Power supply system

Abstract

To provide a power supply system capable of continuing supply of power requested by a vehicle by preventing overheat of a main power source when supplying power to a load by combining outputs from the main power source and a sub power source.SOLUTION: A power supply system comprises: a large capacity type main power source; a high output type sub power source; an output regulator which is connected to at least one of both the power sources; and a control device which controls outputs of both the power sources. The power supply system combines outputs from both the power sources and supplies the combined output to a load. The control device determines an output limit value limiting the output of the main power source in such a manner that an actual temperature of the main power source does not exceed a limit temperature and adjusts output balance of both the power sources via the output regulator on the basis of the output limit value. Thus, the present invention can provide the power supply system capable of continuing supply of power requested by a vehicle by preventing overheat of the main power source.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power supply system, and more particularly to a power supply system that combines outputs from a plurality of power supplies to supply power to a load. [Background technology]

[0002] A known power source for driving an electric vehicle is a main power source that supplies power during normal driving, and also a secondary power source that supplies power when greater power than during normal driving is required, such as during acceleration or climbing a slope.

[0003] Patent Document 1 describes a power supply system for a vehicle that combines multiple power sources, and discloses that when the power required by the vehicle is less than a predetermined value, such as during normal driving, switching control is performed to disconnect one of the power sources from the load. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4433671 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of the system described in Patent Document 1, if the power required by the vehicle continues to be less than a specified value, such as during normal driving, only the main power supply connected to the load will repeatedly perform power running and regeneration, causing the main power supply to overheat and making it necessary to limit the power supply, and therefore it is not possible to continue supplying the power required by the vehicle.

[0006] The present invention has been made in consideration of the problems associated with the conventional technology, and an object of the present invention is to provide a power supply system that prevents overheating of the main power supply and can continue to supply the power required by the vehicle. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above-mentioned object, the inventors have discovered that even when the power required by the vehicle falls below a predetermined value and the power required by the vehicle can be supplied by the main power supply alone, by actively using both power supplies in combination and limiting the output of the main power supply based on the temperature of the main power supply, it is possible to prevent the main power supply from overheating and achieve the above-mentioned object, which has led to the completion of the present invention.

[0008] That is, the power supply system of the present invention is a power supply system comprising a large-capacity main power supply, a high-output secondary power supply, an output regulator connected to at least one of the two power supplies, and a control device that controls the outputs of the two power supplies, and combines the outputs from the two power supplies and supplies the combined output to a load, The control device is characterized in that it determines an output limit value that limits the output of the main power supply so that the actual temperature of the main power supply does not exceed its limit temperature, and adjusts the output balance of both power supplies via the output regulator based on the output limit value. Effect of the Invention

[0009] According to the present invention, since the output of the main power supply is limited based on the temperature of the main power supply and the output balance of both power supplies is adjusted, it is possible to provide a power supply system capable of preventing overheating of the power supply. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a circuit diagram showing an example of a circuit of a power supply system according to the present invention. [Diagram 2] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Diagram 3] 10A and 10B are schematic diagrams showing an example of determining an output limit value. [Figure 4] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Diagram 5] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Figure 6] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Figure 7]FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Figure 8] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Figure 9] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. [Figure 10] FIG. 1 is a diagram illustrating an example of a control device for a power supply system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The power supply system of the present invention will now be described in detail. The power supply system of the present invention is shown in FIG. The power supply system is equipped with a power supply circuit and a control device in which a large-capacity main power supply and a high-output secondary power supply are connected in parallel, the outputs from both power supplies are combined, and power is supplied to a load (motor) via an inverter.

[0012] The main power supply may be a secondary battery such as a lithium ion battery, and the secondary power supply may be an electric double layer capacitor (EDLC) in addition to a secondary battery such as a lithium ion battery. The combination of the main power supply and the secondary power supply is a combination of power supplies with different characteristics, such as output density, capacity density, and internal resistance.

[0013] In the power supply circuit of the power supply system of the present invention, a DC-DC converter is connected in parallel to the secondary power supply, and this DC-DC converter converts the voltage of the secondary power supply based on the gate signal generated by the control device, thereby regulating the power supplied from the secondary power supply to the load and also indirectly regulating the power supplied from the main power supply to the load. Although the DC-DC converter is connected to the secondary power supply in FIG. 1, it may be connected to the main power supply 2, or may be connected to both the main power supply and the secondary power supply.

[0014] The control device receives a torque command value indicating the amount of torque that the motor should generate from the vehicle controller, and calculates the vehicle required power P that the inverter supplies to the motor based on this torque command value.ref Calculate.

[0015] In addition, the control device sets the output limit value P limit Determine the output limit value P limit and the vehicle required power P ref Depending on the result of the comparison, a gate signal is output to the DC-DC converter to adjust the output balance between the main power supply and the sub-power supply.

[0016] Specifically, the vehicle required power P ref is the output limit value P limit If the vehicle power requirement P ref is the output limit value P limit If so, a gate signal for causing the DC-DC converter to operate is output, causing the sub-power supply to supply power P2.

[0017] In this state, the calculated vehicle required power P ref to the motor, the amount of power supplied to the inverter is the sum of power P1 supplied from the main power supply and power P2 supplied from the secondary power supply, so that the power P1 supplied from the main power supply can be indirectly adjusted by adjusting the power P2 supplied from the secondary power supply.

[0018] In other words, when the power supply from the secondary power supply is stopped, power P1 is supplied from the main power supply. Also, when power P2 is being supplied from the secondary power supply, power P1 supplied from the main power supply is reduced, and the current flowing through the main power supply is reduced, thereby suppressing the temperature rise of the main power supply.

[0019] In this way, in the power supply system of the present invention, the output limit value P limit is set sequentially based on the actual temperature of the main power supply measured by the temperature sensor, and the output limit value P limit Since the main power supply is changed, overheating of the main power supply can be prevented, and the supply of electric power required by the vehicle can be continued.

[0020] Generally, since a temperature sensor is installed in the power supply's housing, it is not possible to detect the internal temperature of the power supply. Therefore, the actual temperature of the power supply is not calculated by directly using the temperature detected by the temperature sensor installed in the power supply, but by correcting the value detected by the temperature sensor based on the input / output current (charging current / discharging current) from the power supply.

[0021] <Determining the output limit value> The output limit value P of the above main power supply 2 limit is the limit temperature T ps1 target The amount of heat generated can be determined by calculating the amount not exceeding this range.

[0022] Limit temperature T ps1 target is the upper limit temperature at which the main power supply can be prevented from deteriorating due to overheating when the amount of power output by the main power supply continues for a certain period of time, for example, 30 to 60 seconds. This limit temperature T ps1 target are the internal resistance R1 of the main power supply 2 and the thermal resistance R th1 and heat capacity C1, which are stored in advance in the control device.

[0023] Specifically, as shown in Figure 2, the actual temperature measured by the temperature sensor is used as the starting point, and the temperature of the main power supply is set to the limit temperature T ps1 target The allowable heat value P is the upper limit of the heat value allowed for the main power supply, which does not exceed loss lim is the thermal resistance of the main power supply R th1 and heat capacity C1.

[0024] And the calculated allowable heat amount P loss lim and the internal resistance R1 of the main power supply 2, the upper limit current I limit Calculate the upper limit current I limit and the actual measured mains voltage value Vps1 The product of this and the output limit value P of main power supply 2 limit It can be said that:

[0025] FIG. 3 shows an example of how the output limit value is determined. In Figure 3, the actual temperature of the mains supply is limited by Tps1 target The output limit value of the main power supply P limit has been decided. This makes it possible to easily prevent the main power supply from overheating.

[0026] In addition, the output limit value P of the main power supply limit can also be determined from the actual temperature difference between the primary and secondary power supplies.

[0027] As shown in Figure 4, the actual temperature of the mains, T ps1 and the actual temperature of the secondary power supply T ps2 The actual temperature difference between the main power supply and the sub-power supply at that time is measured as the detection value, 0 as the target value, and the difference between the detection value and the target value as the deviation. The output limit value P of the main power supply is calculated by PI control. limit Determine.

[0028] This allows the actual temperature of the mains, T ps1 and the actual temperature of the secondary power supply T ps2 Since the two power supplies will remain almost the same, it is possible to actively use both power supplies in combination, adjust the output balance of the two power supplies, and prevent the main power supply from overheating.

[0029] Furthermore, the output limit value P limit is the limit temperature of the main power supply T ps1 target is the target value, and the predicted temperature T ps1 est are the detected values, and the difference between these target values ​​and the detected values ​​T ps1 error It can also be determined by PI control with deviation.

[0030] This reduces the heat output to the output limit value P limit Since the influence of modeling errors and disturbances can be reduced compared to when calculating

[0031] (Calculation of expected temperature from power consumption) The above expected temperature T ps1 est As shown in Figs. 5 to 7, the amount of power supplied to the main power supply is calculated, and the amount of heat generated by the main power supply and the temperature rise are calculated from the relationship between the amount of heat generated by the main power supply and the temperature rise when the main power supply supplies that amount of power. The heat generation amount of the above main power supply is the actual temperature T PS1 Starting from the thermal resistance R of the main power supply 2, which is stored in the control device in advance, th1 , and heat capacity C1.

[0032] This allows the expected temperature T of the main power supply to be calculated based on the amount of power actually supplied to the main power supply. ps1 est Therefore, the expected temperature T ps1 est The accuracy is improved.

[0033] The control device also calculates the expected temperature T ps1 est As shown in Fig. 5, the average value P of the amount of power supplied to the main power source from the past to the present is used instead of using 1ave Based on the expected temperature T of the main power supply ps1 est It is preferable to calculate

[0034] Specifically, the moving average value P of the amount of power supplied to the main power source from 30 to 60 seconds ago to the present 1ave Calculate the expected temperature of the main power supply T based on this average value. ps1 est Calculate.

[0035] This allows the main power supply to reach a predicted temperature T ps1 est The expected temperature T of the main power supply, which has little effect on the ps1 est Using this, the output limit value P limit Since the above-mentioned is determined, overheating of the main power supply can be prevented with high accuracy.

[0036] Furthermore, as shown in FIG. 6, the expected temperature T ps1 est The amount of power actually supplied to the main power supply is integrated from the present back by the thermal time constant of the main power supply, and the integral value P lint can also be used.

[0037] Expected temperature of the main power supply T ps1 est The integral value P of the amount of power supplied by the main power supply lintBy calculating using the above average value P 1ave The error is smaller than when using the output limit value P limit can be determined.

[0038] Furthermore, as shown in FIG. 7, the expected temperature T ps1 est The differential value P of the amount of power actually supplied to the main power supply 1dif , that is, the expected temperature T of the main power supply calculated using the slope of the power supply in the range of the thermal time constant of the main power supply ps1 est can also be used.

[0039] As a result, the amount of power supplied from the main power source continues to increase and decrease, and the moving average value of the power amount P 1ave The expected temperature of the main power supply T ps1 est Even if the error of the differential value P 1dif By using this, the expected temperature of the main power supply T ps1 est It is possible to calculate the following.

[0040] (Calculation of expected temperature from temperature change) In addition, the expected temperature T ps1 est is calculated based on the amount of power supplied to the main power supply, but also based on the actual temperature T PS1 The actual temperature T PS1 It can also be calculated from the change in

[0041] This allows the actual temperature of the mains, T PS1 Based on the expected temperature T of the main power supply ps1 est This reduces the effect of modeling errors due to the thermal network, and allows for an output limit value P that can accurately prevent the main power supply from overheating. limit can be determined.

[0042] Specifically, as shown in FIG. 8, the actual temperature T PS1 Moving average value of T ps1ave Calculate the average value Tps1ave Based on the expected temperature T of the main power supply ps1 est Calculate.

[0043] As shown in Fig. 9, the integral value T ps1int can also be used. This results in the above average value T ps1ave The error is smaller than when using the output limit value P limit can be determined.

[0044] Furthermore, as shown in FIG. 10, the expected temperature T ps1 est , the actual temperature of the main power supply T ps1 Derivative of change T ps1dif , i.e. the actual temperature T within the thermal time constant of the mains ps1 The expected temperature of the main power supply, T, calculated using the slope of the change ps1 est can also be used.

[0045] This allows the actual temperature of the mains, T ps1 However, the actual temperature of the main power supply T PS1 Moving average value of T ps1ave The expected temperature of the main power supply T ps1 est Even if the error of the differential value T ps1dif By using this, the expected temperature of the main power supply T ps1 est It is possible to calculate the following.

[0046] The control device of the present invention is a temperature controller for detecting the expected temperature T ps1 est The method of calculating the expected temperature from the above-mentioned amount of electric power or the method of calculating the expected temperature from the above-mentioned temperature change is selected according to the time history of the amount of electric power supplied by the main power source or the time history of the actual temperature of the main power source, and the expected temperature T ps1 est can be determined.

[0047] This allows the expected temperature to be reached T ps1 estThis reduces the difference between the actual temperature of the main power supply and the temperature at which the main power supply is actually generated, thereby preventing overheating of the main power supply and allowing the supply of power required by the vehicle to continue. [Explanation of symbols]

[0048] 1 Main power 2 Sub power supply 3 Inverter 4 Load (motor) 5 Output regulator (DC-DC converter) 6. Control device S Power System

Claims

1. A large-capacity main power supply, A high-output secondary power supply, an output regulator connected to at least one of the two power sources; A control device for controlling the outputs of both power sources, A power supply system that combines outputs from both power supplies and supplies the combined output to a load, The control device determines an output limit value for limiting an output of the main power supply so that an actual temperature of the main power supply does not exceed the limit temperature; A power supply system comprising: a power regulator that adjusts the output balance of the two power supplies based on the output limit value.

2. 2. The power supply system according to claim 1, wherein the control device determines an output limit value of the main power supply from a current value that can be flowed through the main power supply, the current value being calculated from a limit temperature of the main power supply, and an actual voltage value of the main power supply.

3. The control device sequentially measures the temperature of the main power supply and the temperature of the secondary power supply, 2. The power supply system according to claim 1, wherein the output limit value of the main power supply is determined by PI control, with the measured actual temperature difference between the main power supply and the secondary power supply as the detection value, 0 as the target value, and the difference between the detection value and the target value as the deviation.

4. The control device predicts a temperature that the main power supply will reach after a unit time has elapsed; The main power supply limit temperature is the target value, and the predicted temperature is the detection value.

2. The power supply system according to claim 1, wherein the output limit value of the main power supply is determined by PI control using a difference between the target value and the detected value as a deviation.

5. 5. The power supply system according to claim 4, wherein the control device calculates an amount of power supplied by the main power supply, and determines the predicted temperature to be reached based on a relationship between the amount of power and the amount of heat generated by the main power supply.

6. 6. The power supply system according to claim 5, wherein the control device calculates an expected temperature to be reached by the main power supply from the relationship and a moving average value of the amount of power supplied by the main power supply.

7. 6. The power supply system according to claim 5, wherein the control device calculates an expected temperature to be reached by the main power supply from the relationship and an integral value of the amount of power supplied by the main power supply.

8. 6. The power supply system according to claim 5, wherein the control device calculates an expected temperature to be reached by the main power supply from the relationship and a differential value of the amount of power supplied by the main power supply.

9. 5. The power supply system according to claim 4, wherein the control device successively measures the temperature of the main power supply and determines the predicted temperature from the change over time of the actual temperature of the main power supply that is measured.

10. 10. The power supply system according to claim 9, wherein the control device determines the predicted temperature from a moving average value of a time change in an actual temperature of the main power supply.

11. 10. The power supply system according to claim 9, wherein the control device determines the predicted temperature from an integral value of a time change in an actual temperature of the main power supply.

12. 10. The power supply system according to claim 9, wherein the control device determines the predicted temperature from a differential value of a time change in an actual temperature of the main power supply.

13. The control device, The value used to calculate the predicted temperature is determined according to the time history of the amount of power supplied by the main power source. selecting one value selected from the group consisting of a moving average value of the amount of power supplied by the main power source, an integral value of the amount of power supplied by the main power source, and a differential value of the amount of power supplied by the main power source, and determining an expected temperature to be reached by the main power source; or Depending on the time history of the actual temperature of the main power supply, the value used to calculate the expected temperature is: selecting one value selected from the group consisting of a moving average value of the change over time of the actual temperature of the main power supply, an integral value of the change over time of the actual temperature of the main power supply, and a differential value of the change over time of the actual temperature of the main power supply, and determining an expected temperature to be reached by the main power supply; 5. The power supply system according to claim 4 .

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