Current monitoring and circuit temperature measurements
An apparatus includes a controller that measures a first voltage across a first circuit path including a series connection of a first switch and a shunt resistor. The first voltage generated based on first current supplied from a first winding of a motor including multiple windings. Based on the magnitude of the first voltage, the controller determines an ON-resistance of the first switch. The ON-resistance can be used final office action any suitable purpose. For example, the controller can be configured to use the determined ON-resistance of the first switch to controller operation of a motor including the first winding. For example, the determined ON-resistance can be used as a basis to determine an amount of current through first switch and corresponding first winding of the motor.
1. An apparatus comprising:
a controller operative to:
monitor a first voltage across a first circuit path including a series connection of a first switch and a shunt resistor, the first voltage across the first circuit path generated based on first current supplied from a first winding of a motor through the first circuit path; and
based on the monitored first voltage, determine an ON-resistance of the first switch.
2. The apparatus as in claim 1 , wherein the controller is further operative to:
monitor a second voltage across a second circuit path including a series connection of a second switch and the shunt resistor, the second voltage generated based on second current supplied from a second winding of the motor.
3. The apparatus as in claim 2 , wherein the controller is further operative to:
based on the monitored first voltage and the monitored second voltage, determine an ON-resistance of the second switch.
4. The apparatus as in claim 3 , wherein the first winding and the second winding of the motor are connected in series.
5. The apparatus as in claim 1 , wherein the controller is further operative to:
utilize the determined ON-resistance of the first switch to control operation of the motor.
6. The apparatus as in claim 1 , wherein the controller is further operative to:
map a magnitude of the ON-resistance of the first switch to a temperature value indicative of a temperature of the first switch.
7. The apparatus as in claim 6 , wherein the controller is further operative to control operation of the first switch based on the temperature of the first switch.
8. The apparatus as in claim 1 , wherein the controller is further operative to:
determine a magnitude of the first current through the first winding based on a sample magnitude of the first voltage across the first circuit path.
9. The apparatus as in claim 1 , wherein the first switch is a low-side switch disposed in series with a high-side switch, the low-side switch operative to control current through the first winding.
10. The apparatus as in claim 1 , wherein the first voltage is measured during a condition in which the first switch is set to an ON-state.
11. The apparatus as in claim 1 , wherein the controller is further operative to:
obtain a sample of a magnitude of the first voltage during a condition in which a magnitude of current through the shunt resistor is substantially zero; and
determine the ON resistance of the first switch based on the sample.
12. The apparatus as in claim 1 , wherein the first switch is a field effect transistor; and
wherein the ON-resistance of the first switch is an RDS ON-resistance of the field effect transistor.
13. The apparatus as in claim 1 , wherein the controller is further operative to:
produce a first sample (SW) of the first voltage during a first condition in which the first switch is activated to an ON-state;
produce a second sample (SW 1 ) of the first voltage during a second condition in which the first switch is activated to the ON-state;
receive a resistance of the shunt resistor; and
determine the ON-resistance of the first switch based on the first sample (SW), the second sample (SW 1 ), and the resistance of the shunt resistor.
14. The apparatus as in claim 13 , wherein a magnitude of current through the shunt resistor is substantially zero during the first condition; and
wherein the magnitude of current through the shunt resistor is substantially non-zero during the second condition.
15. The apparatus as in claim 1 , wherein the controller is further operative to:
produce a first sample (SW) of the first voltage during a first condition in which the first switch is activated to an ON-state;
produce a second sample (SW 1 ) of the first voltage during the first condition in which the first switch is activated to the ON-state;
produce a third sample (SW 2 ) of the first voltage during the first condition in which the first switch is activated to the ON-state;
receive a resistance of the shunt resistor; and
determine the ON-resistance of the first switch based on the first sample (SW), the second sample (SW 1 ), the third sample (SW 2 ), and the resistance of the shunt resistor;
wherein the ON-resistance of the first switch is equal to Rw;
wherein a resistance of the shunt resistor is RS; and
wherein SW′=(SW 1 +SW 2 )*0.5; and
wherein Rw=SW*RS/(SW′−SW)*RS.
16. The apparatus as in claim 1 , wherein the controller is further operative to:
monitor a second voltage across a second circuit path including a second series connection of a second switch and the shunt resistor, the second voltage generated based on second current supplied from a second winding of the motor; and
determine the ON-resistance of the first switch based on the monitored first voltage and the monitored second voltage.
17. The apparatus as in claim 16 , wherein the controller is further operative to:
produce a first sample (SU) of the first voltage during a first condition in which both the first switch and the second switch are activated to an ON-state;
produce a second sample (SV) of the second voltage during the first condition in which both the first switch and the second switch are activated to the ON-state;
produce a third sample (SV 1 ) of the second voltage during a second condition in which the first switch is deactivated to an OFF-state and the second switch is activated to an ON-state; and
produce a fourth sample (SV 2 ) of the second voltage during a second condition in which the first switch is deactivated to an OFF-state and the second switch is activated to an ON-state; and
determine the ON-resistance of the first switch based on the first sample (SU), the second sample (SV), the third sample (SV 1 ), the fourth sample (SV 2 ) and a resistance of the shunt resistor.
18. The apparatus as in claim 17 , wherein a magnitude of current through the shunt resistor is substantially zero during the first condition; and
wherein the magnitude of current through the shunt resistor is substantially non-zero during the second condition.
19. The apparatus as in claim 17 , wherein the ON-resistance of the first switch is equal to Ru;
wherein a resistance of the shunt resistor is RS;
wherein SV′=(SV 1 +SV 2 )*0.5; and
wherein Ru=SU*RS/(SV′−SV).
20. The apparatus as in claim 1 , wherein the controller is further operative to:
monitor a second voltage across a second circuit path including a second series connection of a second switch and the shunt resistor, the second voltage generated based on second current supplied from a second winding of the motor;
produce a first sample (SU) of the first voltage during a first condition in which both the first switch and the second switch are activated to an ON-state; and
produce a second sample (SW) of the second voltage during the first condition in which both the first switch and the second switch are activated to the ON-state;
produce a third sample (SW 1 ) of the second voltage during a second condition in which the first switch is deactivated to an OFF-state and the second switch is activated to an ON-state;
produce a third sample (SW 4 ) of the second voltage during the second condition in which the first switch is deactivated to an OFF-state and the second switch is activated to an ON-state; and
determine the ON-resistance of the second switch based on the first sample (SU), the second sample (SW), the third sample (SW 1 ), and the fourth sample (SW 4 ), and a resistance of the shunt resistor.
21. The apparatus as in claim 20 , wherein the ON-resistance of the second switch is equal to Ru;
wherein a resistance of the shunt resistor is RS;
wherein SW′=(SW 1 +SW 4 )*0.5; and
wherein Ru=SU*RS/(SW′−SW).
22. A method comprising:
measuring a first voltage across a first circuit path including a series connection of a first switch and a shunt resistor, the first voltage generated based on first current supplied from a first winding of a motor including multiple windings;
based on the magnitude of the first voltage, determining an ON-resistance of the first switch; and
utilizing the determined ON-resistance of the first switch to control operation of the motor.
23. Computer-readable storage media having instructions stored thereon, the instructions, when executed by computer processor hardware, cause the computer processor hardware to:
measure a first voltage across a first circuit path including a series connection of a first switch and a shunt resistor, the first voltage generated based on first current supplied from a first winding of a motor including multiple windings;
based on the magnitude of the first voltage, determine an ON-resistance of the first switch; and
utilize the determined ON-resistance of the first switch to control operation of the motor.