An isolation voltage reduction circuit for a charging pile

Abstract

The utility model relates to a technical field of automobile charging circuit, concretely relates to an isolation step -down circuit for charging stake, including charging stake, input module, isolation voltage transformation module, output module and auxiliary function module, input module includes fuse, precharge resistance, input inductance, input capacitance, full -bridge inverter and full -bridge driver, and the fuse is connected with charging stake, and precharge resistance is connected with the fuse, and input inductance is connected with the fuse, and is located between the fuse and precharge resistance, and input capacitance is connected with precharge resistance, and full -bridge inverter is connected with input capacitance, and full -bridge driver is connected with full -bridge inverter, and isolation voltage transformation module is connected with full -bridge inverter, and output module is connected with isolation voltage transformation module, and auxiliary function module is connected with output module, solve the problem that the existing isolation full -bridge energy storage voltage regulation scheme exists and the efficiency is low, and the volume is huge and the weight is too heavy.

Description

Technical Field

[0001] This utility model relates to the field of automotive charging circuit technology, and in particular to an isolation step-down circuit for charging piles. Background Technology

[0002] The current mainstream charging pile output range is 250-750V, which is difficult to adapt to the DC fast charging needs of micro electric vehicles such as Wuling Mini and FAW Bestune (the voltage platform of micro vehicles is usually around 115V).

[0003] The first energy storage voltage regulation scheme based on isolated full-bridge topology can achieve voltage regulation, but when applied to such low-voltage, high-power scenarios, it has significant drawbacks such as low efficiency and excessive size and weight.

[0004] Secondly, the non-isolated BukC scheme has the following problems: high voltage direct connection risk, inability to meet national isolation standards, large common-mode interference, and input / output common ground pose a great risk to the vehicle. Utility Model Content

[0005] The purpose of this invention is to provide an isolated step-down circuit for charging piles, which solves the problems of low efficiency, large size and excessive weight of existing isolated full-bridge energy storage voltage regulation schemes.

[0006] To achieve the above objectives, this utility model provides an isolated step-down circuit for charging piles, including a charging pile, an input module, an isolated transformer module, an output module, and an auxiliary function module. The input module includes a fuse, a pre-charge resistor, an input inductor, an input capacitor, a full-bridge inverter, and a full-bridge driver. The fuse is connected to the charging pile, the pre-charge resistor is connected to the fuse, the input inductor is connected to the fuse and located between the fuse and the pre-charge resistor, the input capacitor is connected to the pre-charge resistor, the full-bridge inverter is connected to the input capacitor, the full-bridge driver is connected to the full-bridge inverter, the isolated transformer module is connected to the full-bridge inverter, the output module is connected to the isolated transformer module, and the auxiliary function module is connected to the output module.

[0007] The input module further includes an input-side microcontroller, which is connected to the full-bridge driver.

[0008] The isolation transformer module includes a high-frequency transformer, which is connected to the full-bridge inverter.

[0009] The output module includes an output rectifier, an output inductor, an output capacitor, and an output-side microcontroller. The output rectifier is connected to the high-frequency transformer, the output inductor is connected to the output rectifier, the output capacitor is connected to the output inductor, and the output-side microcontroller is connected to the output capacitor.

[0010] The auxiliary function module includes an input-side CAN and an output-side CAN. One end of the input-side CAN is connected to the charging pile, and the other end of the input-side CAN is connected to the input-side microcontroller. One end of the output-side CAN is connected to the output-side microcontroller, and the other end of the output-side CAN is connected to the output capacitor.

[0011] This utility model provides an isolation step-down circuit for charging piles. By innovatively reconstructing the function of the isolation full-bridge circuit, it enables the circuit to perform only the task of efficient electrical isolation. It also makes full use of the inherent system-level voltage regulation capability of the charging pile, thus completely solving the problems of low efficiency, large size and excessive weight of existing isolation full-bridge energy storage voltage regulation schemes. This achieves high efficiency and miniaturization of DC fast charging for microcars. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0013] Figure 1 This is a schematic diagram of the isolation step-down circuit for charging piles according to the first embodiment of this utility model.

[0014] In the diagram: 101-Charging pile, 102-Fuse, 103-Pre-charge resistor, 104-Input inductor, 105-Input capacitor, 106-Full-bridge inverter, 107-Full-bridge driver, 108-Input-side microcontroller, 109-High-frequency transformer, 110-Output rectifier, 111-Output inductor, 112-Output capacitor, 113-Output-side microcontroller, 114-Input-side CAN, 115-Output-side CAN. Detailed Implementation

[0015] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0016] The first embodiment of this application is as follows: Please see Figure 1 ,in, Figure 1This is a schematic diagram of the principle of an isolated step-down circuit for a charging pile according to the first embodiment of this utility model. This utility model provides an isolated step-down circuit for a charging pile 101, including a charging pile 101, an input module, an isolated transformer module, an output module, and an auxiliary function module. The input module includes a fuse 102, a pre-charge resistor 103, an input inductor 104, an input capacitor 105, a full-bridge inverter 106, a full-bridge driver 107, and an input-side microcontroller 108. The isolated transformer module includes a high-frequency transformer 109. The output module includes an output rectifier 110, an output inductor 111, an output capacitor 112, and an output-side microcontroller 113. The auxiliary function module includes an input-side CAN bus 114 and an output-side CAN bus 115. The aforementioned solution solves the problems of low efficiency, large size, and excessive weight of existing isolated full-bridge energy storage voltage regulation solutions.

[0017] In this specific embodiment, the fuse 102 is connected to the charging pile 101, the pre-charging resistor 103 is connected to the fuse 102, the input inductor 104 is connected to the fuse 102 and located between the fuse 102 and the pre-charging resistor 103, the input capacitor 105 is connected to the pre-charging resistor 103, the full-bridge inverter 106 is connected to the input capacitor 105, the full-bridge driver 107 is connected to the full-bridge inverter 106, the isolation transformer module is connected to the full-bridge inverter 106, the output module is connected to the isolation transformer module, and the auxiliary function module is connected to the output module. The fuse 102 is connected in series in the input circuit for overcurrent protection. When a short circuit or large current occurs in the circuit, the fuse 102 blows, cutting off the circuit to prevent damage to downstream components. The pre-charging resistor 103 works in conjunction with the input capacitor 105 to prevent power-on surges. In the initial power-on phase, the current is slowly supplied to the charging pile 101 through the pre-charging resistor 103. The input capacitor 105 is charged to avoid a large current surge caused by direct capacitor connection. After the capacitor voltage stabilizes, the pre-charge resistor 103 can be short-circuited by a relay (not explicitly shown in the figure but its function is implied) to reduce power consumption. The input inductor 104 and the input capacitor 105 form an EMI filter circuit to suppress electromagnetic interference (EMI), filter out high-frequency noise in the input current, and make the input voltage / current more stable, reducing interference to the power grid and subsequent circuits. The full-bridge inverter 106 is an H-type full-bridge inverter composed of four switching transistors. It converts DC to high-frequency AC. Through the timing of "alternating conduction of diagonal switching transistors", the input DC is inverted into high-frequency AC, providing a suitable input form for the high-frequency transformer 109. The full-bridge driver 107 is used to receive the PWM (pulse width modulation) signal from the input-side microcontroller 108, amplify the drive power, and ensure that the full-bridge switching transistors (K1-K4) can be turned on / off quickly and reliably to achieve precise inverter control.

[0018] The input-side microcontroller 108 is connected to the full-bridge driver 107. The input-side microcontroller 108 acquires parameters such as input voltage and current through a data acquisition circuit; generates PWM signals through an FTM (timer module) to control the timing of the full-bridge driver 107; communicates with the output-side microcontroller 113 through a serial port to coordinate the control logic on both sides; and communicates with the charging pile 101 through the interface of the input-side CAN 114 to receive charging commands and report working status.

[0019] Secondly, the high-frequency transformer 109 is connected to the full-bridge inverter 106. The high-frequency transformer 109 performs two main functions: electrical isolation: it electrically isolates the high-voltage side of the charging pile 101 from the low-voltage side of the vehicle battery to ensure charging safety (avoiding direct access of high voltage to the vehicle); and voltage reduction: through the transformer turns ratio design, it reduces the high-frequency AC voltage to a voltage level suitable for the vehicle battery (e.g., from the high-voltage DC of the charging pile 101 to the low-voltage DC of the battery).

[0020] Furthermore, the output rectifier 110 is connected to the high-frequency transformer 109, the output inductor 111 is connected to the output rectifier 110, the output capacitor 112 is connected to the output inductor 111, and the output-side microcontroller 113 is connected to the output capacitor 112. The output rectifier 110 is a full-wave rectifier circuit that converts high-frequency AC to DC. It utilizes the unidirectional conductivity of diodes to convert the high-frequency AC on the secondary side of the transformer into high-frequency pulsating DC. The output inductor 111 and the output capacitor 112 form an LC filter circuit to smooth the output. The DC ripple filter removes high-frequency ripple after rectification, outputting a stable DC voltage to provide a "clean" charging current for the vehicle battery. The output-side microcontroller 113 acquires the output voltage, current, and battery status through the acquisition circuit; it communicates with the input-side microcontroller 108 via a serial port to feed back output-side information; and it communicates with the vehicle's BMS (Battery Management System) through the interface of the output-side CAN 115 to obtain information such as battery SOC (remaining charge) and SOH (state of health), enabling intelligent charging control (such as constant current and constant voltage stage switching).

[0021] Finally, one end of the input CAN114 is connected to the charging pile 101, and the other end of the input CAN114 is connected to the input microcontroller 108. One end of the output CAN115 is connected to the output microcontroller 113, and the other end of the output CAN115 is connected to the output capacitor 112. The input CAN114 is used to connect to the charging pile 101 to realize the command interaction of "charging pile 101 → charging circuit" (such as start, stop, voltage requirement). The output CAN115 is used to connect to the vehicle BMS to realize the status interaction of "charging circuit → battery" (such as battery requirement, charging protection).

[0022] Using the isolation step-down circuit for charging pile 101 in this embodiment, the isolation full-bridge function is innovatively reconstructed so that it only undertakes the task of efficient electrical isolation, and makes full use of the inherent system-level voltage regulation capability of charging pile 101. This completely solves the problems of low efficiency, large size and excessive weight of existing isolation full-bridge energy storage voltage regulation schemes, and realizes the high efficiency and miniaturization of DC fast charging for microcars.

[0023] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. An isolated step-down circuit for a charging pile, comprising a charging pile, characterized in that, It also includes an input module, an isolation transformer module, an output module, and an auxiliary function module; The input module includes a fuse, a pre-charge resistor, an input inductor, an input capacitor, a full-bridge inverter, and a full-bridge driver. The fuse is connected to the charging pile, the pre-charge resistor is connected to the fuse, the input inductor is connected to the fuse and located between the fuse and the pre-charge resistor, the input capacitor is connected to the pre-charge resistor, the full-bridge inverter is connected to the input capacitor, the full-bridge driver is connected to the full-bridge inverter, the isolation transformer module is connected to the full-bridge inverter, the output module is connected to the isolation transformer module, and the auxiliary function module is connected to the output module.

2. The isolation step-down circuit for charging piles as described in claim 1, characterized in that, The input module also includes an input-side microcontroller, which is connected to the full-bridge driver.

3. The isolation step-down circuit for charging piles as described in claim 2, characterized in that, The isolation transformer module includes a high-frequency transformer, which is connected to the full-bridge inverter.

4. The isolation step-down circuit for charging piles as described in claim 3, characterized in that, The output module includes an output rectifier, an output inductor, an output capacitor, and an output-side microcontroller. The output rectifier is connected to the high-frequency transformer, the output inductor is connected to the output rectifier, the output capacitor is connected to the output inductor, and the output-side microcontroller is connected to the output capacitor.

5. The isolation step-down circuit for charging piles as described in claim 4, characterized in that, The auxiliary function module includes an input-side CAN and an output-side CAN. One end of the input-side CAN is connected to the charging pile, and the other end of the input-side CAN is connected to the input-side microcontroller. One end of the output-side CAN is connected to the output-side microcontroller, and the other end of the output-side CAN is connected to the output capacitor.

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