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EP-3206278-B1 - VOLTAGE BALANCING CIRCUIT

EP3206278B1EP 3206278 B1EP3206278 B1EP 3206278B1EP-3206278-B1

Inventors

  • CHENG, KA WAI ERIC
  • YE, Yuanmao
  • XUE, XIANGDANG

Dates

Publication Date
20260506
Application Date
20150602

Claims (7)

  1. A voltage balancing circuit for N power storage devices; any power storage device of the N power storage devices comprises a positive electrode and a negative electrode; the positive electrode of power storage device n of N power storage devices is connected to the negative electrode of power storage device n+1 of N power storage devices; wherein N is an integer greater than or equal to 2, and n is an integer greater than or equal to 1 and less than N; the voltage balancing circuit (100) comprises: N switches (101), each of the N switches comprising a selecting terminal (101_i1); the N switches beingN single-pole double-throw switches (101), the switch i (101_i) further comprises: a first static terminal (101_i2) and a second static terminal (101_i3); the first static terminal (101_i2) of the single-pole double-throw switch i (101_i) is suitable for being connected to the positive electrode of power storage device i of the N power storage devices; the second static terminal (101_i3) of single-pole double-throw switch i (101_i) is suitable for being connected to the negative electrode of power storage device i; wherein i is an integer greater than or equal to 1 and less than or equal to N; N capacitors (102), capacitor i (102_i) of the N capacitors (102) comprises a first terminal (102_i1) and a second terminal (102_i2); the first terminal (102_i1) of capacitor i (102_i) is connected to the selecting terminal (101_i1) of single-pole double-throw switch i (101_i); a switch controller (104) is connected to a switch i (101_i) through a control line (105); the switch controller (104) is configured to control the selecting terminal (101_i1) of the switch i (101_i) to connect to the first static terminal (101_i2) or the second static terminal (101_i3) of the switch i (101_i); the voltage balancing circuit (100) further comprises N inductors (106), wherein the second terminal (102_i2) of capacitor i (102_i) is connected to the common neutral line (103) through inductor i (106_i) of the N inductors (106); the switch controller (104) is configured to send a control signal to the switch i (101_i) through the control line (105) to control the connection between the selecting terminal (101_i1) of the switch i (101_i) and the first static terminal (101_i2) or the second static terminal (101_i3) of the switch i (101_i) and the selecting terminal (101_i1) is connected to the first static terminal (101_i2) or the second static terminal (101_i3) of single-pole double-throw switch i (101_i); when the selecting terminal (101_i1) is connected to the first static terminal (101_i2) or the second static terminal (101_i3), there are two_capacitors and two inductors in charging circuit or discharging circuit.
  2. The voltage balancing circuit according to claim 1, wherein, single-pole double-throw switch i (101_i) comprises: a first metal oxide semiconductor field effect transistor (101_ia); a second metal oxide semiconductor field effect transistor (101_ib) in series connection with the first metal oxide semiconductor field effect transistor (101_ia).
  3. The voltage balancing circuit according to claim 2, wherein the selecting terminal (101_i1) of single-pole double-throw switch i (101_i) is a connection point between the first metal oxide semiconductor field effect transistor (101_ia) and the second metal oxide semiconductor field effect transistor (101_ib); a gate of the first metal oxide semiconductor field effect transistor (101_ia) and a gate of the second metal oxide semiconductor field effect transistor (101_ib) are respectively connected to the switch controller (104) through the control line (105).
  4. The voltage balancing circuit according to one of the preceding claims, wherein, the N power storage devices comprise at least one type of rechargeable batteries and super capacitors.
  5. The voltage balancing circuit according to claim 4, wherein, the rechargeable battery is a single battery cell or a battery pack in which a plurality of single battery cells are connected in series, and the super capacitor is a single capacitor cell or a super capacitor pack in which a plurality of single super capacitor cells are connected in series.
  6. The voltage balancing circuit according to claim 1, wherein, the control signal is a bipolar square wave signal or a pair of complementary unipolar rectangular wave signals.
  7. The voltage balancing circuit according to claim 6, wherein, the control signal is configured to control the single-pole double-throw switch i (101_i) to be switched on/off at a fixed frequency or a variable frequency.

Description

The present application relates to the technical field of voltage equalization of series power storage devices, and particularly relates to a voltage balancing circuit. More specifically, this invention relates to voltage balancing circuits of the preamble part of claim 1. Rechargeable power storage devices, such as lithium-ion batteries and super capacitors, have been widely used in portable devices, industrial applications, hybrid and electric vehicles and other fields. For these power storage devices, the voltage is limited, such as the voltage of lithium-ion battery is about in the range of 3V-4.3V, and the voltage of the super capacitor is usually not more than 2.7V. In order to meet the application requirements of high voltage applications in practical applications, the high storage voltage of these power storage devices is usually obtained by connecting a plurality of power storage devices in series. However, during the charging and discharging of the plurality of power storage devices in series, the voltage imbalance of the respective power storage devices may occur, due to different battery capacity and/or battery leakage. Therefore, for a plurality of power storage devices connected in series, the voltage equalization between the power storage units is very important. Further, in order to reduce the circuit volume of the equalization system and to reduce the cost of consumption, in the related patents (such as US 5,710,504), an automatic battery voltage equalization system based on switched capacitor technology is proposed. As shown in Fig. 1, a battery voltage equalization circuit based on the switching capacitor is provided by the patent, and is used to equalize the voltage of n battery cells (Cell1~Celln) in series. In the equalization circuit of Fig. 1, it comprises n single-pole double-throw switches (S1-Sn, n is an integer greater than or equal to 1), n-1 capacitors (C1~Cn-1) and a control unit; wherein, the two static terminals of any switch of the n single-pole double-throw switches are respectively connected to the positive electrode and the negative electrode of a corresponding battery unit; the selecting terminals of each two adjacent switches of the n single-pole double-throw switches are connected through a corresponding capacitor; the control unit is used to control the n single-pole double-throw switches to be switched off. As can be seen from Fig. 1, the bulky magnetic components are not provided in the battery voltage equalization circuit, reducing the circuit volume and cost consumption of the equalization system. US 5,710,504 further discloses one embodiment in which the connecting nodes of two neighboring capacitors and the terminals of the first and last capacitors not being connected to another capacitor are coupled by inductors to the selecting terminals of the single-pole double-throw switches. The inductors in combination with the associated capacitors provide circuits which exhibit resonant-like characteristics. As such, the peak currents which flow to and from the respective capacitors will be larger than in equalizer systems without inductors. Because of the resonant characteristic, the current flows will now exhibit zero crossings. Switching can in turn be carded out at the current zeros to avoid losses encountered in the switching process. However, the voltage equalization circuit of Fig. 1 provides only a charge transfer path between adjacent cell cells in a plurality of series cells. For the entire voltage equalization system circuit, the voltage equalization speed is limited. Then when the number of batteries in series is relatively large, through this voltage equalization circuit, it takes a lot of time to achieve the voltage balance between the battery cells. US 2008/252266 A1 discloses a device for balancing charge between the individual cells of a double-layer capacitor. A double-layer capacitor consists of a series circuit of individual capacitor cells. Each capacitor cell is assigned to a capacitor, the first terminal of which can be connected via a first switch to the first terminal of the assigned capacitor cell, and can be connected via a second switch to the second terminal of the assigned capacitor cell. The second terminals of the capacitors are connected to each other. US 2014/0139184 A1 and CN 103 733 466 A, which belong to the same patent family, disclose a more complicated circuit design. EP 2 302 757 A1 discloses a system for charging and balancing electrical energy storage cells. The circuit design is similar to the one of US 2008/252266 A1. The main difference is that the commonly connected second terminals of the capacitors are further connected to an AC generator. It is the object of this invention to provide a voltage balancing circuit which has reduced switching noise and EMI. This object is achieved by the subject matter of claim 1. Developments are the subject matter of the dependent claims. Since in the present application, the voltage bal