Energy recovery from a spindle motor using a sequence of a braking phase, an active step-up phase and an active braking phase in response to external power supply failure

A circuit for driving a multiphase motor, comprising:

• a power supply node configured to receive an external power supply for powering the multiphase motor;
• a common reference node;
• a plurality of half bridges coupled between said power supply node and said common reference node, each half bridge comprising a high-side MOS transistor, a low-side MOS transistor and an output node coupled to a respective winding terminal of the multiphase motor;
• and
• a control circuit configured to:
• sense a failure of the external power supply and performing the following sequence of operations:
• a) switch MOS transistors of the half bridges to implement a brake configuration wherein either high-side MOS transistors or low-side MOS transistors of the half bridges are turned on;
• b) then switch MOS transistors of the half bridges to implement an active step-up configuration wherein the high-side MOS transistor of a first half bridge and the low-side MOS transistor of a second half bridge are both turned on and wherein the low-side MOS transistor of the first half bridge and the high-side MOS transistor of the second half bridge are both turned off;
• and
• c) then switch MOS transistors of the half bridges to implement an active brake configuration wherein the low-side MOS transistor of the first half bridge and the high-side transistor of the second half bridge are both turned on and wherein the high-side MOS transistor of the first half-bridge and the low-side transistor of the second half bridge are both turned off.

A method for charging a hold capacitor coupled between power supply nodes of output transistor half-bridge stages driving a multiphase motor, comprising:

• responding to a failure of an external power supply by performing the following sequence of operations:
• a) switching MOS transistors of the output transistor half-bridge stages to implement a brake configuration wherein either high-side MOS transistors or low-side MOS transistors of the output transistor half-bridge stages are turned on;
• b) detecting a direction of current flow through the multiphase motor;
• c) based on the detected direction of current flow, selecting the high-side MOS transistor of one of the output transistor half-bridge stages and the low-side MOS transistor of another of the output transistor half-bridge stages to be both turned on to charge the hold capacitor in an active step-up phase of operation;
• and
• d) based on that same detected direction of current flow, selecting the high-side MOS transistor of the another one of the output transistor half-bridge stages and the low-side MOS transistor of said one of the output transistor half-bridge stages to be both turned on to jump start current flow in an active brake phase of operation prior to a subsequent implementation of the brake configuration.

A circuit for driving a multiphase motor, comprising:

• a power supply node configured to receive an external power supply for powering the multiphase motor;
• a common reference node;
• a hold capacitor coupled between said power supply node and said common reference node;
• a plurality of half bridges coupled between said power supply node and said common reference node, each half bridge comprising a high-side MOS transistor, a low-side MOS transistor and an output node coupled to a respective winding terminal of the multiphase motor;
• and
• a control circuit configured to:
• sense a failure of the external power supply and performing the following sequence of operations:
• a) switch MOS transistors of the output transistor half-bridge stages to implement a brake configuration wherein either high-side MOS transistors or low-side MOS transistors of the output transistor half-bridge stages are turned on;
• b) detect a direction of current flow through the multiphase motor;
• c) based on the detected direction of current flow, select the high-side MOS transistor of one of the output transistor half-bridge stages and the low-side MOS transistor of another of the output transistor half-bridge stages to be both turned on to charge the hold capacitor in an active step-up phase of operation;
• and
• d) based on that same detected direction of current flow, select the high-side MOS transistor of the another one of the output transistor half-bridge stages and the low-side MOS transistor of said one of the output transistor half-bridge stages to be both turned on to jump start current flow in an active brake phase of operation prior to a subsequent implementation of the brake configuration.