Block commutation to reduce inverter losses for bldc drives
AssigneeInfineon Technologies Americas Corp.
InventorsVenkata Anand Prabhala, Vatche Oknaian, Kapil Kelkar
Life of this patent
Estimating the term…
Abstract
Techniques to sense the direction of current through the power transistor of an inverter drive circuit and the position of the rotor for a brushless direct current (BLDC) motor. During the time demagnetizing current flows, the power transistor is turned ON, directing the demagnetizing current through the lower impedance transistor channel rather than through the body diode. Directing current to the transistor channel may reduce the diode losses in the power transistors, thereby reducing the overall power losses. In other examples, the low side as well as the high side power transistor may be turned on during the time the demagnetizing current flows through the given power transistor.
Claims20
A method for controlling a motor, the method comprising:
- sensing, by a controller circuit, a direction of current through a switch, wherein the switch comprises a body diode and wherein the body diode comprises an anode and a cathode;
- sensing, by the controller circuit, a position of a rotor;
- determining, by the controller circuit, based on a position of the rotor, that motor has reached an end of a commutation step;
- and
- in response to determining, by the controller circuit, that the motor has reached the end of the commutation step and that current is in a freewheeling direction through the switch, turning on the switch, wherein the freewheeling direction is from the anode to the cathode of the body diode.
A motor control circuit, the circuit comprising:
- a high side (HS) switch and a low side (LS) switch,
- wherein the LS switch is connected in series with the HS switch,
- wherein the LS switch comprises a first body diode and wherein the first body diode comprises an anode and a cathode, and
- wherein the HS switch comprises a second body diode and wherein the second body diode comprises an anode and a cathode;
- a current sensing element, wherein the current sensing element senses a direction of current through the LS switch;
- a rotor sensing element, wherein the rotor sensing element senses a position of a rotor;
- and
- a processing circuit, wherein the processing circuit is configured to:
- control operation of the HS switch and the LS switch;
- receive rotor position information from the rotor sensing element;
- receive direction of current information from the current sensing element;
- determine, based on a position of the rotor, that a motor has reached an end of a commutation step;
- determine, based on the information from the current sensing element, that that current flows in a freewheeling direction through the LS switch, wherein the freewheeling direction is from the anode to the cathode of the first body diode;
- and
- turn on the LS switch in response to determining that a motor has reached an end of the commutation step and that that the current flows in the freewheeling direction through the LS switch.
A system comprising:
- an inverter circuit comprising:
- a high side (HS) switch and a low side (LS) switch,
- wherein the LS switch is connected in series with the HS switch,
- wherein the LS switch comprises a first body diode and wherein the first body diode comprises an anode and a cathode, and
- wherein the HS switch comprises a second body diode and wherein the second body diode comprises an anode and a cathode;
- and
- a current sensing element, wherein the current sensing element senses a direction of current through the LS switch;
- a gate driver circuit, wherein the gate driver circuit controls a first gate for the HS switch and a second gate for the LS switch;
- a rotor sensing element, wherein the rotor sensing element senses a position of a rotor;
- and
- a controller circuit, wherein the controller circuit is configured to:
- control operation of the gate driver circuit;
- receive rotor position information from the rotor sensing element;
- receive direction of current information from the current sensing element;
- determine, based on a position of the rotor, that a motor has reached an end of a commutation step;
- determine, based on the current sensing element, that that current flows in a freewheeling direction through the LS switch, wherein the freewheeling direction is from the anode to the cathode of the first body diode;
- and
- signal the gate driver circuit to turn on the LS switch in response to determining that a motor has reached an end of the commutation step and that that the current flows in the freewheeling direction through the LS switch.
Dependencies are inferred from the claim text.