Power converter, motor drive device, and refrigeration cycle application apparatus
A power converter includes a capacitor connected to an output end of a rectifier unit that rectifies first AC power, an inverter that is connected across the capacitor and generates second AC power for output to a motor, and a control unit that controls the operation of the inverter such that pulsation according to the power state of the capacitor is superimposed on a drive pattern of the motor. The control unit performs load pulsation compensation control to reduce the vibration of the motor and power pulsation compensation control to reduce the charging and discharging current of the capacitor while preferentially performing constant current load control to control the rotational speed of the motor, and generates a torque current command for the load pulsation compensation control such that a torque current command allocatable to the power pulsation compensation control remains.
1 . A power converter, comprising:
a rectifier rectifying first AC power supplied from a commercial power source;
a capacitor connected to an output end of the rectifier;
an inverter connected across the capacitor, the inverter generating second AC power and outputting the second AC power to a motor; and
processing circuitry controlling operation of the inverter such that pulsation according to a power state of the capacitor is superimposed on a drive pattern of the motor, to reduce a charging and discharging current of the capacitor, the power state of the capacitor including at least one of a rectified current flowing from the rectifier, an inverter input current flowing into the inverter, a capacitor current that is the charging and discharging current of the capacitor, and a capacitor voltage that is a voltage of the capacitor, wherein
the processing circuitry performs load pulsation compensation control to reduce vibration of the motor and power pulsation compensation control to reduce the charging and discharging current of the capacitor while performing constant current load control to control a rotational speed of the motor, and generates a q-axis current margin that is the difference between a q-axis current limit value and a q-axis current command, and uses the q-axis current margin to generate a torque current command for the load pulsation compensation control such that a torque current command allocatable to the power pulsation compensation control remains.
2 . The power converter according to claim 1 , comprising a vibration sensor detecting vibration of an apparatus in which the motor is installed, wherein the processing circuitry adjusts the torque current command for the load pulsation compensation control such that a detected value of the vibration sensor becomes less than or equal to a threshold.
3 . A motor drive device comprising the power converter according to claim 2 .
4 . A refrigeration cycle application apparatus comprising the power converter according to claim 2 .
5 . A motor drive device comprising the power converter according to claim 1 .
6 . A refrigeration cycle application apparatus comprising the power converter according to claim 1 .
7 . The power converter according to claim 1 , wherein the processing circuitry subtracts the q-axis current command from the q-axis current limit value to compute the q-axis current margin prior to generating either the load pulsation compensation control or the power pulsation compensation control.
8 . The power converter according to claim 1 , wherein the processing circuitry constrains the torque current command for the load pulsation compensation control and the torque current command for the power pulsation compensation control such that a sum thereof does not exceed the q-axis current limit value.
9 . The power converter according to claim 1 , wherein the power pulsation compensation control directly adjusts a torque-producing q-axis current component to reduce a magnitude of capacitor charging and discharging current.
10 . A power converter, comprising:
a rectifier rectifying first AC power supplied from a commercial power source;
a capacitor connected to an output end of the rectifier;
an inverter connected across the capacitor, the inverter generating second AC power and outputting the second AC power to a motor; and
processing circuitry controlling operation of the inverter such that pulsation according to a power state of the capacitor is superimposed on a drive pattern of the motor, to reduce a charging and discharging current of the capacitor, the power state of the capacitor including at least one of a rectified current flowing from the rectifier, an inverter input current flowing into the inverter, a capacitor current that is the charging and discharging current of the capacitor, and a capacitor voltage that is a voltage of the capacitor, wherein
the processing circuitry performs load pulsation compensation control to reduce vibration of the motor and power pulsation compensation control to reduce the charging and discharging current of the capacitor while performing constant current load control to control a rotational speed of the motor, and generates a q-axis current margin that is the difference between a q-axis current limit value and a q-axis current command, and uses the q-axis current margin to generate a torque current command for the power pulsation compensation control such that a torque current command allocatable to the load pulsation compensation control remains.
11 . The power converter according to claim 10 , comprising
a voltage detector detecting the capacitor voltage, wherein
the processing circuitry determines by calculation the capacitor current, based on a detected value of the capacitor voltage and a capacitance of the capacitor, and adjusts the torque current command for the power pulsation compensation control such that a calculated value of the capacitor current becomes less than or equal to a threshold.
12 . A motor drive device comprising the power converter according to claim 11 .
13 . A refrigeration cycle application apparatus comprising the power converter according to claim 11 .
14 . The power converter according to claim 10 , comprising
a current detector detecting the capacitor current, wherein
the processing circuitry adjusts the torque current command for the power pulsation compensation control such that a detected value of the capacitor current becomes less than or equal to a threshold.
15 . A motor drive device comprising the power converter according to claim 14 .
16 . A refrigeration cycle application apparatus comprising the power converter according to claim 14 .
17 . A motor drive device comprising the power converter according to claim 10 .
18 . A refrigeration cycle application apparatus comprising the power converter according to claim 10 .