Power supply control device

Abstract

A power supply control device is provided that is capable of reducing the size of a power supply device including a main power supply and multiple auxiliary power supply systems, while stably supplying power to the multiple auxiliary power supply systems. The power supply control device includes: a DC / DC converter that steps down a power supply voltage from a main battery and outputs the stepped-down power supply voltage to a first auxiliary power supply system and a second auxiliary power supply system; and a controller that stops the power supply from the DC / DC converter to the second auxiliary power supply system when a heater load is in a predetermined high load state, and that supplies power from the DC / DC converter to the second auxiliary power supply system when the heater load changes from the predetermined high load state to a predetermined low load state.

Description

Technical Field

[0001] The invention relates to a power supply control device. Background Art

[0002] As a power supply device that converts the voltage of a single main power supply and outputs the converted voltage to multiple auxiliary power supply systems, a power supply device is known, including: a switching power supply circuit that steps down the DC voltage from the main power supply and outputs the stepped-down DC voltage to a first auxiliary power supply system to which high-voltage auxiliary devices, electric power steering, etc. are connected; and a step-up / step-down chopper circuit that steps down the DC voltage from the first auxiliary power supply system and outputs the stepped-down DC voltage to a second auxiliary power supply system to which low-voltage auxiliary devices, etc., are connected (for example, see Patent Document 1). In the power supply device disclosed in Patent Document 1, choke coils serving as power converters are provided on the secondary side of a transformer in the switching circuit, and in the first and second auxiliary power supply systems, respectively.

[0003] Reference List

[0004] Patent Literature

[0005] Patent Document 1: JP-2010-119257-A Summary of the Invention

[0006] Because magnetic components such as the choke coil that constitutes the power converter have a large footprint, the size of the power supply device increases. In the power supply device disclosed in Patent Document 1, since the choke coil is provided not only on the secondary side of the transformer in the switching circuit and on the first auxiliary power system side in the step-up / step-down chopper circuit, but also on the second auxiliary power system side in the step-up / step-down chopper circuit, the increase in device size is unavoidable.

[0007] Here, although the size of the power supply device can be reduced by reducing the number of choke coils, it is necessary to prevent the stable supply of electric power to the plurality of auxiliary power supply systems from being impaired.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply control device capable of reducing the size of a power supply device including a main power supply and a plurality of auxiliary power supply systems and stably supplying power to the plurality of auxiliary power supply systems.

[0009] The power supply control device of the present invention controls a power supply device, which includes a first auxiliary power supply system, a second auxiliary power supply system and a main power supply. A heat-generating electrical component driven by a first voltage is connected to the first auxiliary power supply system, and a battery charged by a second voltage lower than the first voltage and a low-voltage load driven by the second voltage are connected to the second auxiliary power supply system. The power supply control device includes: a voltage conversion circuit, which reduces the power supply voltage from the main power supply and outputs the reduced power supply voltage to the first auxiliary power supply system and the second auxiliary power supply system; and a control unit, which stops supplying power from the voltage conversion circuit to the second auxiliary power supply system when the load of the heat-generating electrical component is in a predetermined high load state, and supplies power from the voltage conversion circuit to the second auxiliary power supply system when the load of the heat-generating electrical component changes from a predetermined high load state to a predetermined low load state. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a diagram showing an electric vehicle including a power supply control device according to an embodiment of the present invention.

[0011] Figure 2 It shows Figure 1 The circuit configuration of the DC / DC converter is shown in the figure.

[0012] Figure 3 Is used to illustrate the Figure 1 and 2 The controller shown is a timing diagram of the control of the DC / DC converter.

[0013] Figure 4 Is used to illustrate the Figure 1 and 2 The controller shown is a timing diagram of the control of the DC / DC converter.

[0014] Figure 5 is a timing chart showing the relationship between the temperature of the heater and the output voltage and output current of the first and second output systems. DETAILED DESCRIPTION

[0015] Hereinafter, the present invention will be described based on preferred embodiments. The present invention is not limited to the embodiments described below, and the embodiments described below can be appropriately modified without departing from the gist of the present invention. In the embodiments described below, some configurations are not shown or described, but it goes without saying that known or well-known technologies are appropriately applied to the omitted technical details within the scope of the content described below.

[0016] Figure 1 FIG. 1 is a diagram showing an electric vehicle 1 including a power supply control device 10 according to an embodiment of the present invention. Figure 1As shown, an electric vehicle 1 includes a motor M, a power supply device 100, a heater 5, and a low-voltage auxiliary device 7. The power supply device 100 includes a main battery 2, a boost converter 3, an inverter 4, a sub-battery 6, and a power supply control device 10. The electric vehicle 1 may be a hybrid vehicle using an internal combustion engine and the motor M as a driving source, or may be an electric vehicle using only the motor M as a driving source.

[0017] Motor M is used to propel the vehicle and is driven by power supplied by a main battery 2. Main battery 2 is a high-voltage battery that supplies power at a higher voltage (e.g., 48V) than that of an auxiliary power supply system (described later) to motor M and a DC / DC converter 20, described later. Examples of main battery 2 include a lithium-ion battery. A boost converter 3 boosts the DC voltage output from main battery 2 and outputs the boosted DC voltage to an inverter 4. Inverter 4 converts the DC voltage output from boost converter 3 into an AC voltage and outputs the AC voltage to motor M.

[0018] The power supply device 100 includes a main power supply system for supplying power to the motor M and an auxiliary power supply system for supplying power to a load having a voltage lower than that of the motor M. The auxiliary power supply system includes a first auxiliary power supply system 10A and a second auxiliary power supply system 10B. A heater 5, a heat-generating electrical component, is connected to the first auxiliary power supply system 10A as a load, and a low-voltage auxiliary device 7, a load having a voltage lower than that of the heater 5, is connected to the second auxiliary power supply system 10B as a load. Examples of the heater 5 include a sheet heater, a defogger, and a catalyst heater. The power supply control device 10 steps down the power supply voltage of the main power supply system and outputs the stepped-down power supply voltage to the first and second auxiliary power supply systems 10A, 10B.

[0019] The power supply control device 10 includes a controller 12 and a DC / DC converter 20. The controller 12 controls the boost converter 3, the inverter 4, and the DC / DC converter 20. The controller 12 has a function of performing switching control of the boost converter 3, a function of performing switching control of the inverter 4, and a function of performing switching control of the DC / DC converter 20, and is configured with a plurality of electrical control units, a microprocessor unit, etc. that communicate with each other.

[0020] Figure 2 It shows Figure 1 FIG. 2 is a diagram showing a circuit configuration of a DC / DC converter 20. Figure 2As shown, the DC / DC converter 20 includes a first switching circuit 21, a transformer 22, a rectifier circuit 23 and a second switching circuit 24. The first switching circuit 21 is a full-bridge switching circuit and includes four switches 211, 212, 213 and 214. The switches 211 to 214 of the present embodiment are metal oxide semiconductor field effect transistors (MOSFETs). The switches 211 to 214 can be transistor switches different from MOSFETs. Switches 211 and 212 are high-side switches, and switches 213 and 214 are low-side switches. Switch 211 and switch 213 are connected in series, and switch 212 and switch 214 are connected in series.

[0021] Transformer 22 includes a primary coil 221 and a secondary coil 222. Primary coil 221 is connected to first switch circuit 21, and secondary coil 222 is connected to rectifier circuit 23. One end of primary coil 221 is connected to a wire connecting switch 211 and switch 213, and the other end of primary coil 221 is connected to a wire connecting switch 212 and switch 214. Ground line SL1 is connected to the center of secondary coil 222. The ratio of the number of turns of primary coil 221 to the number of turns of secondary coil 222 is set so that the voltage in transformer 22 is stepped down.

[0022] In the first switching circuit 21, switches 211 to 214 are PWM-controlled, causing switches 211 and 214, and switches 212 and 213 to alternately conduct. This generates a positive AC voltage on the secondary side of the transformer 22. Thus, through the switching operation of switches 211 to 214 in the first switching circuit 21, the DC voltage output from the main battery 2 is converted to and stepped down into AC voltage, which is then output to the rectifier circuit 23.

[0023] Rectifier circuit 23 includes diode 231, diode 232, and inductor 233. The anode of diode 231 is connected to one end of secondary coil 222, and the anode of diode 232 is connected to the other end of secondary coil 222. The cathodes of diode 231 and diode 232 are connected to one end of inductor 233. When switches 211 and 214 are turned on, the AC power output from secondary coil 222 is rectified into DC power by diode 232 and inductor 233. On the other hand, when switches 212 and 213 are turned on, the AC power output from secondary coil 222 is rectified into DC power by diode 231 and inductor 233. Inductor 233 is a choke coil, and the power output from secondary coil 222 is accumulated therein.

[0024] The second switching circuit 24 is a single inductor multiple output (SIMO) type DC / DC switching power supply circuit and can output two types of power with different voltages from a single inductor 233. The second switching circuit 24 includes a first output system 24A and a second output system 24B. The first output system 24A includes a first switch 241, an inductor 243, and a capacitor 244. The second output system 24B includes a second switch 242 and a capacitor 245. The first output system 24A does not necessarily include the inductor 243, and when the first output system 24A does not include the inductor 243, the size of the DC / DC converter 20 is further reduced.

[0025] In this embodiment, the first switch 241 and the second switch 242 are MOSFETs. The first switch 241 and the second switch 242 may be transistor switches other than MOSFETs. The drain of the first switch 241 and the drain of the second switch 242 are connected to each other and to the other end of the inductor 233. The source of the first switch 241 is connected to one end of the inductor 243, and the source of the second switch 242 is connected to the second power line SP2 and the ground line SL1.

[0026] The other end of the inductor 243 is connected to the first power line SP1. The first power line SP1 is connected to the heater 5 (see Figure 1 ). The capacitor 244 is connected to the first power line SP1 and the ground line SL1. The inductor 243 and the capacitor 244 smooth the DC voltage output from the inductor 233 and convert the DC voltage into a first voltage VL1. The first voltage VL1 is output from the first power line SP1 to the first auxiliary power system 10A (see Figure 1 ).

[0027] The capacitor 245 is connected to the second power supply line SP2 and the ground line SL1. The capacitor 245 smoothes the DC voltage output from the inductor 233 and converts the DC voltage into a second voltage VL2. Here, the second voltage VL2 is a voltage lower than the first voltage VL1 and is output from the second power supply line SP2 to the second auxiliary power supply system 10B (see FIG. Figure 1 ).

[0028] The second power supply line SP2 is connected to the positive terminal of the sub-battery 6, and the ground line SL1 is connected to the negative terminal of the sub-battery 6. The sub-battery 6 is charged by the DC power of the second voltage VL2 output from the second output system 24B. Figure 1 ) is connected to the second power supply line SP2, and is driven by the DC power output from the second output system 24B or the sub-battery 6.

[0029] The controller 12 performs PWM control on the switches 211 to 214 of the first switching circuit 21, and also performs PWM control on the first switch 241 and the second switch 242 of the second switching circuit 24. The control of the first switch 241 and the second switch 242 performed by the controller 12 differs depending on the load conditions of the heater 5, the sub-battery 6, and the low-voltage auxiliary device 7. First, the control of the first switch 241 and the second switch 242 of the second switching circuit 24 performed by the controller 12 when the load of the heater 5 and the like is in a low load state will be described in conjunction with the control of the switches 211 to 214 of the first switching circuit 21.

[0030] Figure 3 Is used to illustrate the Figure 1 and 2 FIG2 shows a timing diagram of the control of DC / DC converter 20 by controller 12. As shown in this timing diagram, controller 12 turns switches 211 to 214 on and off according to PWM signals P1 to P4. PWM signal P1 for PWM control of switch 211 and PWM signal P2 for PWM control of switch 212 have a complementary relationship, where if one is turned on, the other is turned off. Furthermore, PWM signal P3 for PWM control of switch 213 and PWM signal P4 for PWM control of switch 214 have a complementary relationship.

[0031] Furthermore, the first switching circuit 21 is a phase-shifted full-bridge switching circuit, and PWM signals P2 and P4 are phase-shifted relative to PWM signals P1 and P3. The phase shift amount PS between PWM signals P2 and P4 and between PWM signals P1 and P3, as well as the duty cycle (time duty ratio) of PWM signals P1 to P4, are feedback-controlled. For example, the controller 12 adjusts the phase shift amount PS and the duty cycle based on the difference from the target value of the first voltage VL1 output from the first output system 24A and the difference from the target value of the second voltage VL2 output from the second output system 24B.

[0032] When the PWM signal P1 is turned on, the controller 12 turns on the primary coil 221 from one end side ( Figure 2 The controller 12 applies a voltage Vt to the primary coil 221 from the other end side (the upper end side of the primary coil 221) when the PWM signal P2 is turned on. Figure 2 A voltage Vt is applied to the primary coil 221 (the lower end side in FIG).

[0033] Controller 12 turns on / off first switch 241 and second switch 242 based on PWM signals P5 and P6. PWM signal P5, used to perform PWM control on first switch 241, and PWM signal P6, used to perform PWM control on second switch 242, have a complementary relationship: if one is on, the other is off. The duty ratios of PWM signals P5 and P6 are feedback-controlled. For example, controller 12 sets the duty ratio of PWM signal P6 based on the difference from the target value of second voltage VL2 output from second output system 24B, and generates PWM signal P5 by inverting the on / off behavior of PWM signal P6.

[0034] Next, control of the first switch 241 and the second switch 242 of the second switch circuit 24 performed by the controller 12 according to the load states of the heater 5 , the sub-battery 6 , and the low-voltage auxiliary device 7 will be described.

[0035] Figure 4 Is used to illustrate the Figure 1 and 2 1 shows a timing diagram of the control of the DC / DC converter 20 by the controller 12. As shown in this timing diagram, when the load of the heater 5 is in a predetermined high load state, the controller 12 sets the second switch 242 to a continuously OFF state and sets the first switch 241 to a continuously ON state. An example of a "predetermined high load state" for the load of the heater 5 is a state in which the heater 5 is turned on and the temperature of the heater 5 is rising toward the set temperature. Alternatively, an example of a "predetermined low load state" for the load of the heater 5 is a state in which the temperature of the heater 5 stabilizes after rising to the set temperature.

[0036] Figure 5 is the temperature T of the heater 5 heater The timing diagram shows the relationship between the first and second voltages VL1 and VL2 and the first and second currents IL1 and IL2. The timing diagram on the left shows the state where the first auxiliary power supply system 10A and the second auxiliary power supply system 10B are instantly shut down. The timing diagram on the right shows the state where the first auxiliary power supply system 10A and the second auxiliary power supply system 10B are continuously shut down for a period of time. Figure 5 The first current IL1 indicated by the dotted line in FIG is a current value output from the first output system 24A and is represented by Figure 5 The second current IL2 indicated by the dotted line in FIG. 8 is a current value output from the second output system 24B.

[0037] As shown in the timing chart on the left, when the first auxiliary power system 10A is shut down instantaneously, the temperature of the heater 5 does not drop immediately because the heat capacity of the heater 5 is large enough. That is, in response to the instantaneous power cut, the heater 5 does not cause abnormal operation and maintains the temperature T heaterIn addition, as shown in the timing chart on the right, even when the first auxiliary power supply system 10A is continuously turned off for a period of time, the heater 5 maintains the temperature T according to the size of the heat capacity of the heater 5. heater A period of time.

[0038] That is, when the load of the heater 5 is in a high load state, it is necessary to continuously perform the power supply from the first output system 24A to the heater 5, but when the load of the heater 5 is in a low load state, the power supply from the first output system 24A to the heater 5 can be stopped unless the low load state continues for a long time. Therefore, in order to stabilize the output of the first output system 24A and the second output system 24B, as shown in FIG. Figure 4 As shown in the timing diagram of FIG. 1 , the controller 12 controls the output from the first output system 24A to the first auxiliary power supply system 10A and the output from the second output system 24B to the second auxiliary power supply system 10B.

[0039] The controller 12 determines whether the load of the heater 5 is in a high load state or a low load state based on a control signal for turning the heater 5 on / off or increasing / decreasing the temperature. For example, the controller 12 determines that the load of the heater 5 is in a high load state after a predetermined period of time has passed since the control signal for turning the heater 5 on was received. Alternatively, the controller 12 determines whether the load of the heater 5 is in a high load state or a low load state based on a voltage output to the heater 5.

[0040] The controller 12 determines whether the load of the secondary battery 6 or the low-voltage auxiliary device 7 connected to the second auxiliary power supply system 10B is in a high-load state or a low-load state based on the control signal for charging the secondary battery 6 or the control signal for turning on the low-voltage auxiliary device 7. For example, the controller 12 determines that the load of the secondary battery 6 is in a high-load state after a predetermined period of time has elapsed since receiving the control signal for charging the secondary battery 6. Alternatively, the controller 12 determines whether the load of the secondary battery 6 is in a high-load state or a low-load state based on the voltage Vsub of the secondary battery 6.

[0041] First, during period T1, the heater 5 is off and the load on the heater 5 is low. Furthermore, the state of charge of the sub-battery 6 is sufficiently high, and the load on the low-voltage auxiliary device 7 is also low. During period T1, the first and second output systems 24A and 24B have low outputs.

[0042] Next, after the heater 5 is turned on, during a period T2 in which the temperature of the heater 5 is raised to the set temperature, the controller 12 turns on the first switch 241 and turns off the second switch 242 to continuously supply power from the first output system 24A to the heater 5 and cuts off the power supply from the second output system 24B to the second auxiliary power supply system 10B. During the period T2, the second voltage VL2 of the second auxiliary power supply system 10B is maintained by the sub-battery 6.

[0043] Next, at the temperature T of the heater 5 heater In a stable period T3 after rising to the set temperature, the controller 12 turns on the first switch 241 and turns on the second switch 242. In the period T3, since the load of the heater 5 is in a low load state, the output from the first output system 24A to the heater 5 is set to a low output, and the power supply from the second output system 24B to the sub-battery 6 and the low-voltage auxiliary device 7 is resumed.

[0044] Next, for example, during a period T4 in which the load connected to the second auxiliary power supply system 10B is in a high load state, such as when the secondary battery 6 is being charged, the controller 12 turns off the first switch 241 and turns on the second switch 242. During period T4, the power supply from the first output system 24A to the heater 5 is stopped, and the output of the second output system 24B is set to high output. During period T4, the heater 5 operates stably due to its own heat capacity.

[0045] Next, in a period T5 in which the load connected to the second auxiliary power supply system 10B is in a low load state, the controller 12 turns on the first switch 241 and turns on the second switch 242. In the period T5, the temperature T of the heater 5 is lowered by setting both the output from the first output system 24A and the output from the second output system 24B to a low output. heater Maintaining the set temperature, the voltage Vsub of the sub-battery 6 remains constant, and the low-voltage auxiliary device 7 operates normally.

[0046] As described above, in the power supply control device 10 of this embodiment, by using the single-inductor, multi-output type second switching circuit 24, the number of magnetic components, such as choke coils, included in the DC / DC converter 20 is reduced, and the size of the DC / DC converter 20 is reduced. Furthermore, according to the power supply control device 10 of this embodiment, the power supply to the first and second auxiliary power supply systems 10A, 10B is controlled according to the load status of the heater 5 connected to the first auxiliary power supply system 10A. Therefore, since the required load can be suppressed, power can be stably supplied to the first and second auxiliary power supply systems 10A, 10B, while also suppressing the required output capacity of the main battery 2. Consequently, by reducing the size of the main battery 2 and the power supply control device 10, the size of the power supply device 100 can be reduced, while stably supplying power to the first and second auxiliary power supply systems 10A and 10B.

[0047] Here, when the load of the heater 5 changes from a predetermined high load state to a predetermined low load state, the heater 5 maintains the temperature T by its own heat capacity even when the power supply is reduced or cut off. heater Therefore, according to the control of the present embodiment, in which the power supply to the second auxiliary power supply system 10B is restarted or the power supply to the first auxiliary power supply system 10A is cut off when the load of the heater 5 changes from a predetermined high load state to a predetermined low load state, the charging of the sub-battery 6 connected to the second auxiliary power supply system 10B and the driving of the low-voltage auxiliary device 7 connected to the second auxiliary power supply system 10B can be performed normally while allowing the heater 5 to operate normally without any problem.

[0048] Furthermore, during a period in which power supply to the second auxiliary power supply system 10B is cut off when the load of the heater 5 is in a predetermined high load state, the low voltage auxiliary device 7 can be driven by supplying power from the sub-battery 6 to the low voltage auxiliary device 7 .

[0049] In addition, in the second switching circuit 24 of the single inductor multi-output type, when the load of the heater 5 is in a predetermined high load state, the second switch 242 is set to a continuously off state, so that the power supply to the second auxiliary power supply system 10B can be cut off, and when the load of at least one of the sub-battery 6 and the low-voltage auxiliary device 7 is in a predetermined high load state, the first switch 241 is set to a continuously off state, so that the power supply to the first auxiliary power supply system 10A can be cut off.

[0050] Although the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Without departing from the gist of the present invention, the above embodiments may be appropriately modified or known and publicly known technologies may be appropriately combined.

[0051] For example, although the second switch circuit 24 is a SIMO type switch circuit in the above embodiment, the second switch circuit 24 may be replaced by a switch circuit having the same function. In addition, although the first switch circuit 21 is a full-bridge type switch circuit in the above embodiment, the first switch circuit 21 may be replaced by a switch circuit having the same function.

[0052] Beneficial effects

[0053] According to the present invention, by controlling the power supply to the first and second auxiliary power supply systems based on the load status of heat-generating electrical components connected to the first auxiliary power supply system, it is possible to stably supply power to the first and second auxiliary power supply systems even when the number of magnetic components, such as choke coils, provided in the voltage conversion circuit is reduced. Consequently, the size of a power supply device including a main power supply and multiple auxiliary power supply systems can be reduced, and power can be stably supplied to the multiple auxiliary power supply systems.

Claims

1. A power supply control device for controlling a power supply device, the power supply device comprising: a first auxiliary power system to which heat-generating electrical components driven by a first voltage are connected; a second auxiliary power system, to which a storage battery charged by a second voltage lower than the first voltage and a low-voltage load driven by the second voltage are connected; and Mains power supply, The power control device comprises: a voltage conversion circuit that steps down a power supply voltage from the main power supply and outputs the stepped-down power supply voltage to the first auxiliary power supply system and the second auxiliary power supply system; and a control unit that stops the supply of electric power from the voltage conversion circuit to the second auxiliary power supply system when the load of the heat-generating electrical component is in a predetermined high load state, and supplies electric power from the voltage conversion circuit to the second auxiliary power supply system when the load of the heat-generating electrical component changes from the predetermined high load state to a predetermined low load state, wherein, when the load of at least one of the storage battery and the low-voltage load is in the predetermined high-load state, the control unit stops the power supply from the voltage conversion circuit to the first auxiliary power supply system, and when the load of at least one of the storage battery and the low-voltage load changes from the predetermined high-load state to a predetermined low-load state, the control unit supplies power from the voltage conversion circuit to the first auxiliary power supply system, Wherein, the voltage conversion circuit includes: a first switching circuit that steps down a power supply voltage from the main power supply by switching an element and outputs the stepped-down power supply voltage from a transformer; an inductor to which power output from the transformer is input, and a second switching circuit of a single-inductor multi-output type connected to the inductor, the first auxiliary power system, and the second auxiliary power system, the second switching circuit outputting the first voltage to the first auxiliary power system and the second voltage to the second auxiliary power system, Wherein, the second switch circuit includes: a first switch connected to the inductor and the first auxiliary power system and turned on / off by the control unit according to a first PWM signal, and a second switch connected to the inductor and the second auxiliary power system and turned on / off by the control unit according to a second PWM signal, wherein, when the load of the heat-generating electrical component is in the predetermined high load state, the control unit sets the second switch to the continuously off state, and when the load of at least one of the battery and the low-voltage load is in the predetermined high load state, the control unit sets the first switch to the continuously off state, wherein the control unit sets a duty ratio of the second PWM signal based on a difference from a target value of the second voltage, and generates the first PWM signal obtained by inverting on / off of the second PWM signal, wherein the control unit determines whether the load of the heat-generating electrical component is in a high load state based on a control signal for turning on / off the heat-generating electrical component, a control signal for increasing / decreasing the temperature, or a voltage output to the heat-generating electrical component, Whether at least one of the battery and the low-voltage load is in a high-load state is determined based on a control signal for charging the battery, a control signal for turning on the low-voltage load, or the voltage of the battery.

2. The power supply control device according to claim 1, in, When the control unit stops the supply of electric power from the voltage conversion circuit to the second auxiliary power supply system, electric power is supplied from the battery to the second auxiliary power supply system.

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