Insulated Communication System

Abstract

To provide an insulation communication system that makes it possible to increase the data rate while suppressing current consumption per communication symbol communicated by one modulation.SOLUTION: A communication control unit 21, 16 configures communication data at three values or higher including a positive state "1" and a negative state "-1" in which the absolute values of the states expressed by integers are the same, and a zero state "0" in which no current consumption occurs between the positive state and the negative state, and performs isolated communication through an insulating portions 9, 10, 25, 26 using a communication symbol that summarizes the communication data. The communication control unit 21, 16 sets the beginning of the multi-bit data as the negative state "-1" or the positive state "1", and thereafter performs setting so as to take any of the three states.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an isolated communication system. [Background technology]

[0002] CAN, or Controller Area Network, has been proposed as an insulated communication method for in-vehicle use. CAN is a communication standard for intercommunication between ECUs and other devices as defined in ISO 11898, and communication circuits can use circuits that comply with the conventional CAN communication standard. However, in the future, data rates are expected to increase in line with demand for faster in-vehicle communication speeds. Therefore, if the trend toward shorter 1-bit communication cycles becomes more pronounced, current consumption per unit time will increase. In other words, an increase in data rate will increase current consumption.

[0003] On the other hand, in isolated communication technology, there is a method that uses Manchester coding. Manchester coding is also known as binary phase modulation, and is an encoding method that assigns binary states of "1" and "0" to the transition from the negative state "-1" to the positive state "+1", or to the transition between the positive state "+1" and the negative state "-1". As a result, Manchester coding requires the transmission of two signals per bit of transmitted data, which is inefficient in terms of power consumption. However, since the signal does not contain a DC component, it is a coding format that is suitable for isolated communication, which basically cannot transmit DC components. In addition, the timing of the state transitions matches the symbol rate, making it possible to transmit signals with an embedded clock, and it is also a code that enables clock synchronization on the receiving side.

[0004] Communication circuits consume a large amount of power, mainly when transmitting data. Therefore, transmitting data in short pulses is an effective way to reduce power consumption during communication. In order to increase the number of bits transmitted per symbol, which is the transmission unit, without significantly increasing current consumption, the technologies described in Patent Documents 1 and 2 have been proposed. Conventionally, when no data was transmitted, the zero state "0" was used and was not considered to be valid communication data, but Patent Documents 1 and 2 are characterized in that they also encode the zero state "0." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 0050734 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0050736 Summary of the Invention [Problem to be solved by the invention]

[0006] Since communication circuits do not consume signal power when in the zero state "0," the power consumption per symbol transmitted on the transmitting side can be reduced. Also, by using coding methods such as Manchester coding to shorten the period in which the circuit is driven in the positive state "+1" and negative state "-1" as much as possible and lengthening the period in the zero state "0," it is possible to shorten the drive period per unit time and reduce power consumption.

[0007] As disclosed in Patent Document 1, power consumption can be further reduced by transmitting data in short pulses, but such a method cannot be used in the encoding described in Patent Document 2, because communication information is stored between each symbol. Also, even if symbols are transmitted in bursts and periods of time are provided between symbols during which no transmission data is transmitted, the encoding allows the first bit of a symbol to be zero (0), so a unit for detecting the timing of the zero (0) state is required on the receiving side, making it difficult for the receiving side to determine the first bit of a communication symbol.

[0008] An object of the present invention is to provide an isolated communication system that can determine the first bit of a communication symbol on the receiving side while suppressing current consumption per communication symbol communicated in one modulation. [Means for solving the problem]

[0009] The invention described in claim 1 is A modulation is performed in which transmission data of a predetermined amount of information is encoded in one of three or more integer values and converted into a communication symbol that summarizes communication data of a predetermined length, and the communication symbol is used for insulated communication through an insulating section, Communication data is three or more values including a positive state, a negative state where the absolute values of the states expressed as integers are the same, and a zero state where no current consumption occurs between the positive and negative states. The communication control unit that constitutes Equipped with. Communication control unit sets the first communication data in a communication symbol to a positive or negative state, and sets the communication data in the subsequent communication symbols so that they can take any of three or more states. The invention of claim 1 is applied to a battery monitoring system comprising a battery monitoring ECU and a plurality of battery monitoring devices that acquire and monitor the voltage of each battery cell for an assembled battery formed by connecting a plurality of battery cells. The battery monitoring ECU and the plurality of battery monitoring devices each include a communication control unit. The communication control unit of the battery monitoring ECU and the communication control units of the plurality of battery monitoring devices communicate insulatedly using differential signals via an insulating unit. The memory unit stores the length of the communication symbol communicated in one modulation. The communication control unit reads the length of the communication symbol from the memory unit after power is turned on. The length of the communication symbol can be changed by sending a command value from the communication control unit of the battery monitoring ECU and receiving an acknowledgment from the communication control unit of the battery monitoring device. Furthermore, in the invention of claim 2, the communication control unit Manchester encodes the binary state of the first bit of the transmission data and communicates it as the two states of the first communication data that constitute the communication symbol.

[0010] According to the invention of claim 1, the first communication data among the communication symbols is set to a positive or negative state, so the first bit of the communication symbol can be determined on the receiving side. Furthermore, there are no restrictions on the combination of three or more values of the communication data thereafter, so there is no theoretical upper limit on the number of communication symbols that can be configured. This allows the receiving side to determine the first bit of the communication symbol while suppressing the current consumption per communication symbol communicated in one modulation. [Brief explanation of the drawings]

[0011] [Figure 1]Electrical configuration diagram of the battery monitoring system in the first embodiment [Figure 2] Electrical configuration diagram of the transmitter circuit [Figure 3] A diagram showing the switch state and the level of the communication line when the transmitter circuit transmits a data signal. [Figure 4] An example of setting values stored in the storage unit [Figure 5] Time Chart [Figure 6] Example of communication data status setting within a communication symbol when communicating 3-bit data [Figure 7] Example of communication data status setting within a communication symbol when communicating 2-bit data [Figure 8] Example of communication data status setting within a communication symbol when communicating 4-bit data [Figure 9] Illustrative diagram of the effect of this embodiment over the prior art [Figure 10] Malfunction explanation diagram [Figure 11] Example of communication data state setting in a communication symbol when communicating 3-bit data in the second embodiment [Figure 12] Example of communication data status setting within a communication symbol when communicating 4-bit data [Figure 13] Variation 1 of communication data status setting in communication symbol when communicating 3-bit data [Figure 14] Modification 2 of the communication data status setting within the communication symbol when communicating 3-bit data [Figure 15] Example of communication data state setting in a communication symbol when communicating 3-bit data in the third embodiment [Figure 16] Example of communication data status setting within a communication symbol when communicating 4-bit data [Figure 17] Variation 1 of communication data status setting in communication symbol when communicating 3-bit data [Figure 18] Modification 2 of the communication data status setting within the communication symbol when communicating 3-bit data DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, several embodiments of the insulated communication system will be described with reference to the drawings. Parts having the same configuration in each embodiment will be assigned the same reference numerals in the embodiments described below, and their description may be omitted.

[0013] (First embodiment) A first embodiment of a battery monitoring system S will be described with reference to Figs. 1 to 9. As shown in Fig. 1, an assembled battery 1 includes an assembled battery unit 3 in which a plurality of battery cells 2 connected in series are further connected in series. The battery cells 2 are, for example, secondary batteries such as lithium-ion batteries. The battery monitoring system S connected to the assembled battery 1 constitutes an insulated communication system by connecting a battery monitoring ECU 4, which serves as a main node, and battery monitoring devices 5a, 5b, and 5c, which serve as slave nodes, so that they communicate insulated from each other.

[0014] The battery monitoring ECU 4 includes a transceiver 21, a communication controller 22, a storage unit 23, and a high-precision clock generator 24. The transceiver 21 is configured as an insulated communication unit that performs insulated communication with the battery monitoring devices 5a, 5c via insulators 25, 26. The battery monitoring ECU 4 uses the transceiver 21 to transmit and receive communication symbols that summarize communication data between the battery monitoring devices 5a, 5b, and 5c. The battery monitoring ECU 4 operates based on a clock signal generated by the clock generator 24 and by executing a program stored in the storage unit 23. The clock generator 24 is configured using, for example, a crystal oscillator and can generate a clock signal with higher precision than the clock generator 13 used in the battery monitoring devices 5a, 5b, and 5c (described later). A silicon MEMS oscillator may be used instead of the crystal oscillator, or the clock signal may be generated by receiving a GNSS reference frequency from a GNSS satellite.

[0015] The battery monitoring devices 5a, 5b, and 5c measure the voltages between the terminals of some of the battery cells 2 connected in series. The battery monitoring devices 5a, 5b, and 5c at each stage monitor the same number of battery cells 2, but the number of battery cells 2 monitored by the battery monitoring devices 5a, 5b, and 5c at each stage may be different. Furthermore, the battery cells 2 monitored by the battery monitoring devices 5a, 5b, and 5c at each stage may overlap with each other.

[0016] The battery monitoring devices 5a, 5b, and 5c at each stage each have the same components, and therefore the same reference numerals are used for the components. Each battery monitoring device 5a, 5b, and 5c at each stage includes a battery monitoring IC 7 that monitors the battery cells 2 for abnormalities, a filter unit 8, and insulating units 9 and 10.

[0017] The battery monitoring IC 7 includes two transmitter / receivers 11 and 12, a clock generator 13, a memory 14, a battery monitor 15, and a communication controller 16. The filter 8 receives the voltage of the battery cell 2, filters it, and outputs it to the battery monitoring IC 7. The battery monitor 15 performs A / D conversion of the filtered voltage. The battery monitoring devices 5a, 5b, and 5c each operate based on a clock signal generated by the clock generator 13, and also operate by executing a program stored in the memory 14.

[0018] The clock generation unit 13 is composed of an RC oscillator or ring oscillator and can only generate clock signals with lower accuracy than the clock generation unit 24 of the battery monitoring ECU 4 described above. However, the clock generation unit 13 can easily change the oscillation frequency by using a variable capacitance in the capacitor that makes up the oscillator, or by varying the bias current, based on a correction instruction from the communication control unit 16. The battery monitoring ICs 7 of the battery monitoring devices 5a, 5b, and 5c obtain the voltage of their respective battery cells 2 via the filter unit 8 using the battery monitoring unit 15. The battery monitoring unit 15 can also detect the state of the battery cells 2 using an AC impedance method that uses a reference signal that is a reference signal based on the output signal of the clock generation unit 13.

[0019] A communication line 31 is connected between the insulating unit 25 of the battery monitoring ECU 4 and the insulating unit 9 of the battery monitoring device 5a. A communication line 32 is connected between the insulating unit 10 of the battery monitoring device 5a and the insulating unit 9 of the battery monitoring device 5b. A communication line 33 is connected between the insulating unit 10 of the battery monitoring device 5b and the insulating unit 9 of the battery monitoring device 5c. A communication line 34 is connected between the insulating unit 10 of the battery monitoring device 5c and the insulating unit 26 of the battery monitoring ECU 4. In other words, the communication lines 31 to 34 are ring-connected between the battery monitoring ECU 4 and the battery monitoring devices 5a to 5c. The battery monitoring ECU 4 and the battery monitoring devices 5a, 5b, and 5c perform insulated communication using differential signals using communication paths insulated by the insulating units 9, 10, 25, and 26. The insulating units 9, 10, 25, and 26 are configured using insulating elements, such as capacitors, or transformers and filters.

[0020] In addition, when the communication control unit 16 of the battery monitoring devices 5a, 5b, and 5c receives an instruction from the battery monitoring ECU 4 to correct the clock signal of the clock generation unit 13, it corrects the frequency of the clock signal of the clock generation unit 13 using insulated communication so that it approaches the frequency of the high-precision clock signal of the battery monitoring ECU 4.

[0021] The two transmitter / receivers 11 and 12 of the battery monitoring devices 5a, 5b, and 5c at each stage are each connected to a communication control unit 16, and the communication control unit 16 can communicate with the transmitter / receivers 11 and 12 of the adjacent battery monitoring ECU 4 or the battery monitoring device, respectively.

[0022] For example, the two transceivers 11 and 12 of the battery monitoring device 5a are connected to the transceiver 21 of the battery monitoring ECU 4 and the transceiver 11 of the battery monitoring device 5b, respectively. The two transceivers 11 and 12 of the battery monitoring device 5b are connected to the transceiver 12 of the battery monitoring device 5a and the transceiver 11 of the battery monitoring device 5c, respectively. The two transceivers 11 and 12 of the battery monitoring device 5c are connected to the transceiver 12 of the battery monitoring device 5b and the transceiver 21 of the battery monitoring ECU 4, respectively.

[0023] The battery monitoring ECU 4 communicates with the battery monitoring devices 5a, 5b, and 5c in a master-slave manner, allowing it to send command values from the battery monitoring ECU 4 and read out the status of each battery monitoring device 5a, 5b, and 5c and the measurement results of the voltage values of the battery cells 2. In this case, the component circuits of each battery monitoring device 5a, 5b, and 5c obtain a reference ground voltage from the battery cell 2 that they monitor, so the transmit and receive terminals of the transmit and receive units 11 and 12 are insulated by insulators 9 and 10. The battery monitoring ECU 4 and battery monitoring devices 5a, 5b, and 5c communicate using differential signals, ensuring a high S / N ratio even when the communication cycle is shortened, and enabling low current consumption.

[0024] A specific method for encoding the communication symbols is described below. The battery monitoring ECU 4 and each battery monitoring device 5a, 5b, 5c compose communication data using values expressed as integers of three or more values: a zero state "0" that does not consume current, a positive state "1" that is a voltage level higher than the zero state "0", and a negative state "-1" that is lower than the zero state "0". The communication data is then grouped together into a communication symbol, which is then transmitted in an insulated manner via insulating units 25, 26, 9, 10.

[0025] In this embodiment, the coding is characterized by an average value of the transmission voltage value per symbol, i.e., the DC component, being 0, which is convenient for insulated communication. Although a form in which the positive state of a state represented by an integer is "1" and the negative state is "-1" will be described, it is also possible to combine positive and negative states with the same absolute value, such as "2" as the positive state and "-2" as the negative state, so that the average value has a DC component of 0.

[0026] Since the transmitter / receiver units 21, 11, and 12 have the same configuration, only the configuration of the transmitter / receiver unit 11 will be illustrated. Fig. 2 illustrates the configuration of the transmitter circuit 11a of the transmitter / receiver unit 11. As shown in Fig. 2, the transmitter circuit 11a includes an H-bridge circuit configured by connecting a P-channel MOS transistor P1, diodes D1 and D2, and an N-channel MOS transistor N1 between a node to which a power supply voltage VCC is applied and a ground node, and further connecting a P-channel MOS transistor P2, diodes D3 and D4, and an N-channel MOS transistor N2 between the node to which the power supply voltage VCC is applied and the ground node. The transmitter circuit 11a outputs the voltage between a common connection point Nh of the diodes D1 and D2 and a common connection point Nl of the diodes D3 and D4 to the communication line 31 as communication data.

[0027] 3, the transmission circuit 11a turns on the MOS transistors P1 and N2 and turns off the MOS transistors P2 and N1. As a result, the potential of the common connection point Nh can be made higher than the potential of the common connection point Nl and output to the communication line 31. In the following description, the bus state of the communication line 31 at this time is referred to as the positive state "+1."

[0028] Furthermore, when the transmission circuit 11a outputs a negative state "-1," it turns on the MOS transistors P2 and N1 and turns off the MOS transistors P1 and N2. This makes it possible to output to the communication line 31 a potential at the common connection point Nl that is higher than the potential at the common connection point Nh. In the following description, the bus state of the communication line 31 at this time is referred to as the negative state "-1."

[0029] Furthermore, when the transmitting circuit 11a outputs the zero state "0," it turns off the MOS transistors P1, P2, N1, and N2 to keep the common connection points Nh and Nl in an open state. At this time, the receiving circuit on the other side is connected to the communication line 31, and the zero state "0" can be output by outputting a bias potential that is preset to the midpoint between the power supply voltage VCC and ground to the communication line 31. At this time, the transmitting circuit 11a does not consume any current because it turns off all of the MOS transistors P1, P2, N1, and N2.

[0030] Also, a MOS transistor may be connected as a switch between the pair of communication lines 31. Alternatively, a MOS transistor may be connected as a switch via a diode between the pair of communication lines 31. In this case, by turning on the MOS transistor, the potential between the pair of communication lines 31 can be set to a common potential, and the zero state "0" can be output to the communication line 31.

[0031] The receiving circuit on the other side, for example, the transceiver unit 21 of the battery monitoring ECU 4, compares the potential of the communication line 31 with a predetermined high threshold Vth and low threshold Vtl, and if it exceeds the high threshold Vth, receives a digital signal of a positive pulse P and accepts it as a positive state "1", and if it is below the low threshold Vtl, receives a digital signal of a negative pulse N and accepts it as a negative state "-1".

[0032] While the transmitter / receiver 21 accepts these positive state "1" and negative state "-1," if there is a sampling timing where the voltage is below the high threshold Vth and above the low threshold Vtl, it accepts the zero state "0" at this sampling timing. In principle, no current is consumed if the differential voltage of the communication line 31 is maintained at the zero state "0." Therefore, by applying the technology of this embodiment, the data rate can be improved without increasing current consumption.

[0033] The method of encoding communication data and the detailed method of transmitting and receiving the data will be explained below with reference to Figures 4 and 5. As mentioned above, insulated communication, communication data is communicated using communication symbols made up of ternary data of negative state "-1", positive state "1", and zero state "0".

[0034] The communication lines 31 to 34 are connected between the battery monitoring devices 5a, 5b, and 5c, or between the battery monitoring ECU 4 and the battery monitoring devices 5a, 5b, and 5c. Immediately after power-on, these communication lines 31 to 34 are maintained at the same potential as the zero state "0" during normal standby. For this reason, when the battery monitoring ECU 4 or the battery monitoring devices 5a, 5b, and 5c transmit communication data, they do not start from the zero state "0," but set the initial state constituting the communication symbol to a negative state "-1" or a positive state "1." This is because if the zero state were "0," the receiving side would not be able to recognize the communication data as a zero state "0."

[0035] After power-on, when the battery monitoring ECU 4 or the battery monitoring devices 5a, 5b, 5c communicate using insulated communication, the communication control unit 22 or 16 first reads information necessary for communication control, such as the communication format, from the respective storage unit 23 or 14. Since the information stored in the storage units 23 and 14 is generally the same, the following will explain the information stored in the storage unit 14, and will omit explanation of the information stored in the storage unit 23.

[0036] The storage unit 14 of the battery monitoring IC 7 stores a communication symbol length Ts for communication in one modulation. Specifically, as shown in FIG. 4, each storage unit 14 stores a value DEMOD_TH1 predetermined based on the communication symbol length Ts (= t4 - t1) or the communication symbol length Ts, and a value DEMOD_TH2 predetermined based on the communication symbol interval Tp (= t6 - t1) minus the communication symbol length Ts. The value DEMOD_TH1 is predetermined corresponding to the time required to transmit one communication symbol and indicates a threshold value for counting a time longer than the communication symbol length Ts shown in FIG. 5 by a margin time (= t5 - t4). The value DEMOD_TH2 is predetermined corresponding to the time from the reception of one symbol to the reception of the next symbol and indicates a threshold value for counting a time equivalent to the communication symbol interval Tp - (symbol length Ts + margin time) shown in FIG. 5.

[0037] Here, an example is shown in which a communication symbol is transmitted from the battery monitoring ECU 4 to the battery monitoring device 5a. The communication control unit 22 of the battery monitoring ECU 4 generates transmission data consisting of a command and data. At this time, the communication control unit 22 generates the transmission data as one of three values: a negative state "-1", a positive state "1", and a zero state "0". Converts communication data into a specified length and summarizes the communication data The signal is modulated to convert it into a communication symbol and output to the transmitting / receiving unit 21. 3 length This shows a form in which one communication symbol is composed of communication data. In this case, the first communication data of the communication symbol is configured to be in the negative state "-1" or the positive state "1" so that the beginning of the communication data on the receiving side can be determined. The transmitter / receiver 21 converts the series of communication data into an analog communication signal and then transmits it via the insulating unit 25 and the communication line 31. At this time, the symbol length Ts, which is the length of one symbol to be transmitted, is shorter than the communication symbol interval Tp, which is the interval between communication symbols.

[0038] In the battery monitoring device 5a on the receiving side, the transmitter / receiver units 11 and 12 are in a reception standby state from the time of power-on, and the demodulation control signal DEMOD_EN, which controls whether or not to demodulate the received communication signal, is in a demodulation enabled state "H" and is on standby. After power-on, the communication control unit 16 of the battery monitoring IC 7 of the battery monitoring device 5a executes a process of reading the communication symbol length Ts from the memory unit 14. Specifically, after power-on, the communication control unit 16 reads the values DEMOD_TH1 and DEMOD_TH2 pre-stored in the memory unit 14 into a register corresponding to the communication symbol length Ts and then goes into standby.

[0039] When the transmitter / receiver 21 of the battery monitoring ECU 4 transmits a communication analog signal at timing t1 in Figure 5, the transmitter / receiver 11 of the battery monitoring IC 7 compares the received communication analog signal using a comparator set to use a high high threshold Vth as the comparison target and a comparator set to use a low low threshold Vtl as the comparison target, and converts it into a received digital signal.

[0040] The communication control unit 16 of the battery monitoring IC 7 has a built-in counter, and is configured to receive communication symbols from the time when the communication data of the communication symbol is first received until a predetermined number of counts based on the length of the communication symbol stored in the memory unit 14 is counted.

[0041] Specifically, when the transmitter / receiver 11 detects the first signal of the communication symbol, the communication control unit 16 of the battery monitoring IC 7 starts counting up from timing t1 when the first communication data is received. The counter counts up sequentially based on the clock generated by the clock generation unit 13. Since the demodulation control signal DEMOD_EN is active "H", the received digital signal is demodulated at each predetermined timing.

[0042] The communication control unit 16 receives and demodulates communication data through the transceiver units 11 and 12 until the counter reaches the register value DEMOD_TH1, i.e., while the demodulation control signal DEMOD_EN is active "H." That is, while the demodulation control signal DEMOD_EN is active, the communication control unit 16 determines whether the state of the received communication data is a positive state "1," a negative state "-1," or a zero state "0" at the sampling timing generated based on the clock by the clock generation unit 13.

[0043] In this embodiment, the communication symbol is send The data is predetermined to be 3 bits. Therefore, based on the aforementioned value DEMOD_TH1, the 3-bit information, and the counter value, the 3-bit sampling timing can be specified by the counter value, and at the specified sampling timing, it can be determined whether the state is a positive state "1," a negative state "-1," or a zero state "0." Since no power is consumed in the zero state "0," it is possible to achieve both communication speed and power consumption, and further realize communication that is resistant to noise superimposed on the communication lines 31 to 34.

[0044] When the counter reaches the register value DEMOD_TH1 at timing t5, the communication control unit 16 sets the demodulation control signal to "L" to disable demodulation, resets the count value, and continues counting.

[0045] After that, when the counter reaches the register value DEMOD_TH2, the demodulation control signal is changed to the demodulation enabled state "H". While the demodulation control signal is in the state "L", the communication control unit 16 does not perform demodulation operation. Therefore, even if the transmitter / receiver units 11 and 12 malfunction due to noise during the period t5 to t6 when the demodulation control signal is in the state "L", demodulation operation is not performed and a healthy communication state can be maintained. After that, communication symbols can be communicated as shown in t6 to t11 in Figure 5. In this way, the communication processing of communication symbols can be repeated and continued at each communication symbol interval Tp.

[0046] In addition, it is also possible to use another counter installed inside the communication control unit 16 to count the clock of the built-in clock generation unit 13, estimate the error in the oscillation frequency of the clock generation unit 13, and correct the clock frequency of the clock generation unit 13.

[0047] Constructing a single communication symbol send The encoding method for 3-bit data is shown in Figure 6. send When encoding data, it is advisable to define the communication data in chronological order as eight types: "-1" "1" "0", "-1" "1" "-1", "1" "-1", "1" "-1" "0", "1" "-1" "1", "-1" "0" "1", "-1" "0" "-1", "1" "0" "-1", "1" "0" "1". Then, a 3-bit send Data can be expressed in only three units of time, where "-1" indicates a negative state, "1" indicates a positive state, and "0" indicates a zero state.

[0048] Constructing a single communication symbol send The encoding method for 2-bit data is shown in Figure 7. sendTo encode the data, it is advisable to define the communication data in chronological order as four types: "-1", "1", "0", "1", "-1", "0", "-1", "0", "1", "1", "0", "-1", as shown in Figure 7. Then, the 2-bit send Data can be expressed in only three units of time.

[0049] Constructing a single communication symbol send Figure 8 shows the encoding method for 4-bit data. As shown in Figure 8, when encoding 4-bit data, it is recommended to define the communication data in chronological order as one of 16 types: "-1", "1", "0", "1", "-1", "1", "0", "-1", "-1", "1", "-1", "1", "-1", "-1", "-1", "1", "-1", "-1", "1", "-1", "0", "1", "-1", "0", "1", "-1", "0", "1", "-1", "0", "-1", "1", "0", "-1", "1", "0", "-1", "1", "0", "-1", "1", "0", "-1", "1", "0", "-1", "0 ...0", "1", "0", "1", "0", "1", "0", "1", "0", "1". This allows 4-bit data to be expressed in only four units of time.

[0050] That is, in the configuration of multi-bit data, the beginning of the multi-bit data is set as a negative state "-1" or a positive state "1", and thereafter, it may be set so that it can take any of the three states of the negative state "-1", the positive state "1", and the zero state "0". In other words, it is desirable that the rule of communication data satisfies the condition that the positive state "1" is followed by the negative state "-1" or the zero state "0", the negative state "-1" is followed by the positive state "1" or the zero state "0", and the zero state "0" is followed by the positive state "1" or the negative state "-1". This allows for even more bits than 2 to 4 bits.

[0051] <Comparison with comparative examples> Generally, when communication data is transmitted using only the positive state "1" and the negative state "-1," the number of times the switching element switches increases proportionally to the number of times these positive state "1" and negative state "-1" occur, and as shown in characteristic B of the conventional technology in Figure 9, the current consumption increases in direct proportion to the data rate.

[0052] In the communication data setting examples shown in Figures 6 to 8, the data rate at which 1 bit can be transmitted within the ranges of Figures 6 to 8 is set to a reference value of 1. Then, the relative values of the data rates can be expressed as (2-bit data):(3-bit data):(4-bit data) = 4:6:8, as shown in characteristic A of this embodiment in Figure 9.

[0053] As explained with reference to FIGS. 6 to 8, by communicating communication data using the zero state "0," it is possible to suppress an increase in the number of changes between the positive state "1" and the negative state "-1." Furthermore, when changing from the positive state "1" or the negative state "-1" to the zero state "0," or from the zero state "0" to the positive state "1" or the negative state "-1," the change in level is smaller than when changing from the positive state "1" to the negative state "-1." This reduces switching loss and further reduces power consumption. Therefore, even if the data rate is increased, the current consumption does not increase as in the prior art, and power consumption can be reduced. In this embodiment, as shown in characteristic A in FIG. 9, the relative current consumption ratio for (2-bit data):(3-bit data):(4-bit data) can be converted to 4:4.5:5.8.

[0054] According to this embodiment, in the configuration of multi-bit data, the beginning of the multi-bit data is set to a negative state "-1" or a positive state "1", and thereafter, the multi-bit data About the states that make up This allows any of the three levels to be taken. This eliminates the theoretical upper limit on the number of multi-bit data that can be configured, and allows it to be increased as needed. This reduces the current consumption per communication symbol communicated in one modulation while allowing the receiving side to Top state6 to 8 show examples of communication symbol configurations, but it goes without saying that other combinations are also possible.

[0055] (Second embodiment) The second embodiment will be described with reference to Fig. 10 and Fig. 11. For example, when the communication coding method of the first embodiment is used, one communication symbol interval Tp is expressed as a positive state "1" or a negative state "-1". Number of states If is increased, the ratio of zero-state "0" that does not consume current decreases, and the effect of reducing power consumption is diminished. On the other hand, it can be seen that power consumption can be further reduced by increasing the number of zero-state "0" that constitutes communication data per communication symbol interval Tp as much as possible.

[0056] During normal operation, when the analog communication signal transmitted through the communication lines 31-34 reaches the low threshold Vtl or the high threshold Vth, the receiving side recognizes the communication data as a positive state "1" or a negative state "-1." However, if the zero state "0" is significantly increased to maximize the benefits of low power consumption, the zero state "0" period becomes longer. This can result in a drop in standby voltage, which can lead to malfunction. In this case, if the number of negative state "-1"s and positive state "1"s is not balanced, the standby voltage can deviate significantly from the standard value for the zero state "0." If it exceeds a certain range, the communication signal may not reach the low threshold Vtl, resulting in a malfunction. As shown in Figure 10, when the transmitting side transmits continuous communication data in the positive state "1" and negative state "-1," the receiving side cannot reach either the high threshold Vth or the low threshold Vtl. In the example shown in Figure 10, this does not reach the low threshold Vtl, causing a malfunction.

[0057] For this reason, when composing communication data consisting of a positive state "1", a zero state "0", and a negative state "-1", it is desirable to set it so that it contains the same number of positive states "1" and negative states "-1", and so that the sum of the values representing the positive states "1" and negative states "-1" of the communication data in the communication symbol communicated in one modulation is zero.

[0058] In particular, as a combination of the negative state "-1", the positive state "1", and the zero state "0", it is desirable that the negative state "-1" and the positive state "1" occur once per communication symbol interval Tp, and that the number of other zero states "0" occur twice or more.

[0059] Constructing a single communication symbol send The encoding method for 3-bit data is shown in Figure 11. send When setting the negative state "-1" and the positive state "1" once for each data, as shown in Figure 11, it is advisable to set the negative state "-1" at the beginning and shift the position of the positive state "1" to be set thereafter for each communication data, or to set the positive state "1" at the beginning and shift the position of the negative state "-1" to be set thereafter for each communication data. send Data can be expressed in 5 units of time.

[0060] Constructing a single communication symbol send The encoding method for 4-bit data is shown in Figure 12. send When setting the negative state "-1" and the positive state "1" once for each data, as shown in Figure 12, it is advisable to set the negative state "-1" at the beginning and shift the position of the positive state "1" to be set thereafter for each communication data, or to set the positive state "1" at the beginning and shift the position of the negative state "-1" to be set thereafter for each communication data. send Data can be expressed in 9 units of time.

[0061] A modified example is shown in Figures 13 and 14. sendOnly the case where the data is "000" is shown as an example, and other combinations are omitted. If the positive state "1" and the negative state "-1" are the same number in a communication symbol, two positive states "1" may be set and two negative states "-1" may be set. Note that the communication data at the beginning of a communication symbol must be set to the negative state "-1" or the positive state "1", but the position of the zero state "0" may be set at any position other than the beginning, and as shown in Figure 13, it may be set at the middle of a communication symbol. situation Alternatively, as shown in Figure 14, the last symbol of the communication situation You can also set it to .

[0062] In this embodiment, when communicating each communication data per communication symbol interval Tp, the positive state "1" and the negative state "-1" are set to the same number of times, so that the current consumption can be suppressed compared to the first embodiment, and the current consumption when transmitting each communication data can be further reduced to approximately the ideal value. In particular, when the negative state "-1" and the positive state "1" are set to occur only once and the rest constitute multiple zero states "0", the number of zero states "0" can be increased, and the current consumption can be reduced to the maximum.

[0063] (Third embodiment) The third embodiment will be described with reference to Fig. 15 to Fig. 18. When the technology according to the present application is used, the communication data per communication symbol interval Tp is Multi-state If the zero state "0" between the positive state "1" and the negative state "-1" is set for a long period of time, the clock signal that determines the sampling timing on the receiving side may not be synchronized, and normal communication may not be possible.

[0064] Therefore, the first communication data that constitutes the communication symbol is 2 state is It is preferable to use a Manchester coded data structure. Manchester coded data is also known as a binary phase keying scheme, and is an encoding method in which the binary states of "1" and "0" are assigned to the transition from the negative state "-1" to the positive state "+1", or to the transition between the positive state "+1" and the negative state "-1", respectively.

[0065] Figure 15 shows three bits No 4 bits in Figure 16 No In Figures 15 and 16, the first two bits of communication data enclosed in a thick frame are set to a positive state "1" and a negative state "-1", or a negative state "-1" and a positive state "1". 2 states is constructed as a Manchester code. 2 states The timing of the state transitions of the 2 states This allows the transmission of signals embedded with a clock having a period equal to the interval between state transitions.

[0066] In the example of FIG. 15, on the transmitting side, for example, the first 2 states is assigned to the positive state "1" and the negative state "-1" to transmit a communication signal. The third state From then on, a normal transmission digital signal (see FIG. 5) is transmitted, with a positive pulse P for a positive state "1", a negative pulse N for a negative state "-1", and a predetermined stable potential (zero potential) for a zero state "0".

[0067] First Two states When setting the Manchester code of, for example, The third state When setting the communication data to the correct state "1", the first First state The communication data is set to the positive state "1" and Second state It is recommended to set the communication data to the negative state "-1". The third state When setting the communication data as negative state "-1", the first First state The communication data is set to negative state "-1" and Second state It is recommended to set the communication data to the positive state "1".

[0068] In addition, the final communication data, which is the postamble, contains the first First stateThis allows the number of positive states "1" and negative states "-1" per communication symbol interval Tp to be equal, and the potentials of the communication lines 31 to 34 to be balanced.

[0069] The battery monitoring ECU 4 receives the first 2 states When one Manchester-encoded communication symbol is transmitted to the receiver, the transmitter / receiver 11 of the battery monitoring IC 7 on the receiver side converts the Manchester-encoded received analog signal into the first 2 states The rising edge or falling edge of the detected signal is detected as a state transition.

[0070] The communication control unit 16 measures the time interval between state transitions detected in each communication symbol and obtains a recovered clock having a period equal to the communication symbol interval Tp. The communication control unit 16 counts the clock signal of the built-in clock generation unit 13 during the time interval at which an edge of the measured recovered clock occurs. The communication control unit 16 then compares the counted number of clocks of the clock generation unit 13 with a reference clock number estimated in advance and stored in the storage unit 14, thereby estimating an error in the oscillation frequency of the clock generation unit 13 and correcting the oscillation frequency of the clock generation unit 13.

[0071] This makes it possible to correct the difference between the oscillation frequency of the clock signal of the clock generating unit 24 included in the battery monitoring ECU 4 and the oscillation frequency of the clock signal of the clock generating unit 13. In addition, the communication control unit 16 can also perform correction by adding an offset to the count value of the counter, and can also correct various operation timings based on the clock signal of the clock generating unit 13.

[0072] Here, we have shown a form in which the oscillation frequency deviation of the clock signal of the clock generation unit 13 in the battery monitoring device 5a is adjusted to the oscillation frequency of the clock signal of the clock generation unit 24 of the battery monitoring ECU 4, but the same can be applied to adjusting the oscillation frequency deviation of the clock signals of the clock generation units 13 inside other battery monitoring devices 5b and 5c.

[0073] In this case, the battery monitoring ECU 4 receives the first signal via the transmitting / receiving unit 21. 2 states When a communication symbol using Manchester code is transmitted to the battery monitoring devices 5b and 5c through the communication lines 31 to 33 in the order of the ring connection, the signal 2 states This can convey information about the time interval between edges.

[0074] The battery monitoring ECU 4 and the battery monitoring devices 5a, 5b, and 5c are ring-connected by communication lines 31 to 34. For this reason, if a normal signal is transmitted to a later stage, the arrival time error accumulates. 2 states By transmitting information on the time intervals between the state transitions, the battery monitoring ECU 4 can transmit information on the time intervals between the battery monitoring devices 5a, 5b, and 5c. 2 states The time intervals between the state transitions can be made approximately the same.

[0075] Therefore, in the battery monitoring devices 5b and 5c, counting is performed using the clock signal of the clock generating unit 13 built in each device. 2 states By comparing the time interval between the edges of the clock signal with a reference clock number estimated in advance and stored in the storage unit 14, deviations in the oscillation frequency of the clock signal can be corrected in the same way as in the battery monitoring device 5a.

[0076] As a result, the oscillation frequency of the clock signal of the clock generating unit 13 built into each of the battery monitoring devices 5a, 5b, 5c can be easily adjusted to the frequency of the clock signal of the clock generating unit 24, which has a relatively high accuracy.

[0077] In the above description, the time interval between Manchester-encoded falling / rising edges is measured to correct the oscillation frequency of the clock signal of the clock generating unit 13, but this is not limiting. For example, the communication control unit 22 of the battery monitoring ECU 4 may transmit two consecutive pulses through the transmitting / receiving unit 11, and the battery monitoring devices 5a, 5b, and 5c may count the time interval between the rising edges or falling edges of the pulses using a clock signal, compare it with a reference clock number, and correct the oscillation frequency of the clock generating unit 13. Alternatively, the first 1 state The interval, for example, the time interval between a rising edge and a falling edge, or the time interval between a falling edge and a rising edge, may be used to correct the oscillation frequency. 1 state Not limited to the intervals of 1 state The oscillation frequency may be corrected by using the interval.

[0078] Modifications are shown in Figures 17 and 18. Figures 17 and 18 only show the case where the communication data is "001", and omit other combinations. If the number of positive states "1" and negative states "-1" is the same within a communication symbol, three positive states "1" may be set and three negative states "-1" may be set.

[0079] In addition, from the beginning of the communication symbol 2 states The communication data must be set to a negative state "-1" or a positive state "1", but the position of the zero state "0" can be set to any position other than the first two bits. It can also be set to the middle communication data of the communication symbol as shown in Figure 17, or to the last communication data of the communication symbol as shown in Figure 18. 1 state In other words, the polarity of the beginning and end does not have to be reversed, and the beginning may be set to the positive state "1" while the end may be set to the zero state "0".

[0080] (Other embodiments) The present invention is not limited to the above-described embodiment, but can be implemented in various modifications and variations without departing from the spirit of the present invention. For example, the following modifications or extensions are possible.

[0081] In the above embodiment, the communication symbol is configured with three values: a negative state "-1", a positive state "1", and a zero state "0", but the present invention is not limited to this. The negative state is not limited to "-1", and may be coded as a negative state "-2", a negative state "-3", etc., and the communication analog signal may be amplitude-modulated according to the absolute values of these multiple sets of negative states "-1", "-2", and "-3".

[0082] Similarly, the positive state is not limited to "1" and may be coded as a positive state "2," a positive state "3," etc. The analog signal may be amplitude-modulated according to the absolute values of these multiple sets of positive states "1," "2," and "3." In this case, by configuring the communication symbols so that the sum of the numerical values of the communication data is zero, the potentials of the communication lines 31 to 34 can be kept well balanced between positive and negative with respect to the zero potential corresponding to the zero state "0," and the same effects as those of the above-described embodiment can be obtained.

[0083] The communication control unit 16 of the battery monitoring IC 7 has been shown to read the values DEMOD_TH1 and DEVOD_TH2 as the communication symbol length Ts from the memory unit 14 after power-on and set them in a register, but these values DEMOD_TH1 and DEMOD_TH2 may also be able to be changed by instructing the battery monitoring devices 5a, 5b, and 5c from the battery monitoring ECU 4 side.

[0084] For example, the communication control unit 22 of the battery monitoring ECU 4 transmits the command values DEMOD_TH1 and DEVOD_TH2 to the communication data constituting the communication symbol. State ofThis is because by changing the value DEMOD_TH1, the period during which the demodulation control signal DEMOD_EN is active can be changed, and the communication symbol length Ts that can be received on the receiving side can be changed. At this time, the communication control unit of the battery monitoring device 5a, 5b, 5c transmits an acknowledgement (ACK) when it receives this change command. This allows the number of communication data that make up the communication symbol to be changed. Number of states can be configured to be modifiable.

[0085] The battery monitoring ECU 4 and the battery monitoring devices 5a, 5b, and 5c described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the battery monitoring ECU 4 and the battery monitoring devices 5a, 5b, and 5c described herein may be implemented by a special-purpose computer configured with a processor and one or more dedicated hardware logic circuits.

[0086] Alternatively, the battery monitoring ECU 4, battery monitoring devices 5a, 5b, and 5c and the methods described herein may be implemented by one or more dedicated computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured by one or more hardware logic circuits. Also, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitory tangible storage medium.

[0087] Although the present invention has been described based on the above-described embodiment, it is understood that the present invention is not limited to the embodiment or structure. The present invention also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including one, more, or less than one element, are also within the scope and spirit of the present invention. [Explanation of symbols]

[0088] In the drawing, 3 indicates a battery monitoring system (insulated communication system), 4 indicates a battery monitoring ECU, 9, 10, 25, and 26 indicate insulating units, 14 and 23 indicate memory units, and 16 and 22 indicate communication control units.

Claims

1. A device for encoding transmission data of a predetermined amount of information in one of three or more states expressed by integers, modulating the data to convert it into a communication symbol that summarizes communication data of a predetermined length, and communicating insulatedly through an insulating unit (9, 10, 25, 26) using the communication symbol, comprising a communication control unit (21, 16) that configures the communication data with three or more values including one or more positive states ("1", "2") and one or more negative states ("-1", "-2") in which the absolute values of the states expressed by the integers are the same, and a zero state ("0") that does not consume current intermediate between the positive and negative states, the communication control unit is configured to set the first communication data among the communication symbols to the positive state or the negative state, and to set the communication data in the subsequent communication symbols so that they can take any of the three or more states; The present invention is applied to a battery monitoring system (3) including a battery monitoring ECU (4) and a plurality of battery monitoring devices (5a, 5b, 5c) that acquire and monitor the voltages of the battery cells of an assembled battery formed by connecting a plurality of battery cells, the battery monitoring ECU and the plurality of battery monitoring devices each include the communication control unit; a communication control unit (22) of the battery monitoring ECU and a communication control unit (16) of the plurality of battery monitoring devices communicate insulated with each other by differential signals through the insulating unit; A storage unit (14) is provided for storing the length of a communication symbol communicated in one modulation, the communication control unit reads the length of the communication symbol from the storage unit after power-on; An insulated communication system in which the length of the communication symbol can be changed by transmitting a command value from the communication control unit of the battery monitoring ECU and receiving an acknowledgement from the communication control unit of the battery monitoring device.

2. A device for encoding transmission data of a predetermined amount of information in one of three or more states expressed by integers, modulating the data to convert it into a communication symbol that summarizes communication data of a predetermined length, and communicating insulated through an insulating unit (9, 10, 25, 26) using the communication symbol, comprising a communication control unit (21, 16) that configures the communication data with three or more values including one or more positive states ("1", "2") and one or more negative states ("-1", "-2") in which the absolute values of the states expressed by the integers are the same, and a zero state ("0") that does not consume current intermediate between the positive and negative states, the communication control unit is configured to set the first communication data among the communication symbols to the positive state or the negative state, and to set the communication data in the subsequent communication symbols so that they can take any of the three or more states; The communication control unit Manchester encodes the binary state of the first bit of the transmission data and communicates it as two states of the first communication data that constitute the communication symbol.

3. A clock generating unit (13) that generates a clock signal, 3. The isolated communication system according to claim 2, wherein a rising edge or a falling edge is detected by detecting two states of the first Manchester-encoded communication data, the time interval between the falling and rising edges of the detected state transition is measured and obtained as a recovered clock, and the recovered clock is compared with a clock signal of the clock generating unit having the recovered clock, thereby correcting the oscillation frequency of the clock generating unit, the count value of a counter that counts by counting the clock of the clock generating unit, or operation timing based on the clock signal of the clock generating unit.

4. A storage unit (14) is provided for storing the length of a communication symbol communicated in one modulation, 2. The insulated communication system according to claim 1, wherein the communication control unit (16) receives the communication symbol from the time when the communication data of the communication symbol is first received until a predetermined number of counts based on the length of the communication symbol stored in the memory unit is reached.

5. 2. The insulated communication system according to claim 1, wherein the communication control unit sets the sum of values representing the positive and negative states of the communication data in the communication symbols communicated in one modulation to zero.

6. 2. The insulated communication system according to claim 1, wherein the communication control unit sets the communication data using multiple pairs of positive states ("1", "2") and negative states ("-1", "-2"), each of which has the same absolute value as the other, expressed as an integer.

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