Diagnostic apparatus and power system including the same

1. A diagnostic apparatus for a power system that comprises a battery assembly, a first contactor, a second contactor, a first protection capacitor, and a second protection capacitor, the diagnostic apparatus comprising:

a first voltage dividing unit connected between a ground of the power system and a first node to which a positive electrode of the battery assembly and one end of the first contactor are commonly connected, and configured to generate a first detection voltage by dividing a voltage applied between the first node and the ground;

a second voltage dividing unit connected between the ground and a second node to which a negative electrode of the battery assembly and one end of the second contactor are commonly connected, and configured to generate a second detection voltage by dividing a voltage applied between the second node and the ground;

a third voltage dividing unit connected between the second node and a third node to which one end of the first protection capacitor and another end of the first contactor are commonly connected, and configured to generate a third detection voltage by dividing a voltage between the third node and the second node; and

a control unit configured to control the first contactor, the second contactor, and the first through third voltage dividing units,

wherein the first voltage dividing unit comprises:

a first voltage divider configured to divide a voltage applied between the first node and the ground, and comprising a first protection resistor and a first detection resistor; and

a first switch configured to selectively apply the voltage applied between the first node and the ground to the first voltage divider, in response to a signal output from the control unit,

wherein the second voltage dividing unit comprises:

a second voltage divider configured to divide a voltage applied between the second node and the ground, and comprising a second protection resistor and a second detection resistor; and

a second switch configured to selectively apply the voltage applied between the second node and the ground to the second voltage divider, in response to a signal output from the control unit,

wherein the third dividing unit comprises:

a third voltage divider configured to divide a voltage applied between the third node and the second node, and comprising a third protection resistor and a third detection resistor; and

a third switch configured to selectively apply the voltage applied between the third node and the second node to the third voltage divider, in response to a signal output from the control unit,

wherein the control unit is configured to execute a first diagnostic function and a second diagnostic function during an inactive section where the first contactor and the second contactor are controlled in an opened state,

wherein the first diagnostic function is a function of determining a current leakage of the battery assembly based on the first detection voltage and the second detection voltage,

the second diagnostic function is a function of determining a short circuit of at least one of the first contactor and the second contactor based on the third detection voltage,

wherein the inactive section comprises a first switching cycle in which the first switch and the third switch are controlled in a closed state, and the second switch is controlled in an opened state, and

the control unit is configured to record a first pattern comprising values of the third detection voltage measured a plurality of times according to time during the first switching cycle, and determine a short circuit of the first contactor based on the first pattern.

2. The diagnostic apparatus of claim 1 ,

wherein the first detection resistor generates the first detection voltage when the first switch is in a closed state, and

the second detection resistor generates the second detection voltage when the second switch is in a closed state.

3. The diagnostic apparatus of claim 2 ,

wherein the third detection resistor generates the third detection voltage when the third switch is in a closed state.

4. The diagnostic apparatus of claim 1 , wherein the control unit comprises:

a microprocessor;

a multiplexer configured to select at least one of the first to third detection voltages, in response to a signal provided from the microprocessor; and

an analog-digital converter (ADC) configured to convert a detection voltage selected by the multiplexer to a digital signal and transmit the digital signal to the microprocessor.

5. The diagnostic apparatus of claim 1 , wherein another end of each of the first protection capacitor and the second protection capacitor is commonly connected to the ground.

6. The diagnostic apparatus of claim 1 , wherein the control unit is configured to output a first alarm signal notifying an execution result of the first diagnostic function and a second alarm signal notifying an execution result of the second diagnostic function.

7. A power system comprising the diagnostic apparatus according to claim 1 .

8. An electric car comprising the power system according to claim 7 .

9. A diagnostic apparatus for a power system that comprises a battery assembly, a first contactor, a second contactor, a first protection capacitor, and a second protection capacitor, the diagnostic apparatus comprising:

a first voltage dividing unit connected between a ground of the power system and a first node to which a positive electrode of the battery assembly and one end of the first contactor are commonly connected, and configured to generate a first detection voltage by dividing a voltage applied between the first node and the ground;

a second voltage dividing unit connected between the ground and a second node to which a negative electrode of the battery assembly and one end of the second contactor are commonly connected, and configured to generate a second detection voltage by dividing a voltage applied between the second node and the ground;

a third voltage dividing unit connected between the second node and a third node to which one end of the first protection capacitor and another end of the first contactor are commonly connected, and configured to generate a third detection voltage by dividing a voltage between the third node and the second node; and

a control unit configured to control the first contactor, the second contactor, and the first through third voltage dividing units,

wherein the first voltage dividing unit comprises:

a first voltage divider configured to divide a voltage applied between the first node and the ground, and comprising a first protection resistor and a first detection resistor; and

a first switch configured to selectively apply the voltage applied between the first node and the ground to the first voltage divider, in response to a signal output from the control unit, and

wherein the second voltage dividing unit comprises:

a second voltage divider configured to divide a voltage applied between the second node and the ground, and comprising a second protection resistor and a second detection resistor; and

a second switch configured to selectively apply the voltage applied between the second node and the ground to the second voltage divider, in response to a signal output from the control unit,

wherein the third dividing unit comprises:

a third voltage divider configured to divide a voltage applied between the third node and the second node, and comprising a third protection resistor and a third detection resistor; and

a third switch configured to selectively apply the voltage applied between the third node and the second node to the third voltage divider, in response to a signal output from the control unit,

wherein the control unit is configured to execute a first diagnostic function and a second diagnostic function during an inactive section where the first contactor and the second contactor are controlled in an opened state,

wherein the first diagnostic function is a function of determining a current leakage of the battery assembly based on the first detection voltage and the second detection voltage, and

the second diagnostic function is a function of determining a short circuit of at least one of the first contactor and the second contactor based on the third detection voltage,

wherein the inactive section comprises a second switching cycle in which the first switch is controlled in an opened state, and the second switch and the third switch are controlled in a closed state, and

the control unit is configured to record a second pattern comprising values of the third detection voltage measured a plurality of times according to time during the second switching cycle, and determine a short circuit of the second contactor based on the second pattern.

10. A power system comprising the diagnostic apparatus according to claim 9 .

11. An electric car comprising the power system according to claim 10 .

12. A diagnostic apparatus for a power system that comprises a battery assembly, a first contactor, a second contactor, a first protection capacitor, and a second protection capacitor, the diagnostic apparatus comprising:

a first voltage dividing unit connected between a ground of the power system and a first node to which a positive electrode of the battery assembly and one end of the first contactor are commonly connected, and configured to generate a first detection voltage by dividing a voltage applied between the first node and the ground;

a second voltage dividing unit connected between the ground and a second node to which a negative electrode of the battery assembly and one end of the second contactor are commonly connected, and configured to generate a second detection voltage by dividing a voltage applied between the second node and the ground;

a third voltage dividing unit connected between the second node and a third node to which one end of the first protection capacitor and another end of the first contactor are commonly connected, and configured to generate a third detection voltage by dividing a voltage between the third node and the second node; and

a control unit configured to control the first contactor, the second contactor, and the first through third voltage dividing units,

wherein the first voltage dividing unit comprises:

a first voltage divider configured to divide a voltage applied between the first node and the ground, and comprising a first protection resistor and a first detection resistor; and

a first switch configured to selectively apply the voltage applied between the first node and the ground to the first voltage divider, in response to a signal output from the control unit, and

wherein the second voltage dividing unit comprises:

a second voltage divider configured to divide a voltage applied between the second node and the ground, and comprising a second protection resistor and a second detection resistor; and

a second switch configured to selectively apply the voltage applied between the second node and the ground to the second voltage divider, in response to a signal output from the control unit,

wherein the third dividing unit comprises:

a third voltage divider configured to divide a voltage applied between the third node and the second node, and comprising a third protection resistor and a third detection resistor; and

a third switch configured to selectively apply the voltage applied between the third node and the second node to the third voltage divider, in response to a signal output from the control unit,

wherein the control unit is configured to execute a first diagnostic function and a second diagnostic function during an inactive section where the first contactor and the second contactor are controlled in an opened state,

wherein the first diagnostic function is a function of determining a current leakage of the battery assembly based on the first detection voltage and the second detection voltage, and

the second diagnostic function is a function of determining a short circuit of at least one of the first contactor and the second contactor based on the third detection voltage, and

wherein the inactive section comprises:

a first switching cycle in which the first switch and the third switch are controlled in a closed state, and the second switch is controlled in an opened state; and

a second switching cycle in which the first switch is controlled in an opened state, and the second switch and the third switch are controlled in a closed state, and

the control unit is configured to determine that the first contactor and the second contactor are in a normal state when the third detection voltage is gradually decreased while having a positive value during the first switching cycle, and is gradually increased while having a negative value during the second switching cycle.

13. The diagnostic apparatus of claim 12 , wherein the control unit is configured to determine that the first contactor and the second contactor are short-circuited due to malfunction when a value of the third detection voltage is maintained constant during the first switching cycle or the second switching cycle.

14. A power system comprising the diagnostic apparatus according to claim 12 .

15. An electric car comprising the power system according to claim 14 .