Power supply device

Abstract

To provide a power supply that can start up quickly. [Solution] The power supply unit comprises a power supply for the vehicle's motor, first and second inverters, a first relay and a second relay interposed in the power line between the power supply and the inverter, a smoothing capacitor for the inverter, a third relay with one end connected between the second relay and the first inverter, a resistor with one end connected to the other end of the third relay and the other end connected between the power supply and the second relay, a bidirectional DC / DC converter connected to the power line and an auxiliary battery, and a control unit. The control unit switches between a first mode in which the closing of the third relay is not restricted, and a second mode in which the closing of the third relay is restricted, depending on the temperature of the resistor. In the first mode, the first and third relays are closed to charge the capacitor from the power supply, and in the second mode, the first relay is closed to charge the capacitor from the auxiliary battery by controlling the bidirectional DC / DC converter.

Description

Technical Field

[0001] The present invention relates to a power supply device.

Background Art

[0002] Regarding a power supply device, for example, Patent Document 1 discloses two inverters connected to each other via the windings of each phase of a motor mounted on a vehicle. The two inverters and the power supply of the motor are connected by a pair of power lines. Also, a pair of relays (SMR: System Main Relay) are interposed in each power line. Further, a smoothing capacitor is connected between the pair of power lines on the input side of each inverter.

[0003] For example, when the power supply device is started, an inrush current flows from the power supply of the motor toward the inverter. In contrast, before the power supply and the inverter are connected via the pair of relays described above, the power supply device charges (pre-charges) the smoothing capacitor via a resistor for preventing inrush current and another relay. This relay is hereinafter referred to as a "pre-charge relay". By pre-charging the smoothing capacitor, the voltage difference between the power supply and the inverter is reduced compared to before pre-charging, so the inrush current at the start of the power supply device is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a power supply unit starts up in conjunction with an external device (such as a charger), repeated restarts due to a deterioration in the communication environment with the external device may cause the pre-charge relay to open and close frequently, potentially leading to overheating of the resistor. Conversely, if the closing of the pre-charge relay is limited, for example, according to the temperature of the resistor, pre-charging will be impossible until the pre-charge relay has cooled sufficiently, which may delay the startup of the power supply unit.

[0006] Therefore, the present invention has been made in view of the above problems, and aims to provide a power supply device that can be started up quickly. [Means for solving the problem]

[0007] The power supply device of the present invention comprises a power supply for supplying power to a motor that drives a vehicle, a first inverter and a second inverter connected to each other via the windings of each phase of the motor, a first relay and a second relay interposed between both terminals of the power supply and a pair of power lines between the first inverter and the second inverter, a capacitor for smoothing the voltage between the pair of power lines on the input side of the first inverter or the second inverter, a third relay with one end connected between the second relay and the first inverter, a resistor with one end connected to the other end of the third relay and the other end connected between one terminal of the power supply and the second relay, a pair of first input / output terminals connected to the pair of power lines, and a bidirectional DC / DC converter having a pair of second input / output terminals connected to both terminals of the vehicle's auxiliary battery, and the first The system comprises a relay, the second relay, the third relay, and a control unit that controls the bidirectional DC / DC converter. The control unit switches between a first mode in which the closing of the third relay is not restricted and a second mode in which the closing of the third relay is restricted, depending on the temperature of the resistor. When the first relay, the second relay, and the third relay are in the open state, in the first mode, the system charges the capacitor from the power supply by controlling the closing of the first relay and the third relay. After the capacitor is charged, the system controls the closing of the second relay and the opening of the third relay. In the second mode, the system charges the capacitor from the auxiliary battery by controlling the bidirectional DC / DC converter. After the capacitor is charged, the system controls the closing of the second relay.

[0008] In the power supply device described above, the control unit may estimate the temperature of the resistor based on the number of times the third relay has been closed, and switch to the first mode if the temperature is below a threshold, or switch to the second mode if the temperature is above the threshold.

[0009] In the power supply device described above, the control unit may lower the temperature by a predetermined value each time a certain period of time has elapsed. [Effects of the Invention]

[0010] According to the present invention, the power supply unit can be started up quickly. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram illustrating an example of a power supply unit. [Figure 2] Figure 2(A) is a diagram illustrating an example of an ECU (Electronic Control Unit). Figure 2(B) is a circuit diagram illustrating an example of a bidirectional DC / DC converter. [Figure 3] Figure 3(A) illustrates the pre-charge operation of the smoothing capacitor on the input side of one inverter in normal mode. Figure 3(B) illustrates the pre-charge operation of the smoothing capacitor on the input side of one inverter in restricted mode. [Figure 4] Figure 4(A) illustrates the pre-charge operation of the smoothing capacitor on the input side of the other inverter in normal mode. Figure 4(B) illustrates the pre-charge operation of the smoothing capacitor on the input side of the other St inverter in restricted mode. [Figure 5] Figure 5 is a flowchart illustrating the process of switching between normal mode and restricted mode. [Figure 6] Figure 6 is a flowchart illustrating the pre-charge process. [Modes for carrying out the invention]

[0012] (Power supply unit configuration) Figure 1 is a diagram illustrating the configuration of a power supply unit S. The power supply unit S is installed in vehicles such as electric vehicles and hybrid vehicles. The power supply unit S includes a drive unit U, a control unit 1, and a charging unit 3.

[0013] The drive unit U includes a power supply PWR, a motor M, inverters 6 and 7, current sensors 9u to 9w, smoothing capacitors 21 and 22, voltage sensors 23 and 24, relays RL1s to RL4s, RLc to RLe, RL1m to RL3m, resistor r, and an inlet 83. The power supply PWR is connected to inverters 6 and 7 via power lines VDDa and VDDb and a ground line SG. The motor M is connected between inverters 6 and 7. Note that power lines VDDa and VDDb and ground line SG are examples of pairs of power lines.

[0014] Motor M drives the vehicle. Motor M comprises a rotor and a stator (not shown). The stator has u-phase, v-phase, and w-phase windings Lu, Lv, and Lw. The stator generates a rotating magnetic field when a three-phase alternating current flows through the windings Lu, Lv, and Lw. The rotor has, for example, permanent magnets and rotates according to the rotating magnetic field of the stator.

[0015] The current sensors 9u, 9v, and 9w are connected in series with the windings Lu, Lv, and Lw, respectively. The current sensors 9u, 9v, and 9w detect the current values ​​of the u-phase, v-phase, and w-phase, respectively. The current sensors 9u, 9v, and 9w each output the current value to the control unit 1.

[0016] The power supply PWR supplies power to the motor M via power lines VDDa, VDDb and ground line SG. The power supply PWR has batteries Eu, Ed, relays RLa, RLb, and terminals T1a to T3a. Batteries Eu and Ed are, for example, lithium-ion batteries. Batteries Eu and Ed are connected in series with each other via relay RLa. The negative terminal of battery Eu is connected to one end of relay RLa. The positive terminal of battery Ed is connected to the other end of relay RLa.

[0017] The power supply PWR is connected to the inverters 6 and 7 via terminals T1a to T3a. Terminals T1a and T3a are connected to the power supply lines VDDa and VDDb respectively. Terminal T2a is connected to the ground line SG. Terminal T1a is drawn from the positive electrode of the battery Eu. Terminal T2a is drawn from the negative electrode of the battery Ed. Also, terminal T3a is drawn from the contact point between one end of the relay RLa and the positive electrode of the battery Ed.

[0018] One end of the relay RLb is connected to the wiring between one end of the relay RLa and the negative electrode of the battery Eu. The other end of the relay RLb is connected to the wiring between the negative electrode of the battery Ed and the terminal T2a. When the relay RLa is closed and the relay RLb is open, the batteries Eu and Ed are connected in series with each other. Also, when the relay RLa is open and the relay RLb is closed, the batteries Eu and Ed are connected in parallel with each other.

[0019] The inverters 6 and 7 are connected to each other via windings Lu, Lv, and Lw. The inverters 6 and 7 convert the direct current of the power supply PWR into three-phase alternating current and output it to the motor M. Note that the inverters 6 and 7 are examples of the first and second inverters.

[0020] The inverter 6 includes switching elements 61 to 66. The switching elements 61 to 66 are connected between the high-potential side wiring H1v and the low-potential side wiring Hs. The inverter 7 includes switching elements 71 to 76. The switching elements 71 to 76 are connected between the high-potential side wiring H2v and the low-potential side wiring Hs. The high-potential side wiring H1v and the low-potential wiring Hs are the power supply lines in the inverter 6, and the high-potential side wiring H2v and the low-potential wiring Hs are the power supply lines in the inverter 7. The potentials of the high-potential side wirings H1v and H2v are higher than the potential of the low-potential wiring Hs.

[0021] Inverters 6 and 7 have input terminals T1b to T3b. Input terminal T1b is drawn from the high-potential side wiring H1v of inverter 6 and connected to the power line VDDa. Input terminal T2b is drawn from the low-potential side wiring Hs of inverters 6 and 7 and connected to the ground line SG. Input terminal T3b is drawn from the high-potential side wiring H2v of inverter 7 and connected to the power line VDDb.

[0022] Each switching element 61-66, 71-76 has a freewheeling diode connected between its two input / output terminals. The switching elements 61-66, 71-76 are, for example, IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), but other electronic components may also be used.

[0023] In the inverter 6, one input / output terminal of the upper arm switching elements 61-63 is connected to the high-potential wiring H1v, and one input / output terminal of the lower arm switching elements 64-66 is connected to the low-potential wiring Hs. The upper arm switching elements 61-63 and the lower arm switching elements 64-66 are connected in series with each other. The contacts of the upper arm switching elements 61-63 and the lower arm switching elements 64-66 are connected to one end of the windings Lu, Lv, and Lw, respectively.

[0024] In the inverter 7, one input / output terminal of the upper arm switching elements 71-73 is connected to the high-potential wiring H2v, and one input / output terminal of the lower arm switching elements 74-76 is connected to the low-potential wiring Hs. The upper arm switching elements 71-73 and the lower arm switching elements 74-76 are connected in series with each other. The contacts of the upper arm switching elements 71-73 and the lower arm switching elements 74-76 are connected to the other ends of the windings Lu, Lv, and Lw, respectively. In addition, the control terminals of each switching element 61-66 and 71-76 are connected to the control unit 1.

[0025] The contacts of switching elements 61 and 64, and the contacts of switching elements 71 and 74 are connected to the u-phase winding Lu. The contacts of switching elements 62 and 65, and the contacts of switching elements 72 and 75 are connected to the v-phase winding Lv. The contacts of switching elements 63 and 66, and the contacts of switching elements 73 and 76 are connected to the w-phase winding Lw.

[0026] The smoothing capacitor 21 is connected between the high-potential wiring H1v and the low-potential wiring Hs on the input side of the inverter 6. The smoothing capacitor 21 smooths the voltage between the power line VDDa and the ground line SG on the input side of the inverter 6. The voltage sensor 23 is connected in parallel with the smoothing capacitor 21. The voltage sensor 23 detects the voltage VH between both terminals of the smoothing capacitor 21. The voltage sensor 23 outputs the detected value to the control unit 1.

[0027] The smoothing capacitor 22 is connected between the high-potential wiring H2v and the low-potential wiring Hs on the input side of the inverter 7. The smoothing capacitor 22 smooths the voltage between the power line VDDb and the ground line SG on the input side of the inverter 7. The voltage sensor 24 is connected in parallel with the smoothing capacitor 22. The voltage sensor 24 detects the voltage VL between both terminals of the smoothing capacitor 22. The voltage sensor 24 outputs the detected value to the control unit 1. Note that smoothing capacitors 21 and 22 are examples of capacitors.

[0028] Relays RL1m and RL2m are connected between the high-potential wiring H1v and H2v. Relays RL1m and RL2m are connected in series with each other. Relay RL3m is interposed in the high-potential wiring H2v between the input terminal T3b and the voltage sensor 24. When power from batteries Eu and Ed is supplied to motor M, relays RL1m and RL2m are in the closed state, and relay RL3m is in the open state. Also, when only power from battery Ed is supplied to motor M, relays RL1m and RL2m are in the open state, and relay RL3m is in the closed state.

[0029] Relays RL1s to RL4s and resistor r are connected between the power supply PWR and inverters 6 and 7. The connection configuration between the power supply PWR and inverters 6 and 7 is switched depending on the open / closed state of relays RL1s to RL4s.

[0030] Relays RL1s and RL3s are examples of the first relay, and relay RL2s is an example of the second relay. Relay RL1s is interposed in the power line VDDa between terminal T1a of the power supply PWR and input terminal T1b of inverters 6 and 7. Relay RL2s is interposed in the ground line SG between terminal T2a of the power supply PWR and input terminal T2b of inverters 6 and 7. Relay RL3s is interposed in the power line VDDb between terminal T3a of the power supply PWR and input terminal T3b of inverters 6 and 7.

[0031] Furthermore, relay RL4s is an example of a third relay. Relay RL4s is connected in series with resistor r. Both ends of the series circuit of relay RL4s and resistor r are connected to both ends of relay RL2s. One end of relay RL4s is connected between relay RL2s and input terminal T2b of inverters 6 and 7. The other end of relay RL4s is connected to one end of resistor r. The other end of resistor r is connected between terminal T2a of power supply PWR and relay RL2s.

[0032] In the power supply PWR, when relay RLa is open and relay RLb is closed, batteries Eu and Ed are connected in parallel. At this time, for example, a DC charger (not shown) charges batteries Eu and Ed via inlet 83. Inlet 83 is connected via relay RLd to the power line VDDa between relay RL1s and the input terminal T1b of inverter 7. In addition, inlet 83 is connected via relay RLe to the ground line SG between relay RL2s and the input terminal T2b of inverter 7. When batteries Eu and Ed are charged via inlet 83, relays RLd and RLe are closed.

[0033] Furthermore, in the power supply PWR, when relay RLa is closed and relay RLb is open, batteries Eu and Ed are connected in series. In this case, when relays RL1s, RL2s and RL1m, RL2m are closed and relays RL3s, RL4s and RL3m are open, the power from batteries Eu and Ed is supplied to motor M via inverters 6 and 7 from input terminals T1b and T2b. At this time, each switching element 61 to 66 of inverter 6 switches according to the PWM (Pulse Width Modulation) signal input to its control terminal. Also, switching elements 71 to 73 of inverter 7 are in the ON state, and switching elements 74 to 75 are in the OFF state.

[0034] Furthermore, in the power supply PWR, when relays RLa and RLb are open, relays RL2s, RL3s and relays RL1m to RL3m are closed, and when relays RL1s and RL4s are open, only battery Ed is connected to inverters 6 and 7. Power from battery Ed is supplied to motor M via inverter 7 from input terminals T3b and T2b. At this time, each switching element 71 to 76 of inverter 7 switches according to the PWM signal input to its control terminal. Also, switching elements 61 to 63 of inverter 6 are turned on, and switching elements 64 to 65 are turned off.

[0035] In any of the above cases, during startup, the control unit 1 charges (precharges) the smoothing capacitors 21 and 22 via resistor r and relay RL4s from the power supply PWR to suppress welding of relays RL1s to RL3s due to the inrush current from the power supply PWR. Because the smoothing capacitors are precharged, the voltage difference between the power supply PWR and inverters 6 and 7 is reduced compared to before precharging, thus suppressing the inrush current when the power supply S starts up.

[0036] Relay RL4s is a pre-charge relay. When relay RL2s is open, relay RL4s closes when the smoothing capacitors 21 and 22 are pre-charged from the power supply PWR. At this time, the inrush current is reduced by flowing through resistor r, thus suppressing welding of relay RL4s due to the inrush current.

[0037] When the power supply unit S starts up in conjunction with an external device (e.g., a charger), repeated restarts due to a deterioration in the communication environment with the external device may cause the relay RL4s to open and close frequently, potentially leading to overheating of the resistor r. Conversely, if the closing of the relay RL4s is limited according to the temperature of the resistor r, precharging will be impossible until the precharging relay has cooled sufficiently, potentially delaying the startup of the power supply unit S.

[0038] Therefore, when the power supply unit S is started up, if there is a risk of the resistor r overheating, the control unit 1 does not close the relay RL4s, but instead controls the bidirectional DC / DC converter 30 in the charging unit 3 to precharge the smoothing capacitors 21 and 22 from the auxiliary battery 84. Details of the precharging of the smoothing capacitors 21 and 22 will be described later.

[0039] The charging unit 3 charges the auxiliary battery (BAT) 84 using a power supply (PWR). The auxiliary battery 84 supplies power to the vehicle's auxiliary equipment (AUX) 85. The auxiliary equipment 85 includes, for example, the vehicle's surveillance cameras and air conditioner.

[0040] The charging unit 3 includes a bidirectional DC / DC converter 30, a capacitor 31, and a voltage sensor 32. The charging unit 3 is, for example, a 2-in-1 unit. In addition to the above configuration, the 2-in-1 unit also includes an OBC (On Board Charger) (not shown). The OBC includes, for example, a DAB (Dual Active Bridge). The OBC charges the batteries Eu and Ed using an AC charger (not shown).

[0041] The bidirectional DC / DC converter 30 has a pair of primary input / output terminals T1c and T1d, and a pair of secondary input / output terminals T2c and T2d. The input / output terminals T1c and T1d are connected to terminals T1a and T2a of the power supply PWR, respectively. One input / output terminal T1c is connected to the power line VDDa between terminal T1a of the power supply PWR and relay RL1s. The other input / output terminal T1d is connected to the ground line SG between relay RL2s and input terminal T2b of inverters 6 and 7. Relay RLc is connected between input / output terminal T1c and terminal T1a of the power supply PWR. Relay RLc is closed when the auxiliary battery 84 is being charged. Note that input / output terminals T1c and T1d are an example of a pair of first input / output terminals.

[0042] Input / output terminals T2c and T2d are connected to the positive and negative terminals of the auxiliary battery 84, respectively. Note that input / output terminals T2c and T2d are an example of a pair of second input / output terminals.

[0043] Capacitor 31 is connected between input / output terminals T1c and T1d. Capacitor 31 smooths the voltage between input / output terminals T1c and T1d. Voltage sensor 32 is connected in parallel with capacitor 31. Voltage sensor 32 detects the voltage across the capacitor 31.

[0044] Control unit 1 controls the drive unit U and the charging unit 3. Control unit 1 includes a PWM controller (PWM-CNT) 10, a relay controller (RL-CNT) 11, a converter controller (DC / DC-CNT) 12, and a vehicle controller (VH-CNT) 13. Note that control unit 1 is an example of a control unit.

[0045] The PWM controller 10 controls the switching operation of inverters 6 and 7 by outputting PWM signals to them. The PWM controller 10 controls the duty cycle of the PWM signal based on the detected values ​​of current sensors 9u to 9w and voltage sensors 23 and 24, for example, according to the required output torque of motor M.

[0046] The relay controller 11 controls the opening and closing of relays RLa~RLe, RL1s~RL4s, and RL1m~RL3m. The converter controller 12 controls the switching operation of the bidirectional DC / DC converter 30 by outputting a PWM signal to the bidirectional DC / DC converter 30. The vehicle controller 13 outputs instructions to the PWM controller 10, the relay controller 11, and the converter controller 12 to cooperate with each other according to the operating status of the vehicle. The PWM controller 10, the relay controller 11, the converter controller 12, and the vehicle controller 13 are each implemented, for example, by an ECU.

[0047] (ECU configuration) Figure 2(A) is a diagram illustrating an example of an ECU. An ECU is an example of a computer. The ECU includes a CPU (Central Processing Unit) 100, ROM (Read Only Memory) 101, RAM (Random Access Memory) 102, and a communication interface (COM-IF) 103, etc. The CPU 100 operates according to the program stored in the ROM 101. The CPU 100 is electrically connected to the ROM 101, RAM 102, and COM-IF 103 via a bus 109.

[0048] ROM101 stores the program that drives the CPU100. RAM102 functions as the working memory for the CPU100. COM-IF103 handles communication between the CPU100 and other ECUs connected via the global bus 108.

[0049] The PWM controller 10, relay controller 11, converter controller 12, and vehicle controller 13 are each implemented by an ECU. Each ECU is connected to the others via a global bus 108. However, the PWM controller 10, relay controller 11, converter controller 12, and vehicle controller 13 may also be implemented by, for example, one or more integrated circuit (IC) chips.

[0050] (Bidirectional DC / DC converter configuration) Figure 2(B) is a circuit diagram illustrating a bidirectional DC / DC converter 30. The primary circuit of the bidirectional DC / DC converter 30 includes switching elements 301-304, an inductor L1, and bypass capacitors C1p and C2p. The secondary circuit of the bidirectional DC / DC converter 30 includes switching elements 305-308 and an inductor L2. The switching elements 301-308 are, for example, IGBTs or MOSFETs, but other electronic components may also be used. The input / output terminals of the upper arm switching elements 301, 303, 305, and 307 are connected to the input / output terminals of the lower arm switching elements 302, 304, 306, and 308, respectively.

[0051] The primary and secondary circuits of the bidirectional DC / DC converter 30 are connected to each other via a transformer TR. The connection points between the upper arm switching elements 301, 303, 305, and 307 and the lower arm switching elements 302, 304, 306, and 308 are connected to the transformer TR. In addition, inductor L1 is connected between the connection points of switching elements 301 and 302 and the transformer TR. Inductor L2 is connected between the connection points of switching elements 305 and 306 and the transformer TR.

[0052] The other input / output terminals of switching elements 301 and 303 are connected to input / output terminal T1c of the bidirectional DC / DC converter 30. The other input / output terminals of switching elements 302 and 304 are connected to input / output terminal T1d of the bidirectional DC / DC converter 30. Bypass capacitors C1p and C2p are connected between the input / output terminals of switching elements 302 and 304, respectively. The other input / output terminals of switching elements 305 and 307 are connected to input / output terminal T2c of the bidirectional DC / DC converter 30. The other input / output terminals of switching elements 306 and 308 are connected to input / output terminal T2d of the bidirectional DC / DC converter 30.

[0053] The control terminals of switching elements 301 to 308 are connected to the converter controller 12. The converter controller 12 outputs a PWM signal to the control terminals of switching elements 301 to 308. As a result, switching elements 301 to 308 perform switching operations, and voltage conversion occurs between the primary and secondary circuits of the bidirectional DC / DC converter 30. At this time, the smoothing capacitor 21 is pre-charged to smooth the voltage between the input and output terminals T1c and T1d.

[0054] The bidirectional DC / DC converter 30 charges the auxiliary battery 84 from the power supply PWR while the motor M is stopped. This allows the auxiliary battery 85 to operate even when the vehicle is parked.

[0055] (Pre-charge operation) When pre-charging is performed, the vehicle controller 13 switches between normal mode and restricted mode depending on the temperature of resistor r. The closing of relay RL4s is not restricted in normal mode, but is restricted in restricted mode. Note that normal mode is an example of the first mode, and restricted mode is an example of the second mode. The following are examples of the pre-charging operation of smoothing capacitors 21 and 22 in normal mode and restricted mode.

[0056] Figure 3(A) illustrates the pre-charge operation of the smoothing capacitor 22 on the input side of the inverter 7 in normal mode. In Figure 3(A), components common to Figure 1 are indicated by the same reference numerals as in Figure 1. Furthermore, explanations of components common to Figure 1 in Figure 3(A) are omitted here. Before the pre-charge operation, relays RLa~RLe, RL1s~RL4s, RLc~RLe, and RL1m~RL3m are in the open state.

[0057] In normal mode, the vehicle controller 13 charges the smoothing capacitor 22 using only the battery Ed. In normal mode, the relay controller 11 controls relay RL4s to be closed. The charging unit 3 is disconnected from the power supply PWR because relay RLc is in the open state.

[0058] In normal mode, the relay controller 11 closes relays RL1s, RL3s, RL4s, and RL3m according to instructions from the vehicle controller 13. Therefore, the battery Ed is connected in parallel with the smoothing capacitor 22. As a result, the smoothing capacitor 22 is charged from the power supply PWR along the path La. The vehicle controller 13 terminates charging, for example, when the voltage detected by the voltage sensor 24 becomes substantially equal to the voltage of the battery Ed.

[0059] After the smoothing capacitor 22 is charged, the relay controller 11 closes relay RL2s and opens relay RL4s according to the instructions of the vehicle controller 13. As a result, the power lines VDDa and VDDb and the ground line SG between the power supply PWR and the inverters 6 and 7 are energized, and the power supply unit S starts up.

[0060] Figure 3(B) illustrates the pre-charge operation of the smoothing capacitor 22 on the input side of the inverter 7 in the limiting mode. In Figure 3(B), components common to Figure 1 are indicated by the same reference numerals as in Figure 1. Furthermore, the explanation of components common to Figure 1 in Figure 3(B) is omitted here. Before the pre-charge operation, relays RLa~RLe, RL1s~RL4s, RLc~RLe, and RL1m~RL3m are in the open state.

[0061] In restricted mode, the vehicle controller 13 restricts the relay controller 11 from closing relay RL4s. As a result, the relay controller 11 does not close relay RL4s. This suppresses overheating of resistor r.

[0062] Furthermore, in the restricted mode, the relay controller 11 closes relays RL1s, RLc, RL1m, and RL2m according to the instructions of the vehicle controller 13. For this reason, the smoothing capacitor 22 is connected between the input / output terminals T1c and T1d of the bidirectional DC / DC converter 30. Subsequently, the vehicle controller 13 charges the smoothing capacitor 22 along the path Lb from the auxiliary battery 84 by controlling the bidirectional DC / DC converter 30 via the converter controller 12. The vehicle controller 13 terminates charging when, for example, the voltage detected by the voltage sensor 24 becomes substantially equal to the voltage of the battery Ed.

[0063] After the smoothing capacitor 22 is charged, the relay controller 11 controls the second relay RL2s to close. As a result, the power lines VDDa and VDDb and the ground line SG between the power supply PWR and the inverters 6 and 7 are energized, and the power supply unit S starts up.

[0064] Figure 4(A) illustrates the pre-charge operation of the smoothing capacitor 21 on the input side of the inverter 6 in normal mode. In Figure 4(A), components common to Figure 1 are indicated by the same reference numerals as in Figure 1. Furthermore, explanations of components common to Figure 1 in Figure 4(A) are omitted here. Before the pre-charge operation, relays RLa~RLe, RL1s~RL4s, RLc~RLe, and RL1m~RL3m are in the open state.

[0065] In normal mode, the vehicle controller 13 charges the smoothing capacitor 21 from the batteries Eu and Ed. In normal mode, the relay controller 11 controls relay RL4s to be closed. The charging unit 3 is disconnected from the power supply PWR because relay RLc is in the open state.

[0066] In normal mode, the relay controller 11 closes relays RLa, RL1s, and RL4s according to the instructions of the vehicle controller 13. As a result, the batteries Eu and Ed and the smoothing capacitor 21 are connected in parallel. Therefore, the smoothing capacitor 21 is charged from the power supply PWR along the path Ka. The vehicle controller 13 terminates charging, for example, when the voltage detected by the voltage sensor 23 becomes substantially equal to the sum of the voltages of batteries Eu and Ed.

[0067] After the smoothing capacitor 21 is charged, the relay controller 11 closes relay RL2s and opens relay RL4s according to the instructions of the vehicle controller 13. As a result, the power line VDDa and the ground line SG between the power supply PWR and the inverters 6 and 7 are energized, and the power supply unit S starts up.

[0068] Figure 4(B) illustrates the pre-charge operation of the smoothing capacitor 21 on the input side of the inverter 6 in the limiting mode. In Figure 4(B), components common to Figure 1 are indicated by the same reference numerals as in Figure 1. Furthermore, explanations of components common to Figure 1 in Figure 4(B) are omitted here. Before the pre-charge operation, relays RLa~RLe, RL1s~RL4s, RLc~RLe, and RL1m~RL3m are in the open state.

[0069] In restricted mode, the relay controller 11 closes relays RL1s, RLc, and RL3s according to instructions from the vehicle controller 13. For this reason, the smoothing capacitor 21 is connected between the input / output terminals T1c and T1d of the bidirectional DC / DC converter 30. Subsequently, the vehicle controller 13 charges the smoothing capacitor 21 from the auxiliary battery 84 along the path Kb by controlling the bidirectional DC / DC converter 30 with the converter controller 12. The vehicle controller 13 terminates charging, for example, when the voltage detected by the voltage sensor 23 becomes substantially equal to the sum of the voltages of batteries Eu and Ed.

[0070] After the smoothing capacitor 22 is charged, the relay controller 11 controls the second relay RL2s to close. As a result, the power lines VDDa and VDDb and the ground line SG between the power supply PWR and the inverters 6 and 7 are energized, and the power supply unit S starts up.

[0071] Thus, in normal mode, the control unit 1 precharges the smoothing capacitors 21 and 22 from the power supply PWR, and in restricted mode, it precharges the smoothing capacitors 21 and 22 from the auxiliary battery 84 by controlling the bidirectional DC / DC converter 30. For this reason, the power supply unit S can start up quickly in restricted mode without waiting for the resistor r to cool down.

[0072] (Resistor temperature estimation) The vehicle controller 13 estimates the temperature of resistor r based, for example, on the number of times relay RL4s has been closed. If the temperature of resistor r is below a threshold, the vehicle controller 13 switches to normal mode, and if the temperature of resistor r is above the threshold, it switches to restricted mode.

[0073] Figure 5 is a flowchart illustrating the switching process between normal mode and restricted mode. This process is executed, for example, after the power to the control unit 1 is turned on.

[0074] First, the vehicle controller 13 performs initial setup (St1). At this time, the vehicle controller 13 sets the number of times relay RL4s has been closed N to 0. The vehicle controller 13 also sets the initial temperature Tr of resistor r to an appropriate value based on, for example, an ambient temperature sensor (not shown). Next, the vehicle controller 13 starts a timer to measure the cooling time in order to take into account the temperature drop due to natural heat dissipation when estimating the temperature of relay RL4s (St2).

[0075] Next, the vehicle controller 13 determines whether or not to perform a closing control (OFF⇒ON) of relay RL4s based on the control information collected from the relay controller 11 (St3). If the closing control is performed (Yes in St3), the vehicle controller 13 adds 1 to the count N (St4). If the closing control is not performed (No in St3), the vehicle controller 13 does not add to the count N.

[0076] Tr = Tr + N × ΔT ... (1)

[0077] Next, the vehicle controller 13 estimates the temperature Tr of relay RL4s based on the number of cycles N (St5). For example, the vehicle controller 13 calculates the temperature Tr according to equation (1) above. In equation (1), ΔT is the temperature increase due to one closing of relay RL4s.

[0078] Next, the vehicle controller 13 determines whether the timer has expired (St6). The timer expires when a certain period of time has elapsed. If the timer has expired (Yes in St6), the vehicle controller 13 decreases the temperature Tr by a predetermined value (St7). At this time, the vehicle controller 13 determines that the temperature of the relay RL4s has decreased by a certain value due to natural heat dissipation. The amount of temperature decrease is determined based on, for example, the results of prior simulations or experiments. Next, the vehicle controller 13 restarts the timer (St8). Also, if the timer has not expired (No in St6), the processes of St7 and St8 are not executed, and the following process of St9 is executed.

[0079] Next, the vehicle controller 13 compares the temperature Tr with a predetermined threshold value TH (St9). If Tr < TH holds (Yes in St9), the vehicle controller 13 determines that the resistor r is not overheated and switches to the normal mode (St10). Also, if Tr ≧ TH holds (No in St9), the vehicle controller 13 determines that the resistor r is overheated and switches to the restricted mode (St11). The threshold value TH is determined based on, for example, the results of prior simulations or experiments.

[0080] Next, the vehicle controller 13 determines whether to end the operation due to factors such as power-off (St12). If the operation continues (No in St12), the processes after St3 are executed again. If the operation ends (Yes in St12), this process ends.

[0081] In this way, the vehicle controller 13 estimates the temperature Tr of the resistor r based on the number N of times the relay RL4s is closed. When the temperature Tr is less than the threshold value TH, the vehicle controller 13 switches to the normal mode, and when the temperature Tr is greater than or equal to the threshold value TH, the vehicle controller 13 switches to the restricted mode. Therefore, the vehicle controller 13 can obtain the temperature Tr of the resistor r without the need for a temperature sensor or the like. Note that, differently, the vehicle controller 13 may obtain the temperature Tr from a temperature sensor.

[0082] Furthermore, the vehicle controller 13 lowers the temperature Tr by a predetermined value each time a certain period of time has elapsed. Therefore, the vehicle controller 13 can estimate the temperature Tr simply and with high accuracy, taking into account the natural heat dissipation of the resistor r. Note that, for example, when the vehicle controller 13 obtains the temperature Tr from a temperature sensor as described above, it does not need to perform the temperature Tr reduction process.

[0083] (Pre-charge processing) Figure 6 is a flowchart illustrating the pre-charge process. This process is executed when the power supply unit S is started up. When the vehicle controller 13 is in normal mode (Yes in St21), it executes the following processes St22 to St28.

[0084] First, the relay controller 11 closes (turns on) relays RL1s, RL3s, RL4s, and RL3m (St22). As a result, current flows between the battery Ed and the smoothing capacitor 22.

[0085] Next, the vehicle controller 13 precharges the smoothing capacitor 22 from the battery Ed (St23). At this time, the vehicle controller 13 controls the charging period based on the voltage detected by the voltage sensor 24 so that the voltage VL between the terminals of the smoothing capacitor 22 and the voltage of the battery Ed are substantially equal. The voltage of the battery Ed is obtained, for example, from a voltage sensor (not shown) provided on the battery Ed.

[0086] Next, the relay controller 11 opens (turns off) relays RL4s and RL3m (St24). As a result, the power supply between battery Ed and smoothing capacitor 22 is interrupted.

[0087] Next, the relay controller 11 closes relays RL4s and RLa (St25). As a result, current flows between batteries Eu and Ed and the smoothing capacitor 21.

[0088] Next, the vehicle controller 13 precharges the smoothing capacitor 21 from batteries Eu and Ed (St26). At this time, the vehicle controller 13 controls the charging period based on the voltage detected by the voltage sensor 23 so that the voltage VH between both terminals of the smoothing capacitor 21 and the sum of the voltages of batteries Eu and Ed become substantially equal. The voltage of battery Eu is obtained, for example, from a voltage sensor (not shown) provided on battery Eu.

[0089] Next, the relay controller 11 closes relays RL2s and RL3m (St27). As a result, the power line VDDa and the ground line SG between batteries Eu and Ed and inverters 6 and 7 become energized, and the power supply unit S starts up. Next, the relay controller 11 opens relay RL4s (St28).

[0090] In this normal mode, the smoothing capacitors 21 and 22 are pre-charged from the power supply PWR, so the power of the auxiliary battery 84 is not consumed. On the other hand, if the vehicle controller 13 is in restricted mode (St21 No, St29 Yes), it executes the following processes St30 to 34.

[0091] First, the relay controller 11 controls the closing of relays RL1s, RL3s, RLc, RL1m to RL3m (St30). For this reason, the smoothing capacitor 22 is connected between the input / output terminals T1c and T1d of the bidirectional DC / DC converter 30, and the auxiliary battery 84 energizes the smoothing capacitors 21 and 22.

[0092] Next, the vehicle controller 13 precharges the smoothing capacitor 22 from the auxiliary battery 84 by switching the bidirectional DC / DC converter 30 using the converter controller 12 (St31). At this time, the vehicle controller 13 controls the charging period based on the voltage detected by the voltage sensor 24 so that the voltage VL between both terminals of the smoothing capacitor 22 and the voltage of the battery Ed are substantially equal. Before precharging the smoothing capacitor 22, the converter controller 12 precharges the capacitor 31 of the charging unit 3 from the auxiliary battery 84 by switching the bidirectional DC / DC converter 30. At this time, the converter controller 12 controls the bidirectional DC / DC converter 30 based on the voltage detected by the voltage sensor 32.

[0093] Furthermore, in this process, the smoothing capacitor 21 is charged simultaneously with the smoothing capacitor 22. However, as described above, the smoothing capacitor 22 is charged until its voltage VL substantially reaches the voltage of battery Ed, while the smoothing capacitor 21 is charged until its voltage VH substantially reaches the sum of the voltages of batteries Eu and Ed. Therefore, in this process, only the charging of the smoothing capacitor 22 is completed.

[0094] Next, the relay controller 11 opens relays RL1m to RL3m (St32). As a result, the power supply between the auxiliary battery 84 and the smoothing capacitor 22 is cut off. However, the power supply between the auxiliary battery 84 and the smoothing capacitor 21 is maintained.

[0095] Next, the vehicle controller 13 precharges the smoothing capacitor 21 from the auxiliary battery 84 by switching the bidirectional DC / DC converter 30 via the converter controller 12 (St33). At this time, the vehicle controller 13 controls the charging period based on the voltage detected by the voltage sensor 24 so that the voltage VH between both terminals of the smoothing capacitor 21 is substantially equal to the sum of the voltages of the batteries Eu and Ed.

[0096] Next, the relay controller 11 closes relays RLa, RL2s, and RL3m (St34). As a result, the power lines VDDa, VDDb and the ground line SG between batteries Eu, Ed and inverters 6, 7 are energized, and the power supply unit S starts up. If the vehicle controller 13 is not in normal mode or restricted mode (No. in St29), that is, if the mode is undetermined, it will execute the process from St21 onwards again.

[0097] In this restricted mode, the pre-charge relay RL4s is open, but the control unit 1 can charge the smoothing capacitors 21 and 22 from the auxiliary battery 84 through the operation of the bidirectional DC / DC converter 30. Therefore, the power supply U can start up quickly without waiting for the resistor r to cool down. Also, in restricted mode, the smoothing capacitors 21 and 22 are pre-charged from the auxiliary battery 84, saving power from batteries Eu and Ed. In this embodiment, the above pre-charge method is used to pre-charge both smoothing capacitors 21 and 22, but it may also be used for only one of the smoothing capacitors 21 or 22.

[0098] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0099] M: Motor, Lu~Lw: Winding, S: Power supply, PWR: Power supply, 1: Control unit (control section), 3: Charging unit, 6,7: Inverter, 30: Bidirectional DC / DC converter, r: Resistor, 84: Auxiliary battery, RL1s, RL3s: Relay (1st relay), RL2s: Relay (2nd relay), RL4s: Relay (3rd relay), T1a~T3a: Terminals, T1b~T3b: Input terminals, T1c, T1d: Input / Output terminals (a pair of 1st input / output terminals), T2c, T2d: Input / Output terminals (a pair of 2nd input / output terminals)

Claims

1. A power supply that provides power to the motor that drives the vehicle, A first inverter and a second inverter are connected to each other via the windings of each phase of the motor, A first relay and a second relay are interposed between both terminals of the power supply and a pair of power lines between the first inverter and the second inverter, respectively. A capacitor for smoothing the voltage between the pair of power lines on the input side of the first inverter or the second inverter, A third relay, one end of which is connected between the second relay and the first inverter, A resistor having one end connected to the other end of the third relay and the other end connected between one terminal of the power supply and the second relay, A bidirectional DC / DC converter comprising a pair of first input / output terminals connected to the pair of power lines and a pair of second input / output terminals connected to both terminals of the vehicle's auxiliary battery, The system includes a first relay, a second relay, a third relay, and a control unit that controls the bidirectional DC / DC converter, The control unit, Depending on the temperature of the resistor, it switches between a first mode in which the closing of the third relay is not restricted, and a second mode in which the closing of the third relay is restricted. When the first relay, the second relay, and the third relay are in the open state, In the first mode, the capacitor is charged from the power supply by closing the first relay and the third relay, and after the capacitor is charged, the second relay is closed and the third relay is opened. In the second mode, the first relay is closed and the bidirectional DC / DC converter is controlled to charge the capacitor from the auxiliary battery, and after the capacitor is charged, the second relay is closed. power supply.

2. The control unit, The temperature of the resistor is estimated based on the number of times the third relay has been closed. If the temperature is below the threshold, the system switches to the first mode; if the temperature is above the threshold, the system switches to the second mode. The power supply device according to claim 1.

3. The control unit lowers the temperature by a predetermined value each time a certain period of time has elapsed. The power supply device according to claim 2.

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