Relay temperature estimation control method and estimation control system

Abstract

To provide a relay temperature estimation control method and a relay temperature estimation control system that highly accurately estimate relay temperature at which a power source circuit is turned on and off and accurately control the relay on the basis of the estimated temperature value.SOLUTION: In a relay temperature estimation control system 10, a control unit 12 of a battery pack 32 calculates the degradation level of a relay on the basis of the-number-of-times information from a counter that counts the number of times of connections and disconnections of relays 18-22, determines a temperature estimation factor KO for estimating the temperature of the relay from a current flowing through the relay on the basis of the degradation level of a relay, measures a temperature Ta in the battery pack by a temperature sensor 26, and measures a current value I flowing through the relay with a current sensor 16 installed inside the battery pack. A temperature T1 of the relay is estimated by T1=KO*I+Ta from the measured temperature Ta inside the battery pack, the measured current value I, and the temperature estimation factor KO. When the estimated relay temperature T1 is higher than a preset value Tset, the relay is controlled for cooling.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a relay temperature estimation control method and an estimation control system, and more particularly to a relay temperature estimation control method and an estimation control system for estimating and controlling the relay temperature of a relay that controls the on / off of an in-vehicle power supply circuit. [Background technology]

[0002] A relay is mounted on the power supply circuit of a vehicle, and the vehicle is started and stopped by controlling the on / off of this relay. Since the power supply is high voltage, the on / off operation of the relay causes deterioration of the contacts due to arc discharge. Normally, the temperature inside the box that contains the relay is measured using a temperature sensor, and control is performed to prevent relay failure based on the measured temperature.

[0003] In Patent Document 1, two temperature sensors, a positive running circuit temperature sensor and a negative running circuit temperature sensor, are provided to measure the temperature inside the junction box housing the relays etc. separately for the positive circuit and the negative circuit, and the positive and negative relays are controlled based on the measured temperatures.

[0004] Patent Document 2 discloses a relay temperature estimation means that estimates the relay temperature based on the voltage applied to the relay winding and the resistance value of the winding. This calculates the amount of heat generated in the entire relay from the voltage applied to the relay and the internal resistance of the relay, and estimates the relay temperature from this amount of heat generation. Then, the relay is controlled based on this estimated temperature. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6671440 [Patent Document 2] JP 2007-276552 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the measured temperature inside the box is regarded as the temperature of the relay, and the relay is controlled based on this temperature. However, the measured temperature does not take into account, for example, the degree of relay deterioration or changes in resistance. In other words, controlling the relay based only on the measured temperature inside the box is, so to speak, a rough control, and cannot be said to be precise control according to the state of the relay at that time.

[0007] The relay temperature estimation means in Patent Document 2 estimates the temperature by calculating the amount of heat generated based only on the voltage applied to the winding of the relay and the resistance value of the winding, so the estimation accuracy is not high. For example, deterioration of the contacts of the relay is not taken into consideration. Furthermore, the temperature of the location where the relay is installed is not taken into consideration.

[0008] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a relay temperature estimation control method and an estimation control system for estimating with high accuracy the temperature of a relay that turns a power supply circuit on and off, and accurately controlling the relay based on the estimated temperature value. [Means for solving the problem]

[0009] In order to achieve the above object, the relay temperature estimation method according to claim 1 comprises the steps of: A relay temperature estimation control method including a relay installed in a battery pack that is installed between a battery module and a load and connects / disconnects the battery module and the load, and a temperature sensor installed in the battery pack, and a control unit controls the relay based on a temperature measured by the temperature sensor, comprising: The control unit is Calculate the relay deterioration level based on the number of times information from a counter that counts the number of times the relay is connected and disconnected. 、 before The temperature sensor measures a temperature Ta inside the battery pack; A current sensor installed in the battery pack detects the current flowing through the relay. addition Measure the value I, The degree of deterioration of the relay The temperature rise of the relay can be calculated by multiplying it by the current integral I, which is the integral of the current flowing through the relay per unit time. Determine the temperature estimation coefficient KO, The relay Estimation Temperature T1 of , the measured internal temperature Ta of the battery pack, addition From the value I and the temperature estimation coefficient KO 、 It is estimated as T1=KO·I+Ta, The estimated relay Estimation of When the temperature T1 is higher than a preset value Tset, the relay is cooled.

[0010] The relay temperature estimated by this method is calculated by the temperature coefficient determined based on the relay deterioration degree and the current flowing through the relay. Current integration The accuracy is high because the estimation is made by taking into account the temperature measured by the temperature sensor and the temperature value. In other words, it is more precise than conventional control in that it takes into account the degree of relay deterioration. In addition, since the relay is controlled based on the highly accurate estimated temperature, accurate control according to the relay state at that time is performed. Therefore, it is possible to accurately estimate the relay temperature using a simple method and accurately control the relay.

[0011] The relay temperature estimation control method according to claim 2 is the relay temperature estimation control method according to claim 1. The control unit is The estimated relay Estimation of If the temperature is lower than the preset temperature, The estimated relay Estimation of Temperature and the measured current addition calculating a first resistance value Rs of the relay from the value; The difference between the voltage of the battery module and the voltage applied to the load and the current addition Calculating a second resistance value R1 of the relay from the value; When the second resistance value R1 is higher than a preset resistance value Rset, the current flowing through the relay is controlled to be equal to or lower than a predetermined current value.

[0012] In this way, when the estimated temperature of the relay is lower than the set temperature, the resistance of the two relays is calculated. addition The first resistance value Rs of the relay calculated from the value, the difference between the voltage of the battery module and the voltage applied to the load, and the current addition The second resistance value R1 of the relay is calculated from the set resistance value Rset. If the second resistance value R1 of the relay is higher than the set resistance value Rset, it is determined that the deterioration of the contacts of the relay is progressing. That is, as the deterioration of the relay progresses, the resistance value of the relay generally increases. In such a situation, if the current value flowing through the relay is high, the resistance value is high, so the amount of heat generated increases, and there is a risk of the relay contact welding. Therefore, by limiting the current value flowing, it is possible to prevent the relay contact welding. Therefore, in addition to the relay temperature being estimated with high accuracy, when it is determined that the deterioration of the relay contacts is progressing, accurate control is performed to limit the current flowing through the relay.

[0013] The relay temperature estimation control method according to claim 3 is the relay temperature estimation control method according to claim 1 or 2, further comprising: If the second resistance value R1 is lower than a set resistance value, the first resistance value Rs is compared with the second resistance value R1; When the second resistance value R1 is higher than the first resistance value Rs, the temperature estimation coefficient KO is corrected to KO·R1 / Rs.

[0014] With this method, the relay is judged to have deteriorated to a certain extent, although it has not deteriorated enough to require restrictions to prevent ignition because the second resistance value R1 is lower than the set resistance value Rset. This is because the resistance value of the relay increases as deterioration progresses. Therefore, a correction is made to increase the temperature estimation coefficient KO from its previous value by R1 / Rs. This results in a current of additionTherefore, the relay temperature is estimated to be high even if the relay temperature is increased by the above-mentioned temperature estimation coefficient, and the relay temperature is estimated appropriately. Therefore, the temperature estimation coefficient according to the deterioration is determined, and the relay temperature is estimated with high accuracy.

[0015] In order to achieve the above object, the relay temperature estimation control system according to claim 4 comprises: A relay temperature estimation control system for executing the relay temperature estimation control method according to any one of claims 1 to 3, A counter for counting the number of times the relay is connected and disconnected; a relay deterioration level calculation unit that calculates a relay deterioration level based on the number information from the counter; The degree of deterioration of the relay The temperature rise of the relay can be calculated by multiplying the current I, which is the integrated current value of the current flowing through the relay, by the proportionality. a temperature estimation coefficient calculation unit that determines a temperature estimation coefficient KO; a temperature sensor for measuring a temperature inside the battery pack; The current through the relay addition a current sensor installed in the battery pack for measuring a current value; The relay Estimation The temperature T1 is the measured temperature Ta, and the measured current addition From the value I and the temperature estimation coefficient KO, T1 is estimated as T1 = KO·I + Ta, The estimated relay Estimation of When the temperature T1 is higher than the set temperature Tset, the relay is cooled. The above-mentioned assumption Relay Estimation If the temperature T1 is lower than a preset temperature Tset, the estimated temperature and the measured current addition A first resistance value Rs of the relay is calculated from the value, and a difference between the voltage of the battery module and the voltage applied to the load and the current addition a second resistance value R1 of the relay is calculated from the value, and if the second resistance value R1 is higher than a set resistance value, a control is performed to limit the current flowing through the relay; When the second resistance value R1 is lower than a set resistance value, the first resistance value Rs and the second resistance value R1 are compared, and when the second resistance value R1 is higher than the first resistance value Rs, the temperature estimation coefficient KO is corrected to KO·R1 / Rs.

[0016] With this configuration, the estimated relay temperature is a temperature determined based on the relay deterioration degree. recommendation Constant coefficient and current through relay Current integration value Since the estimation is made by taking into account the temperature measured by the temperature sensor, the accuracy is high. In other words, the control is more precise than conventional control in that it takes into account the degree of relay deterioration. Furthermore, since the relay is controlled based on the highly accurate estimated temperature, accurate control according to the relay state at that time is performed. Therefore, it is possible to estimate the relay temperature with high accuracy using a simple method and to accurately control the relay. Effect of the Invention

[0017] According to the relay temperature estimation control method and the relay temperature estimation control system of the present invention, the relay temperature is estimated based on the relay deterioration degree. recommendation Constant coefficient and current through relay Current integration value and the temperature measured by the temperature sensor are taken into consideration. In other words, the relay temperature can be estimated with higher accuracy by taking the deterioration degree of the relay into consideration. In addition, since the relay is controlled based on the highly accurate estimated temperature, accurate control is performed by accurately capturing the state of the relay at that time, and therefore improvement of the reliability of the relay is achieved by a simple method. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing a relay temperature estimation control system according to the present invention; [Diagram 2] 3 shows a flowchart of a relay temperature estimation control method of the present invention. [Diagram 3] 3 shows a flowchart of a relay temperature estimation control method of the present invention. [Figure 4] The relationship between the current integrated value I and the estimated temperature T1 in the relay temperature estimation control method of the present invention will be described. [Diagram 5] The relationship between the estimated temperature T1 and the estimated resistance value Rs in the relay temperature estimation control method of the present invention will be described. [Figure 6] The relationship between the voltage difference and the estimated resistance value R1 in the relay control method of the present invention will be described. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a relay temperature estimation control method and a relay temperature estimation control system according to the present invention will be described in detail with reference to the accompanying drawings.

[0020] 1 is a schematic diagram of a relay temperature estimation control system 10 of the present invention. The relay temperature estimation control system 10 has a control unit (battery control unit: BCU) 12, a battery module 14, a current sensor 16, a main relay (N: negative electrode) 18, a pre-charge relay 20, a main relay (P: positive electrode) 22, a fuse 24, and a temperature sensor 26 in a battery pack 32.

[0021] The voltage of the battery module 14 is applied to the load, such as the inverter 28 and high voltage unit 30, via the relays 18, 20, and 22. The method of applying voltage to the load by the relays is as follows: first, the main relay (N) 18 is turned on. Next, the pre-charge relay 20 is turned on to apply a voltage lower than the total voltage Vpn1 of the battery module 14 to the load. After that, the main relay (P) 22 is turned on to apply the total voltage Vpn1 of the battery module to the load. This procedure prevents a large current from suddenly flowing through the relay, which could damage the relay. The total voltage Vpn1 of the battery module 14 is expressed as Vpn1=v1+v2+···vn.

[0022] The current sensor 16 measures the current that flows through the main relay 22 when a voltage is applied from the battery module 14 to the load. It is assumed that a voltage of Vpn2 is applied to the load. Even if the full voltage of the battery module 14 is applied to the load, Vpn1 and Vpn2 are not equal due to voltage drops due to wiring resistance between the battery module 14 and the load side and due to contact resistance of the relay.

[0023] The temperature sensor 26 measures the temperature inside the battery pack 32, but does not directly measure the temperature of the relay. The fuse 24 melts when the current flowing through it exceeds a predetermined value, thereby cutting off the power supply to the load.

[0024] The control unit (battery control unit: BCU) 12 is connected to the current sensor 16, the temperature sensor 26, the battery module 14, and the inverter 28, and receives as input the current value measured by the current sensor 16, the temperature value measured by the temperature sensor 26, the voltage Vpn1 of the battery module 14, and the voltage Vpn2 applied to the inverter 28. The control unit 12 also has a temperature estimation coefficient setting unit that calculates the relay deterioration degree from the number of times the relay is connected and disconnected and determines a temperature estimation coefficient based on the relay deterioration degree, and a relay temperature estimation unit that estimates the relay temperature from the measured temperature inside the battery pack, the measured current value, and the temperature estimation coefficient. Note that a counter that counts the number of times the relay is connected and disconnected is not shown.

[0025] As will be explained in detail below, this configuration allows the relay temperature to be estimated with high accuracy, since it is estimated taking into consideration a temperature coefficient determined based on the relay deterioration degree, the current flowing through the relay, and the temperature measured by the temperature sensor. In addition, since the relay is controlled based on the highly accurate estimated temperature, appropriate control is performed according to the state of the relay at that time. The control includes, for example, cooling the relay and limiting the current to prevent damage to the relay and prevention of relay failure.

[0026] Fig. 2 is a flow diagram of the relay temperature estimation control method of the present invention. Control begins when the vehicle starts to travel (step S1). First, the temperature estimation coefficient KO is determined by the temperature estimation coefficient calculation unit of the control unit 12 (step S2). As shown in Fig. 4, the temperature estimation coefficient KO is an important coefficient that determines the relationship between the current integrated value I and the estimated relay temperature T1. The temperature estimation coefficient KO is a coefficient that is proportional to the number of times the relay is counted and the number of times it is interrupted in an emergency. A large temperature estimation coefficient KO means that the relay contacts have deteriorated significantly.

[0027] Next, the temperature Ta inside the battery pack is measured by the temperature sensor 26 (step S3), the value of the current flowing to the load side is obtained by the current sensor 16, and converted into a current integration value I per unit time (step S4).

[0028] The relay temperature is estimated from the current integration value I and the temperature estimation coefficient KO (step S5). As shown in FIG. 4, the estimated temperature T1 of the relay is approximated by T1=KO·I+Ta. This approximation formula was established in advance through experiments to be more realistic. The initial temperature Ta is the temperature inside the battery pack measured by a temperature sensor. The larger the temperature estimation coefficient KO is, the higher the estimated temperature T1 is even for the same current integration value I. This physically corresponds to the fact that the greater the deterioration of the relay contacts, the higher the resistance value of the relay becomes, and the more heat is generated by the current flow, resulting in a higher estimated temperature. Note that the approximation formula is not limited to the above T1=KO·I+Ta, and various approximation formulas (estimation formulas) can be used. For example, it is also possible to use a quadratic expression of the current integration value I.

[0029] Next, the estimated temperature T1 is compared with the set temperature Tset (step S6). If the estimated temperature T1 is higher than the set temperature Tset (step S3: Yes), the control unit 12 performs cooling control of the relay (step S7). After performing the predetermined cooling, the process returns to step S3 and continues the control. The reason for cooling the relay is to make the temperature of the relay equal to or lower than the set temperature Tset.

[0030] If the estimated temperature T1 is lower than the set temperature Ts (step S6: No), the process proceeds to step S8 in FIG. 3. Step S8 is a process for calculating an estimated resistance value Rs of the relay from the estimated temperature T1 and the current integrated value I. The estimated resistance value Rs can be easily obtained by creating a relationship diagram between the estimated temperature T1 and the estimated resistance value Rs as shown in FIG. 5. For example, a coefficient IO that depends on the current integrated value I can be obtained in advance by experiment or the like so that the estimated resistance Rs and the estimated temperature T1 have the relationship Rs=IO·T1. Note that this equation is not limited to this equation, and various estimation relational equations can be used.

[0031] That is, the coefficient IO is determined by finding the amount of heat generated from the estimated resistance value Rs and the current integrated value I, and calculating the estimated temperature using the specific heat of the materials that make up the relay. Then, for example, the temperature of the relay is accurately measured just once, and the coefficient IO is determined so that the estimated temperature value matches this temperature. By determining IO in this manner, the relationship between the estimated resistance value Rs and the estimated temperature T1 has an accuracy that is suitable for practical use. The coefficient IO becomes smaller as the current integrated value I increases, and becomes larger as I decreases.

[0032] Next, an estimated resistance value R1 is calculated from the voltage difference and the current integrated value I (step S9). The voltage difference is calculated as Vpn1-Vpn2. The estimated resistance value R1 is calculated by dividing this by the current integrated value I. The estimated resistance value R1 is larger as the current integrated value I is smaller, and is smaller as I is larger. The relationship between the voltage difference and the estimated resistance value R1 is as shown in FIG. 5.

[0033] Next, the estimated resistance value R1 is compared with the set value Rset (step S10). If the estimated resistance value R1 is higher than the set value Rset (step S10: Yes), the current flowing through the relay is limited. This is because the estimated resistance value R1 is higher than the set value Rset, and it is predicted that if the maximum allowable current value is passed, heat generation beyond the specified level is generated. After that, the process returns to step S3, and the control of the relay is continued.

[0034] If the estimated resistance value R1 is lower than the set value Rset (step S10: No), the estimated resistance value Rs calculated from the estimated temperature and the current integrated value (step S8) is compared with the estimated resistance value R1 calculated from the voltage difference and the current integrated value (step S9) (step S12).

[0035] If the estimated resistance value R1 is greater than the estimated resistance value Rs (step S12: Yes), the temperature estimation coefficient KO is corrected to KO·R1 / Rs (step S13). In other words, it is assumed that the deterioration of the relay contacts has progressed, and KO is increased by R1 / Rs times from the previous value. This makes it possible to estimate the relay temperature with higher accuracy.

[0036] If the estimated resistance value R1 is smaller than the estimated resistance value Rs (step S12: No), the process returns to step S3, and relay temperature estimation control is performed.

[0037] According to the relay temperature estimation control method and estimation control system of the present invention, the relay temperature is estimated taking into consideration a temperature coefficient determined based on the relay deterioration degree, the current flowing through the relay, and the temperature measured by a temperature sensor. Since the relay deterioration degree is taken into consideration, the accuracy is high. Furthermore, since the relay is controlled based on the highly accurate estimated temperature, accurate control is performed. Therefore, it is possible to accurately estimate the relay temperature using a simple method and accurately control the relay. As a result, the relay temperature is estimated with high accuracy and accurate control is performed based on the estimated temperature, improving the reliability of the relay.

[0038] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the first resistance value Rs is estimated from the estimated relay temperature T1 and the current integrated value I by Rs=IO·T1 (IO is a coefficient), but other approximation formulas (estimation formulas) may be used. [Explanation of symbols]

[0039] 10 Relay temperature estimation control system 12 Control section (battery control unit: BCU) 14 Battery module 16 Current Sensor 18 Main relay (N) 20 Precharge Relay 22 Main relay (P) 24. Fuse 26 Temperature Sensor 28 Inverter (load) 30 High voltage unit (load) 32 Battery pack

Claims

1. A relay temperature estimation control method including a relay installed in a battery pack that is installed between a battery module and a load and that connects and disconnects the battery module and the load, and a temperature sensor installed in the battery pack, and in which the relay is controlled by a control unit based on a temperature measured by the temperature sensor, comprising: The control unit is Calculating a relay deterioration level based on number information from a counter that counts the number of times the relay is connected and disconnected; The temperature sensor measures a temperature Ta in the battery pack; A current sensor installed in the battery pack measures an integrated current value I flowing through the relay; a temperature estimation coefficient K0 that is proportional to the deterioration degree of the relay and that can be used to obtain a temperature rise of the relay by multiplying the temperature estimation coefficient K0 by a current integral value I that is an integral value of a current flowing through the relay per unit time; The estimated temperature T1 of the relay is estimated from the measured internal temperature Ta of the battery pack, the current integrated value I, and the temperature estimation coefficient KO by T1 = KO · I + Ta; A relay temperature estimation and control method, comprising the steps of: controlling the relay to be cooled when an estimated relay temperature T1 is higher than a preset value Tset.

2. The control unit is If the estimated temperature of the relay is lower than a preset temperature, calculating a first resistance value Rs of the relay from the estimated temperature of the relay and the measured integrated current value; calculating a second resistance value R1 of the relay from a difference between a voltage of the battery module and a voltage applied to the load and the current integrated value; 2. The relay temperature estimation control method according to claim 1, wherein when the second resistance value R1 is higher than a preset resistance value Rset, a control is performed to adjust the current flowing through the relay to a predetermined current value or less.

3. The control unit is If the second resistance value R1 is lower than a set resistance value, the first resistance value Rs is compared with the second resistance value R1; 3. The relay temperature estimation control method according to claim 2, wherein when the second resistance value R1 is higher than the first resistance value Rs, the temperature estimation coefficient KO is corrected to KO·R1 / Rs.

4. A relay temperature estimation control system for executing the relay temperature estimation control method according to any one of claims 1 to 3, A counter that counts the number of times the relay is connected and disconnected; a relay deterioration level calculation unit that calculates a relay deterioration level based on the number information from the counter; a temperature estimation coefficient calculation unit that determines a temperature estimation coefficient K0 that is proportional to the relay deterioration degree and that determines a temperature rise of the relay by multiplying the relay by a current integrated value I of the current flowing through the relay; a temperature sensor for measuring a temperature inside the battery pack; a current sensor installed in the battery pack for measuring an integrated value of a current flowing through the relay; The estimated temperature T1 of the relay is estimated from the measured temperature Ta, the measured current integrated value I, and the temperature estimation coefficient KO by T1 = KO · I + Ta; When the estimated temperature T1 of the relay is higher than a set temperature Tset, the relay is cooled. When the estimated temperature T1 of the relay is lower than a preset temperature Tset, a first resistance value Rs of the relay is calculated from the estimated temperature and the measured current integrated value, and a second resistance value R1 of the relay is calculated from the current integrated value and a difference between the voltage of the battery module and the voltage applied to the load, and when the second resistance value R1 is higher than a preset resistance value, control is performed to impose a limit on the current flowing through the relay; a relay temperature estimation control system comprising: a relay temperature estimation coefficient calculating section for calculating a temperature estimation coefficient of a relay temperature estimation coefficient; a relay temperature estimation coefficient calculating section for calculating a temperature estimation coefficient of a relay temperature estimation coefficient;

Images