CURRENT SENSOR

Description

[0001] The development concerns a current sensor for measuring current in a vehicle with two independent measurement principles.

[0002] Vehicles, especially electric and hybrid vehicles, use batteries with high voltages. During vehicle operation, it is necessary to continuously monitor the battery currents to accurately determine the battery's state of charge.

[0003] To ensure the required reliability and accuracy of current measurement in the automotive sector, it is necessary to provide redundant current measurement, particularly with two independent sensors and / or measurement principles. Such sensors are shown, for example, in EP2732295A1, US 2017 / 261536 A1, WO 2007 / 068221 A1, DE 102016 218 049 A1, or WO 2013 / 007833 A1.

[0004] The object of the invention is to improve a sensor described above by increasing the measurement accuracy and the reliability.

[0005] To solve the problem, a battery sensor is provided for detecting the current flowing through an electrical conductor. The battery sensor has at least two independent measuring devices for detecting the current flowing through the electrical conductor. The measuring devices are structurally and electrically completely separated from each other. Each measuring device is arranged on a separate circuit board. This complete separation of the measuring devices reliably ensures that they do not interfere with each other. This means that the measuring devices do not share any components, so that influences from one component do not affect the other measuring device. In particular, circuit boards with different layouts can be used, so that design disadvantages of a particular circuit board can only occur in one of the two measuring devices.In particular, the circuit boards can be manufactured separately, so that errors in production cannot affect both measuring devices.

[0006] To ensure complete independence of the measuring devices, each device has its own separate power supply. Therefore, faults in one of the power supplies do not affect the other measuring devices.

[0007] At least one measuring device operates on a magnetic measuring principle. However, other magnetic measuring principles can also be used that detect changes in the magnetic field due to the current flowing through the conductor.

[0008] At least one measuring device includes at least one measuring resistor and a voltage detection device for measuring the voltage drop across the measuring resistor. From the measured voltage difference and the known electrical resistance of the measuring resistor, the current flowing through the measuring resistor can be calculated using Ohm's law.

[0009] Furthermore, each measuring device has a separate signal input and signal output. This means that there is no shared signal processing or evaluation within the battery sensor.

[0010] In particular, the measuring devices are electrically isolated from each other to reliably prevent mutual interference. For example, the measuring devices are galvanically isolated or galvanically decoupled from each other. The measuring device, which operates according to a magnetic measuring principle, preferably includes a Hall sensor.

[0011] This measuring device is preferably connected to the electrical conductor before and after the measuring resistor for voltage detection. To prevent voltage flashover within this measuring device from the electrical conductor to the signal output or signal input and / or the power supply, devices for electrical isolation of the measuring device from the signal inputs or signal outputs and a connection for the power supply are preferably provided.

[0012] For example, these devices include at least one transformer. In particular, such a transformer can be arranged within the circuit board to save space.

[0013] In an unclaimed embodiment, two measuring devices with the same measuring principle can also be used, for example, with a measuring resistor or a magnetic measuring principle. It is only necessary to ensure that the measuring devices are completely independent of each other in order to exclude or at least reduce interference from a common source of disturbance. However, it is possible for both measuring devices to use the same measuring resistor, as long as the detection of the voltage drops and the signal processing are completely independent of each other and interference from a common source of disturbance is excluded.

[0014] Further advantages and features can be found in the following description in conjunction with the attached drawings. These show: Figure 1 is a schematic representation of a battery sensor; Figure 2 is a second schematic representation of a battery sensor; Figure 3 is a perspective view of a battery sensor.

[0015] The current sensor has an electrical conductor (800V bus) that is located in the high-voltage circuit and is therefore carrying battery current. The current sensor is preferably used in electric or hybrid vehicles to measure the high currents supplied by the vehicle battery or those present during charging.

[0016] A first measuring device is provided on the first section of the electrical conductor. This device performs contactless current measurement using a magnetic measuring principle with a Hall sensor (contactless ASIC or open-loop HALL). The Hall sensor is powered by a low-voltage circuit with 5V (Power Supply 2), for example, by a vehicle battery (12V). The Hall sensor also has a signal output (Analog Out) for displaying the measured values. The Hall sensor itself is not connected to the electrical conductor and therefore has no electrical contact with the high-voltage (HV) side. The Hall sensor is thus located entirely on the low-voltage (LV) side. A second measuring device is provided on the second section. This device consists of a measuring resistor (shunt) and a measuring device (shunt Quibz + Z), which is contacted with the electrical conductor both before and after the measuring resistor.The measuring device can measure the voltage before and after the measuring resistor and thus the voltage drop across the measuring resistor. From the voltage difference and the known electrical resistance of the measuring resistor, the current flowing through the measuring resistor can be calculated using Ohm's law.

[0017] The second measuring device also has a low-voltage power connection with 5 V or 12 V (Power Supply 1) and a signal output (CAN out) for outputting the measured values.

[0018] As particularly in Figure 1As can be seen, the second measuring device is connected to the high-voltage circuit via the connections before and after the measuring resistor. The separation between the high-voltage and low-voltage sides is achieved in the power supply (DC / DV) and the correspondingly isolated signal output (Isolated CAN Driver), respectively. On the circuit board of the second measuring device, for example, a transformer is provided for both the power supply and the signal output, thus separating the high-voltage and low-voltage sides.

[0019] Alternatively, other devices or constructive measures may be provided that enable signal transmission or power supply but reliably exclude a voltage exceeding a certain threshold.

[0020] To ensure that the Hall sensor and the shunt measurement are completely independent of each other, they are located on different sections of the electrical conductor.

[0021] Furthermore, the power supply to both measuring devices is independent of each other, i.e., faults within the power supply only affect the respective measuring device and not both measuring devices.

[0022] Furthermore, as in Figure 3 As can be seen, separate circuit boards (PCB1, PCB2) are provided for both measuring devices. This ensures that the measuring devices are completely isolated from each other and cannot influence one another. In particular, the measuring devices can be positioned anywhere relative to each other. Furthermore, different circuit boards can be selected, for example, to minimize production-related influences.

[0023] Additionally, design measures can be implemented to separate the printed circuit boards and prevent any mutual discharge. For example, galvanic isolation or decoupling can be provided.

Claims

1. A battery sensor for detecting a current flowing through an electrical conductor, wherein the battery sensor has at least two mutually independent measuring apparatuses for detecting the current flowing through the electrical conductor, wherein the measuring apparatuses are structurally and electrically completely separated from one another, wherein each measuring apparatus is arranged on a separate printed circuit board, wherein at least one measuring apparatus functions according to a magnetic measuring principle, and at least one measuring apparatus has at least one measuring resistor as well as a voltage detection apparatus for detecting the voltage dropping across the measuring resistor, and a separate power supply is provided for each measuring apparatus, and each measuring apparatus has a separate signal input and signal output.

2. The battery sensor according to claim 1, characterised in that the measuring apparatuses are insulated from one another.

3. The battery sensor according to any one of the preceding claims, characterised in that the measuring apparatus functioning according to a magnetic measuring principle has a Hall sensor.

4. The battery sensor according to any one of the preceding claims, characterised in that devices for electrical separation of the measuring apparatus from the signal inputs or signal outputs as well as a connection for the power supply are provided in the measuring apparatus having the measuring resistor.

5. The battery sensor according to claim 4, characterised in that the devices can have at least one transformer.