Abstract: A method of operating an electric motor is disclosed. The method includes: determining a d-axis resistance of an electric motor and a Q-axis resistance of the electric motor as a function of a bulk current; determining a d-axis inductance of the electric motor and a Q-axis inductance of the electric motor as a function of the bulk current; generating an estimated flux of the electric motor based on the d-axis resistance of the electric motor, the Q-axis resistance of the electric motor, the d-axis inductance of the electric motor, and the Q-axis inductance of the electric motor; generating an estimated angle of the electric motor based on the estimated flux of the electric motor; and, based on the estimated angle of the electric motor, controlling switching of an inverter that powers the electric motor.

Abstract: An indication system is provided and includes evaluation, messaging, and display modules and a display. The evaluation module generates a message based on a parameter of a compressor or a drive. The messaging module: generates a message based on the parameter; generates a string of glyphs based on the message; selects a predetermined number of glyphs in the string of glyphs; generates column data for the selected glyphs; and generates packets including the column data. The display module generates output signals based on the packets. The display includes an array of LEDs, does not include a transistor, and illuminates the LEDs based on the output signals. The display module is configured to generate the output signals to illuminate one or more of the LEDS in a column-by-column format, such that power is only provided to one column of the array of LEDs at any moment in time.

Abstract: A circuit for driving a motor of a compressor includes a microcontroller, which includes an op-amp, a comparator, a first serial interface, and a first dedicated pin. The op-amp amplifies a value indicating current in a power factor correction converter, which includes a power switch. The comparator asserts a comparison signal in response to the amplified value exceeding a reference value. The comparison signal is output on the first dedicated pin. A programmable logic device (PLD) includes a second serial interface in communication with the first serial interface and a second dedicated pin. The comparison signal is received on the second dedicated pin and the PLD receives control messages from the microcontroller via the second serial interface. The PLD sets a value in an off-time register based on a control message from the microcontroller. The PLD controls the power switch according to the comparison signal and the off-time register.

Abstract: A control system for a refrigeration system motor includes an angle determination module that generates an output rotor angle indicating a desired angle of a rotor of the motor. A control module controls the motor based on the output rotor angle. An estimator module determines an estimated rotor angle. A transition module generates a transition signal in response to convergence of the estimator module. Upon startup, the angle determination module generates the output rotor angle based on a first rotor angle. Upon generation of the transition signal, the angle determination module generates the output rotor angle based on the first rotor angle and the estimated rotor angle. After generation of the transition signal, the angle determination module reduces a contribution of the first rotor angle to the output rotor angle over time until the output rotor angle is based on the estimated rotor angle independent of the first rotor angle.

Abstract: A control circuit for a motor of a compressor includes an inverter control module configured to control power switching devices of an inverter to generate output voltages from a DC power supply. The output voltages are applied to windings of the motor. A current control module is configured to generate voltage signals based on a torque demand. The inverter control module controls the power switching devices according to the voltage signals. A selector is configured to output one of an open loop torque value and a closed loop torque value as the torque demand. An open loop torque module is configured to generate the open loop torque value. The open loop torque module is configured to apply an upper limit to the open loop torque value. The upper limit is based on a voltage of the DC power supply.

Abstract: A system includes a compressor having a shell housing a compression mechanism driven by an electric motor in an on state and not driven by the electric motor in an off state. The system also includes a variable frequency drive that drives the electric motor in the on state by varying a frequency of a voltage delivered to the electric motor and that supplies electric current to a stator of the electric motor in the off state to heat the compressor.

Abstract: A control system for a refrigeration system motor includes an angle determination module that generates an output rotor angle indicating a desired angle of a rotor of the motor. A control module controls the motor based on the output rotor angle. An estimator module determines an estimated rotor angle. A transition module generates a transition signal in response to convergence of the estimator module. Upon startup, the angle determination module generates the output rotor angle based on a first rotor angle. Upon generation of the transition signal, the angle determination module generates the output rotor angle based on the first rotor angle and the estimated rotor angle. After generation of the transition signal, the angle determination module reduces a contribution of the first rotor angle to the output rotor angle over time until the output rotor angle is based on the estimated rotor angle independent of the first rotor angle.

Abstract: A power factor correction (PFC) system includes a desired OFF period module that determines a desired OFF period for a switch of a PFC circuit based on an input voltage to the PFC circuit and an output voltage of the PFC circuit. A switching control module transitions the switch from an ON state to an OFF state when a measured current through an inductor of the PFC circuit is greater than a demanded current through the inductor and maintains the switch in the OFF state for the desired OFF period after the transition from the ON state to the OFF state.

Abstract: A power factor correction (PFC) system includes an error control module that determines a first current demand based on a difference between a desired direct current (DC) voltage and a measured DC voltage. A filter module applies a filter to the first current demand to produce a second current demand. A weighting module (i) based on the difference, determines first and second weighting values for the first and second current demands, respectively, (ii) determines a third current demand based on the first current demand and the first weighting value, and (iii) determines a fourth current demand based on the second current demand and the second weighting value. A current demand module determines a final current demand based on the third current demand and fourth current demand. A current control module controls switching of a switch of a PFC device based on the final current demand.

Abstract: A PFC circuit is provided. A first bridge rectifier receives an AC voltage. A power converter includes a switch and receives an output of the first bridge rectifier, converts the output to a first DC voltage, and supplies the first DC voltage to a DC bus to power a compressor. A second bridge rectifier receives the AC voltage and bypasses at least one of the first bridge rectifier, a choke and a diode of the PFC circuit to provide a rectified AC voltage out of the second bridge rectifier to the DC bus to power the compressor. A control module controls operation of a driver to transition the switch between open and closed states to adjust a second DC voltage on the DC bus, where the second DC voltage, depending on the AC and second DC voltages, is based on the first DC voltage or the rectified AC voltage.

Abstract: A drive includes an inverter power circuit that applies power to an electric motor of a compressor from a direct current (DC) voltage bus. A power factor correction (PFC) circuit outputs power to the DC voltage bus based on input alternating current (AC) power. The PFC circuit includes: (i) a switch having a first terminal, a second terminal, and a control terminal; (ii) a driver that switches the switch between open and closed states based on a control signal; (iii) an inductor that charges and discharges based on switching of the switch; and (iv) a circuit that outputs a signal indicating whether the switch is in the open state or the closed state based on a voltage across the first and second terminals of the switch.

Abstract: A power factor correction (PFC) system includes a PFC circuit that receives an alternating current (AC) voltage and that, using a switch, generates a direct current (DC) voltage from the AC voltage. A zero crossing module determines a zero crossing of the AC voltage based on: a first voltage and a first time when the AC voltage transitioned from less than a first predetermined voltage to greater than the first predetermined voltage; and a second voltage and a second time when the AC voltage transitioned from less than a second predetermined voltage to greater than the second predetermined voltage. The first predetermined voltage is negative, and the second predetermined voltage is positive. A reference module, based on the zero crossing, generates a sinusoidal reference signal corresponding to the AC voltage in phase and frequency. A switching control module controls switching of the switch based on the sinusoidal reference signal.

Abstract: An isolated temperature sensing system includes a thermistor that measures a temperature of a compressor system. An isolation circuit charges a capacitor, sets an output signal to a first state during charging of the capacitor, discharges the capacitor to the thermistor, and sets the output signal to a second state during discharging of the capacitor to the thermistor. The first state is different than the second state. A control module receives the output signal via an isolation barrier and determines the temperature of the compressor system based on a ratio of: (i) a first period that the output signal is in the first state to (ii) a second period that the output signal is in the second state.

Abstract: A PFC circuit is provided. A bridge rectification circuit receives an AC voltage and generates a rectified AC voltage. A power converter converts the rectified AC voltage to a first DC voltage, where the power converter includes a switch and supplies the first DC voltage to a DC bus to power a compressor. A current sensor detects an amount of current. A control module, while operating in a correction mode: based on the rectified AC voltage, a phase angle of the rectified AC voltage, a second DC voltage of the DC bus, or the detected amount of current, control operation of the switch to transition between operating in a high activity mode and an inactive or low activity mode; transition the switch between open and closed states while in the high and low activity modes; and maintain the power converter in an OFF state while in the inactive mode.

Abstract: An indication system is provided and includes evaluation, messaging, and display modules and a display. The evaluation module generates a message based on a parameter of a compressor or a drive. The messaging module: generates a message based on the parameter; generates a string of glyphs based on the message; selects a predetermined number of glyphs in the string of glyphs; generates column data for the selected glyphs; and generates packets including the column data. The display module generates output signals based on the packets. The display includes an array of LEDs, does not include a transistor, and illuminates the LEDs based on the output signals. The display module is configured to generate the output signals to illuminate one or more of the LEDS in a column-by-column format, such that power is only provided to one column of the array of LEDs at any moment in time.

Abstract: A circuit for driving a motor of a compressor includes a microcontroller, which includes an op-amp, a comparator, a first serial interface, and a first dedicated pin. The op-amp amplifies a value indicating current in a power factor correction converter, which includes a power switch. The comparator asserts a comparison signal in response to the amplified value exceeding a reference value. The comparison signal is output on the first dedicated pin. A programmable logic device (PLD) includes a second serial interface in communication with the first serial interface and a second dedicated pin. The comparison signal is received on the second dedicated pin and the PLD receives control messages from the microcontroller via the second serial interface. The PLD sets a value in an off-time register based on a control message from the microcontroller. The PLD controls the power switch according to the comparison signal and the off-time register.

Abstract: A method of operating an electric motor is disclosed. The method includes: starting the electric motor in an open loop control mode; operating an estimator that estimates operating conditions of the electric motor; and, while the electric motor is in the open loop control mode, evaluating a first parameter of the estimator. The method further includes: in response to the evaluation of the first parameter, determining whether the estimator has converged; and in response to a determination that the estimator has not converged within a predetermined period of time after starting the electric motor, signaling a first fault condition.

Abstract: A method of operating an electric motor is disclosed. The method includes: determining a d-axis resistance of an electric motor and a Q-axis resistance of the electric motor as a function of a bulk current; determining a d-axis inductance of the electric motor and a Q-axis inductance of the electric motor as a function of the bulk current; generating an estimated flux of the electric motor based on the d-axis resistance of the electric motor, the Q-axis resistance of the electric motor, the d-axis inductance of the electric motor, and the Q-axis inductance of the electric motor; generating an estimated angle of the electric motor based on the estimated flux of the electric motor; and, based on the estimated angle of the electric motor, controlling switching of an inverter that powers the electric motor.

Abstract: A control system for a motor in a refrigeration system includes an angle determination module configured to generate an output rotor angle indicative of a desired angle of a rotor of the motor. The control system controls current supplied to the motor based on the output rotor angle. The control system determines an estimated rotor angle of the motor. The angle determination module, upon startup of the motor, generates the output rotor angle based on a first rotor angle. Upon generation of a transition signal, the angle determination module generates the output rotor angle based on both the first rotor angle and the estimated rotor angle. Subsequent to generation of the transition signal, the angle determination module reduces a contribution of the first rotor angle to the output rotor angle over time until the output rotor angle is based on the estimated rotor angle independent of the first rotor angle.

Abstract: A method of operating an electric motor is disclosed. The method includes: starting the electric motor in an open loop control mode; operating an estimator that estimates operating conditions of the electric motor; and, while the electric motor is in the open loop control mode, evaluating a first parameter of the estimator. The method further includes: in response to the evaluation of the first parameter, determining whether the estimator has converged; and in response to a determination that the estimator has not converged within a predetermined period of time after starting the electric motor, signaling a first fault condition.