CN-121984145-A - Bidirectional charger circuit and control method

CN121984145ACN 121984145 ACN121984145 ACN 121984145ACN-121984145-A

Abstract

The invention discloses a bidirectional charger circuit and a control method, wherein the circuit comprises a control circuit, a chopper circuit and a full-bridge LLC resonant conversion circuit, the chopper circuit is connected with the full-bridge LLC resonant conversion circuit, the control circuit is used for outputting control signals and controlling the on or off of each control switch in the chopper circuit and the full-bridge LLC resonant conversion circuit, the current direction in the control circuit is detected, when the current flowing from the chopper circuit to the full-bridge LLC resonant conversion circuit is detected, the forward operation is determined, the chopper circuit reduces the input voltage and outputs the input voltage after passing through the full-bridge LLC resonant conversion circuit, when the current flowing from the full-bridge LLC resonant conversion circuit to the chopper circuit is detected, the full-bridge LLC resonant conversion circuit converts the input voltage, the chopper circuit outputs the converted voltage after boosting, the current is switched seamlessly when flowing bidirectionally, the zero voltage is ensured to be opened and the zero voltage is turned off when the current flows unidirectionally, and the loss of the charger rectifying circuit is reduced.

Inventors

GENG ZHIDONG
ZHOU SHUAI
YI TAO
SONG SEN
YANG HAO
BI LANG

Assignees

株洲中车时代电气股份有限公司

Dates

Publication Date: 20260505
Application Date: 20241030

Claims (15)

1. A bidirectional charger circuit is characterized by comprising a control circuit, a chopper circuit and a full-bridge LLC resonant conversion circuit, wherein the chopper circuit is connected with the full-bridge LLC resonant conversion circuit, the control circuit is used for detecting the current direction in the charger circuit, outputting control signals and controlling the on or off of each control switch in the chopper circuit and the full-bridge LLC resonant conversion circuit, the current direction in the control circuit is detected, when the current is detected to flow from the chopper circuit to the full-bridge LLC resonant conversion circuit, the forward operation is determined, the chopper circuit reduces the input voltage, the full-bridge LLC resonant conversion circuit outputs the input voltage, when the current is detected to flow from the full-bridge LLC resonant conversion circuit to the chopper circuit, the full-bridge LLC resonant conversion circuit is determined to work reversely, the chopper circuit boosts the converted voltage, and the chopper circuit outputs the converted voltage.
2. The bidirectional charger circuit of claim 1, wherein the chopper circuit comprises a three-level BUCK-BOOST circuit, and the chopper circuit is used as the BUCK circuit in forward operation and used as the BOOST circuit in reverse operation.
3. The bidirectional charger circuit of claim 2, wherein the three-level BUCK-BOOST circuit comprises a switching circuit, a first inductor and a first supporting capacitor, wherein a first output end of the switching circuit is connected to one end of the first inductor, the other end of the first inductor is connected to the first end of the first supporting capacitor and serves as a first output end of the three-level BUCK-BOOST circuit, and a second output end of the switching circuit and a second end of the first supporting capacitor are connected together and serve as a second output end of the three-level BUCK-BOOST circuit.
4. A bi-directional charger circuit as defined in claim 3, wherein the switching circuit comprises a first switching sub-circuit and a second switching sub-circuit connected in series, the first terminal of the first switching sub-circuit and the second terminal of the second switching sub-circuit being respectively used as two input terminals of the switching circuit, the second terminal of the first switching sub-circuit and the first terminal of the second switching sub-circuit being connected together, the third terminal of the first switching sub-circuit and the third terminal of the second switching sub-circuit being respectively used as two output terminals of the switching circuit.
5. A bidirectional charger circuit as recited in claim 1 wherein the full-bridge LLC resonant conversion circuit comprises a full-bridge primary side circuit and a full-bridge secondary side circuit, the full-bridge primary side circuit comprises a first full-bridge circuit, the full-bridge secondary side circuit comprises a second full-bridge circuit, the control circuit controls all control switches in the first full-bridge circuit to be primary switches when detecting forward operation, all control switches in the second full-bridge circuit to be synchronous rectification switches, and controls all control switches in the first full-bridge circuit to be synchronous rectification switches when detecting reverse operation, and all control switches in the second full-bridge circuit to be primary switches.
6. A control method of a bidirectional charger circuit is characterized in that the bidirectional charger circuit according to any one of claims 1-5 is adopted, current flows in from a chopper circuit during forward operation and flows out from a full-bridge secondary side of a full-bridge LLC resonant conversion circuit, the chopper circuit is controlled by the control circuit to be converted into a boost circuit during forward operation and vice versa, a full-bridge primary side control signal of the full-bridge LLC resonant conversion circuit is gradually converted into a full-bridge secondary side control signal during forward operation and a full-bridge secondary side control signal during forward operation is gradually converted into a full-bridge primary side control signal during forward operation, current flows out from the full-bridge secondary side of the full-bridge LLC resonant conversion circuit during reverse operation and flows out from the chopper circuit, the chopper circuit is controlled by the control circuit to be boosted during reverse operation and the full-bridge LLC resonant conversion circuit is controlled by the control circuit to be converted into a buck circuit, and the full-bridge primary side control signal is gradually converted into a full-bridge secondary side control signal during reverse operation and vice versa.
7. The method of claim 6, wherein the first control switch and the fourth control switch connected to the main loop are main switches in the chopper circuit, the second control switch connected to the branch loop is a synchronous rectifier of the first control switch, the third control switch connected to the branch loop is a synchronous rectifier of the fourth control switch, the control circuit outputs control signals, the first control signal of the first control switch is identical to the fourth control signal of the fourth control switch, the phase is 180 degrees different, the first control signal is complementary to the second control signal of the second control switch, and there is a first dead time, the fourth control signal is complementary to the third control signal of the third control switch, and there is a first dead time.
8. The method of claim 6, wherein the first control switch and the fourth control switch connected to the main loop are synchronous rectification switches, the second control switch and the third control switch connected to the branch loop are synchronous rectification switches, the first control switch connected to the main loop is a synchronous rectification switch tube of the second control switch, the fourth control switch connected to the main loop is a synchronous rectification switch tube of the third control switch, the control circuit outputs control signals, the second control signal of the second control switch is identical to the third control signal of the third control switch in duty ratio, the phase difference is 180 degrees, the second control signal is complementary to the first control signal of the first control switch, and there is a second dead time, the third control signal is complementary to the fourth control signal of the fourth control switch, and there is a second dead time.
9. The control method of the bidirectional charger circuit according to claim 6, wherein four control switches in a first full-bridge circuit in the full-bridge LLC resonant conversion circuit are main switching tubes, four control switches in a second full-bridge circuit are synchronous rectification switching tubes, the control circuit outputs control signals to control the fifth control switch and the eighth control switch in the first full-bridge circuit to be simultaneously turned on or turned off, the sixth control switch and the seventh control switch are simultaneously turned on or turned off, the ninth control switch and the twelfth control switch in the second full-bridge circuit are simultaneously turned on or turned off, the fifth control signal of the fifth control switch is identical to the eighth control signal of the eighth control switch in duty ratio, the phase is identical to the phase of the fifth control signal, the sixth control signal of the sixth control switch is complementary to the fifth control signal, a third dead time exists between the fifth control signal and the eighth control signal, the ninth control signal of the ninth control switch is complementary to the eighth control signal, the ninth control signal of the ninth control switch is simultaneously turned on or turned off, the ninth control switch and the twelfth control switch is simultaneously turned on or turned off, the ninth control signal is identical to the phase of the tenth control signal is delayed, the tenth control signal is identical to the phase of the eighth control signal of the eighth control switch, the tenth control signal is turned on, the tenth control signal is identical to the phase of the eighth control signal is turned off, and the eighth control signal is identical to the phase of the eighth control signal is turned on.
10. The control method of the bidirectional charger circuit according to claim 6, wherein when the bidirectional charger circuit works in the reverse direction, four control switches in a second full-bridge circuit in the full-bridge LLC resonant conversion circuit are main switching tubes, four control switches in a first full-bridge circuit are synchronous rectification switching tubes, the control circuit outputs control signals to control the fifth control switch and the eighth control switch in the first full-bridge circuit to be simultaneously turned on or turned off, the sixth control switch and the seventh control switch are simultaneously turned on or turned off, the ninth control switch and the twelfth control switch in the second full-bridge circuit are simultaneously turned on or turned off, the ninth control signal of the ninth control switch is identical to the twelfth control signal of the twelfth control switch in duty ratio, the phase is identical to the ninth control signal, the tenth control signal of the tenth control switch is complementary to the ninth control signal, a third dead time exists between the tenth control signal and the tenth control signal, a third time exists between the eleventh control signal and the eleventh control signal, the fifth control signal of the fifth control switch and the seventh control switch is simultaneously turned on or turned off, the ninth control signal of the ninth control switch and the eighth control switch is simultaneously turned on or turned off, the ninth control signal is identical to the eighth control signal is turned on or off, the eighth control signal is identical to the eighth control signal is phase, the eighth control signal is identical to the eighth control signal is on, and is identical to the eighth control signal is turned off, and the eighth control signal is identical to the eighth on.
11. The method of claim 6, wherein the control circuit controls the main switching tube and the synchronous rectifying tube to switch each other in the chopper circuit when the forward operation is turned into the reverse operation, the control signal of the main switching tube is converted into the control signal of the synchronous rectifying tube, the control signal of the synchronous rectifying tube is converted into the control signal of the main switching tube, the first control switch and the fourth control switch connected to the main circuit are converted into the synchronous rectifying tube by the main switching tube, and the second control switch and the third control switch connected to the circuit are converted into the main switching tube by the synchronous rectifying tube.
12. The method of claim 6, wherein the control circuit controls the control signals of the control switches in the primary side of the full bridge in the full bridge LLC resonant conversion circuit when the full bridge is operated in the forward direction and the reverse direction, the rising edge is gradually delayed until the first time, the falling edge is gradually advanced until the second time, the control signals of the control switches in the secondary side of the full bridge, the rising edge is gradually advanced until the first time, and the falling edge is gradually delayed until the second time.
13. The method of claim 6, wherein the main switching tube and the synchronous rectifying tube are mutually switched in the chopper circuit when the reverse operation is switched to the forward operation, the control circuit controls the control signal of the main switching tube to be switched to the control signal of the synchronous rectifying tube, the control signal of the synchronous rectifying tube is switched to the control signal of the main switching tube, the first control switch and the fourth control switch connected to the main circuit are switched to the main switching tube by the synchronous rectifying tube, and the second control switch and the third control switch connected to the circuit are switched to the synchronous rectifying tube by the main switching tube.
14. The method of claim 6, wherein the control circuit controls the control signals of the control switches in the full-bridge secondary side of the full-bridge LLC resonant conversion circuit when the full-bridge LLC resonant conversion circuit is operated in a reverse direction and a forward direction, the rising edge is gradually delayed until a first time, the falling edge is gradually advanced until a second time, the control signals of the control switches in the full-bridge primary side are gradually advanced until the first time, and the falling edge is gradually delayed until the second time.
15. A bidirectional charger circuit control terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method of any one of claims 6-14 when executing the computer program.

Description

Bidirectional charger circuit and control method Technical Field The invention relates to the technical field of rail transit equipment, in particular to a bidirectional charger circuit and a control method. Background The charger is an essential key component of the rail transit vehicle auxiliary system, provides a stable direct current power supply for a low-voltage direct current load of the rail transit vehicle, and simultaneously charges the storage battery according to the characteristics of the storage battery. The existing charger circuit adopts a single-module full-bridge or half-bridge topological structure or adopts a multi-module serial topological structure, a power device in the single-module full-bridge or half-bridge topological structure needs a switching tube with high voltage level, the high-voltage switching tube is high in loss, the frequency is difficult to improve, the system efficiency is low, the cost is also greatly improved, the multi-module serial topological structure can reduce the power of a single module, the insulation voltage resistance required by the switching tube is still high when the multi-module serial topological structure is used for connecting the multi-module serial, the input end is connected with the half-bridge in series in the multi-module serial topological structure, and the output end is connected with the multi-module serial topological structure in parallel, so that the method is unidirectional charging. The charger with unidirectional charging has high loss of a rectification circuit of the charger, and can not realize bidirectional current flow. Therefore, how to realize the bidirectional current operation of the charger is a problem to be solved at present. Disclosure of Invention The object of the present invention is to solve at least one of the above problems. The invention provides a bidirectional charger circuit and a control method, when detecting that the current directions of the circuits are different, the duty ratio and the time sequence of control signals in the charger circuit are changed in the process of converting the previous working state into the next working state, different control signals are adopted to control a main switching tube and a synchronous rectifying tube of a chopper circuit and a full-bridge LLC resonant conversion circuit to convert, the bidirectional flow of the current in the charging circuit is realized, synchronous rectification is carried out during unidirectional flow, zero voltage on and zero voltage off are ensured, the loss of the rectifier circuit of the charger is reduced, the current directions are detected during bidirectional flow, and the energy bidirectional flow control strategies of the synchronous rectifying tube and the main switching tube are designed to carry out bidirectional flow and seamless fast switching, thereby improving the functions of the charger and expanding the application field. In a first aspect, the present invention provides a bidirectional charger circuit, which is implemented by the following technical scheme: A bidirectional charger circuit comprises a control circuit, a chopper circuit and a full-bridge LLC resonant conversion circuit, wherein the chopper circuit is connected with the full-bridge LLC resonant conversion circuit, the control circuit is used for detecting the current direction in the charger circuit and outputting control signals, each control switch in the chopper circuit and the full-bridge LLC resonant conversion circuit is controlled to be turned on or off, the current direction in the control circuit is detected, when the current flowing from the chopper circuit to the full-bridge LLC resonant conversion circuit is detected, the positive operation is determined, the chopper circuit reduces the input voltage and outputs the voltage after passing through the full-bridge LLC resonant conversion circuit, when the current flowing from the full-bridge LLC resonant conversion circuit to the chopper circuit is detected, the reverse operation is determined, the full-bridge LLC resonant conversion circuit converts the input voltage, the chopper circuit boosts the converted voltage, and the voltage is output from the chopper circuit. The invention is further arranged that the chopper circuit comprises a three-level BUCK-BOOST circuit, which is used as the BUCK circuit when working in the forward direction and used as the BOOST circuit when working in the reverse direction. The three-level BUCK-BOOST circuit comprises a switching circuit, a first inductor and a first supporting capacitor, wherein the first output end of the switching circuit is connected to one end of the first inductor, the other end of the first inductor is connected to the first end of the first supporting capacitor and serves as the first output end of the three-level BUCK-BOOST circuit, and the second output end of the switching circuit and the second end of the first supporting capacitor are co