PMW inverter control apparatus and control method
First Claim
1. A PWM inverter control apparatus in which four switching units are connected in series for each phase between a DC bus voltage having a plus level and a DC bus voltage having a minus level, comprising:
- a current detecting circuit for detecting a current value of an output current; and
a controller for outputting a zero vector to be started from an O state in which all phases are turned ON by second and third switching units from the DC bus voltage side having the plus level to output an intermediate potential to be a voltage between the plus and minus levels of the DC bus voltage when the current value measured by the current detecting circuit is equal to or greater than a first reference value which is preset and has a lower level than a level of a second reference value which is higher than a level of the first reference value, carrying out a base block operation for bringing all of the switching units into an OFF state after outputting the zero vector when the current value is equal to or greater than the second reference value and has a lower level than a level of a third reference value which is higher than the level of the second reference value, and executing an emergency stop when the current value is equal to or greater than the third reference value.
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Accused Products
Abstract
It is an object of the invention to provide a multilevel PWM inverter control apparatus capable of safely carrying out switching from a normal operation to a protecting operation and performing a reset from the protecting operation to the normal run safely and smoothly without requiring a complicated control algorithm.
In the invention, if a current value I which is measured is set to have a level which is equal to or higher than the level of a first reference value I1 and is lower than the level of a second reference value I2, a zero vector to be started from an OOO state in which an intermediate potential is output for all of phases is output (Step 22). If the current value I is set to have a level which is equal to or higher than the level of the second reference value I2 and is lower than the level of a third reference value I3, a base block operation for bringing all of switching units into an OFF state is carried out after outputting the zero vector (Step 28). If the current value I is equal to or greater than the third reference value I3, an emergency stop is carried out (Step 29). When a reset to a normal operation is carried out after the execution of the base block operation, the reset to the normal operation is performed after the execution of the operation for outputting the zero vector.
15 Citations
8 Claims
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1. A PWM inverter control apparatus in which four switching units are connected in series for each phase between a DC bus voltage having a plus level and a DC bus voltage having a minus level, comprising:
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a current detecting circuit for detecting a current value of an output current; and a controller for outputting a zero vector to be started from an O state in which all phases are turned ON by second and third switching units from the DC bus voltage side having the plus level to output an intermediate potential to be a voltage between the plus and minus levels of the DC bus voltage when the current value measured by the current detecting circuit is equal to or greater than a first reference value which is preset and has a lower level than a level of a second reference value which is higher than a level of the first reference value, carrying out a base block operation for bringing all of the switching units into an OFF state after outputting the zero vector when the current value is equal to or greater than the second reference value and has a lower level than a level of a third reference value which is higher than the level of the second reference value, and executing an emergency stop when the current value is equal to or greater than the third reference value. - View Dependent Claims (2, 4)
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3. A PWM inverter control apparatus in which four switching units are connected in series for each phase between a DC bus voltage having a plus level and a DC bus voltage having a minus level, comprising:
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a current detecting circuit for detecting a current value of an output current; and a controller for outputting such a zero vector as to bring an O state in which all of phases are turned ON by second and third switching units from the DC bus voltage side having the plus level to output an intermediate potential to be a voltage between the plus and minus levels of the DC bus voltage and then carrying out a base block operation for bringing all of the switching units into an OFF state when the current value measured by the current detecting circuit is equal to or greater than a preset reference value, and for outputting such a zero vector as to bring all of the phases into the O state and then performing a reset to a normal run when the current value is smaller than the reference value.
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5. A PWM inverter control method for controlling a PWM inverter control apparatus in which four switching units are connected in series for each phase between a DC bus voltage having a plus level and a DC bus voltage having a minus level, comprising the steps of:
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detecting a current value of an output current; outputting a zero vector to be started from an O state in which all phases are turned ON by second and third switching units from the DC bus voltage side having the plus level to output an intermediate potential to be a voltage between the plus and minus levels of the DC bus voltage when the current value is equal to or greater than a first reference value which is preset and has a lower level than a level of a second reference value which is higher than a level of the first reference value; carrying out a base block operation for bringing all of the switching units into an OFF state after outputting the zero vector when the current value is equal to or greater than the second reference value and has a lower level than a level of a third reference value which is higher than the level of the second reference value; and executing an emergency stop when the current value is equal to or greater than the third reference value. - View Dependent Claims (6, 8)
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7. A PWM inverter control method for controlling a PWM inverter control apparatus in which four switching units are connected in series for each phase between a DC bus voltage having a plus level and a DC bus voltage having a minus level, comprising the steps of:
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detecting a current value of an output current; outputting such a zero vector as to bring an O state in which all of phases are turned ON by second and third switching units from the DC bus voltage side having the plus level to output an intermediate potential to be a voltage between the plus and minus levels of the DC bus voltage when the current value is equal to or greater than a preset reference value; carrying out a base block operation for bringing all of the switching units into an OFF state after outputting the zero vector; and outputting such a zero vector as to bring all of the phases into the O state and then performing a reset to a normal run when the current value is smaller than the reference value.
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Specification