off and on of the relays K1 and K2 based on the charge-discharge mode, the set voltage value, and the total output voltage includes: in a charging mode, judging whether the set voltage value is larger than a preset value or not; if yes, judging a series mode, controlling the relay K1 and the relay K2 to be turned off so as to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in series, otherwise judging a parallel mode, controlling the auxiliary power supply 400 to stop charging output capacitors of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120, and controlling the relay K1 and the relay K2 to be turned on so as to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in parallel; and/or in the discharging mode, determining whether the total output voltage is greater than a preset value, if yes, determining that a series mode is performed, controlling the relay K1 and the relay K2 to be turned off so as to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in series, otherwise determining that a parallel mode is performed, controlling the auxiliary power supply 400 to stop charging output capacitors of the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120, and controlling the relay K1 and the relay K2 to be turned on so as to connect the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 in parallel; wherein the on-time of the relay K2 is delayed by a set time from the on-time of the relay K1.
The bidirectional dc-dc series-parallel relay control method can be implemented by the bidirectional dc-series-parallel relay control device shown in fig. 1 to 3, and will not be described here again.
Fig. 5 is a flow chart of a preferred embodiment of the bi-directional dc series-parallel relay control method of the present invention. As shown in fig. 5, after the DSP controller is started, the two relays K1 and K2 are maintained in an off state, i.e., in a series state. And then controlling the auxiliary power supply to charge the output capacitors of the bidirectional direct current power supply network 110 and the output capacitor of the V2, and judging whether the single-network output voltage of the bidirectional direct current power supply network 120 detected by the low-side voltage sampling circuit and the total output voltage detected by the output voltage sampling circuit are in approximately half relation, for example, the ratio is between 0.45 and 0.55. If the proportion is not in the range, the relay adhesion is indicated, and the fault is reported. If the set voltage value is greater than 500V in the charging mode, the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 should be set to the series mode, and the relays K1 and K2 are not operated. If the set voltage is less than 500V, the bi-directional dc power network 110 and 120 should be set in parallel mode, and the relays K1 and K2 need to be switched. If the relays K1 and K2 need to be switched, the auxiliary power supply 400 is turned off, the relay K1 is turned on first, and the relay K2 is turned on after a delay of 20 ms. If in the discharge mode, it is determined whether the total output voltage detected by the output voltage sampling circuit 210 is greater than 500V. If the total output voltage is greater than 500V, then the bi-directional dc power network 110, 120 should be set to series mode, where relays K1 and K2 are not active. If the total output voltage is less than 500V, the bi-directional dc power network 110, 120 should be set to the parallel mode, where relays K1 and K2 need to be switched. If the relays K1 and K2 need to be switched, the auxiliary power supply 400 is turned off, the relay K1 is turned on first, and the relay K2 is turned on after a delay of 20 ms. If the single-network output voltage outputted from the bidirectional dc power supply network 120 is detected by the low-side voltage sampling circuit 220 and the total output voltage detected by the output voltage sampling circuit 210 are in an approximately equal relationship, for example, the ratio is between 0.95 and 1.05, if not, a fault is reported.
In the control method of the bidirectional direct current series-parallel relay, the control signals of the relays K1 and K2 are sent by the DSP controller, and the switching sequence is adjusted according to the switching state, so that the condition that the relay K1 is turned off and the relay K2 is turned on is ensured to enable the output anode and the output cathode of the bidirectional direct current power supply network 120 to be directly communicated. When the connection relationship between the bidirectional dc power supply network 110 and the bidirectional dc power supply network 120 is switched from parallel connection to series connection, the DSP controller firstly sends out a control signal to turn off the relay K2, and after a short delay (e.g., 20 ms), then sends out a control signal to turn off the relay K1. When the connection relationship between the bidirectional direct current power supply network 110 and the bidirectional direct current power supply network 120 is switched from serial connection to parallel connection, the DSP controller firstly sends out a control signal to turn on the relay K1, and after a short delay (for example, 20 ms), then sends out a control signal to turn on the relay K2; after the DSP controller is started, the two relays K1 and K2 are kept in an off state, namely in a series state; the auxiliary power supply is then controlled to charge the output capacitance of the bi-directional dc power supply network 110 and V2, and is sampled by the low voltage sampling circuit 220 and the output voltage sampling circuit 210 and passed to the DSP controller. Therefore, the control method of the bidirectional direct current series-parallel relay realizes stable series-parallel switching of the output of the bidirectional direct current converter; the delay is prolonged by detecting and judging the output voltage under different serial-parallel connection conditions, so that the system is stable or whether the system has faults is judged; by controlling the switching of the relays K1, K2, the output voltage range is widened.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. A control device of a bidirectional direct current series-parallel relay is applied to bidirectional direct current series-parallel equipment; the bidirectional direct current series-parallel connection equipment comprises a first bidirectional direct current power supply network, a second bidirectional direct current power supply network, a first relay, a second relay, a first relay driving circuit and a second relay driving circuit; the first relay and the second relay are respectively connected with the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the first relay driving circuit and the second relay driving circuit respectively drive the first relay and the second relay to be turned off or on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series or in parallel; it is characterized in that the method comprises the steps of,
The bidirectional DC series-parallel relay control device comprises:
an output voltage sampling circuit for sampling a total output voltage of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network;
the low-voltage side sampling circuit is used for sampling the single-network output voltage of the second bidirectional direct current power supply network;
the DSP controller is used for judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage and generating a first relay control signal, a second relay control signal and an auxiliary power supply control signal based on a charging and discharging mode, a set voltage value and the total output voltage;
an auxiliary power supply for charging output capacitances of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the auxiliary power supply control signal;
the first relay driving circuit drives the first relay to be turned off or turned on based on the first relay control signal, and the second relay driving circuit drives the second relay to be turned off or turned on based on the second relay control signal.
2. The bi-directional dc series-parallel relay control device of claim 1, wherein the DSP controller is configured to generate a first shutdown signal and a second shutdown signal after start-up; the first relay and the second relay are turned off based on the first turn-off signal and the second turn-off signal, respectively, to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series;
The DSP controller is further used for generating a charging signal after starting, and the auxiliary power supply charges output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the charging signal;
the DSP controller is further used for judging whether the ratio of the total output voltage to the single-network output voltage is out of a first set range or not when the first relay and the second relay are turned off so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, and generating a fault signal indicating that relay adhesion occurs if the ratio of the total output voltage to the single-network output voltage is out of the first set range.
3. The bi-directional dc series-parallel relay control device of claim 2, wherein the DSP controller is further configured to determine, in a charging mode, whether the set voltage value is greater than a preset value, and if so, maintain outputting the first off signal and the second off signal, and otherwise output a first on signal, a second on signal, and a stop charging signal;
the auxiliary power supply stops charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the stop charging signal;
The first relay and the second relay are respectively conducted based on the first conduction signal and the second conduction signal so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, wherein the second conduction signal is delayed by a set time than the first conduction signal.
4. A bi-directional dc series-parallel relay control unit according to claim 2 or 3, wherein the DSP controller is further configured to determine, in a discharging mode, whether the total output voltage is greater than a preset value, and if so, maintain outputting the first turn-off signal and the second turn-off signal, and otherwise output a first turn-on signal, a second turn-on signal, and a stop charging signal;
the auxiliary power supply stops charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the stop charging signal;
the first relay and the second relay are respectively conducted based on the first conduction signal and the second conduction signal so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, wherein the second conduction signal is delayed by a set time than the first conduction signal.
5. The bi-directional dc series-parallel relay control device of claim 4, wherein the DSP controller is further configured to determine whether a ratio of the total output voltage to the single-network output voltage is outside a second set range when the first relay and the second relay are turned on to connect the first bi-directional dc power network and the second bi-directional dc power network in parallel, and if so, generate a fault signal indicating that relay sticking occurs.
6. The bi-directional dc series-parallel relay control device according to claim 5, wherein the first setting range is 0.45 to 0.55, the second setting range is 0.95 to 1.05, and the preset value is greater than 500V.
7. A control method of a bidirectional direct current series-parallel relay is applied to bidirectional direct current series-parallel equipment; the bidirectional direct current series-parallel connection equipment comprises a first bidirectional direct current power supply network, a second bidirectional direct current power supply network, a first relay, a second relay, a first relay driving circuit and a second relay driving circuit; the first relay and the second relay are respectively connected with the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the first relay driving circuit and the second relay driving circuit respectively drive the first relay and the second relay to be turned off or on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series or in parallel; the control method is characterized by comprising the following steps of:
Controlling the first relay and the second relay to turn off after starting so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series;
controlling an auxiliary power supply to charge output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network;
sampling a total output voltage of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network and a single-network output voltage of the second bidirectional direct current power supply network;
judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage;
and controlling the charging operation of the auxiliary power supply and the turning-off and turning-on of the first relay and the second relay based on the charging and discharging mode, the set voltage value and the total output voltage.
8. The method of claim 7, wherein the determining whether relay blocking occurs based on the total output voltage and the single-network output voltage comprises:
when the first relay and the second relay are turned off to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, judging whether the proportion of the total output voltage to the single-network output voltage is out of a first set range, and if so, generating a fault signal for indicating relay adhesion;
When the first relay and the second relay are conducted so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel, judging whether the proportion of the total output voltage to the single-network output voltage is out of a second set range, and if so, generating a fault signal for indicating relay adhesion;
the first setting range is 0.45-0.55, and the second setting range is 0.95-1.05.
9. The bi-directional dc series-parallel relay control method according to claim 7, wherein the controlling the charging operation of the auxiliary power supply and the turning-off and turning-on of the first relay and the second relay based on the charge-discharge mode, the set voltage value, and the total output voltage includes:
in a charging mode, judging whether the set voltage value is larger than a preset value or not; if so, judging a series mode, controlling the first relay and the second relay to be turned off so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, otherwise, judging a parallel mode, controlling the auxiliary power supply to stop charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network, and controlling the first relay and the second relay to be turned on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel;
In a discharging mode, judging whether the total output voltage is larger than a preset value, if yes, judging a serial mode, controlling the first relay and the second relay to be turned off so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series, otherwise judging a parallel mode, controlling the auxiliary power supply to stop charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network, and controlling the first relay and the second relay to be turned on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in parallel;
wherein the on-time of the second relay is delayed from the on-time of the first relay by a set time.
10. The bidirectional direct current series-parallel connection system is characterized by comprising bidirectional direct current series-parallel connection equipment and a bidirectional direct current series-parallel connection relay control device;
the bidirectional direct current series-parallel connection equipment comprises a first bidirectional direct current power supply network, a second bidirectional direct current power supply network, a first relay, a second relay, a first relay driving circuit and a second relay driving circuit; the first relay and the second relay are respectively connected with the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the first relay driving circuit and the second relay driving circuit respectively drive the first relay and the second relay to be turned off or on so as to connect the first bidirectional direct current power supply network and the second bidirectional direct current power supply network in series or in parallel;
The bidirectional direct current series-parallel relay control device comprises an output voltage sampling circuit, a low-voltage side sampling circuit, a DSP controller and an auxiliary power supply; the output voltage sampling circuit is used for sampling the total output voltage of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network; the low-voltage side sampling circuit is used for sampling the single-network output voltage of the second bidirectional direct current power supply network; the DSP controller is used for judging whether relay adhesion occurs or not based on the total output voltage and the single-network output voltage, and generating a first relay control signal, a second relay control signal and an auxiliary power supply control signal based on a charging and discharging mode, a set voltage value and the total output voltage; the auxiliary power supply is used for charging output capacitors of the first bidirectional direct current power supply network and the second bidirectional direct current power supply network based on the auxiliary power supply control signal;
the first relay driving circuit drives the first relay to be turned off or turned on based on the first relay control signal, and the second relay driving circuit drives the second relay to be turned off or turned on based on the second relay control signal.
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