Battery detection circuit and battery management system
The present disclosure provides a battery detection circuit and a battery management system. The battery detection circuit includes a positive relay, a negative relay, a first positive sampling unit, a first negative sampling unit, a second positive sampling unit, a second negative sampling unit, and a reference voltage terminal, wherein: all of the first positive sampling unit, the first negative sampling unit, the second positive sampling unit, the second negative sampling unit and a power battery pack to be detected are connected to the reference voltage terminal. With the battery detection circuit and the battery management system of the present disclosure, both the cost of the battery detection circuit and the complexity of the structure of the battery detection circuit can be reduced.
1. A battery management system, comprising a battery detection circuit and a processor connected to the battery detection circuit, wherein the battery detection circuit comprises a positive relay, a negative relay, a first positive sampling unit, a first negative sampling unit, a second positive sampling unit, a second negative sampling unit, and a reference voltage terminal, wherein:
a first terminal of the positive relay is connected to a positive electrode of a power battery pack to be detected, a first terminal of the negative relay is connected to a negative electrode of the power battery pack to be detected, and each of the first positive sampling unit, the first negative sampling unit, the second positive sampling unit, and the second negative sampling unit is connected to the reference voltage terminal;
the first positive sampling unit is configured to acquire a first positive sampled signal of the power battery pack to be detected at the first terminal of the positive relay;
the first negative sampling unit is configured to acquire a first negative sampled signal of the power battery pack to be detected at the first terminal of the negative relay;
the second positive sampling unit is configured to acquire a second positive sampled signal of the power battery pack to be detected at a second terminal of the positive relay; and
the second negative sampling unit is configured to acquire a second negative sampled signal of the power battery pack to be detected at a second terminal of the negative relay,
wherein the battery detection circuit further comprises a first fixed resistor network and a second fixed resistor network, wherein:
the first fixed resistor network comprises at least a resistor, and the second fixed resistor network comprises at least a resistor;
the first fixed resistor network and the first positive sampling unit are connected in parallel between the positive electrode of the power battery pack to be detected and the reference voltage terminal; and
the second fixed resistor network and the first negative sampling unit are connected in parallel between the negative electrode of the power battery pack to be detected and the reference voltage terminal,
wherein the processor is configured to:
calculate a voltage at the first terminal of the positive relay based on the first positive sampled signal;
calculate a voltage at the first terminal of the negative relay based on the first negative sampled signal;
obtain a relay-input voltage of the power battery pack to be detected, based on the voltage at the first terminal of the positive relay and the voltage at the first terminal of the negative relay, wherein the relay-input voltage of the power battery pack to be detected is a voltage between the first terminal of the positive relay and the first terminal of the negative relay;
calculate a voltage at the second terminal of the positive relay based on the second positive sampled signal;
calculate a voltage at the second terminal of the negative relay based on the second negative sampled signal; and
obtain a relay-output voltage of the power battery pack to be detected, based on the voltage at the second terminal of the positive relay and the voltage at the second terminal of the negative relay, wherein the relay-output voltage of the power battery pack to be detected is a voltage between the second terminal of the positive relay and the second terminal of the negative relay, and
wherein the processor is further configured to:
control a first switch and a second switch to be in a first switch state by turning on both the first switch and the second switch;
calculate a voltage at a positive terminal of the power battery pack to be detected and a voltage at a negative terminal of the power battery pack to be detected under the first switch state, based on the first positive sampled signal and the first negative sampled signal acquired under the first switch state;
control the first switch and the second switch to be in a second switch state by turning on the first switch and turning off the second switch;
calculate the voltage at the positive terminal of the power battery pack to be detected under the second switch state, based on the first positive sampled signal acquired under the second switch state;
control the first switch and the second switch to be in a third switch state by turning off the first switch and turning on the second switch;
calculate the voltage at the negative terminal of the power battery pack to be detected under the third switch state, based on the first negative sampled signal acquired under the third switch state; and
calculate a first parallel resistance value of a positive insulation resistance value of the power battery pack to be detected and a resistance value of the first fixed resistor network, and a second parallel resistance value of a negative insulation resistance value of the power battery pack to be detected and a resistance value of the second fixed resistor network, based on the voltage at the positive terminal of the power battery pack to be detected under the first switch state, the voltage at the negative terminal of the power battery pack to be detected under the first switch state, the voltage at the positive terminal of the power battery pack to be detected under the second switch state and the voltage at the negative terminal of the power battery pack to be detected under the third switch state.
2. The battery management system of claim 1 , wherein the battery detection circuit further comprises a first positive sampling point, a first negative sampling point, a second positive sampling point, and a second negative sampling point, wherein:
the first positive sampling unit is further configured to provide the first positive sampled signal to the first positive sampling point;
the first negative sampling unit is further configured to provide the first negative sampled signal to the first negative sampling point;
the second positive sampling unit is further configured to provide the second positive sampled signal to the second positive sampling point; and
the second negative sampling unit is further configured to provide the second negative sampled signal to the second negative sampling point.
3. The battery management system of claim 2 , wherein:
a terminal of the first positive sampling unit is connected to the first terminal of the positive relay and the positive electrode of the power battery pack to be detected, and the other terminal of the first positive sampling unit is connected to the first positive sampling point and the reference voltage terminal;
a terminal of the first negative sampling unit is connected to the first terminal of the negative relay and the negative electrode of the battery pack to be detected, and the other terminal of the first negative sampling unit is connected to the first negative sampling point and the reference voltage terminal;
a terminal of the second positive sampling unit is connected to the second terminal of the positive relay, and the other terminal of the second positive sampling unit is connected to the second positive sampling point and the reference voltage terminal;
a terminal of the second negative sampling unit is connected to the second terminal of the negative relay, and the other terminal of the second negative sampling unit is connected to the second negative sampling point.
4. The battery management system of claim 3 , wherein:
the first positive sampling unit comprises a first resistor network and a second resistor network in series;
a terminal of the first resistor network is connected to the first terminal of the positive relay and the positive electrode of the power battery pack to be detected, and the other terminal of the first resistor network is connected to the first positive sampling point and a terminal of the second resistor network; and
the other terminal of the second resistor network is connected to the reference voltage terminal.
5. The battery management system of claim 4 , wherein:
the first positive sampling unit further comprises a first switch; and
a terminal of the first resistor network is connected, via the first switch, to the positive electrode of the power battery pack to be detected.
6. The battery management system of claim 3 , wherein:
the first negative sampling unit comprises a third resistor network and a fourth resistor network in series;
a terminal of the third resistor network is connected to the reference voltage terminal, and the other terminal of the third resistor network is connected to the first negative sampling point and a terminal of the fourth resistor network; and
the other terminal of the fourth resistor network is connected to the first terminal of the negative relay and the negative electrode of the power battery pack to be detected.
7. The battery management system of claim 6 , wherein:
the first negative sampling unit further comprises a second switch; and
a terminal of the third resistor network is connected to the reference voltage terminal via the second switch.
8. The battery management system of claim 3 , wherein:
the second positive sampling unit comprises a fifth resistor network and a sixth resistor network in series;
a terminal of the fifth resistor network is connected to the second terminal of the positive relay, and the other terminal of the fifth resistor network is connected to the second positive sampling point and a terminal of the sixth resistor network; and
the other terminal of the sixth resistor network is connected to the reference voltage terminal.
9. The battery management system of claim 8 , wherein:
the second positive sampling unit further comprises a third switch; and
a terminal of the fifth resistor network is connected to the second terminal of the positive relay via the third switch.
10. The battery management system of claim 3 , wherein:
the second negative sampling unit comprises a seventh resistor network and an eighth resistor network in series;
a terminal of the seventh resistor network is connected to the reference voltage terminal, and the other terminal of the seventh resistor network is connected to the second negative sampling point and a terminal of the eighth resistor network; and
the other terminal of the eighth resistor network is connected to the second terminal of the negative relay.
11. The battery management system of claim 10 , wherein:
the second negative sampling unit further comprises a fourth switch; and
a terminal of the seventh resistor network is connected to the reference voltage terminal via the fourth switch.
12. The battery management system of claim 2 , wherein the battery detection circuit further comprises a first voltage pull-up unit and a second voltage pull-up unit, wherein:
the first voltage pull-up unit is connected to the first negative sampling point, and the first voltage pull-up unit is configured to pull up the first negative sampled signal to be a positive voltage signal;
the second voltage pull-up unit is connected to the second negative sampling point, and the second voltage pull-up unit is configured to pull up the second negative sampled signal to be a positive voltage signal.
13. The battery management system of claim 12 , wherein:
the first voltage pull-up unit comprises a first DC voltage source and a ninth resistor network; and
a terminal of the ninth resistor network is connected to the first negative sampling point, and the other terminal of the ninth resistor network is connected to the first DC voltage source.
14. The battery management system of claim 12 , wherein:
the second voltage pull-up unit comprises a second DC voltage source and a tenth resistor network; and
a terminal of the tenth resistor network is connected to the second negative sampling point, and the other terminal of the tenth resistor network is connected to the second DC voltage source.
15. The battery management system of claim 1 , further configured to:
diagnose an operating state of the positive relay based on a preset voltage threshold of the positive relay, the voltage at the first terminal of the positive relay and the voltage at the second terminal of the positive relay; and
diagnose an operating state of the negative relay based on a preset voltage threshold of the negative relay, the voltage at the first terminal of the negative relay and the voltage at the second terminal of the negative relay.