Single-cell power supply and discharge circuit

Abstract

The utility model relates to the field of circuits, in particular to a single-cell power supply and discharge circuit, which comprises a bidirectional LLC circuit and a single-cell battery, the bidirectional LLC circuit is connected with the single-cell battery, and the bidirectional LLC circuit is respectively connected with a motor and a charger. The bidirectional LLC circuit adopts a full bridge and comprises a resonant cavity and a transformer, the turn ratio of the transformer is N, the gain of the resonant cavity is G, N is larger than or equal to 14 and smaller than or equal to 13.8 * G, and G is larger than or equal to 1.01. Compared with the prior art, the single-cell power supply and discharge circuit provided by the utility model adopts the combination of the bidirectional LLC circuit and the single cell for charging and discharging, is different from the traditional BMS and multi-cell series control, and has the following advantages in the application of the single cell: the single cell supplies power independently, has no wooden barrel short plate effect, and can discharge more electric quantity; the problem of consistency among multiple series-connected cells is avoided, and equalization is not needed; a single-cell OCV curve is easy for SOC estimation, and the accuracy is higher; the battery pack integrated production process is simple, capacity grading and group matching are not needed, the production procedures are reduced, and the cost is reduced; and the energy density is high, the size is smaller and the weight is lower.

Description

[Technical Field]

[0001] This utility model relates to the field of circuits, and in particular to a single-cell power supply and discharge circuit. [Background Technology]

[0002] Existing BMS and multi-cell series control systems suffer from inconsistency issues between cells due to the use of multiple cells in series, requiring balancing. Furthermore, multiple cells are prone to the "weakest link" effect, which is detrimental to ensuring efficiency. [Utility Model Content]

[0003] To overcome the above problems, this utility model proposes a single-cell power supply and discharge circuit that can effectively solve the above problems.

[0004] The present invention provides a technical solution to solve the above-mentioned technical problems by providing a single-cell power supply and discharge circuit, including a bidirectional LLC circuit and a single-cell battery. The bidirectional LLC circuit and the single-cell battery are connected together. The bidirectional LLC circuit is connected to a motor and a charger respectively. The bidirectional LLC circuit adopts a full-bridge design and includes a resonant cavity and a transformer. The transformer turns ratio is N, the resonant cavity gain is G, 14≤N≤13.8*G, and G≥1.01.

[0005] Preferably, a switching transistor is provided at the connection point between the bidirectional LLC circuit and the motor side.

[0006] Preferably, the charger has a charging voltage of 58V, which is stepped down to 2.0V-4.2V by a bidirectional LLC circuit to charge the single-cell battery.

[0007] Preferably, the voltage of the single-cell battery is 2.0V-4.2V, which is boosted to 48V by a bidirectional LLC circuit to power the motor.

[0008] Compared with existing technologies, the single-cell power supply and discharge circuit of this utility model uses a bidirectional LLC circuit combined with a single cell for charging and discharging, which is different from the traditional BMS and multi-cell series control. It has the following advantages in the application of single cells: each cell is independently powered, without the bottleneck effect, and can release more power; there is no consistency problem between cells in multi-cell series, and no balancing is required; the single-cell OCV curve is easy to estimate SOC with higher accuracy; the battery pack integration manufacturing process is simple, without the need for capacity matching, reducing production steps and costs; and it has high energy density, smaller size and lower weight. [Attached Image Description]

[0009] Figure 1 This is a block diagram of the single-cell power supply and discharge circuit of this utility model;

[0010] Figure 2 This is a schematic diagram of the bidirectional LLC circuit of the single-cell power supply and discharge circuit of this utility model.

Detailed Implementation Methods

[0011] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this utility model.

[0012] It should be noted that in this embodiment of the invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0013] Furthermore, in this utility model, the use of terms such as "first," "second," etc., is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0014] Please see Figure 1 and Figure 2 The single-cell power supply and discharge circuit of this utility model includes a bidirectional LLC circuit and a single-cell battery. The bidirectional LLC circuit and the single-cell battery are connected. The bidirectional LLC circuit is connected to a motor and a charger respectively.

[0015] The bidirectional LLC circuit adopts a full-bridge design, including a resonant cavity and a transformer. The transformer turns ratio is designed to be N, and the resonant cavity gain of the LLC part is G. The charger charging voltage is 58V, which is stepped down to 2.0V-4.2V by the bidirectional LLC circuit. To meet the charging requirements of the battery cell, 58V*G / N≥4.2V, that is, N≤13.8*G.

[0016] During the cell discharge stage, the input cell voltage is 2.0V-4.2V, and the output is DC. At this time, the switching transistor connected to the motor side of the bidirectional LLC circuit is in rectification state with a gain of N, which boosts the voltage to 48V to drive the motor. To meet the motor drive requirements, 2.0V*N≥48 must be satisfied, so N≥14.

[0017] Considering the gain requirements during the charging and discharging stages, 14≤N≤13.8*G, and G≥1.01, by reasonably selecting the resonant gain G and the transformer turns ratio N, the operating points of the LLC during the charging and discharging stages can be satisfied, allowing the LLC bidirectional topology to both charge a single cell and supply power to the motor in reverse.

[0018] The bidirectional LLC circuit includes switching transistors Q1, Q2, Q3, and Q4. Switching transistors Q1 and Q3 are connected, Q2 and Q4 are connected, and Q3 and Q4 are connected.

[0019] The bidirectional LLC circuit includes transformers T1A, T1B, and T1C. One end of transformer T1A is connected between switching transistors Q1 and Q3, and the other end of transformer T1A is connected to a resonant inductor L1. One end of the resonant inductor L1 is connected to a resonant capacitor C3, and one end of the resonant capacitor C3 is connected between switching transistors Q2 and Q4.

[0020] The transformer T1B is connected to a secondary synchronous rectifier tube Q5, and the transformer T1C is connected to a secondary synchronous rectifier tube Q6.

[0021] Explanation of the principle:

[0022] 1. Forward charging of the battery: The charger supply voltage is 58V (i.e., VBUS+ and VBUS- voltages), which is stepped down to 2.0V-4.2V by a typical full-bridge LLC circuit to charge the single-cell battery. Q1, Q2, Q3, and Q4 are the switching transistors of the full-bridge LLC circuit; T1A, T1B, and T1C are the full-bridge LLC transformers; L1 is the full-bridge LLC resonant inductor; C3 is the full-bridge LLC resonant capacitor; Q5 and Q6 are the synchronous rectifier diodes on the secondary side of the LLC circuit; C1 is the high-voltage filter capacitor; and C2 is the battery filter capacitor.

[0023] 2. Reverse cell discharge, i.e., the charger supplies power to VBUS in reverse through the battery cell. The circuit topology is a push-pull resonant converter, i.e., Q5 and Q6 conduct alternately, and the switching frequency is the resonant frequency of inductor L1 and capacitor C1, i.e.

[0024] Compared with existing technologies, the single-cell power supply and discharge circuit of this utility model uses a bidirectional LLC circuit combined with a single cell for charging and discharging, which is different from the traditional BMS and multi-cell series control. It has the following advantages in the application of single cells: each cell is independently powered, without the bottleneck effect, and can release more power; there is no consistency problem between cells in multi-cell series, and no balancing is required; the single-cell OCV curve is easy to estimate SOC with higher accuracy; the battery pack integration manufacturing process is simple, without the need for capacity matching, reducing production steps and costs; and it has high energy density, smaller size and lower weight.

[0025] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. Any modifications, equivalent substitutions and improvements made within the concept of the present utility model should be included within the patent protection scope of the present utility model.

Claims

1. A single-cell power supply and discharge circuit, characterized in that, It includes a bidirectional LLC circuit and a single-cell battery, wherein the bidirectional LLC circuit and the single-cell battery are connected, and the bidirectional LLC circuit is connected to a motor and a charger respectively; The bidirectional LLC circuit adopts a full-bridge design, including a resonant cavity and a transformer. The transformer turns ratio is N, the resonant cavity gain is G, 14≤N≤13.8*G, and G≥1.

01.

2. The single-cell power supply and discharge circuit as described in claim 1, characterized in that, A switching transistor is provided at the connection point between the bidirectional LLC circuit and the motor side.

3. The single-cell power supply and discharge circuit as described in claim 1, characterized in that, The charger has a charging voltage of 58V, which is stepped down to 2.0V-4.2V by a bidirectional LLC circuit to charge the single-cell battery.

4. The single-cell power supply and discharge circuit as described in claim 1, characterized in that, The single-cell battery has a voltage of 2.0V-4.2V, which is boosted to 48V by a bidirectional LLC circuit to power the motor.

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