JP5071322B2 - Power control system - Google Patents

Description

  The present invention relates to a power control system in which two power supply units including a power supply and a voltage converter are connected in parallel.

  2. Description of the Related Art Conventionally, there is known a power control system that performs control to supply power from the power source side to the drive system side or supply power regenerated on the drive system side to the power source side. For example, a hybrid vehicle is equipped with a power control system that controls transmission / reception of power between a battery and a motor. Among such power control systems, there are those in which a plurality of power supply units including a power supply and a voltage converter are connected in parallel (for example, Patent Documents 1 and 2 below).

  The voltage converter mounted on this power supply unit usually has two arms consisting of a diode and a transistor. By driving these two arms with an appropriate duty ratio, a desired boosting operation is realized. ing. Here, for some reason, if the arm in this voltage converter breaks down and sticks ON, a short circuit between two power supply units connected in parallel (battery short circuit) or within one power supply unit This causes a short circuit (short circuit in the battery). Such a short circuit between batteries or a short circuit within a battery may cause not only a decrease in efficiency and lifetime of the power control system but also a failure of other components, and it is desirable to detect them at an early stage.

  Therefore, even in the past, the failure of the arm of the voltage converter is detected based on the current value and the voltage value flowing through the voltage converter, and when the failure occurs, the operation of the voltage converter is stopped or the voltage converter is There has been proposed a technique for shutting off the provided power supply unit from the entire system (for example, Patent Document 3 below). According to such a technique, a certain degree of failure can be detected.

JP 2004-6138 A JP 2003-209969 A JP 2003-244801 A

  However, many conventional failure detection technologies assume a single power supply unit. When this technology is applied to a system in which multiple power supply units are connected in parallel, it is possible to detect the occurrence of a short circuit, but among the multiple voltage converters, specify which voltage converter has an abnormality. There is a problem that you can not do.

  Therefore, an object of the present invention is to provide a power control system that can detect a failure of a voltage converter more appropriately.

  The power control system of the present invention is two power supply units connected in parallel to each other, each of which can be recharged, a voltage converter connected to the power supply and raising and lowering the supplied voltage, A power source unit, a reactor current acquisition means for acquiring a value and direction of a reactor current that is a current flowing in at least one voltage converter of the two power units, and a drive of the power unit And determining whether or not there is a short circuit between the two power supply units based on the acquired value of the reactor current, and if there is a short circuit between the power supply units, based on the direction of the reactor current And a control means for identifying the power supply unit that has caused the short circuit.

  In a preferred aspect, the battery further includes a battery current detection unit that is provided for each power supply unit and detects a battery current value that is a current value output from the power supply of the corresponding power supply unit, and the control unit includes the battery Based on the current value, it is determined whether there is an internal short circuit in the power supply unit corresponding to the battery current. In another preferred aspect, the power supply device further includes a shut-off unit that is provided for each power source and disconnects the power source from the system, and when the short circuit occurs, the control unit drives the shut-off unit to cause the short circuit. Disconnect the power supply of the power supply unit from the power control system.

In another preferred aspect, the control means calculates a value obtained by multiplying a current value output to the motor by a power distribution ratio between two power supply units as a power balance current value, and calculates the reactor current value from the value of the reactor current. A value obtained by subtracting the power balance current value is calculated as an inter-battery balance current value, and when the absolute value of the inter-battery balance current value exceeds a specified threshold, it is determined that a short circuit between the batteries has occurred. . In this case, the control means determines whether or not there is a short circuit between the batteries based on the inter-battery balance current value in a state where the electric motor is connected to the power supply unit, and when it is determined that the short circuit between the batteries has occurred. It is preferable to determine again whether or not there is a short circuit between the batteries based on the reactor current value in a state where the electric motor is temporarily disconnected from the power supply unit.

  In another preferred aspect, the control unit stores in advance a threshold value that serves as a reference for determining whether or not there is a short circuit, and the threshold value is a fluctuation value that varies according to temperature.

  According to the present invention, not only the value of the reactor current but also the direction is detected, and the power supply unit that caused the short circuit can be specified based on this direction.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a power control system 12 according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the power control system 12. The power control system 12 is a system mounted on, for example, a hybrid vehicle or an electric vehicle, and supplies power to the two motor units 50a and 50b or is charged by the power generated by the motor units 50a and 50b. System. In the following description, the two motor units 50a and 50b will be simply referred to as “motor unit 50” without the suffixes a and b unless otherwise distinguished. The same applies to the components of each electric motor unit 50.

The power control system 12 includes two power supply units connected in parallel, that is, a master power supply unit 14 _M and a slave power supply unit 14 _S, and a control unit 16 that controls the power supply units 14 _M and 14 _S (not shown in FIG. 1). ). In the power supply units 14 _S and 14 _M , when the master and the slave are not distinguished, the subscripts M and S are omitted and simply referred to as “power supply unit 14”. The same applies to the components of each power supply unit 14.

The control unit 16 calculates the total required power in accordance with a request from the host control device, and controls driving of the power supply unit 14 so as to obtain the power. The control unit 16, various current sensors S _L, S _BM, to determine the quality of the power supply unit 14 on the basis of such the orientation of the detected current value and the current at S _BS, defect and determined to be the power supply unit 14 The battery 20 is disconnected from the system. Hereinafter, the power control system 12 will be described in detail.

  First, the motor unit 50 connected to the power control system 12 will be briefly described. The electric motor unit 50 is a circuit unit including an electric motor 52 and an inverter 54. The electric motor 52 functions as a drive motor that generates torque for driving the drive wheels of the vehicle when supplied with an AC voltage. The electric motor 52 also functions as a generator that generates electric power by being driven by the braking force of the vehicle during regenerative braking. The electric power (AC voltage) generated by the electric motor 52 is converted into a DC voltage by the inverter 54 and then output to the power supply unit 14. The battery 20 provided in the power supply unit 14 is charged by being supplied with this DC voltage. When the electric motor 52 functions as a drive motor, the inverter 54 converts the DC voltage supplied from the power supply unit 14 into an AC voltage, and then supplies the AC voltage to the electric motor 52. In response to the supply of the AC voltage, the electric motor 52 functions as a motor and generates torque for driving the driving wheels of the vehicle. The currents flowing through the two electric motors 52a and 52b are detected as the first motor current value Ia and the second motor current value Ib, respectively, and input to the control unit 16 of the power control system 12. In addition, a gate (not shown in the figure, which is configured from a relay, for example) that is controlled to open / close by the control unit 16 is provided between the electric motor unit 50 and the power supply unit 14. It can be disconnected from the system 12.

Next, the power control system 12 which is embodiment of this invention is demonstrated. As described above, the power control system 12 is roughly divided into a master power supply unit 14 _M and a slave power supply unit 14 _S connected in parallel, and a control unit 16 that controls the two power supply units 14 _M and 14 _S. Is done. The control unit 16 performs drive control so that the total output from the two power supply units 14 _M and 14 _S becomes the total required power.

The two power supply units 14 _M and 14 _S have almost the same configuration. Therefore, the configuration of the power supply unit 14 will be described below by taking the slave power supply unit _14S as an example. Figure 2 is a diagram showing the configuration of the slave power supply unit 14 _S.

The slave power supply unit 14 _S includes a slave side battery 20 _S. This is between the battery 20 _S and the motor unit 50, the slave converter 22 _S for elevating the voltage is connected. In addition, a first capacitor C1 _S and a second capacitor C2 _S that smooth the supplied voltage are provided between the battery 20 _S and the converter 22 _S and between the converter 22 _S and the inverter 54. The battery _20S is a chargeable / dischargeable secondary battery, and is made of, for example, nickel hydride or lithium ion.

Converter 22 _S is the supplied voltage, as appropriate, is a voltage converter for lifting. The converter 22 _S includes a plurality of diodes D1 _S and D2 _S , a plurality of transistors T1 _S and T2 _S , a reactor L _{S and the} like. One end of the reactor L _S is connected to the power line of the battery 20 _S. Further, the other end of the reactor L _S is connected between an intermediate point between the transistor T1 _S and the transistor T2 _S , in other words, between the emitter of the transistor T1 _{S and} the collector of the transistor T2 _S. The transistors T1 _S and T2 _S are connected in series between the power supply line and the earth line. That is, the collector of the transistor T1 _S is connected to the power supply line, and the emitter of the transistor T2 _S is connected to the ground line. In addition, diodes D1 _S and D2 _S that flow current from the emitter side to the collector side are arranged between the collectors and emitters of the transistors T1 _S and T2 _S , respectively. Then, the DC voltage is raised or lowered by appropriately driving the transistors T1 _S and T2 _S functioning as switching elements with an appropriate duty ratio. In the following description, the transistor T1 _S may be referred to as “slave side upper arm T1 _S ”, and the transistor T2 _S may be referred to as “slave side lower arm T2 _S ”. Similarly, the two transistors T1 _M and T2 _M provided in the master power supply unit 14 _M are referred to as “master side upper arm T1 _M ” and “master side lower arm T2 _M ”.

Between the midpoint of the reactor _{L S} and two transistors _{T1 S,} T2 S, slave reactor current sensor _{S L} is provided. The reactor current sensor S _L, as well as for detecting a current flowing in the converter 22 _S as reactor current value I _L, the direction of the reactor current (positive or negative) also detects and outputs to the control unit 16. Control unit 16 determines the presence or absence of a short circuit between the battery based on the reactor current value I _L that is detected by the reactor current sensor. Moreover, when the short circuit between batteries has arisen, the converter 22 which caused the short circuit between the said batteries is identified based on the direction of a reactor current. The reactor current sensor S _L may be provided in both the master power supply unit 14 _M and the slave power supply unit 14 _S. However, in this embodiment, only the slave power supply unit 14 _S is provided in the present embodiment because of cost and the like. A current sensor _SL is provided (see FIG. 1).

A slave side battery current sensor _SBS is provided between the battery 20 _S and the converter 22 _S. The battery current sensor S _BS detects a current value of the battery 20 _S near a sensor which outputs to the control unit 16 as the slave battery current value I _BS. Incidentally, the battery current sensor is different from the reactor current sensor _{S L,} the master power supply unit 14 _M and is provided on both of the slave power supply unit 14 _S, each of the power supply units ₁₄ M, 14 battery current in _{the S} value _{I BM,} I _BS is adapted to be individually detected. Control unit 16, the battery current sensor S _BM, based on the current value detected by the S _BS, the presence judgment of the battery in short-circuit, and a specific power supply unit 14 _M, 14 _S that caused the battery in short-circuit I do.

Between the battery 20 _S and the converter 22 _S , a slave-side system master relay (hereinafter abbreviated as “SMR”) that is driven and controlled by the control unit 16 is provided. When a short circuit occurs, the control unit 16 identifies the power supply unit 14 that has caused the short circuit. Then, the SMR of the power supply unit 14 causing the short circuit is driven, and the battery 20 mounted on the power supply unit 14 causing the short circuit is disconnected from the power control system 12. This prevents damage to the battery 20 due to a short circuit.

In the present embodiment, the master power supply unit 14 _M, accessory 40 such as a DCDC converter is connected. The accessory 40 is generally driven by electric power supply from the master battery 20 _M. However, abnormality of the master power supply unit 14 _M is detected, if the master-side battery 20 _M is disconnected from the power control system 12 so as to drive the accessory 40 by the power supply from the slave battery 20 _S ing.

The control unit 16 is a part that controls driving of the two power supply units 14 _M and 14 _S. The control unit 16 calculates the total required power and the like based on a request from the host control device. Then, the drive of the arms of the converters 22 _M and 22 _S is controlled so as to satisfy this total required power. Note that this control may be performed by current feedback control that feeds back a current value, or voltage feedback control that feeds back a voltage value.

Further, as described above, the control unit 16 determines whether or not there is a short circuit between the batteries or a short circuit in the battery based on the detection results of the various current sensors S _L , S _BM , and S _BS , and when the short circuit occurs, the short circuit occurs. The power supply unit 14 that caused the problem is also identified. Hereinafter, the basic principle of this short circuit determination and the like will be described in detail with reference to FIG.

FIG. 3 is a schematic diagram showing the flow of current in the power control system 12. In FIG. 3, the black bold line arrows when the fixed master on the arm T1 _M is, the arrow of white抜太lines indicate the flow of current when the slave on the arm T1 _S is stuck.

Usually, the slave converter 22 reactor current flowing through the _S I _L, the amount of current outputted to the electric motor unit 50 (power running is a positive value, the regenerative negative values) two power supply units 14 _M, 14 _S The value obtained by multiplying the power distribution ratio between the two and the amount of current corresponding to the exchange between the batteries is added. Specifically, the current value _IL is expressed by the following formulas 1 to 4.

I _L = I ₁ + I ₂ Formula 1
I ₁ = (Ia + Ib) × K Equation 2
K = V _H / (V _H −V _LS ) × γ Expression 3
I ₂ = (V _LM −V _LS ) × D / R Equation 4
Here, γ is a power distribution ratio between the two power supply units 14 _M and 14 _S , and R is an internal resistance value. _{V H,} V LM, V _LS, respectively, the supply voltage to the motor unit 50, the master-side battery 20 _M of the output voltage, the output voltage of the slave battery 20 _S. Also, D is, VL1 <VL2 master on the arm T1 _M duty in the case of, VL1> For VL2 is the duty of the slave on the arm T1 _S. (Ia + Ib) means total power running power or total regenerative power, in other words, the amount of current output to the motor unit 50, and takes a positive value during power running and a negative value during regenerative charging. Hereinafter, I ₁ , which is a value obtained by multiplying the total power running power or total regenerative power by the power distribution ratio, is referred to as “power balance current value I ₁ ”. Further, I ₂ means an amount of current corresponding to the exchange between the batteries. Hereinafter, this I _{2 is referred} to as “battery balance current value I ₂ ”.

When the upper arm is fixed while the upper arm is fixed to ON, a short circuit occurs between the batteries, and the value of the duty D becomes excessive. In this case, as is clear from Equation 4, the inter-battery balance current value I ₂ also becomes excessive. Therefore, the control unit 16, based on the reactor current value I _L and the power balance component of the current value I _1, and calculates the inter-battery balance component current value I _2. Specifically, the calculation of I ₂ = I _L −I ₁ is executed. When the inter-battery balance current value I ₂ obtained by this calculation exceeds the specified threshold value α, it is determined that the upper arms T1 _M and T1 _S are fixed to ON, that is, a short circuit between the batteries has occurred. Further, when the direction of the reactor current at this time is the direction from the slave side to the master side (that is, I _L > 0, the direction of the thick line arrow in FIG. 3), the master-side upper arm T1 _M is fixed. Judge that Conversely, the direction of the reactor current, direction from the master side to the slave side (i.e., IL <0, the arrow direction of the white抜太line in FIG. 3) are fixed slave on the arm T1 _S is in the case of Judge. That is, in summary, when I ₂ = I _L −I ₁ > α, the control unit 16 determines that the master side upper arm T1 _M is fixed ON, and I ₂ = I _L −I ₁ <−. In the case of α, it is determined that the slave side upper arm T1 _S is fixed ON, and in the case of −α ≦ I _L −I ₁ ≦ α, the upper arms T1 _M and T1 _S are fixed ON (short circuit between batteries). It is judged that no has occurred.

When it is determined that the upper arm T1 is fixed ON, the control unit 16 drives the SMR of the power supply unit 14 in which the upper arm T1 is fixed ON, and the battery 20 mounted on the power supply unit 14 is driven. Is disconnected from the power control system 12. Here, if the master-side upper arm T1 _M is stuck, naturally, will be the master-side battery 20 _M is disconnected from the system 12. In this case, accessory 40 connected to the master power supply unit 14 _M is driven by power supply from the slave power supply unit 14 _S.

As is clear from the above description, in the present embodiment, not only the determination of the presence or absence of a short circuit between the batteries based on the current value, but also the identification of the power supply unit 14 in which the upper arm T1 is stuck on based on the current direction is specified. ing. As a result, only the battery 20 of the power supply unit 14 in which a failure has occurred can be disconnected from the system 12. Further, in the present embodiment, on the basis of the reactor current value I _L and the power balance component of the current value I _1, and calculates the inter-battery balance component current value I _2, based on the value of the battery between balance component current value I ₂ Whether or not there is a short circuit between the batteries is determined. As a result, even if the value of the output current amount to the electric motor greatly fluctuates, it is possible to accurately determine whether or not there is a short circuit between the batteries.

In the present embodiment, when it is determined that the short circuit between the battery based on the value of I 2 ₌ I _L -I ₁ occurs, blocking the gate provided between the motor unit 50 and the power supply unit 14 Then, the electric motor unit 50 is disconnected from the system 12, and in that state, the presence / absence of a short circuit between the batteries based on the current value is determined again.

That is, the power balance current value I ₁ used to calculate the inter-battery balance current value I ₂ is a current sensor (not shown) mounted on the motor 52 or a voltage sensor (see FIG. (See formulas 2 and 3). It is difficult to completely remove the error from the various detection values, the power balance equivalent current value I ₁ is said to be a value including some errors. After calculating the inter-battery balance partial current I ₂ by subtracting such power balance equivalent current values I ₁ from the reactor current value I _L, so that the error of I ₁ is superimposed on the error of the I _L. As a result, there is a problem that an error amount increases contained in the balance component current value I ₂ between the calculated battery.

Therefore, when it is determined that a short circuit between the batteries has occurred with the electric motor unit 50 connected to the power supply unit 14, the electric motor unit 50 is temporarily disconnected from the power supply unit 14 (gate is cut off), Then, it is determined again whether or not there is a short circuit between the batteries. When the electric motor unit 50 is disconnected from the power supply unit 14, the output current amount (Ia + Ib) = 0 to the electric motor unit 50, and consequently, the power balance current value I ₁ = 0. In this case, I ₂ = _IL is established. Accordingly, when disconnecting the electric motor unit 50 from the power supply unit 14, the reactor current value I _L is in whether exceeds the threshold α'defined, it is possible to determine the presence or absence of ON sticking of the upper arm. In this case, and a current sensor that is mounted from the battery between balance component current value I ₂ to the electric motor 52, it is possible to eliminate the influence of the error of the voltage sensor provided to the power supply unit 14, more precisely the presence or absence of a short circuit between the battery Can be judged. In order to make a more accurate determination, the threshold value α ′ used when the motor unit 50 is disconnected is set to a value (α ′ <α) smaller than the threshold value α used when the motor unit 50 is connected. It is desirable.

Next, the determination of whether or not the lower arm T2 is stuck on will be described. Whether the lower arm T2 is fixed to ON (determining whether there is a short circuit in the battery) is determined by the battery current values I _BM , I detected by the battery current sensors S _BM , S _BS provided in the vicinity of the batteries 20 _M , 20 _S. Determined based on _BS . That is, it is known that the battery current becomes excessive when a short circuit occurs in the battery where the lower arm T2 is fixed ON. Therefore, the control unit 16, battery current sensor _{S BM,} monitors the battery current detected by the _{S BS} value _{I BM, I BS,} the battery current value _{I BM,} if _{I BS} is larger than the threshold value β defined It is determined that the lower arm T2 is fixed ON. More specifically, the control unit _16, in the case of _{I BM>} beta arm T2 _M under the master _side, in the case of _{I BS>} beta determines the slave lower arm T2 _S is stuck ON .

  Next, the flow of the short circuit detection process in the power control system 12 will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of short circuit detection processing.

In the case of detecting a short circuit, the control unit 16 first calculates an inter-battery balance current value I ₂ = I _L −K · (Ia + Ib) = I _L −I ₁ , and its absolute value exceeds a specified threshold value α. It is determined whether or not to perform (S10). If | I _L −I ₁ | ≦ α, the process proceeds to step S22 to determine whether there is a short circuit in the battery. On the other hand, if | I _L −I ₁ |> α, it is temporarily determined that a short circuit between the batteries has occurred. In this case, the gate provided between the power supply unit 14 and the electric motor unit 50 is shut off, and the electric motor unit 50 is disconnected from the power control system 12 (S12). Then, it is determined whether or not the absolute value of the reactor current value I _L (= I ₂ ) detected in this state exceeds a specified threshold value α ′ (S14). According to this determination, the influence of the error included in the power balance current value I ₁ = (Ia + Ib) K can be eliminated, so that the presence or absence of the short circuit between the batteries can be determined with higher accuracy. If | I _L | ≦ α ′, it is determined that no short circuit between the batteries has occurred. In this case, after the gate is opened again (S40), the process proceeds to step S22 to determine whether there is a short circuit in the battery. On the other hand, if | IL |> α ′, it is determined that a short circuit between the batteries has occurred (S16). In this case, the control unit 16, based on the orientation (positive and negative I _L) of the current, to identify the power supply unit 14 ON fixation of the upper arm T1 has occurred. Specifically, it is determined whether the reactor current value I _L is positive or negative. If I _L > 0, it is determined that the master-side upper arm T1 _M is fixed (S18, S20). In this case, it cuts off the master SMR, disconnecting the master battery 20 _M from the system 12. On the other hand, if I _L <0, it is determined that the slave-side upper arm T1 _S is fixed (S30). In this case, it shuts off the slave SMR, disconnect the slave battery 20 _S from the system 12 (S36).

On the other hand, when the battery short circuit (upper arm ON sticking) has not occurred, the process proceeds to step S22. In step S22, first, the master side battery current value _IBM is compared with a prescribed threshold value β. Result of the comparison, if the master battery current value _{I BM} exceeds the threshold value β _{(I BM>} β), it is determined that the stuck ON master lower arm T2 _M occurs (S24). In this case, it cuts off the master SMR, disconnecting the master battery 20 _M from the system (S26).

On the other hand, if _IBM is less than the threshold value β, then the slave battery current value I _BS is compared with the threshold value β (S32). Result of the _comparison, in the case of _{I BS>} beta, it is determined that the stuck ON slave lower arm T2 _S occurs (S34). In this case, blocks the slave SMR, disconnect the slave battery 20 _S from the system 12 (S36).

  If NO in both step S22 and step S32, the control unit determines that neither an inter-battery short circuit or an in-battery short circuit has occurred. In this case, after waiting for a specified time, the process returns to step S10 again. In other words, the control unit 16 repeatedly performs a short circuit presence / absence inspection.

As is apparent from the above description, according to the present embodiment, it is possible to specify not only the presence / absence of the short circuit between the batteries and the short circuit within the battery but also which power supply unit 14 has an abnormality. As a result, only the battery 20 of the power supply unit 14 in which an abnormality has occurred can be disconnected from the system 12, and more efficient operation is possible while preventing damage to the battery. Also, the reactor current value I _L, and calculates the inter-battery balance partial current I ₂ by subtracting the power balance equivalent current value I _1, it is determined whether a short circuit between the battery based on the value of the I ₂ . Therefore, regardless of the size of the power consumption of the electric motor 52, can be reliably detected excessive inter-battery balance component current value I _2. Furthermore, when there is a suspicion of a short circuit between the batteries, the electric motor unit 50 is temporarily disconnected from the power supply unit 14, and therefore the presence or absence of the short circuit between the batteries can be determined more accurately.

  Note that the threshold values α, α ′, and β serving as a reference for short circuit determination may be fixed values or may be fluctuating values that vary according to various conditions. For example, the threshold values α, α ′, and β may be fluctuation values that vary depending on the temperature. With such a configuration, it is possible to more accurately determine the presence or absence of a short circuit. That is, when the temperature changes, the internal resistance and the like also change, and the current value also changes. In other words, it can be said that the current value at the occurrence of a short circuit varies depending on the temperature. Therefore, as shown in FIG. 5, it is desirable to vary the threshold values α, α ′, and β according to the temperature. In FIG. 5, the horizontal axis indicates the temperature, and the vertical axis indicates the current value. The solid line indicates the threshold value α, the broken line indicates the threshold value α ′, and the alternate long and short dash line indicates the threshold value β. As is apparent from FIG. 5, in this example, the absolute values of the threshold values α, α ′, β are made smaller as the temperature is lower. This is because the internal resistance increases as the temperature decreases, and the current value during short-circuiting also decreases. As described above, if the threshold values α, α ′, and β are varied according to the temperature, it is possible to more accurately determine whether or not there is a short circuit.

  Moreover, in this embodiment, as shown in FIG. 4, the presence or absence determination of the short circuit between batteries is performed twice (S10, S14), but either one of step S10 and step S14 may be omitted.

Furthermore, in the above description has a configuration that detects the reactor current value I _L of the slave side reactor current sensor S _L that is installed at the slave side converter 22 _S, battery current sensor S _BM, were detected in S _BS Based on the battery current values I _BM and I _BS , the reactor current value, and hence the inter-battery balance current value may be calculated.

Specifically, it is assumed that the master side battery current value I _BM is substantially the same as the master side reactor current value I _LM . In this case, the following formula 5 is established.

I _BM ≈I _LM = (Ia + Ib) × {V _H / (V _H −V _LM ) × (1−γ)} + Id + {(V _LS −V _LM ) / R × D} Equation 5

Here, Id is a current value flowing through the auxiliary machine. The auxiliary machine current value Id may be a detection value detected by a sensor or the like, or may be a value expected to be obtained as a result of control. In this equation 5, when K _M = {V _H / (V _H −V _LM ) × (1−γ)}, I _2M = (V _LS −V _LM ) / R × D, To establish.

I _BM ≈ (Ia + Ib) K _M + I _2M + Id
I _2M ≒ I _BM- (Ia + Ib) K _M -Id (6)

It can be said that I _2M , which is a value obtained by multiplying the upper arm duty, is an excessive value when the upper arm is stuck on. Therefore, when determining the presence or absence of a short circuit, the control unit compares this I _2M with a prescribed threshold value α ₁ (α ₁ > 0). As a result of comparison, when I _2M <−α ₁ , the master-side upper arm T1 _M is turned on, and when I _2M > α ₁ , the slave-side upper arm T1 _S is turned on. Judge.

Similarly, the slave-side battery current value I _BS is added to the slave-side reactor current value I _L (hereinafter, the subscript S is added to clarify the distinction from the master-side reactor current value I _LM). The following expression 7 is established when it is considered that the value is I _{LS (} hereinafter, K and I ₂ are also the same).

I _BS ≒ I _LS
= (Ia + Ib) × {V _H / (V _H −V _LS ) × γ} + (V _LM −V _LS ) × D / R
When K _S = {V _H / (V _H −V _LS ) × γ}, I _2S = (V _LM −V _LS ) × D / R,
I _BS = (Ia + Ib) · K _S + I _2S
I _2S = I _BS − (Ia + Ib) · K _S Equation 7

Similarly to I _2M , I _2S in Equation 7 is also a value that becomes excessive when the upper arm is stuck on. Therefore, when determining the presence or absence of a short circuit, this I _2S may be compared with a prescribed threshold value α ₂ (α ₂ > 0). As a result of the comparison, when I _2S <−α ₂ , the slave-side upper arm T1 _S is turned on, and when I _2S > α ₂ , the master-side upper arm T1 _M is turned on. It can be judged.

It is a figure which shows the structure of the electric power control system which is embodiment of this invention. It is an enlarged view of a slave side power supply unit. It is the schematic which shows the flow of an electric current. It is a flowchart which shows the flow of a short circuit detection process. It is a graph which shows an example of a threshold value.

Explanation of symbols

C1, C2 capacitor, D1, D2 diode, L _S reactor, S _BM , S _BS battery current sensor, S _L reactor current sensor, T1 _M , T1 _S upper arm (transistor), T2 _M , T2 _S lower arm (transistor) , 12 Power control system, 14 _M , 14 _S power supply unit, 16 control unit, 20 _M , 20 _S battery, 22 _M , 22 _S converter, 40 auxiliary machine, 50 a, 50 b motor unit, 52 a, 52 b motor, 54 a, 54 b Inverter.

Claims (6)

Two power supply units connected in parallel to each other, each having a power source that can be recharged, and a voltage converter that is connected to the power source and that raises and lowers the supplied voltage. ,
Reactor current acquisition means for acquiring a value and direction of a reactor current that is a current flowing through at least one voltage converter of the two power supply units;
When controlling the drive of the power supply unit, determining the presence or absence of a short circuit between the two power supply units based on the acquired value of the reactor current, and when a short circuit occurs between the power supply units Control means for identifying the power supply unit that caused the short circuit based on the direction of the reactor current;
A power control system comprising: The power control system of claim 1, further comprising:
Provided for each power supply unit, comprising battery current detection means for detecting the value of the battery current that is the current value output from the power supply of the corresponding power supply unit,
The control means determines the presence or absence of an internal short circuit in the power supply unit corresponding to the battery current based on the value of the battery current.
A power control system characterized by that. The power control system according to claim 1 or 2, further comprising:
Provided for each power supply, with a shut-off means to disconnect the power supply from the system,
When the short circuit occurs, the control unit drives the shut-off unit to disconnect the power source of the power supply unit that caused the short circuit from the power control system.
A power control system characterized by that. The power control system according to any one of claims 1 to 3,
The control means calculates, as a power balance current value, a value obtained by multiplying the current value output to the motor by the power distribution ratio between the two power supply units, and calculates the power balance current value from the reactor current value. Power control characterized by calculating a subtracted value as an inter-battery balance current value and determining that a short-circuit between the batteries has occurred when the absolute value of the inter-battery balance current value exceeds a specified threshold system. The power control system according to claim 4,
The control means determines whether or not there is a short circuit between the batteries based on the current balance value between the batteries in a state where the electric motor is connected to a power supply unit. A power control system, wherein the presence or absence of a short circuit between batteries is determined again based on the reactor current value in a state where the electric motor is temporarily disconnected from the power supply unit. The power control system according to any one of claims 1 to 4,
The control unit stores in advance a threshold value that is a criterion for determining whether there is a short circuit,
The threshold value is a variation value that varies according to temperature.
A power control system characterized by that.

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