Battery control device

Abstract

A battery control device is provided. The battery control device includes: a plurality of voltage detection circuits provided corresponding to a plurality of battery modules configuring a battery, detecting voltages of the battery modules; a plurality of communication lines connecting each of the voltage detection circuits in a daisy chain manner via a coupling capacitor; and a control circuit performing transmission and reception of communication signals with the voltage detection circuits via the communication lines, and controlling the battery based on the voltages received from the voltage detection circuits, a communication terminal of the voltage detection circuit connected to the communication line being grounded via a prescribed passive circuit.

Description

Technical Field

[0001] This invention relates to a battery control device. Background Technology

[0002] Patent Document 1 discloses a voltage detection device. This voltage detection device includes: multiple voltage detection circuits arranged for each battery module of a storage battery, detecting the voltage of each battery cell; multiple voltage detection lines connecting the battery cells to the voltage detection circuits; and a control device that controls the charging and discharging of the battery cells based on detection information obtained from the voltage detection circuits. The voltage detection circuits detect the voltage of each battery cell via the voltage detection lines. The multiple voltage detection circuits are connected in series via communication lines, and one end of the series-connected voltage detection circuit is connected to the control device via the communication line. In adjacent voltage detection circuits, the lowest potential voltage detection line connected to one voltage detection circuit and the highest potential voltage detection line connected to another voltage detection circuit are adjacent to each other and connected via a first capacitor.

[0003] Prior technology documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-136255

[0005] The aforementioned background technology connects multiple voltage detection circuits and a control device in a so-called daisy-chain manner, with each voltage detection circuit notifying the control device of the voltage of each battery cell detected by the other voltage detection circuits. In this background technology, each voltage detection circuit is electrically isolated by inserting a first capacitor into the communication line connecting the multiple voltage detection circuits, thereby reducing the influence of noise and ensuring the stable operation of each voltage detection circuit.

[0006] In this background technology, because each voltage detection circuit is electrically insulated, the potential of the communication signal transmitted through the communication line may be unstable. Moreover, if the potential of the communication signal is unstable, accurate communication cannot be achieved among the multiple voltage detection circuits and the control device, so it may be impossible to accurately notify the control device of the voltage of each battery cell detected by each voltage detection circuit. Summary of the Invention

[0007] The present invention was made in view of the above circumstances, and its object is to ensure the stability of the potential of the communication signal when multiple voltage detection circuits are connected in a daisy chain manner via capacitors.

[0008] In a first aspect of the present invention, the present invention comprises: a plurality of voltage detection circuits corresponding to a plurality of battery modules constituting a battery, for detecting the voltage of the battery modules; a plurality of communication lines daisy-chained together with each of the voltage detection circuits via coupling capacitors; and a control circuit for transmitting and receiving communication signals with the voltage detection circuits via the communication lines, and for controlling the battery based on the voltage received from the voltage detection circuits, wherein the communication terminals of the voltage detection circuits connected to the communication lines are grounded via a predetermined passive circuit.

[0009] According to the first method described above, in the second method of the present invention, the communication line separately includes a first communication line for uplink communication and a second communication line for downlink communication, and the first communication terminal connected to the first communication line and the second communication terminal connected to the second communication line in the voltage detection circuit are respectively grounded via the passive circuit.

[0010] According to the second embodiment described above, in the third embodiment of the present invention, the passive circuit comprises: a first resistor, one end of which is connected to the first communication terminal; a second resistor, one end of which is connected to the second communication terminal; and a capacitor, one end of which is connected to the other end of the first resistor and the other end of the second resistor, and the other end of which is grounded.

[0011] According to the third method described above, in the fourth method of the present invention, the power supply terminal of the voltage detection circuit is connected to the other end of the first resistor via a second capacitor.

[0012] According to any one of the first to third methods described above, in the fifth method of the present invention, the power supply terminal of the voltage detection circuit is grounded via a second passive circuit.

[0013] Invention Effects

[0014] According to the present invention, the stability of the potential of the communication signal can be ensured when multiple voltage detection circuits are connected in a daisy chain manner via capacitors. Attached Figure Description

[0015] Figure 1 This is a block diagram illustrating the overall structure of an on-board battery control device according to one embodiment of the present invention.

[0016] Figure 2 This is a circuit diagram illustrating the overall functional configuration of a voltage detection circuit according to an embodiment of the present invention.

[0017] Figure 3 This is a circuit diagram illustrating the main functional components of a voltage detection circuit according to one embodiment of the present invention.

[0018] Figure 4(a) to (c) are waveform diagrams representing the communication signals of a voltage detection circuit according to an embodiment of the present invention.

[0019] Figure 5A This is a circuit diagram illustrating a modified example of a voltage detection circuit according to an embodiment of the present invention.

[0020] Figure 5B This is a circuit diagram illustrating a modified example of a voltage detection circuit according to an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures

[0022] A. On-board battery control device; B. Battery pack; C1. First coupling capacitor; C2. Second coupling capacitor; D1-Dn. Voltage detection circuit; d1. Digital I / O circuit; d2. Digital power supply circuit; I. Insulation circuit; S. Control circuit; T. Communication line; t1. First communication line; t2. Second communication line; 1. Voltage detection IC; 2. CR filter; 3. Communication auxiliary circuit; 4. First resistor; 5. Second resistor; 6. First capacitor; 7. Second capacitor. Detailed Implementation

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] like Figure 1 As shown, the vehicle-mounted battery control device A according to this embodiment includes: n voltage detection circuits D1 to Dn, a communication line T, an insulation circuit I, and a control circuit S. This vehicle-mounted battery control device A is installed in electric vehicles such as electric cars and hybrid electric vehicles that use a motor as a power source, and controls a battery pack B such as a lithium-ion battery. Furthermore, in this embodiment, "n" is a natural number.

[0025] Let's begin with the battery pack B in this embodiment. Battery pack B is composed of n battery modules M1 to Mn connected in series, and for example, it has an output voltage (battery voltage) of several hundred volts. Although not illustrated, battery pack B is a secondary battery that supplies power to the PCU (Power Control Unit), which serves as the driving circuit. The power output (battery power) of battery pack B is converted into motor driving power (AC power) by the PCU.

[0026] n battery modules M1 to Mn are modules that are connected in series or / and in parallel with multiple battery cells, and output DC power at a specified output voltage (module voltage). Such a battery pack B composed of n battery modules M1 to Mn is equivalent to the battery of the present invention.

[0027] n voltage detection circuits D1 to Dn are integrated circuits that are configured corresponding to n battery modules M1 to Mn. These n voltage detection circuits D1 to Dn detect and monitor the voltage (cell voltage) of each battery cell in their corresponding battery modules M1 to Mn. The cell voltage of each battery cell is a physical quantity that represents the state of the battery pack B, i.e., the n battery modules M1 to Mn.

[0028] Such voltage detection circuits D1 to Dn are electronic circuits that transmit the voltages (battery information) of multiple units in each battery module M1 to Mn to the control circuit S via multiple communication lines T. The multiple communication lines T are signal lines that communicatively connect the n voltage detection circuits D1 to Dn and the control circuit S in a daisy-chain configuration.

[0029] In other words, multiple communication lines T connect n voltage detection circuits D1 to Dn, which act as slave circuits, in a series relative to the control circuit S, which acts as the master circuit. More specifically, the multiple communication lines T are interconnected in the following order: voltage detection circuit D1 → voltage detection circuit D2 → voltage detection circuit D3 → (omitted) → voltage detection circuit Dn → control circuit S.

[0030] Such multiple communication lines T include: a first communication line t1 for uplink communication, a first coupling capacitor C1, a second communication line t2 for downlink communication, and a second coupling capacitor C2. Furthermore, one of the multiple communication lines T, the communication line T that connects the nth voltage detection circuit Dn to the control circuit S, is as follows: Figure 1 The circuit I is used to replace the first coupling capacitor C1 and the second coupling capacitor C2.

[0031] In the multiple communication lines T, each first communication line t1 is a wire that transmits the uplink communication signal output from each voltage detection circuit D1 to Dn to the control circuit S. Furthermore, in the multiple communication lines T, each first coupling capacitor C1 is disposed at the midpoint of each first communication line t1 to cut off the transmission of the DC component between each voltage detection circuit D1 to Dn.

[0032] In the multiple communication lines T, each second communication line t2 is a wire that transmits downlink communication signals from the control circuit S to each voltage detection circuit D1 to Dn. Furthermore, in the multiple communication lines T, each second coupling capacitor C2 is located at the midpoint of each second communication line t2 to cut off the transmission of the DC component between each voltage detection circuit D1 to Dn.

[0033] In other words, the first coupling capacitor C1 and the second coupling capacitor C2 in each communication line T are circuit elements that ensure the electrical isolation of each voltage detection circuit D1 to Dn. Since each voltage detection circuit D1 to Dn is connected to each other in a daisy-chain manner through multiple communication lines T equipped with the first coupling capacitor C1 and the second coupling capacitor C2, mutual interference can be suppressed.

[0034] An insulating circuit I is provided in one of the multiple communication lines T that connects the nth voltage detection circuit Dn to the control circuit S. This insulating circuit I is used to achieve electrical isolation, similar to the first coupling capacitor C1 and the second coupling capacitor C2 mentioned above; for example, it is an optocoupler or a pulse transformer. This insulating circuit I suppresses electrical interference between the n battery modules M1 to Mn and the control circuit S.

[0035] The control circuit S communicates with n voltage detection circuits D1 to Dn via communication lines T, and controls the battery pack B based on the unit voltages of each battery module M1 to Mn received from the n voltage detection circuits D1 to Dn. The control circuit S sends control commands to the n voltage detection circuits D1 to Dn via the second communication line t2 of the multiple communication lines T, and also receives the voltage (unit voltage) of each battery cell from the n voltage detection circuits D1 to Dn via the first communication line t1 of the multiple communication lines T.

[0036] Next, the detailed structures of the n voltage detection circuits D1 to Dn described above will be explained. Furthermore, since the n voltage detection circuits D1 to Dn are configured in a substantially identical manner, the detailed structure of voltage detection circuit D1 (the first voltage detection circuit) will be explained below as an example.

[0037] like Figure 2 As shown, the first voltage detection circuit D1 includes: a voltage detection IC1, multiple CR filters 2, and a communication auxiliary circuit 3. The voltage detection IC1 is as follows: Figure 2 The integrated circuit is provided with multiple connection terminals as shown. Among these connection terminals, terminals IN0 to IN16 are analog voltage input terminals that are connected to the electrodes of each battery cell constituting the first battery module M1 via the CR filter 2.

[0038] For example, terminal IN0 is connected via the first CR filter 2 to the positive electrode of the first battery cell, which has the highest voltage among the plurality of battery cells constituting the first battery module M1. Additionally, terminal IN1 is connected via the second CR filter 2 to the negative electrode of the aforementioned first battery cell, which is the positive electrode of the second battery cell, which has the lowest voltage among the first battery cells.

[0039] Additionally, terminal IN2 is connected via the third CR filter 2 to the negative electrode of the second battery cell, which is the positive electrode of the third battery cell located at the lower voltage level of the second battery cell. Furthermore, terminal IN16 is connected via the seventeenth CR filter 2 to the negative electrode of the sixteenth battery cell, which is located at the lowest voltage level among the plurality of battery cells constituting the first battery module M1.

[0040] In addition to terminals IN0 to IN16, the voltage detection IC1 also includes at least a first communication terminal DPL, a second communication terminal DML, and a power monitoring terminal CVDD. The first communication terminal DPL is an output terminal that outputs an uplink communication signal to one end of the first communication line t1. The second communication terminal DML is an input terminal that receives a downlink communication signal via the second communication line t2.

[0041] Here, the first communication terminal DPL and the second communication terminal DML correspond to the communication terminals of the present invention. Furthermore, the first communication terminal DPL corresponds to the first communication terminal of the present invention, and the second communication terminal DML corresponds to the second communication terminal of the present invention. Also, the power monitoring terminal CVDD corresponds to the power terminal of the present invention.

[0042] Apart from Figure 2 In addition to, Figure 3 As shown, the power monitoring terminal CVDD is a monitoring terminal connected to the digital I / O circuit d1 (digital input / output circuit) connected to the first communication terminal DPL and the second communication terminal DML. The digital I / O circuit d1 is a digital circuit that generates uplink communication signals for communication with the outside via the communication line T and shapes the waveform of downlink communication signals.

[0043] The digital I / O circuit d1 operates by being powered by the digital power supply circuit d2 (digital power supply) and generates communication signals and shapes the waveform of downlink communication signals. The aforementioned power monitoring terminal CVDD is connected to the power input terminal of such digital I / O circuit d1, i.e., the output terminal of digital power supply circuit d2, and is an output terminal used to monitor the voltage value of the digital power supply.

[0044] like Figure 2 As shown, the multiple CR filters 2 are low-pass filters composed of resistors and capacitors. In each CR filter 2, one end of the resistor is connected to the electrode of each battery cell, and the other end is connected to terminals IN0 to IN16 and one end of the capacitor. In addition, in each CR filter 2, one end of the capacitor is connected to the other end of the resistor and terminals IN0 to IN16, and the other end is grounded.

[0045] Such a CR filter 2 is a low-pass filter that removes noise superimposed on the voltage input from each battery cell to terminals IN0 to IN16. In this embodiment, the vehicle battery control device A and the battery pack B, which is controlled by the vehicle battery control device A, are connected via a predetermined wire (voltage detection line). Sometimes, noise enters from the outside through this voltage detection line. Each CR filter 2 suppresses such noise from flowing into terminals IN0 to IN16.

[0046] The communication auxiliary circuit 3 is a characteristic component of the vehicle-mounted battery control device A according to this embodiment. This communication auxiliary circuit 3 corresponds to the passive circuit and the second passive circuit of the present invention, such as... Figure 2 As shown, it includes a first resistor 4, a second resistor 5, a first capacitor 6, and a second capacitor 7.

[0047] The first resistor 4 has a first resistance value Ra, one end of which is connected to the first communication terminal DPL, and the other end of which is connected to one end of the first capacitor 6 and one end of the second capacitor 7. The second resistor 5 has a second resistance value Rb, one end of which is connected to the second communication terminal DML, and the other end of which is connected to one end of the first capacitor 6, one end of the second capacitor 7, and the other end of the first resistor 4. Furthermore, the first resistance value Ra and the second resistance value Rb are, for example, set to the same value.

[0048] The first capacitor 6 has a first electrostatic capacitance Ca, one end of which is connected to the other end of the first resistor 4, the other end of the second resistor 5, and one end of the second capacitor 7, and the other end is grounded. The second capacitor 7 has a second electrostatic capacitance Cb, one end of which is connected to the other end of the first resistor 4, the other end of the second resistor 5, and one end of the first capacitor 6, and the other end is connected to the power monitoring terminal CVDD. Furthermore, the first electrostatic capacitance Ca and the second electrostatic capacitance Cb are, for example, set to the same value.

[0049] In the first resistor 4, the second resistor 5, the first capacitor 6, and the second capacitor 7, the first resistor 4, the second resistor 5, and the first capacitor 6 constitute the passive circuit of the present invention. That is, the first resistor 4, the second resistor 5, and the first capacitor 6 form a passive circuit in which the first communication terminal DPL is connected to GND (ground potential) via a first resistance value Ra and a first electrostatic capacitor Ca, and the second communication terminal DML is connected to GND (ground potential) via a second resistance value Rb and a first electrostatic capacitor Ca.

[0050] Furthermore, the second capacitor 7 is a passive circuit (passive component) that connects the first communication terminal DPL, which is connected via a first resistance value Ra, and the second communication terminal DML, which is connected via a second resistance value Rb, to the digital power supply via a second electrostatic capacitor Cb. This second capacitor 7, together with the aforementioned first capacitor 6, constitutes the second passive circuit of the present invention.

[0051] Next, also refer to Figure 4 as well as Figure 5A , Figure 5B The operation of the vehicle battery control device A according to this embodiment will be explained in detail.

[0052] In the vehicle battery control device A, if the control circuit S outputs a voltage transmission command requesting the transmission of unit voltage to the second communication line t2, the voltage transmission command is received by all voltage detection circuits D1 to Dn as a downlink communication signal via the second communication line t2 of each communication line T and each voltage detection circuit D1 to Dn.

[0053] As a result, all voltage detection circuits D1 to Dn will output a detection voltage signal with their own identification number attached to the unit voltage of their corresponding battery modules M1 to Mn to the first communication line t1. The detection voltage signal output by each voltage detection circuit D1 to Dn to the first communication line t1 is used as an uplink communication signal and is received by the control circuit S via the first communication line t1 of each communication line T and each voltage detection circuit D1 to Dn.

[0054] Here, a communication auxiliary circuit 3 is provided in each voltage detection circuit D1 to Dn. The communication auxiliary circuit 3 functions as follows when transmitting uplink communication signals and receiving downlink communication signals in the voltage detection circuits D1 to Dn.

[0055] In the voltage detection IC1 that generates the uplink communication signal, the first communication terminal DPL for outputting the uplink communication signal is set in an AC manner via the first resistor 4 (first resistance value Ra) and the first capacitor 6 (first electrostatic capacitor Ca), so the potential of the uplink communication signal is stabilized by the first resistor 4 (first resistance value Ra) and the first capacitor 6 (first electrostatic capacitor Ca).

[0056] In addition, in the voltage detection IC1 that generates the downlink communication signal, the second communication terminal DML for outputting the downlink communication signal is set in an AC manner via the second resistor 5 (second resistance value Rb) and the first capacitor 6 (first electrostatic capacitor Ca), so the potential of the downlink communication signal is stabilized by the second resistor 5 (second resistance value Rb) and the first capacitor 6 (first electrostatic capacitor Ca).

[0057] According to this embodiment, since the first communication terminal DPL and the second communication terminal DML, which are used for inputting and outputting communication signals, are AC grounded through a passive circuit consisting of the first resistor 4, the second resistor 5, and the first capacitor 6, the stability of the communication signal potential can be ensured.

[0058] In addition, in the communication auxiliary circuit 3, besides the passive circuit mentioned above, a second capacitor 7 is also provided. That is, the power supply monitoring terminal CVDD in the voltage detection IC1, or in other words, the power supply (digital power supply) of the digital IO circuit d1 that ultimately inputs and outputs communication signals in the voltage detection IC1, is AC grounded through the second passive circuit composed of the second capacitor 7 and the first capacitor 6.

[0059] According to this embodiment, such as Figure 4 (a) ~ Figure 4 As shown in (c), in the case where there is no pulsed noise superimposed on GND (ground potential) ( Figure 4 (a) and in the case of superimposed pulse noise ( Figure 4 (b) shows a different waveform for the communication signal. That is, in the absence of added noise ( Figure 4 (a) does not produce waveform distortion of the communication signal, but when noise is superimposed in GND, such as ( Figure 4 (b) The communication signal waveform is damaged by noise, resulting in waveform distortion.

[0060] Regarding such noise, according to this embodiment, the digital power supply can be changed synchronously with the noise superimposed on GND (ground potential). That is, according to this embodiment, due to the noise, GND (ground potential) and the digital power supply (5V) change synchronously, such as... Figure 4 In (c), the waveform of the communication signal is also superimposed on the noise in GND (ground potential) and changes synchronously, so the waveform distortion of the communication signal can be suppressed, thus enabling stable communication.

[0061] In the vehicle battery control device A according to this embodiment, a plurality of CR filters 2 are provided. As described above, the other end of these CR filters 2 is connected to GND (ground potential), so that noise from the external voltage detection line is detoured to GND (ground potential) through the aforementioned capacitor. Therefore, there is a tendency for pulse noise to be superimposed on GND (ground potential).

[0062] However, the control circuit S determines the state of each battery module M1 to Mn or the battery pack B based on the unit voltage of each battery module M1 to Mn received from each voltage detection circuit D1 to Dn, and controls each battery module M1 to Mn or the battery pack B based on the determination result.

[0063] For example, if one of the battery cells in the first battery module M1 has an abnormal voltage, the control circuit S sets the discharge circuit in each battery cell of the first battery module M1 that is connected in parallel with the battery cell corresponding to the abnormal voltage from the OFF state to the ON state, thereby controlling the charging current to not flow into the battery cell corresponding to the abnormal voltage.

[0064] Furthermore, the present invention is not limited to the above-described embodiments; for example, the following variations are considered.

[0065] (1) In the above embodiment, the case where the communication line T has a first communication line for uplink communication and a second communication line t2 for downlink communication has been described, but the present invention is not limited thereto. The present invention can also be applied to communication lines that transmit downlink communication signals and uplink communication signals through a single communication line.

[0066] (2) In the above embodiment, the first capacitor 6 and the second capacitor 7 constituting the second passive circuit are used to AC ground the power monitoring terminal CVDD, but the present invention is not limited thereto. The essential function of the second passive circuit is to synchronize the power supply (digital power) of the digital IO circuit d1 that inputs and outputs downlink and uplink communication signals with the pulse-like noise superimposed on GND (ground potential). Therefore, any circuit part that can synchronize the power supply (digital power) of the digital IO circuit d1 with the aforementioned pulse-like noise can be any circuit part other than the power monitoring terminal CVDD.

[0067] (3) A communication auxiliary circuit 3 comprising a first resistor 4, a second resistor 5, a first capacitor 6, and a second capacitor 7 is employed, but the present invention is not limited thereto. For example, Figure 5A As shown, communication auxiliary circuit 3A can also be used instead of communication auxiliary circuit 3.

[0068] The communication auxiliary circuit 3A does not connect one end of the second capacitor 7 to the other end of the first resistor 4, the other end of the second resistor 5, and one end of the first capacitor 6, but instead connects it to GND (ground potential). According to this communication auxiliary circuit 3A, the potential of the communication signal can be stabilized and the effects of noise reduced, similar to the communication auxiliary circuit 3. In this communication auxiliary circuit 3A, the second capacitor 7 corresponds to the second passive circuit of the present invention.

[0069] (4) The above embodiment uses a communication auxiliary circuit 3, but it can also use... Figure 5BThe communication auxiliary circuit 3C shown is used instead of the communication auxiliary circuit 3. The communication auxiliary circuit 3C is a circuit that replaces the first resistor 4 with a third series circuit Ze, and also replaces the second resistor 5 with a fourth series circuit Zf. The third series circuit Ze and the fourth series circuit Zf are, for example, series circuits of a resistor and a capacitor.

Claims

1. A battery control device comprising: a plurality of voltage detection circuits, corresponding to a plurality of battery modules constituting a battery, for detecting the voltage of the battery modules; and a plurality of communication lines, connected in a daisy-chain manner to each of the voltage detection circuits via coupling capacitors; The system also includes a control circuit that communicates with the voltage detection circuit via the communication line, and controls the battery based on the voltage received from the voltage detection circuit. The communication terminal in the voltage detection circuit that is connected to the communication line is grounded via a specified passive circuit. The communication line is equipped with a first communication line for uplink communication and a second communication line for downlink communication. In the voltage detection circuit, the first communication terminal connected to the first communication line and the second communication terminal connected to the second communication line are respectively grounded via the passive circuit. The passive circuit has the following features: A first resistor, one end of which is connected to the first communication terminal; The second resistor has one end connected to the second communication terminal; as well as A first capacitor has one end connected to the other end of the first resistor and the other end of the second resistor, and its other end is grounded. The power supply terminal of the voltage detection circuit is connected to the other end of the first resistor via a second capacitor.

2. The battery control device according to claim 1, wherein, The power supply terminal of the voltage detection circuit is grounded via a second passive circuit.

Images