JP6394565B2 - Power supply - Google Patents

Description

  The present invention relates to control of a power supply apparatus including a plurality of boost converters connected in parallel to an electric load and receiving power supply from a single power supply.

  Japanese Patent Laying-Open No. 2011-114918 (Patent Document 1) discloses a power supply device including a plurality of boost converters connected in parallel to an electric load and receiving power supply from a single power supply.

JP 2011-114918 A

  However, if there is a difference in circuit resistance between the multiple boost converters, depending on the required power, the amount of power loss may vary between when boosting is performed independently and when boosting is performed by combining multiple boost converters. It may not always be constant. For this reason, it is necessary to appropriately select the boost converter to be operated.

  The present invention has been made to solve the above-described problems, and provides a power supply device that appropriately selects a converter to be operated among a plurality of boost converters.

  A power supply device according to an aspect of the present invention includes a first boost converter that is electrically connected to an electrical load, and is electrically connected to the electrical load and connected in parallel to the first boost converter with respect to the electrical load. A second boost converter, a power storage device connected to each of the first boost converter and the second boost converter, and a control device for controlling the boost operation of the first boost converter and the second boost converter. When the control device causes the boost operation to be performed using the first boost converter alone, when the boost operation in which the current flowing through the first boost converter is larger than the limit value of the first boost converter is required, The requested boosting operation is performed using both the first boost converter and the second boost converter. Even if the control device performs the boosting operation using the first boost converter alone, if the boosting operation in which the current flowing through the first boost converter is smaller than the limit value is required, the control device alone uses the first boost converter. The first booster and the second booster according to the power distribution ratio obtained from the ratio between the circuit resistance value of the first booster converter and the circuit resistance value of the second booster converter when the first power loss amount due to the boosting operation is used. When the amount of power loss is smaller than the amount of second power loss caused by performing the boost operation using both converters, the requested boost operation is performed using the first boost converter alone. When the first power loss amount is larger than the second power loss amount, the control device performs the requested boost operation according to the power distribution ratio using both the first boost converter and the second boost converter.

  According to the present invention, both the first boost converter and the second boost converter are used when the first power loss amount is larger than the second power loss amount even when the first boost converter can be used alone and the boost operation is possible. Using this, a boosting operation is performed. Therefore, the boosting operation can be performed using the first boost converter and the second boost converter in a combination with a lower power loss amount. Therefore, it is possible to provide a power supply device that appropriately selects a converter to be operated among a plurality of boost converters.

It is a whole lineblock diagram of a hybrid vehicle carrying a power unit concerning this embodiment. It is a flowchart which shows an example of the control processing performed by a control apparatus. It is a figure which shows the relationship between a voltage and electric power.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

  FIG. 1 is an overall configuration diagram of a hybrid vehicle 1 (hereinafter simply referred to as a vehicle 1) equipped with a power supply device according to the present embodiment. Vehicle 1 includes motor generators MG1 and MG2, boost converters CNV1 and CNV2, a system main relay SMR, an inverter 20, an engine 30, a power split device 40, drive wheels 50, a battery 70, and an ECU (Electronic Control Unit) 200. The power supply device according to the present embodiment includes boost converters CNV1 and CNV2, a battery 70, and ECU 200.

  Motor generators MG 1, MG 2 and engine 30 are connected to power split device 40. Vehicle 1 travels by driving force from at least one of engine 30 and motor generator MG2.

  The power generated by engine 30 is divided by power split device 40 into a path that is transmitted to drive wheels 50 and a path that is transmitted to motor generator MG1.

  Each of motor generators MG1 and MG2 is an AC rotating electric machine, for example, a three-phase AC rotating electric machine including a rotor in which a permanent magnet is embedded. Electric power is generated by motor generator MG1 using the power of engine 30 divided by power split device 40. The AC power generated by motor generator MG1 is converted into DC power by inverter 20 and supplied to battery 70 via boost converter CNV1 or boost converter CNV2.

  Motor generator MG2 generates driving force using at least one of the electric power supplied from battery 70 and the electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to driving wheel 50. When the vehicle is braked, etc., motor generator MG2 is driven by drive wheels 50, and motor generator MG2 operates as a generator. Thus, motor generator MG2 operates as a regenerative brake that converts braking energy into electric power. The AC power generated by motor generator MG2 is converted into DC power by inverter 20 and supplied to battery 70 via boost converter CNV1 or boost converter CNV2.

  Power split device 40 includes a planetary gear mechanism having a sun gear, a pinion gear, a carrier, and a ring gear. The pinion gear meshes with each of the sun gear and the ring gear. The carrier supports the pinion gear so as to be capable of rotating, and is connected to the crankshaft of the engine 30. The sun gear is coupled to the rotation shaft of motor generator MG1. Ring gear is coupled to the rotation shaft of motor generator MG2 and the output shaft connected to drive wheel 50.

  The battery 70 is a direct current power source constituted by a secondary battery such as a nickel metal hydride battery or a lithium ion battery. The battery 70 is configured, for example, by connecting two battery cell groups each having a plurality of battery cells connected in series. Battery 70 is connected to each of boost converters CNV1, CNV2 via system main relay SMR.

  System main relay SMR includes a relay SMRB, a relay SMRP, and a relay SMRG. Opening / closing of each of relay SMRB, relay SMRP, and relay SMRG is controlled based on a signal from ECU 200.

  Relay SMRB switches connection and disconnection of a path between positive electrode line PL1 and positive electrode of battery 70. Relay SMRP switches connection and disconnection of a path between negative electrode line NL and negative electrode of battery 70 via a precharge resistor. Relay SMRG switches connection and non-connection of the path between negative electrode line NL and the negative electrode of battery 70 without passing through the precharging resistor.

  When relay SMRB and relay SMRG are closed, battery 70 is electrically connected to inverter 20.

  A voltage sensor 72 and a current sensor 74 are provided between the battery 70 and the system main relay SMR. The voltage sensor 72 detects the inter-terminal voltage VB of the battery 70. Current sensor 74 detects current IB flowing through battery 70. Each of these sensors outputs a detection result to ECU 200.

  The capacitor C1 is connected to the battery 70 in parallel. Capacitor C1 smoothes voltage VB of battery 70 and supplies it to boost converters CNV1 and CNV2.

  Voltage sensor 36 detects the voltage across capacitor C1, that is, voltage VL between positive line PL1 and negative line NL, and outputs a signal indicating the detection result to ECU 200.

  Each of boost converters CNV1 and CNV2 boosts the voltage between positive line PL1 and negative line NL based on a signal from ECU 200. Inverter 20 converts DC power boosted by boost converters CNV1 and CNV2 into AC power based on a signal from ECU 200, and outputs the AC power to motor generators MG1 and MG2.

  Boost converter CNV1 includes a reactor L1, switching elements Q1, Q2, and diodes D1, D2. Each of switching elements Q1 and Q2 and switching elements Q3 and Q4 described later are, for example, IGBT (Insulated Gate Bipolar Transistor) elements. Switching elements Q1, Q2 are connected in series with each other between power line PL2 and power line NL connecting boost converter CNV1 and inverter 20. Diodes D1 and D2 are connected in antiparallel between the collectors and emitters of switching elements Q1 and Q2, respectively. Reactor L1 has one end connected to a positive line PL1 on the high potential side of battery 70. The other end of reactor L1 is connected to an intermediate point between switching element Q1 and switching element Q2 (a connection point between the emitter of switching element Q1 and the collector of switching element Q2).

  Boost converter CNV1 boosts voltage VB of battery 70 in accordance with PWM (Pulse Width Modulation) control signal PWMC1 for switching each of switching elements Q1, Q2, and applies the boosted voltage to positive line PL2. And supplied to the negative electrode line NL. Further, boost converter CNV1 may step down DC voltage of positive line PL2 and negative line L supplied from inverter 20 and charge battery 70 in accordance with control signal PWMC1.

  Boost converter CNV2 includes a reactor L2, switching elements Q3 and Q4, and diodes D3 and D4. Switching elements Q3, Q4 are connected in series between power line PL3 branched from power line PL2 and power line NL1 branched from power line NL. Diodes D3 and D4 are connected in antiparallel between the collectors and emitters of switching elements Q3 and Q4, respectively. One end of reactor L2 is connected to positive electrode line PL1. Reactor L2 has the other end connected to an intermediate point between switching element Q3 and switching element Q4 (a connection point between the emitter of switching element Q3 and the collector of switching element Q4).

  Boost converter CNV2 boosts voltage VB of battery 70 in accordance with PWM (Pulse Width Modulation) control signal PWMC2 for switching each of switching elements Q3 and Q4, and supplies the boosted voltage to positive line PL3. And supplied to the negative electrode line NL1. Boost converter CNV2 may charge battery 70 by reducing the DC voltage of positive line PL3 and negative line NL1 supplied from inverter 20 in accordance with control signal PWMC2.

  Current sensor 75 detects current IL1 flowing through reactor L1, and outputs a signal indicating the detection result to ECU 200. Current sensor 76 detects current IL2 flowing through reactor L2, and outputs a signal indicating the detection result to ECU 200.

  Capacitor C2 is connected in parallel to each of boost converters CNV1 and CNV2. Capacitor C2 smoothes the DC voltage supplied from boost converter CNV1 or boost converter CNV2 and supplies the smoothed voltage to inverter 20.

  Voltage sensor 24 detects a voltage across capacitor C2, that is, a voltage between positive line PL2 and negative line NL (hereinafter also referred to as “system voltage”) VH, and outputs a signal indicating the detection result to ECU 200. .

  When system voltage VH is supplied from boost converters CNV1 and CNV2, inverter 20 converts DC voltage into AC voltage based on control signal PWMI to operate motor generators MG1 and MG2. Thus, motor generators MG1 and MG2 are operated so as to generate torques specified by the respective torque command values. Inverter 20 includes a plurality of switching elements (not shown) that perform a switching operation in accordance with control signal PWMI.

  ECU 200 includes a CPU (Central Processing Unit) and a memory (not shown). ECU 200 is configured to execute predetermined arithmetic processing based on a map and a program stored in the memory.

  In vehicle 1 having the above-described configuration, ECU 200 places both boost converters CNV1 and CNV2 in a stopped state when there is no boost request during operation of vehicle 1. ECU 200 turns on switching elements Q1, Q3 and turns off switching elements Q2, Q4. Thus, since switching operation is not performed in switching elements Q1-Q4, both boost converters CNV1, CNV2 are stopped.

  ECU 200 determines, for example, whether there is a request for boosting based on required power Pe required for vehicle 1. The ECU 200 calculates the required power Pe required for the vehicle 1 based on the depression amount of the accelerator pedal, the vehicle speed, and the like. The ECU 200 estimates the magnitude of the current (Pe / VL) flowing through the inverter 20 when the boosting operation is not performed by dividing the calculated required power Pe by the voltage VL. It is determined whether it is larger than the current limit value. ECU 200 determines that there is a request for boosting when the estimated current is larger than the current limit value of inverter 20. The current limit value of the inverter 20 is, for example, a predetermined value and is adapted experimentally or designally.

  When it is determined that there is a request for boosting during operation of vehicle 1, ECU 200 uses both first control mode in which boosting operation is performed using boosting converter CNV1 alone, and boosting converters CNV1, CNV2. One of the control modes is selected from the second control mode in which the boosting operation is performed.

  In the first control mode, boost converter CNV1 is controlled so that voltage VH becomes a target value based on a boost request, and boost converter CNV2 is controlled so that current IL2 becomes zero.

  On the other hand, in the second control mode, boost converter CNV1 is controlled so that voltage VH becomes a target value based on a boost request, and a predetermined ratio between boost converters CNV1 and CNV2 (hereinafter, distribution ratio). Boost converter CNV2 is controlled so that power is distributed at K).

  Distribution ratio K is larger than 0 and smaller than 1, and is calculated from the ratio of circuit resistances of boost converters CNV1 and CNV2. For example, when the circuit resistance value of boost converter CNV1 is R1, and the circuit resistance value of boost converter CNV2 is R2, distribution ratio K is calculated by the equation K = R1 / (R1 + R2).

  In the second control mode, boost converter CNV2 is such that the power in boost converter CNV1 is (1-K) × Pe and the power in boost converter CNV2 is K × Pe with respect to the required power Pe required for vehicle 1. Is controlled. More specifically, the operation of boost converter CNV2 is controlled such that a value obtained by multiplying current IL2 and voltage VL is distributed power K × Pe.

  However, if there is a difference in circuit resistance between boost converters CNV1 and CNV2, depending on the required power, boost converter CNV1 performs a boost operation alone, or boost converters CNV1 and CNV2 perform a boost operation. In some cases, the amount of power loss is not always constant. For this reason, it is necessary to appropriately select the boost converter to be operated.

  Therefore, in the present embodiment, ECU 200 is assumed to perform the following operation.

  In other words, when ECU 200 performs the boosting operation using boost converter CNV1 alone, boosting converter CNV1 is required when the boosting operation in which the current flowing through boosting converter CNV1 is larger than the limit value of boosting converter CNV1 is required. , CNV2 are used to perform the requested boosting operation.

  Even if ECU 200 performs a boost operation using boost converter CNV1 alone, if a boost operation in which the current flowing through boost converter CNV1 is smaller than the limit value is required, the first power loss amount is the second power loss. When the amount is smaller than the amount, the boosting operation requested is performed using boost converter CNV1 alone. When the first power loss amount is larger than the second power loss amount, ECU 200 performs the requested boost operation according to the power distribution ratio using both boost converters CNV1 and CNV2.

  The first power loss amount is a power loss amount due to the step-up operation using the boost converter CNV1 alone. The second power loss amount depends on the power distribution ratio K (= R1 / (R1 + R2)) obtained from the ratio of the circuit resistance value R1 of the boost converter CNV1 and the circuit resistance value R2 of the boost converter CNV2 to both boost converters CNV1 and CNV2. Is the amount of power loss due to the step-up operation using.

  In this way, even when boosting operation is possible using boost converter CNV1 alone, when the first power loss amount is larger than the second power loss amount, the boost operation is performed using both boost converters CNV1 and CNV2. Done. Therefore, the boosting operation can be performed using boosting converters CNV1 and CNV2 with a combination having a lower power loss amount.

  FIG. 2 is a flowchart showing a control process executed by ECU 200 included in the power supply device according to the present embodiment. This flowchart is repeatedly executed at a predetermined cycle. Each step of the flowchart is basically described as being realized by software processing by the ECU 200, but may be realized by hardware processing using an electronic circuit created in the ECU 200.

  In step (hereinafter, step is referred to as S) 100, ECU 200 determines whether or not there is a request for boosting. Since the method for determining whether or not there is a request for boosting is as described above, detailed description thereof will not be repeated. If it is determined that there is a request for boosting (YES in S100), the process proceeds to S102. If not (NO in S100), the process proceeds to S104.

  In S102, ECU 200 determines whether or not the magnitude (absolute value) of required power Pe is smaller than a value obtained by multiplying voltage VL and limit value A of current IL1.

  Limit value A of current IL1 is a predetermined value. ECU 200 detects voltage VL by voltage sensor 36. By determining whether or not the magnitude (absolute value) of the required power Pe is smaller than the value obtained by multiplying the voltage VL and the limit value A, the limit is required when the required power Pe performs a boost operation by the boost converter CNV1 alone. It is determined whether or not the power is such that a current flows beyond the value A.

  When it is determined that the magnitude (absolute value) of required power Pe is smaller than the value obtained by multiplying voltage VL and limit value A of current IL1 (YES in S102), the process proceeds to S106. If not (NO in S102), the process proceeds to S110.

  In S104, ECU 200 stops boosting of both boost converters CNV1, CNV2. At this time, the current from the battery 70 flows freely in the boost converters CNV1 and CNV2. The current from battery 70 branches and flows in boost converters CNV1 and CNV2 in accordance with the ratio between the circuit resistance value of boost converter CNV1 and the circuit resistance value of boost converter CNV2 (ie, power distribution ratio K).

  In S106, ECU 200 determines that the power loss amount L1 in boost converter CNV1 in the first control mode is the sum of the power loss amount L2 in boost converter CNV1 and the power loss amount L3 in boost converter CNV2 in the second control mode. It is determined whether it is smaller than (L2 + L3).

ECU 200 calculates, as power loss amount L1, an estimated power loss amount in boost converter CNV1 when performing a boosting operation in the first control mode using, for example, an equation of L1 = R1 × (Pe / VL) ² .

Further, ECU 200 uses, for example, an equation of L2 = R1 × ((1−K) × Pe / VL) ² to estimate the amount of power loss in boost converter CNV1 when performing a boost operation in the second control mode. Is calculated as the power loss amount L2.

Further, ECU 200 uses, for example, an equation of L3 = R2 × (K × Pe / VL) ² to calculate an estimated value of the power loss amount in boost converter CNV2 when performing the boost operation in the second control mode. Calculated as L3.

  The ECU 200 determines whether or not the power loss amount L1 in the first control mode is smaller than the sum L2 + L3 of the power loss amounts in the second control mode. When it is determined that power loss amount L1 in the first control mode is smaller than sum L2 + L3 of power loss amounts in second control mode (YES in S106), the process proceeds to S108. If not (NO in S106), the process proceeds to S110.

  In S108, ECU 200 executes the boost control in the first control mode. Specifically, ECU 200 determines boost target value VHt based on required power Pe, and controls the operation of boost converter CNV1 so that voltage VH detected by voltage sensor 24 becomes determined boost target value VHt. To do. ECU 200 may determine boost target value VHt from required power Pe using, for example, a map indicating the relationship between required power Pe and boost target value VHt.

  ECU 200 may execute feedback control for determining a command value (for example, a duty value) for boost converter CNV1 according to the difference between voltage VH detected by voltage sensor 24 and boost target value VHt, for example.

  Further, ECU 200 performs feedback control for determining a command value (for example, a duty value) of boost converter CNV2 such that current IL2 becomes zero by current sensor 76.

  In S110, ECU 200 executes boost control in the second control mode. Specifically, ECU 200 determines boost target value VHt based on required power Pe, and controls the operation of boost converter CNV1 so that voltage VH detected by voltage sensor 24 becomes determined boost target value VHt. . Further, ECU 200 controls the operation of boost converter CNV2 so that a value obtained by multiplying current IL2 and voltage VH matches distribution ratio K × required power Pe.

  The operation of ECU 200 of the power supply device according to the present embodiment based on the above-described structure and flowchart will be described. In the following description, for convenience of explanation, for example, vehicle 1 is in an electric running state where engine 30 is stopped and boosting operation is stopped in each of boost converters CNV1 and CNV2. Assuming that

  If the magnitude of the value obtained by dividing required power Pe required for vehicle 1 by voltage VL is smaller than the current limit value of inverter 20, it is determined that there is no request for boosting (NO in S100), and boosting operation is performed. Is stopped (S104).

  On the other hand, if the driver depresses the accelerator pedal and the required power Pe increases, and the magnitude of the value obtained by dividing the required power Pe by the voltage VL is greater than or equal to the current limit value of the inverter 20, a boost request is made. It is determined that there is (YES in S100).

  If the magnitude of required power Pe required for vehicle 1 is not less than the value obtained by multiplying voltage VL and limit value A of current IL1 (NO in S102), boost control is performed in the second control mode. It is executed (S110). That is, as described above, ECU 200 controls the operation of boost converter CNV1 so that voltage VH becomes boost target value VHt, and a value obtained by multiplying current IL2 and voltage VH is a distribution ratio K × Pe. Controls the operation of boost converter CNV2.

  On the other hand, when the required power Pe required for vehicle 1 is smaller than the value obtained by multiplying voltage VL and limit value A of current IL1 (YES in S102), the power loss in the first control mode is lost. It is determined whether or not the amount L1 is smaller than the sum L2 + L3 of the power loss amount in the second control mode (S106).

  When the power loss amount L1 in the first control mode is equal to or greater than the sum L2 + L3 of the power loss amounts in the second control mode (NO in S106), the boost control is executed in the second control mode (S110).

  On the other hand, when power loss amount L1 in the first control mode is smaller than sum L2 + L3 of power loss amounts in second control mode (YES in S106), boost control is executed in first control mode (S108). ). As described above, ECU 200 controls the operation of boost converter CNV1 so that voltage VH becomes boost target value VHt. Further, ECU 200 controls the operation of boost converter CNV2 so that current IL2 becomes zero.

  FIG. 3 shows the relationship between the required power Pe and the voltage VL. The vertical axis in FIG. 3 indicates the required power Pe, and the horizontal axis in FIG. 3 indicates the voltage VL. The solid line in FIG. 3 indicates the upper limit of the required power Pe that can be boosted in the first control mode. The broken line in FIG. 3 indicates a region where the boost control in the second control mode has a smaller power loss than the boost control in the first control mode.

  The hatched area in FIG. 3 is an area surrounded by the solid line and the broken line in FIG. The shaded area in FIG. 3 is an area in which the boost control in the first control mode can be executed and the amount of power loss in the boost control in the second control mode is smaller than that in the first control mode. Therefore, in such a region, increase in power loss is suppressed by performing boost control in the second control mode.

  As described above, according to the power supply device according to the present embodiment, even when boost control can be executed in the first control mode, the power loss amount L1 in the first control mode is the power in the second control mode. When the amount of loss is larger than L2 + L3, the boost control is executed in the second control mode. Thus, the boosting operation can be performed using boosting converters CNV1 and CNV2 with a combination of lower power loss amounts. Therefore, it is possible to provide a power supply device that appropriately selects a converter to be operated among a plurality of boost converters.

Hereinafter, modifications will be described.
In the above-described embodiment, the case where the present invention is applied to the hybrid vehicle 1 shown in FIG. 1 has been described as an example. However, the vehicle to which the present invention can be applied is not limited to the hybrid vehicle. You may apply to the electric vehicle which does not have.

  In the above-described embodiment, the case where the vehicle 1 is mounted with the battery 70 has been described as an example, but the battery 70 may use a power storage device other than the secondary battery. For example, a capacitor may be used instead of the secondary battery.

In addition, you may implement combining the above-mentioned modification, all or one part.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 hybrid vehicle, 20 inverter, 24, 36, 72 voltage sensor, 30 engine, 40 power split device, 50 drive wheel, 70 battery, 74, 75, 76 current sensor.

Claims (1)

A first boost converter electrically connected to an electrical load;
A second boost converter electrically connected to the electrical load and connected in parallel to the first boost converter with respect to the electrical load;
A power storage device connected to each of the first boost converter and the second boost converter;
A control device for controlling the boosting operation of the first boost converter and the second boost converter;
The control device includes:
When the step-up operation is performed by using the first step-up converter alone, the step-up operation in which the current flowing through the first step-up converter is larger than the limit value of the first step-up converter is required. Performing the required boosting operation using both the 1 boost converter and the second boost converter;
Even if the boost operation is performed by using the first boost converter alone, if the boost operation in which the current flowing through the first boost converter is smaller than the limit value is required, the first boost converter is used alone. The first power loss due to the boost operation using the first boost converter according to the power distribution ratio obtained from the ratio of the circuit resistance value of the first boost converter and the circuit resistance value of the second boost converter, and When the boosting operation is performed using both of the second boost converters, the requested boosting operation is performed using the first boost converter alone, and the first power loss amount is obtained. Is larger than the second power loss amount, both the first boost converter and the second boost converter are used to obey the power distribution ratio. Performs the requested boost operation, the power supply device.

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