Power system

Abstract

This suppresses the discrepancy between the capacitor detection voltage transmitted to the charging equipment and the actual capacitor voltage. [Solution] When an instruction to start external charging is given, which involves supplying power from the charging equipment to the charging line via the system-side connector to the battery with voltage conversion by a motor and inverter, the detected voltage detected by the voltage sensor is corrected using the first capacitor voltage, which is the capacitor voltage when the system main relay is turned off, and the second capacitor voltage, which is the battery voltage and capacitor voltage when power from the battery is supplied to the charging line with the system main relay turned on, and the corrected detected voltage is transmitted to the charging equipment.

Description

Technical Field

[0001] The present disclosure relates to a power system.

Background Art

[0002] Conventionally, as this type of power system, there has been proposed a system including a motor (electric motor) having a three-phase coil, a battery, a three-phase inverter (PCU) connected to a power line from the battery and the motor, and a system-side connector (charging inlet) connected to a charging line having a positive electrode line and a negative electrode line connected to a neutral point to which the three-phase coil is connected (see, for example, Patent Document 1). In this system, the motor and the inverter are controlled so that the power supplied from the charging facility via the neutral point of the motor is boosted and then supplied to the battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above power system, when the voltage of a capacitor connected to the charging line is detected by a voltage sensor and transmitted to the charging facility side, if the detection accuracy of the voltage sensor is low, the deviation between the detected voltage of the capacitor transmitted to the charging facility side and the actual voltage of the capacitor becomes large, and there may be a case where appropriate processing cannot be executed on the charging facility side.

[0005] The main object of the power system of the present disclosure is to suppress the deviation between the detected voltage of the capacitor transmitted to the charging facility side and the actual voltage of the capacitor.

Means for Solving the Problems

[0006] The power system of this disclosure employs the following means to achieve the main objective described above. The power system of this disclosure comprises a motor having three-phase coils, a battery, a three-phase inverter connected to a power line from the battery and the motor, a system-side connector connected to a charging line having a positive electrode line and a negative electrode line connected to a neutral point to which the three-phase coils are connected, a system main relay attached to the power line, a capacitor connected to the charging line, and a voltage sensor for detecting the voltage of the capacitor. The gist of the power system is that when an instruction to start external charging is given to supply power from a charging device to the charging line via the system-side connector to the battery, accompanied by voltage conversion by the motor and the inverter, the power system of this disclosure includes a control device that corrects the detected voltage detected by the voltage sensor using a first capacitor voltage, which is the voltage of the capacitor when the system main relay is turned off, and a second capacitor voltage, which is the voltage of the battery and the voltage of the capacitor when power from the battery is supplied to the charging line with the system main relay turned on, and transmits the corrected detected voltage to the charging device. In the power system of this disclosure, this configuration makes it possible to suppress the discrepancy between the detected capacitor voltage transmitted to the charging equipment and the actual capacitor voltage. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram of the power system according to the embodiment of this disclosure. [Figure 2] This is a flowchart showing an example of a processing routine. [Figure 3] An explanatory diagram showing the relationship between the actual voltage of a capacitor and the voltage detected by a voltage sensor (detected value). [Modes for carrying out the invention]

[0008] Embodiments for implementing this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of a power system according to an embodiment of this disclosure. As shown in the figure, the power system 20 of the embodiment includes a motor 22, an inverter 24, a capacitor 25, a battery 26, a connector (system-side connector) 40, a system main relay SMR, relays R1 and R2, and an electronic control unit (control device) 60. The power system 20 is used in electric vehicles and hybrid vehicles.

[0009] The motor 22 is configured as a three-phase AC motor having a rotor with permanent magnets embedded in the rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils wound around the stator core. The inverter 24 comprises six transistors T11 to T16 and six diodes D11 to D13 connected in parallel to each of the six transistors T11 to T16. The transistors T11 to T16 are arranged in pairs, with the positive line 30p and negative line 30n (power lines) to which the battery 26 is connected acting as the source and sink sides. Each connection point of a pair of transistors T11 to T16 is connected to the U-phase, V-phase, and W-phase coils of the motor 22, respectively. The capacitor 25 is connected to the positive line 30p and the negative line 30n. The battery 26 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the inverter 24 via a positive electrode line 30p, a negative electrode line 30n, and a system main relay SMR. The system main relay SMR connects and disconnects the battery 26 from the positive electrode line 30p and the negative electrode line 30n by switching it on and off.

[0010] Connector 40 is configured to connect to a connector 72 provided in a charging facility 70 such as a home or charging station, and is connected to the neutral point of the motor 22 via a charging relay DCR, a positive electrode line 42p, and a relay R1, as well as to the negative electrode line 30n via a charging relay DCR and a negative electrode line 42n. Connector 40 is also connected to the positive electrode line 30p via a positive electrode line 42p and a relay R2. Capacitors 43 are connected to the positive electrode line 42p and the negative electrode line 42n. Relay R1 connects and disconnects the neutral point of the motor 22 and the positive electrode line 42p by switching it on and off. When relay R1 is on, a three-phase step-up / step-down converter is formed between the positive electrode line 42p and the negative electrode line 42n and the positive electrode line 30p and the negative electrode line 30n by the motor 22 and the inverter 24. Specifically, a U-phase step-up / step-down converter is formed by the U-phase coil of motor 22 and transistors T11 and T14, a V-phase step-up / step-down converter is formed by the V-phase coil of motor 22 and transistors T12 and T15, and a W-phase step-up / step-down converter is formed by the W-phase coil of motor 22 and transistors T13 and T16. Relay R2 connects and disconnects positive line 30p and positive line 42p by switching it on and off. Charging relay DCR connects and disconnects positive line 42p and negative line 42n to connector 40 by switching it on and off.

[0011] The electronic control unit 60 is equipped with a microcomputer. The electronic control unit 60 receives input from the rotation position sensor 22a (rotation position θm of the motor 22), the U-phase, V-phase, and W-phase currents Iu, Iv, and Iw of the motor 22 from current sensors 22u, 22v, and 22w, the battery voltage Vb from the voltage sensor 26v, the battery current Ib from the current sensor 26i, the current In flowing to the neutral point of the motor 22 from the current sensor 42a, and the capacitor voltage Vc from the voltage sensor 43v which detects the voltage of the capacitor 43. Here, the voltage sensor 26v is a sensor that has a higher voltage detection accuracy than the voltage sensor 43v. The electronic control unit 60 outputs control signals to transistors T11 to T16 of the inverter 24, and control signals to the system main relay SMR, relays R1 and R2. The electronic control unit 60 calculates the state of charge (SOC) of the battery 26 based on the integrated value of the battery current Ib. The electronic control unit 60 is capable of communicating with the charging equipment 70.

[0012] In the power system 20 of this embodiment, when the system is stopped, connector 40 and connector 72 are connected, and when the charging start button installed on the charging equipment 70 side is turned on to instruct the start of external charging, external charging is performed to charge the battery 26 using power from the charging equipment 70. When performing external charging, the system main relay SMR, relay R1 and charging relay DCR are turned on, and relay R2 is turned off, and the inverter 24 is controlled so that the power supplied from the charging equipment 70 to the neutral point of the motor 22 is supplied to the battery 26 with a voltage boost by the three-phase step-up / step-down converter (motor 22 and inverter 24).

[0013] Next, the operation of the power system 20 of the embodiment configured in this way, in particular, the operation when initiating external charging, will be described. Figure 2 is a flowchart of an example of a processing routine executed by the electronic control unit. This routine is executed by the electronic control unit 60 after the connector 40 and connector 72 are connected when the system is stopped, and after the charging start button installed on the charging equipment 70 side is turned on, but before external charging is started. Before the electronic control unit 60 starts executing this routine, the system main relay SMR, relays R1 and R2, and charging relay DCR are turned off. Also, it is assumed that the capacitor 43 is fully discharged. When connector 40 and connector 72 are connected, the charging equipment 70 transmits the upper limit voltage Vsmax, which is the upper limit of the charging voltage that the charging equipment 70 will allow during external charging, to the electronic control unit 60.

[0014] When this routine is executed, the electronic control unit 60 receives the upper limit voltage Vsmax from the charging equipment 70 (S100). Next, the electronic control unit 60 receives the capacitor voltage Vc from the voltage sensor 43v (S110). Then, the electronic control unit 60 sets the capacitor voltage Vc received in S110 to the first capacitor voltage Vc1 (S120). At this time, the actual voltage Vre as the actual voltage of the capacitor 43 is considered to be 0. When the detection accuracy of the voltage sensor 43v is sufficiently high, the capacitor voltage Vc from the voltage sensor 43v is 0. However, in this embodiment, since the detection accuracy of the voltage sensor 43v is relatively low, the capacitor voltage Vc from the voltage sensor 43v may be a value other than 0. Therefore, the first capacitor voltage Vc1 may be set to a value other than 0.

[0015] Next, the electronic control unit 60 connects relay R1 (S130). Then, the electronic control unit 60 connects the system main relay SMR (S140). Next, the electronic control unit 60 turns on transistors T11, T12, and T13 on the upper arm of the inverter 24 (and turns off transistors T14, T15, and T16 on the lower arm) (S150). Next, the electronic control unit 60 receives the battery voltage Vb from the voltage sensor 26v and the capacitor voltage Vc from the voltage sensor 43v as input (S160). Then, the electronic control unit 60 sets the voltage Vb input in S160 to the second battery voltage Vb2 and the capacitor voltage Vc input in S160 to the second capacitor voltage Vc2 (S170). When relay R1 and the system main relay SMR are connected and the upper arm of the inverter 24 is turned on, the actual voltage of capacitor 43 becomes the same as the voltage of battery 26. Therefore, when the detection accuracy of the voltage sensor 43V and the detection accuracy of the voltage sensor 26V are the same, the input voltage Vb in S150 and the capacitor voltage Vc will be the same, and in S170 the second battery voltage Vb2 and the second capacitor voltage Vc2 will be set to the same voltage. In this embodiment, since the detection accuracy of the voltage sensor 43V is lower than that of the voltage sensor 26V, the second battery voltage Vb2 and the second capacitor voltage Vc2 may be set to different voltages in S170.

[0016] Next, the electronic control unit 60 performs a pre-charge of the capacitor 43 in preparation for the start of external charging (S180). During the pre-charge of the capacitor 43, the electronic control unit 60 controls the inverter 24 to exchange power between the battery 26 and the capacitor 43, with voltage conversion by a three-phase step-up / step-down converter (motor 22 and inverter 24), so that the capacitor voltage Vc of the voltage sensor 43v becomes the upper limit voltage Vsmax.

[0017] Then, the electronic control unit 60 receives the capacitor voltage Vc from the voltage sensor 43v (S190). The electronic control unit 60 then uses the following equation (1) to calculate the corrected voltage Vcdet, which is obtained by correcting the capacitor voltage Vc input in S190 using the first capacitor voltage Vc1 set in S120 and the second battery voltage Vb2 and second capacitor voltage Vc2 set in S170, and transmits the corrected voltage Vcdet to the charging equipment 70 (S200), and then terminates this routine. The following equation (1) is a relational expression for converting the capacitor voltage Vc to the actual voltage Vre of capacitor 43, assuming that the voltage Vb from the voltage sensor 26v input in S160, i.e., the second battery voltage Vb2 in S170, represents the actual voltage Vre of capacitor 43. Figure 3 is an explanatory diagram showing the relationship between the actual voltage of the capacitor and the voltage detected by the voltage sensor (detected value). The relationship in equation (1) can be easily derived from the relationship in Figure 3. Therefore, the corrected voltage Vcdet will be the same as or very close to the actual voltage Vre of capacitor 43. In this way, by transmitting the corrected voltage Vcdet, which is obtained by correcting the capacitor voltage Vc using the first capacitor voltage Vc1 set in S120 and the second battery voltage Vb2 and second capacitor voltage Vc2 set in S170, to the charging equipment 70, the discrepancy between the corrected voltage Vcdet transmitted to the charging equipment 70 and the actual voltage Vre of capacitor 43 can be suppressed. After this routine is completed, the electronic control unit 60 will start external charging.

[0018] Vcdet=(Vc-Vc1) / (Vc2-Vc1)·(Vb2-0)···(1)

[0019] Upon receiving the corrected voltage Vcdet, the charging equipment 70 compares the corrected voltage Vcdet with the voltage supplied to the connector 72 detected by the charging equipment 70. If the difference between the corrected voltage Vcdet and the voltage supplied to the connector 72 is greater than or equal to a predetermined difference, the power supply to the connector 72 is stopped. Because the discrepancy between the detected voltage of the capacitor 43 (corrected voltage Vcdet) and the actual voltage of the capacitor 43 (actual voltage Vre) is suppressed, the power supply to the connector 72 can be stopped at an appropriate timing.

[0020] According to the power system 20 of the present embodiment described above, when an external charging start instruction is given to supply the power supplied from the charging facility 70 to the positive electrode line 42p and the negative electrode line 42n (charging line) via the connector 40 to the battery 26 with voltage conversion by the motor 22 and the inverter 24, the first capacitor voltage Vc1 which is the voltage of the capacitor 43 in the state where the system main relay SMR is off, and the second battery voltage Vb2 which is the voltage of the battery 26 when supplying the power from the battery 26 to the positive electrode line 42p and the negative electrode line 42n in the state where the system main relay SMR is on and the second capacitor voltage Vc2 which is the capacitor voltage Vc are used to correct the capacitor voltage Vc detected by the voltage sensor 43v, and by transmitting the corrected voltage Vcdet to the charging facility 70 side, the deviation between the detected voltage (corrected voltage Vcdet) of the capacitor 43 transmitted to the charging facility 70 side and the actual voltage (actual voltage Vre) of the capacitor 43 can be suppressed.

[0021] In the above-described embodiment, the power from the battery 26 is supplied to the positive electrode line 42p and the negative electrode line 42n by connecting the relay R1 and fixing the upper arm of the inverter 24 on in S130 to S150. However, instead of S130 to S150, the power from the battery 26 may be supplied to the positive electrode line 42p and the negative electrode line 42n by turning on the relay R2.

[0022] Note that the correspondence relationship between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems is an example for specifically explaining the form for implementing the invention described in the column of means for solving the problems in the embodiment, and thus does not limit the elements of the invention described in the column of means for solving the problems. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the column of means for solving the problems.

[0023] As described above, the embodiments for implementing the present disclosure have been described using embodiments. However, the present disclosure is not limited to such embodiments, and it is needless to say that the present disclosure can be implemented in various forms without departing from the gist thereof.

Industrial Applicability

[0024] The present disclosure can be used in the manufacturing industry of power systems and the like.

Explanation of Signs

[0025] 20 Power system, 22 Motor, 22a Rotation position sensor, 22u Current sensor, 22v Current sensor, 22w Current sensor, 24 Inverter, 25 Capacitor, 26 Battery, 26i Current sensor, 26v Voltage sensor, 30n Negative electrode line, 30p Positive electrode line, 40 Connector, 42a Current sensor, 42n Negative electrode line, 42p Positive electrode line, 43 Capacitor, 43v Voltage sensor, 60 Electronic control unit, 70 Charging equipment, 72 Connector, D11 Diode, D12 Diode, D13 Diode, DCR Charging relay, R1 Relay, R2 Relay, SMR System main relay, SOC State of charge, T11 Transistor, T12 Transistor, T13 Transistor, T14 Transistor, T15 Transistor, T16 Transistor.

Claims

[Claim 1] A power system comprising: a motor having three-phase coils; a battery; a three-phase inverter connected to a power line from the battery and the motor; a system-side connector connected to a charging line having a positive electrode line and a negative electrode line connected to the neutral point to which the three-phase coils are connected; a system main relay attached to the power line; a capacitor connected to the charging line; and a voltage sensor for detecting the voltage of the capacitor, When an instruction is given to start external charging, which supplies power from the charging equipment to the charging line via the system-side connector to the battery, with voltage conversion by the motor and the inverter, the control device corrects the detected voltage detected by the voltage sensor using a first capacitor voltage, which is the voltage of the capacitor when the system main relay is off, and a second capacitor voltage, which is the voltage of the battery and the capacitor when power from the battery is supplied to the charging line with the system main relay on, and transmits the corrected detected voltage to the charging equipment. A power system equipped with the following features.

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