JP2011010501A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device capable of improving the whole efficiency in charging and discharging of electric storage.SOLUTION: The power device includes a DC-DC converter 23 connected to a generator 11 and a main power supply 17; an electrical storage 29 connected to the other end and an output voltage detector 31 connected to the generator 11. The power device, further, consists of a charging-state detecting means (a current detector 34) connected to the main power supply 17, and a control circuit 35 connected to the DC-DC converter 23, the output voltage detector 31 and the charging-state detecting means. When the generator 11 generates regenerative power, the control circuit 35 controls the DC-DC converter 23, in such a way that when a charging state SOC is small, an output voltage Vd is raised; and when the charging state SOC is large it is lowered within a range from a lower control voltage Vdk lower by a first specified voltage width ΔV1 than a first specified output voltage Vdc1 to an upper control voltage Vdu which is higher by a second specified voltage width ΔV2 than a second specified output voltage Vdc2.

Description

  The present invention relates to a power supply device that stores electric power in a power storage element and discharges it when necessary.

  In recent years, vehicles have been proposed that achieve fuel efficiency by storing and effectively using regenerative power generated during braking in a power storage unit made up of power storage elements. For example, Patent Document 1 proposes a power control device used in such a vehicle. FIG. 4 is a block circuit diagram of such a power control apparatus.

  The main power source 101 is a lead battery, and a load 105 is connected to the positive electrode via an ignition switch 103. A vehicle generator 107 is connected to the positive electrode of the main power supply 101. Since the generator 107 is mechanically connected to the engine 109, the generator 107 is driven by the operation of the engine 109. Further, the tire 109 is mechanically connected to the engine 109, and the tire 111 is rotated by the driving force of the engine 109 to drive the vehicle. Further, at the time of deceleration due to braking, the tire 111 rotates due to the inertia of the vehicle, whereby the engine 109 also rotates. The generator 107 is driven by this rotational energy, and regenerative power is obtained.

  In order to efficiently recover the regenerative power from such a vehicle, the power generator 107 is connected to a power storage means 115 as the power storage unit via a DC / DC converter 113. Since a large-capacity electric double layer capacitor is used as the power storage element in the power storage means 115, a large amount of short-term power generated during sudden deceleration can be efficiently recovered. The DC / DC converter 113 is connected to an arithmetic device 117 for controlling its operation. Further, the arithmetic unit 117 is provided with a signal receiving terminal 119 for receiving various signals from the vehicle side. Accordingly, the arithmetic unit 117 receives the vehicle running state, the engine 109 operating state, the voltage state of the main power supply 101, and the like from the signal receiving terminal 119, thereby charging and discharging the power storage means 115 according to those states. Control is performed on the DC / DC converter 113.

  By using the power control device with such a configuration, the regenerative power during deceleration including large power generated in a short period of time is once charged in the power storage means 115, and the regenerative power charged other than during deceleration is charged. Can be supplied to the main power supply 101 and the load 105. As a result, efficient regeneration of braking energy is possible.

Japanese Patent No. 3465293

  According to the power control device described above, it is possible to reduce the fuel consumption of the vehicle by efficient regeneration, but the charging destination of the regenerative power generated during deceleration is controlled so as to be changed by the voltage of the main power supply 101. ing. That is, if the voltage is 13V or more, the regenerative power is charged to the power storage means 115 by the DC / DC converter 113, and if the voltage is less than 13V, the regenerative power is charged to the main power source 101. This voltage of 13V substantially corresponds to the open voltage at the time of full charge in a lead battery of 12V specification. Therefore, although the voltage is less than 13V, if it is in the vicinity of 13V, the main power supply 101 close to full charge is connected to the main power supply 101. Regenerative power will be charged. Therefore, when the main power supply 101 is close to being fully charged and the charge acceptance (charging efficiency) is low, that is, the state of charge SOC (corresponding to the amount of power charged in the main power supply 101 is 100% and fully charged) is 100%. If it is large in the vicinity, the main power supply 101 may not be able to be efficiently charged with the regenerative power.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a power supply device that can efficiently charge regenerative power to a main power supply.

  In order to solve the conventional problems, a power supply device of the present invention includes a DC / DC converter electrically connected to an output terminal of a generator to which a main power supply is connected, and the other end of the DC / DC converter. An electrically connected power storage unit, an output voltage detection circuit that is electrically connected to the output terminal and a ground terminal of the generator, and detects an output voltage (Vd) of the output terminal; And a control circuit electrically connected to the DC / DC converter, an output voltage detection circuit, and a charge state detection means, which are connected to each other and detect the state of charge (SOC) of the main power source. The generator increases the adjustment voltage (Va) of the output terminal to the first predetermined output voltage (Vdc1) when generating regenerative power, and the adjustment voltage (Va) when not generating the regenerative power. Second already The control circuit reduces the output voltage (Vdc2) to a first predetermined voltage width (ΔV1) that is greater than the first predetermined output voltage (Vdc1) when the regenerative power is generated. ) In a range from a lower control voltage (Vdk) lower than the second predetermined output voltage (Vdc2) to an upper control voltage (Vdu) higher by a second predetermined voltage width (ΔV2) than the second predetermined output voltage (Vdc2). The DC / DC converter is controlled so as to increase when the state of charge (SOC) is large, so that the output voltage (Vd) is increased when the regenerative power is not generated. The DC / DC converter is controlled to be Vdu).

  According to the present invention, the adjustment voltage (Va) of the generator is raised to the first predetermined output voltage (Vdc1) at the time of regeneration, and is lowered to the second predetermined output voltage (Vdc2) at other times. Electric power can be obtained and efficiency is improved. Further, when charging the regenerative power obtained in this way, the state of charge (SOC) should be large so that the output voltage (Vd) at the output terminal of the generator will be high if the state of charge (SOC) of the main power supply is small. Since the DC / DC converter is controlled so that the output voltage (Vd) is low, the regenerative power is charged to the main power source when the charging state (SOC) is small and the charging efficiency is high, When the state of charge (SOC) is large and the charging efficiency is low, charging of the regenerative power to the main power supply is suppressed. At this time, since the control range of the output voltage (Vd) is from the lower control voltage (Vdk) to the upper control voltage (Vdu), the output voltage (Vd) is controlled to be higher than the lower control voltage (Vdk). In this case, unnecessary power from the power storage unit and unnecessary power from the main power source when the output voltage (Vd) is controlled lower than the upper control voltage (Vdu) are suppressed. As a result, it is possible to efficiently charge the regenerative power to the main power source and further improve the efficiency of the entire power supply device.

1 is a block circuit diagram of a power supply device according to an embodiment of the present invention. Correlation diagram of charge state SOC and charge efficiency in main power supply of power supply device according to the embodiment of the present invention It is a time-dependent change figure of the various characteristics of the power supply device in embodiment of this invention, (a) is a time-dependent change figure of a vehicle speed, (b) is a time-dependent change figure of the adjustment voltage Va of a generator, (c) is a main power supply. (D) is a time-dependent change diagram of the output voltage Vd of the generator, (e) is a time-dependent change diagram of the reference voltage Vst of the DC / DC converter, and (f) is a power storage unit of the power storage means. Time course of voltage Vc Block diagram of a conventional power control device

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a block circuit diagram of a power supply device according to an embodiment of the present invention. FIG. 2 is a correlation diagram between the state of charge SOC and the charging efficiency in the main power supply of the power supply device according to the embodiment of the present invention. FIG. 3 is a time-dependent change diagram of various characteristics of the power supply device according to the embodiment of the present invention, (a) is a time-dependent change diagram of the vehicle speed, (b) is a time-dependent change diagram of the adjustment voltage Va of the generator, (c) is a time-dependent change diagram of the state of charge SOC of the main power supply, (d) is a time-dependent change diagram of the generator output voltage Vd, (e) is a time-dependent change diagram of the reference voltage Vst of the DC / DC converter, f) shows the time-dependent change figure of the electrical storage part voltage Vc of an electrical storage means, respectively. In FIG. 1, thick lines indicate power system wirings, and thin lines indicate signal system wirings. Moreover, in each figure of FIG. 3, a horizontal axis is time.

  In FIG. 1, a generator 11 is mechanically connected to an engine (not shown), and generates electric power according to the rotation of the engine. Note that the output voltage Vd at the output terminal 13 of the generator 11 is set by a signal from a vehicle-side control circuit (not shown), that is, an adjustment voltage Va. In the present embodiment, it is assumed that the adjustment voltage Va has two stages of the first predetermined output voltage Vdc1 (= 15V) and the second predetermined output voltage Vdc2 (= 13V).

  A main power supply 17 is electrically connected to the output terminal 13 of the generator 11 by power system wiring. The main power source 17 is composed of a lead battery. Further, a load 19 and a starter 21 are electrically connected to the output terminal 13 by the power system wiring. The load 19 is various on-vehicle electrical components, and the starter 21 is a motor for starting the engine. The starter 21 is controlled to be driven and stopped by an ignition switch (not shown). The ground terminal 22 of the generator 11 is electrically connected to the ground on the vehicle side.

  The output terminal 13 is connected to one end (input / output terminal 25) of the DC / DC converter 23 by the power wiring. On the other hand, a power storage unit 29 is electrically connected to the other end (power storage unit terminal 27) of the DC / DC converter 23. Here, the power storage unit 29 has a configuration in which four electric double layer capacitors having a rated voltage of 2.5 V are connected in series. Therefore, the upper limit voltage Vcu of the power storage unit 29 is 10V. In consideration of the withstand current of the DC / DC converter 23, the lower limit voltage Vck was determined to be 5V. Therefore, the power storage unit voltage Vc changes between 5V and 10V.

  Accordingly, the voltage at the input / output terminal 25 of the DC / DC converter 23 is the output voltage Vd (set to either 13V or 15V) at the output terminal 13, and the voltage at the power storage unit terminal 27 is the power storage unit voltage Vc. (5 to 10 V), the DC / DC converter 23 steps down the voltage at the input / output terminal 25 to charge the power storage unit 29 and boosts the power storage unit voltage Vc to discharge from the input / output terminal 25. It has a converter configuration.

  Further, an output voltage detection circuit 31 is directly and electrically connected to the output terminal 13 and the ground terminal 22 through a signal system wiring. Thereby, it is possible to detect the output voltage Vd of the output terminal 13 with reference to the ground terminal 22 with high accuracy without being affected by the internal resistance value in each wiring.

  Similarly, a power storage unit voltage detection circuit 33 that detects a power storage unit voltage Vc is electrically connected between the power storage unit terminal 27 and the power storage unit 29.

  The main power supply 17 is electrically connected in series with a current detection circuit 34 which is a part of the charge state detection means for detecting the state of charge SOC. In the present embodiment, since the state of charge SOC is obtained by time integration of the current Ib flowing through the main power supply 17, the current detection circuit 34 detects the current Ib necessary for the calculation. The current detection circuit 34 may be configured to directly detect the current Ib based on the voltage across the shunt resistor (not shown), or may be configured to detect the current Ib in a non-contact manner using a Hall element or the like. Here, the time integration of the obtained current Ib is performed by the control circuit 35 described later. Therefore, the current detection circuit 34 and the time integration operation of the control circuit 35 are collectively referred to as a charge state detection means. The current detection circuit 34 may have a built-in time integration function as charge state detection means, and the charge state SOC may be directly output.

  The DC / DC converter 23, the output voltage detection circuit 31, the power storage unit voltage detection circuit 33, the current detection circuit 34, and the vehicle side control circuit are electrically connected to the control circuit 35 by signal system wiring. The control circuit 35 outputs the output voltage Vd detected by the output voltage detection circuit 31, the power storage unit voltage Vc detected by the power storage unit voltage detection circuit 33, the current Ib detected by the current detection circuit 34, and the vehicle side control circuit. Based on the regenerative signal reg, the control signal cont of the DC / DC converter 23 is output. Here, the control circuit 35 is a circuit for comparing the output voltage Vd and the storage unit voltage Vc with each reference signal, a logic circuit, a pulse waveform generating circuit for switching the DC / DC converter 23, etc. (all not shown). It is comprised by. The control circuit 35 may have a digital circuit configuration including a microcomputer and peripheral circuits.

  Next, the operation of such a power supply device will be described.

  First, the correlation between the state of charge SOC and the charging efficiency in the main power supply 17 is shown in FIG. As shown in FIG. 2, when the state of charge SOC is small, the charging efficiency to the main power supply 17 is close to 100%. Therefore, it turns out that it can charge with high efficiency. However, when the state of charge SOC is large, particularly when it exceeds 97%, the charge efficiency decreases rapidly, and when the state of charge SOC approaches 100%, the charge efficiency decreases to just over 50%. Therefore, even if regenerative power is generated due to deceleration or braking of the vehicle, if the state of charge SOC is large, the regenerative power cannot be sufficiently recovered and the efficiency is reduced.

  Based on such characteristics, a specific operation in the present embodiment will be described with reference to FIG. In the following description, traveling of a vehicle is defined as a state in which the vehicle is traveling at a reduced speed (inertial traveling) without acceleration, constant speed, or driver's braking operation, The decelerating traveling accompanied by the driver's braking operation is called braking.

  As shown in FIG. 3A, the vehicle starts traveling at time t0, and the vehicle speed increases with time. At this time, the vehicle-side control is performed so that the output voltage Vd of the generator 11 becomes the second predetermined output voltage Vdc2 (= 13V) when the vehicle is running and the first predetermined output voltage Vdc1 (= 15V) when braking. The adjustment voltage Va is output from the circuit. Therefore, since the generator 11 is running from the time t0 to the time t1 when the acceleration ends, the adjusted voltage Va of 13V is input to the generator 11 as shown in FIG. However, in the present embodiment, the power generation of the generator 11 caused by the engine consuming fuel is stopped until the state of charge SOC of the main power supply 17 falls below 90%. As a result, fuel consumption for driving the generator 11 is reduced while the state of charge SOC is 90% or more, so that fuel consumption can be reduced and the efficiency of the vehicle is improved.

  Therefore, from the time t0 to the time t1, the state of charge SOC is 90% or more as shown in FIG. 3C, so that although the adjustment voltage Va is input to the generator 11, power generation is not performed. As is clear from FIG. 3C, the present embodiment describes a case where the state of charge SOC does not fall below 90% during the vehicle travel period.

  From these facts, from time t0 to time t1, the generator 11 does not generate power, and as shown in FIG. 3 (f), the power storage unit voltage Vc of the power storage unit 29 becomes the lower limit voltage Vck (= 5V). Therefore, the power of the main power supply 17 is supplied to the load 19. As a result, as shown in FIG. 3C, the state of charge SOC decreases with time. At the same time, the output voltage Vd (corresponding to the voltage of the main power supply 17 here) gradually decreases with time, but here it is shown as being approximately 13 V from the scale relationship of FIG.

  At time t0, the power storage unit voltage Vc is discharged to the lower limit voltage Vck as described above. Therefore, in order to prevent the DC / DC converter 23 from discharging any more, The reference voltage Vst as the control target becomes the lower limit voltage Vck. As described above, when the power storage unit voltage Vc reaches the upper limit voltage Vcu (= 10 V) or the lower limit voltage Vck (= 5 V), control is performed to maintain those values in order to avoid overcharge and overdischarge. Further, since the efficiency of the DC / DC converter 23 is reduced when the power storage unit voltage Vc is too low, the lower limit voltage Vck is set to avoid this. Note that a thick dotted line from time t0 to time t1 in FIG. 3E indicates the reference voltage Vst with respect to the voltage of the input / output terminal 25 that is originally controlled. Therefore, from time t0 to time t1 in FIG. 3 (e), the voltage is originally controlled to the upper control voltage Vdu (= 13.1 V), which will be described later, but since the storage unit voltage Vc is the lower limit voltage Vck, DC / DC The converter 23 indicates that the power storage unit voltage Vc is controlled to maintain the lower limit voltage Vck. The meaning of the thick dotted line in FIG.

  Next, at time t1, the vehicle performs braking as shown in FIG. As a result, regenerative power is generated, so that the regenerative signal reg is turned on and input from the vehicle side control circuit to the control circuit 35. As a result, as shown in FIG. 3B, the adjustment voltage Va of the generator 11 becomes the first predetermined output voltage Vdc1 (= 15V), and the generator 11 attempts to generate power by raising the output voltage Vd to 15V. . As a result, as much kinetic energy as possible from braking can be recovered as the regenerative electric power, and the efficiency of the entire vehicle is improved. However, at this time, the control target of the DC / DC converter 23 is switched to the output voltage Vd, and the reference voltage Vst becomes the lower control voltage Vdk as shown in FIG. As a result, as shown in FIG. 3D, the output voltage Vd is controlled by the DC / DC converter 23 so as to become the lower control voltage Vdk instead of the first predetermined output voltage Vdc1.

  Details of these operations will be described below.

  First, the basic operation during braking will be described. In the present embodiment, when the regenerative power is generated, the control circuit 35 sets the charge state SOC to the default charge so that the output voltage Vd becomes the lower control voltage Vdk if the charge state SOC is smaller than the default charge state SOCs. If the state SOCs or higher, the DC / DC converter 23 is controlled so that the output voltage Vd becomes the upper control voltage Vdu.

  Here, the definition of each constant is as follows.

  The default state of charge SOCs is the state of charge SOC when the charging efficiency rapidly decreases in FIG. 2, and in this embodiment, the state of charge SOC = 97% is determined as the default state of charge SOCs.

  The lower control voltage Vdk means a voltage lower than the first predetermined output voltage Vdc1 by the first predetermined voltage width ΔV1, and is specifically determined as follows.

  The first predetermined voltage width ΔV1 is obtained as a total error width ΔVer which is the sum of the output voltage maximum error width of the generator 11 and the voltage control maximum error width of the DC / DC converter 23. Note that the voltage control maximum error width of the DC / DC converter 23 includes the detection error of the output voltage detection circuit 31. Specifically, as a result of actual measurement, the output voltage maximum error width of the generator 11 was about 0.05V, and the voltage control maximum error width of the DC / DC converter 23 was about 0.05V. It was determined to be 0.1V. From this value, the lower control voltage Vdk is determined to be lower than the first predetermined output voltage Vdc1 (= 15V) by the first predetermined voltage width ΔV1 (= 0.1V), that is, Vdk = 14.9V.

  The upper control voltage Vdu means a voltage that is higher than the second predetermined output voltage Vdc2 by a second predetermined voltage width ΔV2, and is specifically determined as follows.

  First, the second predetermined voltage width ΔV2 is obtained as a total error width ΔVer (= 0.1 V) in the same manner as the first predetermined voltage width ΔV1. From this value, the upper control voltage Vdu is determined to be higher than the second predetermined output voltage Vdc2 (= 13V) by a second predetermined voltage width ΔV2 (= 0.1V), that is, Vdu = 13.1V.

  From the above, when the regenerative signal reg is turned on at time t1, the control circuit 35 determines whether the state of charge SOC at that time is equal to or higher than the predetermined state of charge SOCs according to the basic operation. As shown in FIG. 3C, the state of charge SOC at time t1 is about 96.2%, which is smaller than the predetermined state of charge SOCs (= 97%). Therefore, the regenerative power can be charged to the main power source 17 with high efficiency from FIG. Therefore, the control circuit 35 controls the DC / DC converter 23 so that the output voltage Vd becomes the lower control voltage Vdk (= 14.9 V). Specifically, the control target of the DC / DC converter 23 is switched to the output voltage Vd, and the reference voltage Vst becomes the lower control voltage Vdk as shown in FIG. As a result, the DC / DC converter 23 has a first predetermined voltage width ΔV1 (= 0.1 V) lower than the first predetermined output voltage Vdc1 (= 15 V) when the generator 11 generates the regenerative power. Since the power storage unit 29 is charged via the DC / DC converter 23 because of the control, the absolute amount is small, and the regenerative power is mainly charged to the main power source 17 having a small charge state SOC and good charging efficiency.

  When these operations are described with reference to FIG. 3, the output voltage Vd becomes the lower control voltage Vdk as shown in FIG. 3D at time t1, and the power storage unit 29 is charged as shown in FIG. At the same time as Vc rises, the main power supply 17 is mainly charged as shown in FIG. 3C, and the state of charge SOC rises with time. At this time, a part of the regenerative power is supplied to the load 19. Further, since the power storage unit 29 is composed of the electric double layer capacitor excellent in rapid charge / discharge characteristics, the absolute amount of charge to the power storage unit 29 is smaller than that of the main power supply 17, but the initial generation of the regenerative power (time t1) The steep change in can be fully charged. Therefore, the overall recovery efficiency is improved.

  Here, in order to obtain a high efficiency by performing control to charge the main power supply 17 with as much regenerative power as possible, it is desirable that the lower control voltage Vdk is as close to the first predetermined output voltage Vdc1 as possible. However, if it is too close, the output voltage Vd may exceed the first predetermined output voltage Vdc1 due to fluctuations in the output voltage Vd and control errors of the DC / DC converter 23. In this case, although the regenerative power is generated, the power storage unit 29 cannot be charged, and the power is discharged from the power storage unit 29 and flows backward. Therefore, the lower control voltage Vdk is determined as a voltage lower than the first predetermined output voltage Vdc1 by the first predetermined voltage width ΔV1 (= total error width ΔVer). As a result, the regenerative power as much as possible can be charged to the main power supply 17 while reducing the backflow from the power storage unit 29, and the overall efficiency can be improved. The first predetermined voltage width ΔV1 may be determined to be larger than the total error width ΔVer. However, as described above, in order to charge the regenerative power to the main power source 17 as much as possible, the first predetermined voltage width ΔV1 It is desirable to make ΔV1 close to the total error width ΔVer.

  Thereafter, at time t2 during braking, the power storage unit voltage Vc reaches the upper limit voltage Vcu as shown in FIG. Thus, DC / DC converter 23 performs control so that power storage unit voltage Vc maintains upper limit voltage Vcu in order to avoid overcharging of power storage unit 29. As a result, since the output voltage Vd is no longer controlled by the DC / DC converter 23, the output voltage Vd becomes the first predetermined output voltage Vdc1 (= 15V) at time t2 as shown in FIG. And the regenerative power is supplied to the load 19. In addition, when the charging of the power storage unit 29 is stopped, the regenerated power corresponding to that amount is charged to the main power supply 17 when the power consumption of the load 19 is constant. Therefore, as shown in FIG. 3C, the gradient of the change in the state of charge SOC with time is larger from time t2 to time t3 than from time t1 to time t2.

  Next, at time t3, as shown in FIG. 3A, the vehicle is accelerated again. As a result, the regenerative signal reg is turned off, so that the adjustment voltage Va returns to the second predetermined output voltage Vdc2 (= 13 V) as shown in FIG. Note that the state of charge SOC at this time is about 98.3% from FIG. 3C, and is larger than the value (90%) of the state of charge SOC at which the generator 11 consumes fuel and starts power generation. Therefore, even when the adjustment voltage Va returns to the second predetermined output voltage Vdc2 as described above, the generator 11 does not generate power.

  Accordingly, at time t3, the DC / DC converter 23 discharges the regenerative power stored in the power storage unit 29. Specifically, as shown in FIG. 3E, the reference voltage Vst is switched to the upper control voltage Vdu (= 13.1 V), and the output voltage Vd is controlled to become the upper control voltage Vdu. The method for determining the upper control voltage Vdu is as described above.

  When the reference voltage Vst is set to the upper control voltage Vdu as described above, the DC / DC converter 23 discharges the regenerative power from the power storage unit 29. As a result, as shown in FIG. 3D, the output voltage Vd maintains the upper control voltage Vdu during traveling from time t3 to time t4. Further, as described above, since the regenerative power is discharged from the power storage unit 29, the power storage unit voltage Vc decreases with time from time t3 to time t4 as shown in FIG. 3 (f). On the other hand, since the upper control voltage Vdu is slightly higher than the voltage of the main power supply 17, the amount of power that the regenerative power once charged in the power storage unit 29 is charged in the main power supply 17 is suppressed, and is mainly supplied to the load 19. The Therefore, an overall highly efficient power supply device can be realized. As a result, as shown in FIG. 3C, the state of charge SOC becomes substantially constant from time t3 to time t4.

  Here, in order to obtain high efficiency by such control, it is desirable that the upper control voltage Vdu be as close to the second predetermined output voltage Vdc2 as possible. However, if it is too close, the output voltage Vd may fall below the second predetermined output voltage Vdc2 due to fluctuations in the output voltage Vd and control errors of the DC / DC converter 23. In this case, since the output voltage Vd is lower than the voltage of the main power supply 17 (here, the charged state SOC is about 98.3% and is almost fully charged, which is about 13 V), the power storage unit 29 is connected to the regenerative power. In some cases, the power of the main power supply 17 is unnecessarily charged even though the battery is being discharged. Therefore, the upper control voltage Vdu is determined as a voltage higher than the second predetermined output voltage Vdc2 by the second predetermined voltage width ΔV2 (= total error width ΔVer). Thus, the regenerative power stored in the power storage unit 29 can be supplied to the load 19 without charging the main power source 17 as much as possible while reducing the possibility of unnecessary charging from the main power supply 17 to the power storage unit 29. The overall efficiency can be improved. The second predetermined voltage width ΔV2 may be determined to be larger than the total error width ΔVer. However, as described above, in order to prevent charging from the power storage unit 29 to the main power source 17 as much as possible, 2 It is desirable to make the predetermined voltage width ΔV2 close to the total error width ΔVer.

  In addition, although the first predetermined voltage width ΔV1 and the second predetermined voltage width ΔV2 are both equal (= total error width ΔVer), this is not limited to the same value. When the accuracy changes according to the absolute value of the voltage, or when the control accuracy at the time of charging the power storage unit 29 by the DC / DC converter 23 differs from the control accuracy at the time of discharge, etc. The first predetermined voltage width ΔV1 and the second predetermined voltage width ΔV2 may be set individually.

  Thereafter, when the power storage unit voltage Vc reaches the lower limit voltage Vck at time t4 as shown in FIG. 3F, the reference voltage Vst is switched to the lower limit voltage Vck as shown in FIG. As a result, the power storage unit voltage Vc maintains the lower limit voltage Vck after time t4. At the same time, the DC / DC converter 23 does not control the output voltage Vd. At this time, as shown in FIG. 3C, the state of charge SOC is about 98.3%, which exceeds 90%. Therefore, the power generation by the generator 11 is not performed, and the power storage unit 29 is not powered. Instead, the main power supply 17 supplies power to the load 19. Accordingly, after time t4, the state of charge SOC decreases with time. Along with this, the output voltage Vd becomes the voltage of the main power supply 17, but since the state of charge SOC at this time is about 98.3% and is almost fully charged, the voltage of the main power supply 17 is a value close to the open voltage of 13V. It becomes. Therefore, as shown in FIG. 3D, the output voltage Vd is 13 V (corresponding to the second predetermined output voltage Vdc2). Thereafter, with the power supply from the main power supply 17 to the load 19, the output voltage Vd also decreases with time. As described above, the output voltage Vd is shown to be approximately 13V from the scale relationship of FIG.

  Note that the state from time t4 to time t5 is the same state as from time t0 to time t1.

  Thereafter, the vehicle brakes again at time t5. As a result, the regeneration signal reg is turned on, and the control circuit 35 compares the state of charge SOC with the predetermined state of charge SOCs in the same manner as at time t1. Here, from FIG. 3C, the state of charge SOC at time t5 is about 97.3%, which is larger than the predetermined state of charge SOCs (= 97%). In this case, as described above, the control circuit 35 controls the DC / DC converter 23 so that the output voltage Vd becomes the upper control voltage Vdu. This is a point greatly different from the operation at time t1.

  That is, if the state of charge SOC is equal to or higher than the predetermined state of charge SOCs, the efficiency is reduced when the regenerative power is charged to the main power supply 17 from FIG. Therefore, the control circuit 35 controls the DC / DC converter 23 so that the output voltage Vd becomes the upper control voltage Vdu (= 13.1 V). Specifically, the control target of the DC / DC converter 23 is switched to the output voltage Vd, and the reference voltage Vst becomes the upper control voltage Vdu as shown in FIG. As a result, the upper control voltage Vdu (= 13.1 V) is much lower than the first predetermined output voltage Vdc1 (= 15 V) when the generator 11 generates the regenerative power with respect to the output voltage Vd. Therefore, most of the regenerative power is charged to the power storage unit 29 via the DC / DC converter 23. Therefore, the charging to the main power source 17 having a large state of charge SOC and low charging efficiency is suppressed as much as possible, so that the recovery efficiency of the regenerative power is improved.

  These operations will be described with reference to FIG. 3. At time t5, the output voltage Vd becomes the upper control voltage Vdu as shown in FIG. 3D, and the power storage unit 29 is charged as shown in FIG. Vc increases with time. The inclination at this time is larger than the time t1 to the time t2, and a larger amount of the regenerative power is charged in the power storage unit 29 in a short time. Further, since the main power supply 17 is hardly charged, as shown in FIG. 3C, the state of charge SOC keeps a substantially constant value. At this time, a part of the regenerative power is supplied to the load 19.

  Here, in order to obtain high efficiency by the control at time t5, it is desirable that the upper control voltage Vdu be as close to the second predetermined output voltage Vdc2 as possible as described from time t3 to time t4. However, if it is too close, the output voltage Vd may fall below the second predetermined output voltage Vdc2 due to fluctuations in the output voltage Vd and control errors of the DC / DC converter 23. In this case, particularly when the voltage is lower than the voltage of the main power supply 17 (about 13 V), the power storage unit 29 is also charged with the power of the main power supply 17 in addition to the regenerated power. As a result, unnecessary power is taken out from the main power supply 17 to reduce the efficiency, and the regenerated power cannot be sufficiently collected in the power storage unit 29 by the amount taken out from the main power supply 17. Therefore, since the overall efficiency is lowered, the upper control voltage Vdu is determined as a voltage higher than the second predetermined output voltage Vdc2 by the second predetermined voltage width ΔV2 (= total error width ΔVer). Thereby, while reducing the possibility of charging to the main power supply 17 with low charging efficiency, it is possible to reduce the carry-out of unnecessary power from the main power supply 17 to the power storage unit 29 and to improve the overall efficiency. The second predetermined voltage width ΔV2 may be determined to be larger than the total error width ΔVer. However, as described above, in order to prevent the regenerative power from being charged to the main power supply 17 as much as possible, the second predetermined voltage width ΔV2 It is desirable to make the predetermined voltage width ΔV2 close to the total error width ΔVer.

  The upper control voltage Vdu from time t3 to time t4 is also used from time t5 to time t6. However, this is not limited to the same value. For example, the amount of charge to the main power supply 17 is set according to the state of charge SOC. When it is desired to change in multiple stages, it may be set as a different value.

  Thereafter, as shown in FIG. 3F, at time t6, the power storage unit voltage Vc reaches the upper limit voltage Vcu (= 10 V). Accordingly, since the power storage unit 29 can no longer charge the regenerative power, the control target of the DC / DC converter 23 is switched from the output voltage Vd to the power storage unit voltage Vc as shown in FIG. Vst is switched from the upper control voltage Vdu to the upper limit voltage Vcu. As a result, as shown in FIG. 3F, the power storage unit voltage Vc maintains the upper limit voltage Vcu from time t6 to time t7. As a result, the DC / DC converter 23 does not control the output voltage Vd. However, since the regenerative power continues to be generated at time t6, the output voltage Vd becomes the first predetermined output voltage Vdc1 (= 15V) generated by the generator 11, as shown in FIG. . Therefore, the first predetermined output voltage Vdc1 is much higher than the voltage of the main power supply 17 (about 13V), and the regenerative power is charged in the main power supply 17. As a result, as shown in FIG. 3C, the state of charge SOC increases with time. In this case, as described above, since the state of charge SOC is large, the charging efficiency to the main power supply 17 is low. However, since the power storage unit 29 can no longer be charged, the regenerative power is supplied to the main power supply even if the charging efficiency is low. 17 to collect. That is, if the state of charge SOC is equal to or higher than the predetermined state of charge SOCs, first, the regenerative power is preferentially charged to the power storage unit 29, and the regenerative power is still generated even when the power storage unit 29 is fully charged. In this case, the main power source 17 is charged. Thereby, the charging to the main power source 17 with the lowest possible charging efficiency can be suppressed and the efficiency can be improved.

  Thereafter, braking of the vehicle is completed at time t7, and the vehicle is accelerated again as shown in FIG. Thereby, as shown in FIG.3 (b), the adjustment voltage Va of the generator 11 becomes the 2nd predetermined output voltage Vdc2. However, as shown in FIG. 3 (c), the state of charge SOC is about 98.7%, which is larger than 90%. Therefore, the generator 11 does not generate power that consumes fuel. When the regeneration signal reg is turned off, the control circuit 35 switches the control target of the DC / DC converter 23 from the power storage unit voltage Vc to the output voltage Vd, and sets the reference voltage Vst to the upper control voltage Vdu. Thereby, the electric power of the electrical storage part 29 is discharged similarly to the time t4 from the time t3. Further, as shown in FIG. 3 (f) at time t8, when the storage unit voltage Vc reaches the lower limit voltage Vck, the discharge from the storage unit 29 is stopped and the discharge from the main power supply 17 is started. Since the operation from time t7 to time t8 is the same as the operation from time t3 to time t5, detailed description is omitted.

  Thereafter, the overall efficiency can be improved by charging and discharging the regenerative power by repeating these operations.

  With the above configuration and operation, the amount of regenerative power charged to the main power supply 17 can be varied in accordance with the state of charge SOC of the main power supply 17, whereby the regenerative power of the main power supply 17 can be recovered with high efficiency, and the vehicle A power supply device capable of improving the overall efficiency can be realized.

  In the present embodiment, the example in which the power storage unit 29 is fully charged during braking has been described. However, when the braking period is short and the battery is not fully charged, the time instantly even if the power storage unit voltage Vc does not reach the upper limit voltage Vcu. The operation at t3 or time t7 is performed, and the power storage unit 29 is discharged. Thereby, the regenerative electric power can be supplied to the load 19 as much as possible, and the efficiency improves.

  In the present embodiment, an example in which the storage unit voltage Vc reaches the lower limit voltage Vck during traveling from time t3 to time t4 or from time t7 to time t8 in FIG. If the power storage unit 29 is braked shortly before being discharged to the lower limit voltage Vck, the operation at time t1 or time t5 is immediately performed to charge the main power supply 17 and the power storage unit 29 with the regenerative power. Also by this, the regenerative power can be recovered even a little until the power storage unit voltage Vc reaches the upper limit voltage Vcu, and the efficiency is improved.

  In addition, the power supply device described in this embodiment may be applied to an idling stop vehicle. In this case, when the vehicle stops and the engine stops, power supply to the load 19 during that time may be preferentially performed from the power storage unit 29. This is because, as is clear from FIG. 3 (f), the power storage unit 29 is charged with the regenerative power regardless of the state of charge SOC. Therefore, by consuming as much power from the power storage unit 29 as possible during idling stop, there is a high possibility that as much regenerative power as possible can be charged during the next braking. As a result, the overall efficiency is improved.

  Note that by applying the power supply device to the idling stop vehicle, the possibility that the regenerative power stored in the power storage unit 29 can be discharged to the lower limit voltage Vck by the starter 21 is increased. Accordingly, the use efficiency of the regenerative power is increased by such control, and as much of the regenerative power as possible can be charged at the time of next braking, so that the recovery efficiency can be further improved. Further, since the idling stop vehicle itself does not consume fuel when the vehicle is stopped, the idling stop vehicle equipped with the power supply device of the present embodiment improves the total efficiency of the vehicle and enables fuel saving. Furthermore, since the charging / discharging frequency of the main power supply 17 is suppressed, it is possible to extend its life.

  Further, in the idling stop vehicle equipped with the power supply device of the present embodiment, the power supply source to the load 19 during idling stop and the drive power source of the starter 21 are controlled according to the power storage unit voltage Vc and the state of charge SOC. Accordingly, the state of charge SOC of the main power supply 17 may be adjusted. In this case, since the power consumption of the load 19 during idling stop is generally larger than the power consumption for driving the starter 21, for example, when the state of charge SOC is large, the drive of the starter 21 having a low power consumption is stored. The power supply to the load 19 during idling stop is performed by the unit 29, and the power of the main power supply 17 is given priority. As a result, the state of charge SOC can be adjusted to decrease. On the other hand, when the state of charge SOC is small, the starter 21 is driven by the power of the main power supply 17, and power is supplied from the power storage unit 29 to the load 19 during idling stop. Thereby, the fall of charge condition SOC can be suppressed as much as possible. However, in order to achieve such a configuration, the power storage unit 29 needs to have a power storage capacity value that can sufficiently drive the load 19 during idling stop.

  In the present embodiment, the case where the power storage unit voltage Vc is always equal to or higher than the lower limit voltage Vck (= 5V) has been described. When the vehicle starts to be used, the power storage unit voltage Vc may be lower than the lower limit voltage Vck. In this case, the control circuit 35 may control the DC / DC converter 23 to initially charge the power storage unit 29 until the power storage unit voltage Vc reaches the lower limit voltage Vck after the engine is started, for example.

  In the present embodiment, the regeneration signal reg is an on / off signal corresponding to whether or not the driver is stepping on the brake, but this may be made to correspond to a fuel cut signal. As a result, even when the vehicle is traveling in the inertial manner, the regenerative power can be charged in the power storage unit 29, and the recovery efficiency can be further improved. However, since the mechanical load of the generator 11 to the engine increases due to the recovery of the regenerative power, the inertial traveling distance is shortened. Therefore, whether or not to perform regenerative power recovery during the inertial traveling, or the degree of the recovered amount is determined depending on whether the recovered amount of the regenerative power is important or the inertial traveling distance. Good.

  In the present embodiment, when generating the regenerative power, the control circuit 35 controls the output voltage Vd to be controlled depending on whether or not the state of charge SOC of the main power supply 17 is equal to or higher than the predetermined state of charge SOCs. Control is performed to switch the reference voltage Vst of the DC / DC converter 23 into two stages of a lower control voltage Vdk and an upper control voltage Vdu, which sets the reference voltage Vst in multiple stages according to the value of the state of charge SOC. Alternatively, a correlation between the state of charge SOC and the reference voltage Vst (a correlation where the reference voltage Vst is high if the state of charge SOC is small and the reference voltage Vst is low if the state of charge SOC is large) is obtained in advance. A reference voltage Vst suitable for the state of charge SOC may be determined from the correlation. However, the range of the reference voltage Vst must be a range from the lower control voltage Vdk to the upper control voltage Vdu as described in the embodiment.

  Summarizing such operations, when the regenerative power is generated, the control circuit 35 determines the output voltage Vd from the lower control voltage Vdk lower by the first predetermined voltage width ΔV1 than the first predetermined output voltage Vdc1. In the range up to the upper control voltage Vdu that is higher than the predetermined output voltage Vdc2 by the second predetermined voltage width ΔV2, the DC / DC converter 23 increases so that the charged state SOC becomes higher and the charged state SOC becomes lower. Will be controlled. As a result, although the control is complicated as compared with the case where the reference voltage Vst is switched in two stages, the regenerative power can be charged to the main power supply 17 more efficiently according to the state of charge SOC.

  In the present embodiment, control circuit 35 controls DC / DC converter 23 to maintain upper limit voltage Vcu when power storage unit voltage Vc reaches upper limit voltage Vcu, so that power storage unit voltage Vc is lower limit voltage Vck. In this case, the DC / DC converter 23 is controlled so as to maintain the lower limit voltage Vck, which is sufficiently higher than the regenerative power amount obtained by one braking of the vehicle and the power consumption amount of the load 19. In the case of a vehicle system that includes a power storage unit 29 having a large capacity value and further that the regenerative power amount and the power consumption amount are substantially balanced when the vehicle is used, control using the upper limit voltage Vcu and the lower limit voltage Vck is particularly performed. There is no need. Therefore, such a vehicle system may be configured without the power storage unit voltage detection circuit 33.

  Further, in the present embodiment, the adjustment voltage Va is configured to be variable in two stages, but either an analog signal or a digital signal may be used as the signal of the adjustment voltage Va. However, when the analog signal is used, the adjustment voltage Va may fluctuate due to noise or the like. Therefore, for example, by adopting a configuration in which the adjustment voltage Va is input to the generator 11 by a digital signal conforming to a vehicle communication standard, the influence of the noise or the like is small, and the adjustment voltage Va can be transmitted with higher accuracy. Therefore, since the regenerative power can be collected more reliably and the efficiency is improved, a configuration using the digital signal is desirable.

  In the present embodiment, when the adjustment voltage Va is switched between the first predetermined output voltage Vdc1 and the second predetermined output voltage Vdc2, the adjustment voltage Va is immediately switched as shown in FIG. However, depending on the load 19, the operation may become unstable due to such a steep voltage change. Therefore, in this case, control may be performed so that the adjustment voltage Va is switched to the first predetermined output voltage Vdc1 or the second predetermined output voltage Vdc2 at a predetermined change speed v (for example, 1 to 2 V / second). Thereby, since the output voltage Vd changes slowly with the predetermined change speed v, the possibility that the operation of the load 19 becomes unstable can be reduced.

  There are the following two methods for switching the adjustment voltage Va at the predetermined change speed v.

  First, there is a method of directly changing the signal of the adjustment voltage Va from the vehicle side control circuit at a predetermined change speed v. Here, when the second predetermined output voltage Vdc2 (= 13V) is increased to the first predetermined output voltage Vdc1 (= 15V), the reference voltage Vst of the DC / DC converter 23 is not suddenly switched to the lower control voltage Vdk. It is necessary to perform the follow-up control so that the adjustment voltage Va is lower by a first predetermined voltage width ΔV1. Thereby, the backflow from the electrical storage part 29 to the output terminal 13 side can be prevented. Similarly, when the first predetermined output voltage Vdc1 (= 15V) is lowered to the second predetermined output voltage Vdc2 (= 13V), the DC / DC converter 23 is set to a value higher than the adjustment voltage Va by the second predetermined voltage width ΔV2. It is necessary to perform follow-up control so that Thereby, the backflow charge from the output terminal 13 side to the power storage unit 29 can be prevented. In the case of the above control, it is necessary to use a configuration in which the generator 13 can output multistage voltages.

  As another method, first, a configuration is adopted in which the signal of the adjustment voltage Va from the vehicle-side control circuit is also input to the control circuit 35. Next, for example, when the adjustment voltage Va increases from the second predetermined output voltage Vdc2 (= 13V) to the first predetermined output voltage Vdc1 (= 15V), the control circuit 35 detects this change, and the reference voltage Vst changes to the predetermined value. Control is performed so that the lower control voltage Vdk is reached at the speed v. As a result, the output voltage Vd of the DC / DC converter 23 also reaches the lower control voltage Vdk at a predetermined change speed v. Similarly, when the adjustment voltage Va decreases from the first predetermined output voltage Vdc1 to the second predetermined output voltage Vdc2, the control circuit 35 performs control so that the reference voltage Vst becomes the upper control voltage Vdu at the predetermined change speed v. Therefore, even with this method, the adjustment voltage Va is substantially switched gradually at the predetermined change rate v.

  In the present embodiment, an electric double layer capacitor is used for power storage unit 29, but this may be another capacitor such as an electrochemical capacitor or a secondary battery.

  Moreover, although this embodiment demonstrated the case where a power supply device was applied to a vehicle, you may apply not only to this but to the apparatus which generate | occur | produces regenerative electric power with construction machines, such as a crane, and an elevator.

  In the present embodiment, the load 19 and the starter 21 are electrically connected to the output terminal 13 as power consuming electrical components, but these are not essential in the power supply device of the present embodiment. That is, for example, when the generator 11 is a motor generator having the role of the starter 21 in the idling stop vehicle, and the regenerative power stored in the power storage unit 29 is consumed only by the motor generator, the minimum of the power supply device is used. The load 19 and the starter 21 are not required for the configuration. Similarly, when the power supply apparatus is applied to the construction machine or the elevator and the motor that drives them generates regenerative power, the regenerative power stored in the power storage unit 29 is consumed only by the motor. If so, the load 19 is unnecessary.

  In addition, at time t3 and time t7 in FIG. 3B in the present embodiment, the adjustment voltage Va of the generator 11 is changed from the first predetermined output voltage Vdc1 (= 15V) to the second predetermined output voltage Vdc2 (= 13V). It has been switched. At this time, the output voltage Vd reaches the upper control voltage Vdu (= 13.1 V) in about several seconds at the maximum because the voltage followability of the main power supply 17 is slow, but the horizontal axis of FIG. Since the time scale is only a few seconds, FIG. 3D shows that the output voltage Vd immediately reaches the upper control voltage Vdu from the first predetermined output voltage Vdc1 at time t3.

  Since the power supply device according to the present invention can improve the overall efficiency by controlling the charging and discharging of the power storage unit, it is particularly useful as a power supply device that stores regenerative power in the power storage unit during braking and discharges it when necessary.

DESCRIPTION OF SYMBOLS 11 Generator 13 Output terminal 17 Main power supply 22 Ground terminal 23 DC / DC converter 29 Power storage part 31 Output voltage detection circuit 33 Power storage part voltage detection circuit 34 Current detection circuit 35 Control circuit

Claims (6)

A DC / DC converter electrically connected to the output terminal of the generator to which the main power supply is connected;
A power storage unit electrically connected to the other end of the DC / DC converter;
An output voltage detection circuit that is electrically connected to the output terminal and a ground terminal of the generator and detects an output voltage (Vd) of the output terminal;
A charge state detecting means electrically connected to the main power source and detecting a state of charge (SOC) of the main power source;
A control circuit electrically connected to the DC / DC converter, the output voltage detection circuit and the charge state detection means;
When the generator generates regenerative power, the output terminal adjustment voltage (Va) is raised to a first predetermined output voltage (Vdc1),
The adjustment voltage (Va) can be lowered to the second predetermined output voltage (Vdc2) when the regenerative power is not generated,
When the regenerative power is generated, the control circuit causes the output voltage (Vd) to decrease from a lower control voltage (Vdk) that is lower than the first predetermined output voltage (Vdc1) by a first predetermined voltage width (ΔV1). In the range up to the upper control voltage (Vdu) higher by the second predetermined voltage width (ΔV2) than the second predetermined output voltage (Vdc2), the state of charge is set to be higher if the state of charge (SOC) is small. The DC / DC converter is controlled to be low if (SOC) is large;
A power supply apparatus configured to control the DC / DC converter so that the output voltage (Vd) becomes the upper control voltage (Vdu) when the regenerative power is not generated. When the regenerative power is generated, the control circuit is configured so that the output voltage (Vd) becomes the lower control voltage (Vdk) if the state of charge (SOC) is smaller than a predetermined state of charge (SOCs). 2. The DC / DC converter according to claim 1, wherein the DC / DC converter is controlled so that the output voltage (Vd) becomes the upper control voltage (Vdu) if the state of charge (SOC) is equal to or higher than a predetermined state of charge (SOCs). The power supply described. A power storage unit voltage detection circuit that is electrically connected to the power storage unit and the control circuit and detects a power storage unit voltage (Vc);
The control circuit controls the DC / DC converter to maintain the upper limit voltage (Vcu) when the power storage unit voltage (Vc) reaches the upper limit voltage (Vcu),
The power supply device according to claim 1, wherein the DC / DC converter is controlled to maintain the lower limit voltage (Vck) when the power storage unit voltage (Vc) reaches the lower limit voltage (Vck). The first predetermined voltage width (ΔV1) and the second predetermined voltage width (ΔV2) are the total error width (the sum of the output voltage maximum error width of the generator and the voltage control maximum error width of the DC / DC converter). The power supply device according to claim 1, wherein ΔVer). The power supply device according to claim 1, wherein the adjustment voltage (Va) is input to the generator by a digital signal. When the adjustment voltage (Va) is switched between the first predetermined output voltage (Vdc1) and the second predetermined output voltage (Vdc2), the adjustment voltage (Va) is gradually switched at a predetermined switching speed (v). Item 2. The power supply device according to Item 1.

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