Method for inspecting relay contacts for contact weld in battery power source device

ABSTRACT

A method for inspecting relay open/close contacts for a contact weld is provided, each relay open/close contact being connected serially to each of a plurality of battery pack blocks. Battery ECUs for controlling the operating condition of each of the battery pack blocks employ one battery pack block for transmitting an inspection signal and the other battery pack blocks for receiving the inspection signal, such that the transmitting battery ECU transmits the inspection signal with its open/close contact closed. When any one of the other battery pack blocks receives the inspection signal at its battery ECU in which its open/close contact has not been closed, the open/close contact is determined to be welded. This inspection is performed successively with the transmitting and receiving battery ECUs being employed alternately in order to check the plurality of open/close contacts and their secondary open/close contacts for a contact weld.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described below in more detail with reference to the accompanying drawings in accordance with the embodiment to further the understanding of the invention. The embodiment described below is an implementation example of the present invention and not intended to limit the technical scope of the invention.

This embodiment relates to a battery power source device that is employed as a power source for driving a hybrid vehicle, especially a large hybrid vehicle, which incorporates a motor and an engine. As shown in FIG. 1, to meet a large power load demanded by the large hybrid vehicle, a battery power source device according to this embodiment includes six battery pack blocks to in which the battery pack blocks and , the battery pack blocks and , and the battery pack blocks and are connected in series, respectively, and then those three serially connected sets are connected in parallel, or serially in parallel, so as to supply a large output voltage and output current.

The battery pack blocks to each include forty battery modules connected in series, each battery module having six nickel-metal hydride rechargeable batteries connected in series. The battery pack blocks to are further provided with sensing devices, such as current sensors to , voltage sensors (not shown), and temperature sensors (not shown), and cooling fans for cooling the batteries (not shown). Additionally, the battery pack blocks to are connected with battery ECUs to to constitute battery pack systems A to F, respectively.

The battery ECUs to monitor the operating conditions of the battery pack blocks to based on the charge/discharge current and voltage of the battery pack blocks to , the voltage and temperature of each battery module, and the temperature (ambient temperature) of the air for cooling the battery pack blocks to , all of which are detected by the current sensors to , and the voltage and temperature sensors. In addition, the battery ECUs to provide control to the rotation of the cooling fans and compute the SOC (State of Charge), that is the amount of charge accumulated relative to the battery capacity, based on the voltages, currents, and temperatures detected, requiring a vehicle ECU serving as a vehicle controller to provide such a charge and discharge state so as to maintain the SOC at an appropriate state. The data on the voltage, current, and temperature as well as the computed SOC are delivered to the vehicle ECU as information on the operating condition.

The battery pack blocks to are provided with open/close relay contacts to which are connected in series thereto and closed only upon operation of the battery power source device, thereby preventing an operator from receiving an electric shock when the operator contacts, upon assembly or maintenance, positive terminals to and negative terminals to , a positive charge/discharge terminal , and a negative charge/discharge terminal , which are externally exposed. The battery pack blocks , , and , serving as the positive side in the serial connection, are provided with secondary open/close contacts , , and via resistors , , and in parallel with the open/close relay contacts , , and . As shown in FIG. 2, upon starting the battery power source device , the secondary open/close contacts , , and are turned on prior to the open/close relay contacts , , and , thereby preventing an excessive inrush current caused by a charge current flowing into a smoothing capacitor that is connected between the positive charge/discharge terminal and the negative charge/discharge terminal .

There is a possibility of causing the open/close relay contacts to and the secondary open/close contacts , , and to be welded due to a large current passing therethrough. In this context, upon starting the battery power source device or when the battery power source device begins to supply power to the hybrid vehicle, an inspection is automatically performed for a contact weld of the open/close relay contacts to and the secondary open/close contacts , , and . Now, a method of inspecting for a contact weld is described below.

As shown in FIG. 2, when the battery power source device is mounted in the hybrid vehicle, the smoothing capacitor and an inverter are connected between the positive charge/discharge terminal and the negative charge/discharge terminal . The inverter converts direct current power supplied by the battery power source device into alternating current power to drive a motor for driving the vehicle.

As shown in FIG. 3, in the battery ECUs to , connected to a microcomputer are an inspection signal transmitter circuit for outputting an inspection signal and an inspection signal receiver circuit for checking for an inspection signal or detecting the peak value of sinusoidal waves. Since the battery ECUs to and the battery pack blocks to have circuits configured in the same way, they are labeled with the battery ECU and the battery pack block in FIG. . The inspection signal transmitter circuit shapes the waveform of and provides gain control to a signal delivered by the microcomputer to deliver a sinusoidal wave having a predetermined peak value to the negative side of the battery pack block . On the other hand, the inspection signal receiver circuit determines whether the inspection signal delivered by another battery ECU has been transmitted to the negative side of the battery pack block , and is configured as a band pass filter.

In the inspection for a contact weld, one of the six battery pack systems A to F transmits an inspection signal, and the other five systems determine whether the inspection signal has been received. The inspection can be performed in any order. For example, with the battery pack system A serving as a transmitting system, the battery ECU turns on the open/close relay contact or the secondary open/close contact while delivering the inspection signal from the inspection signal transmitter circuit , thereby checking for a contact weld of each of the open/close contacts , , , and of the battery pack systems C, D, E, and F and the secondary open/close contacts and . The battery pack system B is connected in series to the battery pack system A, thus detecting the inspection signal irrespective of the presence or absence of a short circuit of the open/close contact . This inspection signal is transmitted through the closed open/close contact or the closed secondary open/close contact to the battery pack systems C and E arranged in parallel therewith as well as through the positive charge/discharge terminal , the smoothing capacitor , and the negative charge/discharge terminal to the battery pack systems B, D, and F arranged in series therewith.

At this time, if no inspection signal is received at the battery pack systems C, D, E, and F, it is determined that the open/close relay contacts , , , and of the battery pack systems C, D, E, and F and the secondary open/close contacts and have not been welded. Subsequently, the same procedure is followed by the battery pack system C transmitting the inspection signal, and all the battery pack systems A to F are determined not to be welded if no inspection signal is received at the battery pack systems A, B, E, and F.

For example, suppose that the contact weld of the open/close contact of the battery pack system D has occurred among the battery pack systems C, D, E, and F. In this case, the inspection signal transmitted is received at the battery ECU and then sensed at the microcomputer through the inspection signal receiver circuit . At the same time, the inspection signal is also received at the battery pack system C that is serially connected to the battery pack system D. Thus, it is not possible to determine which of the open/close contacts , and the secondary open/close contact in the battery pack system C or the battery pack system D are welded, however, it can be known that at least one of the battery pack systems C and D is welded. To determine whether the battery pack system C or the battery pack system D is welded, the same procedure is followed by the battery pack system C transmitting the inspection signal with the open/close contact and the secondary open/close contact being turned off. If it is found that no inspection signal is sensed at both the battery pack systems C and D, then it is determined that the open/close contact of the battery pack system D is welded.

In this manner, by carrying out the inspection for a contact weld twice, the open/close contacts and the secondary open/close contacts of all the battery pack systems are checked for a contact weld, thereby reducing the time required to find a contact weld.

To perform the inspection automatically, with one of the battery pack systems A to F being set as a master and the other five being set as slaves, each of the battery ECUs to is provided with a communication device and connected to each other via communication lines. For example, with the battery ECU of the battery pack system A being employed as a master, the battery ECU provides control to and assigns an inspection signal to itself and the other battery pack systems B to F to collect inspection results through the communication lines. Since the communication lines can be connected to a vehicle control network, the results of the inspection for a contact weld can be transmitted from the battery ECU , serving as the master, to the vehicle so as to provide control to take countermeasures against a welded contact or data for maintenance.

As described above, according to the present invention, in the battery power source device having a plurality of battery pack blocks connected in parallel or serially in parallel, a contact weld in a relay open/close contact connected to each battery pack block is detected without employing a voltage sensor or the like external to the battery power source device.

Although the present invention has been fully described in connection with the preferred embodiment thereof, it is to be noted that various changes and modifications apparent to those skilled in the art are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of a battery power source device;

FIG. 2 is a block diagram showing the configuration of external connections of the battery power source device;

FIG. 3 is a block diagram showing the internal configuration of a battery ECU for use with an inspection for a contact weld; and

FIG. 4 is a block diagram illustrating the arrangement of a conventional inspection for a contact weld.

CLAIMS

1. A method of inspecting relay contacts for a contact weld in a battery power source device, the battery power source device including a plurality of battery pack systems connected in series, in parallel, or in a series-parallel arrangement, each battery pack system having a battery pack block having a plurality of rechargeable batteries serially connected for charging and discharging operations in a vehicle via a positive charge/discharge terminal and a negative charge/discharge terminal that are connected to the battery pack systems; a battery electronic control unit (ECU) connected with the battery pack block, that controls an operating condition of the battery pack block; and a charge/discharge circuit included with the battery pack block, the charge/discharge circuit having a relay open/close contact, a smoothing capacitor connected between the positive charge/discharge terminal and the negative charge/discharge terminal in the vehicle, the method comprising: determining the existence of an open/close contact weld of the battery pack block by closing the open/close contacts, with the battery ECUs, one by one in an arbitrary order; delivering an inspection signal to the charge/discharge circuit; and determining, with the battery ECU of the other battery pack systems, whether the inspection signal has been received through a parallel connection circuit and the smoothing capacitor.

2. The method of inspecting relay contacts for a contact weld in a battery power source device according to claim 1, wherein one of the plurality of battery ECUs is set as a master ECU and the remaining ECUs are set as slave ECUs, each battery ECU including a communication device connected to the other ECUs via a communication line, and the slave battery ECUs transmit an inspection result of the open/close contacts to the master battery ECU with the communication device via the communication line.

3. The method of inspecting relay contacts for a contact weld in a battery power source device according to claim 2, wherein the communication line is connected to the vehicle to form a network that transmits an inspection result to the vehicle.

4. A method of inspecting relay contacts for a contact weld in a battery power source device, the battery power source device including a plurality of battery pack systems connected in series, in parallel, or in a series-parallel arrangement, each battery pack system having a battery pack block having a plurality of rechargeable batteries serially connected for charging and discharging operations in a vehicle via a positive charge/discharge terminal and a negative charge/discharge terminal that are connected to the battery pack systems; a battery electronic control unit (ECU) connected with the battery pack block, that controls an operating condition of the battery pack block; and a charge/discharge circuit included with the battery pack block, the charge/discharge circuit having a relay open/close contact, a smoothing capacitor connected between the positive charge/discharge terminal and the negative charge/discharge terminal in the vehicle, the method comprising: determining the existence of an open/close contact weld of the battery pack block by closing the open/close contacts, with the battery ECUs, one by one in an arbitrary order; delivering an inspection signal to the charge/discharge circuit; and determining, with the battery ECU of the other battery pack systems, whether the inspection signal has been received through a parallel connection circuit and the smoothing capacitor, wherein one of the plurality of battery ECUs is set as a master ECU and the remaining ECUs are set as slave ECUs, each battery ECU including a communication device connected to the other ECUs via a communication line, and the slave battery ECUs transmit an inspection result of the open/close contacts to the master battery ECU with the communication device via the communication line.

5. The method of inspecting relay contacts for a contact weld in a battery power source device according to claim 4, wherein the communication line is connected to the vehicle to form a network that transmits an inspection result to the vehicle.

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