Method and apparatus for sensing direct current of one polarity in a conductor and electronically commutated motor control responsive to sensed motor current

Apparatus for generating a isolated signal which is a function of the instantaneous total effective current in the winding stages of a motor wherein the stages are wye-connected and have a neutral point, said apparatus comprising:

• means for producing winding output signals comprising:
• a core inductively coupled to each of the winding stages such that each said core is subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current flowing in the respective winding stage toward the neutral point, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the winding stages;
• a rectified output winding around each said core for producing a winding output signal having a magnitude which is a function of the direct current in the respective winding stage when the direct current flows in the respective winding toward the neutral point before the aforesaid period of time and which is substantially zero when direct current flows in the respective winding toward the neutral point after the aforesaid period of time and which is substantially zero when the direct current flows in the respective winding away from the neutral point;
• and
• means for periodically resetting the magnetic orientation of each core to a predefined state before the aforesaid period of time elapses whereby each winding output signal produced between periodic resets has a magnitude which is a function of the direct current flowing in the respective winding stage toward the neutral point;
• and
• means for summing the winding output signals and providing a sum signal corresponding thereto whereby the sum signal produced between periodic resets has a magnitude which is a function of the instantaneous sum of total effective current in the winding stages of the motor and comprises the isolated signal.

An apparatus for generating for a signal which is a function of direct current in the winding stages of a motor where the winding stages carry an effective motor current, said apparatus comprising:

• means for producing an output signal comprising:
• a core inductively coupled to each winding stage, each said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the winding stage, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the winding stages;
• an array of rectified output windings, each around one of said cores for producing the output signal which is a function of the effective direct current in the winding stage when the cores are not saturated but which is not a function of the effective direct current in the winding stages after the aforesaid period of time;
• and
• means for periodically applying a magnetic field to the cores to periodically reset the magnetic orientation of the cores to a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the effective direct current in the winding stages and comprises the effective motor current.

A control system for an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current and further having a rotatable assembly, and which control system is adapted to receive a control signal representing a desired operating torque or speed for the motor, the control system comprising:

• means for applying a motor voltage to one or more of the winding stages at a time in accordance with a regulating signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly;
• means for sensing the effective motor current including:
• means for producing an output signal comprising:
• a core inductively coupled to each winding stage, said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the winding stage, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• an array of rectified output windings, each around one of said cores for producing the output signal which is a function of the effective direct current in the winding stage when the cores are not saturated but which is not a function of the effective direct current in the winding stages after the aforesaid period of time;
• and
• means for periodically applying a magnetic field to the cores to periodically reset the magnetic orientation of the cores to a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the effective direct current in the winding stages and comprises the effective motor current;
• means responsive to the sensing means for generating the regulating signal having a duty cycle which is a function of the control signal and the output signal, whereby the operating torque or speed of the motor is a function of the control signal.

A control system for an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current and further having a rotatable assembly, the control system being adapted to receive a control signal representing a desired operating torque or speed for the motor, the control system being operatively connected to a commutating circuit for applying a motor voltage to one or more of the winding stages at a time in accordance with a regulating signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly, the control system comprising:

• means for sensing the effective motor current including:
• means for producing an output signal comprising:
• a core inductively coupled to each winding stage, said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the winding stage, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• an array of rectified output windings, each around one of said cores for producing the output signal which is a function of the effective direct current in the winding stage when the cores are not saturated but which is not a function of the effective direct current in the winding stages after the aforesaid period of time;
• and
• means for periodically applying a magnetic field to the cores to periodically reset the magnetic orientation of the cores to a a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the effective direct current in the winding stages and comprises the effective motor current;
• and
• means responsive to the sensing means for generating the regulating signal having a duty cycle which is a function of the control signal and the output signal, whereby the operating torque or speed of the motor is a function of the duty cycle of the control pulses.

Apparatus for generating a sensing signal which is a function of an effective direct current flowing in a conductor comprising:

• means for producing a first output signal comprising:
• a first core inductively coupled to the conductor, said first core being subject to magnetic saturation after a first period of time as a result of a magnetic field generated by the direct current in one direction in the conductor, the first period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the one direction in the conductor;
• a first output winding around said first core for producing the first output signal which is a function of the direct current in the one direction in the conductor when the first core is not saturated but which is substantially zero when current flows in the one direction after the first period of time and which is substantially zero when the current flows in the other direction;
• and
• means for periodically applying a magnetic field to the first core to periodically reset the magnetic orientation of the first core to a predefined state before the first period of time elapses whereby the first output signal produced between periodic resets has a magnitude which is a function of the direct current in the one direction in the conductor;
• means for producing a second output signal comprising:
• a second core inductively coupled to the conductor, said second core being subject to positive magnetic saturation after a second period of time as a result of a magnetic field generated by the direct current in the other direction in the conductor, the second period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the other direction in the conductor;
• and
• a second output winding around said second core for producing the second output signal which is a function of the direct current in the other direction in the conductor when the second core is not saturated but which is substantially zero when current flows in the other direction after the second period of time and which is substantially zero when the current flows in the one direction;
• means for periodically applying a magnetic field to the second core to periodically reset the magnetic orientation of the second core to the predefined state before the second period of time elapses whereby the second output signal produced between periodic resets has a magnitude which is a function of the direct current in the other direction in the conductor;
• and
• means for summing the first and second output signals and providing a sum signal corresponding thereto whereby the sum signal produced between periodic resets has a magnitude which is a function of the effective direct current in the conductor and comprises the sensing signal.

Method for generating a sensing signal which is a function of a direct current flowing in a particular direction in a conductor comprising the steps of:

• producing an output signal comprising the steps of:
• inductively coupling a core to the conductor, said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the conductor, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• producing from an output winding around said core the output signal which is a function of the direct current in the conductor when the core is not saturated but which is not a function of the direct current in the conductor after the aforesaid period of time;
• and
• periodically applying a magnetic field to the core to periodically reset the magnetic orientation of the core to a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the direct current in the conductor and comprises the sensing signal.

Method for generating an isolated signal which is a function of the instantaneous total effective current in the winding stages of a motor wherein the stages are wye-connected and have a neutral point, said method comprising the steps of:

• producing winding output signals comprising the steps of:
• inductively coupling a core to each of the winding stages such that each said core is subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current flowing in the respective winding stage toward the neutral point, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• producing from a rectified output winding around each core a winding output signal having a magnitude which is a function of the direct current in the respective winding stage when the direct current flows in the respective winding toward the neutral point before the aforesaid period of time and which is substantially zero when direct current flows in the respective winding toward the neutral point after the aforesaid period of time and which is substantially zero when the direct current flows in the respective winding away from the neutral point;
• and
• periodically applying a magnetic field to each core to periodically reset the magnetic orientation of each core to a predefined state before the aforesaid period of time elapses whereby each winding output signal produced between periodic resets has magnitude which is a function of the direct current flowing in the respective winding stage toward the neutral point;
• and
• summing the winding output signals and providing a sum signal corresponding thereto whereby the sum signal produced between periodic resets has a magnitude which is a function of the instantaneous sum of total effective current in the winding stages of the motor and comprises the isolated signal.

A method for generating a signal which is a function of direct current in the winding stages of a motor where the winding stages carry an effective motor current, said method comprising the steps of:

• producing an output signal comprising the steps of:
• inductively coupling a core to each winding stage, said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the winding stage, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• producing from a series array of rectified output windings, each around one of said cores the output signal which is a function of the effective direct current in the winding stage when the cores are not saturated but which is not a function of the effective direct current in the winding stages after the aforesaid period of time;
• and
• periodically applying a magnetic field to the cores to periodically reset the magnetic orientation of the cores to a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the effective direct current in the winding stages and comprises the effective motor current.

A control method for an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current and further having a rotatable assembly, and which control method is adapted to receive a control signal representing a desired operating torque or speed for the motor, the control method comprising the steps of:

• applying a motor voltage to one or more of the winding stages at a time in accordance with a regulating signal and commutating the winding stages in a preselected sequence to rotate the rotatable assembly;
• sensing the effective motor current including:
• producing an output signal comprising the steps of:
• inductively coupling a core to each winding stage, said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the winding stage, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• producing from a series array of rectified output windings, each around one of said cores the output signal which is a function of the effective direct current in the winding stage when the cores are not saturated but which is not a function of the effective direct current in the winding stages after the aforesaid period of time;
• and
• periodically applying a magnetic field to the cores to periodically reset the magnetic orientation of the cores to a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the effective direct current in the winding stages and comprises the effective motor current;
• generating in response to the sensing step the regulating signal having a duty cycle which is a function of the control signal and the output signal, whereby the operating torque or speed of the motor is a function of the control signal.

A control method for an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current and further having a rotatable assembly, the control method being adapted to receive a control signal representing a desired operating torque or speed for the motor, the control method being operatively connected a commutating circuit for applying a motor voltage to one or more of the winding stages at a time in accordance with a regulating signal and for commutating the winding stages in a preselected sequence to rotate the rotatable assembly, the control method comprising the steps of:

• sensing the effective motor current including:
• producing an output signal comprising the steps of:
• inductively coupling a core to each winding stage, said core being subject to magnetic saturation after a period of time as a result of a magnetic field generated by the direct current in the winding stage, the aforesaid period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the conductor;
• producing from a series array of rectified output windings, each around one of said cores the output signal which is a function of the effective direct current in the winding stage when the cores are not saturated but which is not a function of the effective direct current in the winding stages after the aforesaid period of time;
• and
• periodically applying a magnetic field to the cores to periodically reset the magnetic orientation of the cores to a predefined state before the aforesaid period of time elapses whereby the output signal produced between periodic resets has a magnitude which is a function of the effective direct current in the winding stages and comprises the effective motor current;
• and
• generating in response to the sensing step the regulating signal having a duty cycle which is a function of the control signal and the output signal, whereby the operating torque or speed of the motor is a function of the duty cycle of the control pulses.

Method for generating a sensing signal which is a function of an effective direct current flowing in a conductor comprising the steps of:

• producing a first output signal comprising the steps of:
• inductively coupling a first core to the conductor, said first core being subject to magnetic saturation after a first period of time as a result of a magnetic field generated by the direct current in one direction in the conductor, the first period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the one direction in the conductor;
• producing from a first output winding around said first core the first output signal which is a function of the direct current in the one direction in the conductor when the first core is not saturated but which is substantially zero when current flows in the one direction after the first period of time and which is substantially zero when the current flows in the other direction;
• and
• periodically applying a magnetic field to the first core to periodically reset the magnetic orientation of the first core to a predefined state before the first period of time elapses whereby the first output signal produced between periodic resets has a magnitude which is a function of the direct current in the one direction in the conductor;
• producing a second output signal comprising the steps of:
• inductively coupling a second core to the conductor, said second core being subject to positive magnetic saturation after a second period of time as a result of a magnetic field generated by the direct current in the other direction in the conductor, the second period of time being a function of the magnitude of the magnetic field generated by the direct current flowing in the other direction in the conductor;
• and
• producing from a second output winding around said second core the second output signal which is a function of the direct current in the other direction in the conductor when the second core is not saturated but which is substantially zero when current flows in the other direction after the second period of time and which is substantially zero when the current flows in the one direction;
• periodically applying a magnetic field to the second core to periodically reset the magnetic orientation of the second core to the predefined state before the second period of time elapses whereby the second output signal produced between periodic resets has a magnitude which is a function of the direct current in the other direction in the conductor;
• and
• summing the first and second output signals and providing a sum signal corresponding thereto whereby the sum signal produced between periodic resets has a magnitude which is a function of the effective direct current in the conductor and comprises the sensing signal.