Control of motor drives with output sinewave filter capacitor current compensation using sinewave filter transfer function
First Claim
1. A power conversion system, comprising:
- an inverter comprising a DC input, an AC output, and a plurality of switching devices coupled between the DC input and the AC output and operative according to inverter switching control signals to convert DC electrical power received at the DC input to provide AC electrical output power at the AC output to drive a motor load through an intervening output filter; and
a controller configured to;
compute a speed error value according to a speed reference value and a speed feedback value using a summing component;
compute a torque reference value according to the speed error value using a first proportional-integral (PI) control component;
compute a motor current reference value according to the torque reference value using a lookup table or a parametric equation;
compensate the motor current reference value according to capacitor currents of the output filter by computing an inverter output current reference value according to the motor current reference value and an inverter operating frequency using a first transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load; and
provide the inverter switching control signals to control the inverter according to the inverter output current reference value;
wherein the controller is operative to control the inverter according to the inverter output current reference value by;
computing an inverter output current value according to the inverter output current reference value and an inverter output current value, andproviding the inverter switching control signals to control the inverter according to the inverter output current value; and
wherein the controller is operative to estimate the speed feedback value by;
computing a motor current value according to the inverter output current value and the inverter operating frequency using the first transfer function,computing a motor torque value according to the motor current value, andcomputing the speed feedback value according to the motor torque value.
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Accused Products
Abstract
Disclosed examples include power conversion systems, methods and computer readable mediums to operate an inverter to drive a motor load through an intervening filter, by computing a speed error value according to a speed reference value and a speed feedback value, computing a torque reference value according to the speed error value, computing a motor current reference value according to the torque reference value, compensating the motor current reference value according to capacitor currents of the output filter using a transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load, and controlling the inverter according to the inverter output current reference value.
70 Citations
14 Claims
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1. A power conversion system, comprising:
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an inverter comprising a DC input, an AC output, and a plurality of switching devices coupled between the DC input and the AC output and operative according to inverter switching control signals to convert DC electrical power received at the DC input to provide AC electrical output power at the AC output to drive a motor load through an intervening output filter; and a controller configured to; compute a speed error value according to a speed reference value and a speed feedback value using a summing component; compute a torque reference value according to the speed error value using a first proportional-integral (PI) control component; compute a motor current reference value according to the torque reference value using a lookup table or a parametric equation; compensate the motor current reference value according to capacitor currents of the output filter by computing an inverter output current reference value according to the motor current reference value and an inverter operating frequency using a first transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load; and provide the inverter switching control signals to control the inverter according to the inverter output current reference value; wherein the controller is operative to control the inverter according to the inverter output current reference value by; computing an inverter output current value according to the inverter output current reference value and an inverter output current value, and providing the inverter switching control signals to control the inverter according to the inverter output current value; and wherein the controller is operative to estimate the speed feedback value by; computing a motor current value according to the inverter output current value and the inverter operating frequency using the first transfer function, computing a motor torque value according to the motor current value, and computing the speed feedback value according to the motor torque value. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of operating an inverter to drive a motor load through an intervening filter, the method comprising:
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using at least one processor implementing a summing component, computing a speed error value according to a speed reference value and a speed feedback value; using the at least one processor implementing a first proportional-integral (PI) control component, computing a torque reference value according to the speed error value; using the at least one processor implementing a lookup table or a parametric equation, computing a motor current reference value according to the torque reference value; using the at least one processor, compensating the motor current reference value according to capacitor currents of the output filter by computing an inverter output current reference value according to the motor current reference value and an inverter operating frequency using a first transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load; using the at least one processor, providing inverter switching control signals to control the inverter according to the inverter output current reference value; using the at least one processor, estimating the speed feedback value according to the inverter output current reference value; using the at least one processor, computing an inverter output current value according to the inverter output current reference value and an inverter output current value; using the at least one processor, providing the inverter switching control signals to control the inverter according to the inverter output current value; and using the at least one processor, estimating the speed feedback value by; computing a motor current value according to the inverter output current value and the inverter operating frequency using the first transfer function, computing a motor torque value according to the motor current value, and computing the speed feedback value according to the motor torque value. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A non-transitory computer readable medium, comprising instructions that, when executed by at least one processor, cause the at least one processor to:
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implement a summing component to compute a speed error value according to a speed reference value and a speed feedback value; implement a first proportional-integral (PI) control component to compute a torque reference value according to the speed error value; implement a lookup table or a parametric equation to compute a motor current reference value according to the torque reference value; compensate the motor current reference value according to capacitor currents of the output filter by computing an inverter output current reference value according to the motor current reference value and an inverter operating frequency using a first transfer function representing an output current to input current amplitude vs. frequency behavior of the output filter and the motor load; provide the inverter switching control signals to control the inverter according to the inverter output current reference value; estimate the speed feedback value according to the inverter output current reference value; compute an inverter output current value according to the inverter output current reference value and an inverter output current value; provide the inverter switching control signals to control the inverter according to the inverter output current value; compute a motor current value according to the inverter output current value and the inverter operating frequency using the first transfer function; compute a motor torque value according to the motor current value; and compute the speed feedback value according to the motor torque value. - View Dependent Claims (14)
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Specification