HVAC Power Factor Correction with Dynamic Bus Voltage Adjustment
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Solution Overview
Problem
Existing HVAC and refrigeration systems face inefficiencies due to constant bus voltage in power factor correction (PFC) subsystems, leading to magnetic core losses and resource wastage at lighter loads, as they must maintain high voltage to support peak operations, sacrificing efficiency and resources.
Innovation Solution
A controller dynamically adjusts the output voltage set point of the PFC subsystem based on load conditions and individual efficiency values of motor drives, optimizing system efficiency by reducing bus voltage during light loads while ensuring sufficient voltage during peak operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the PFC subsystem maintains a constant high bus voltage to support peak operations, then the system can provide sufficient power during peak loads, but magnetic core losses and PFC subsystem losses increase significantly at light load conditions
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant bus voltage approach to a dynamic variable bus voltage approach. The controller continuously adjusts the bus voltage setpoint based on real-time load conditions, allowing the system to adapt its voltage output dynamically. This resolves the contradiction by enabling high voltage during peak loads (maintaining power supply capability) while reducing voltage during light loads (minimizing magnetic core losses).
Solution Approach 2:
The patent changes the key parameter of bus voltage from a fixed constant value to a variable parameter that changes according to load conditions. By implementing a variable bus voltage setpoint that is adjusted based on actual power demand, the system optimizes the trade-off between maintaining sufficient power capability and reducing energy losses. This parameter change enables the system to operate efficiently across different load scenarios.
2Power
If the PFC subsystem maintains a constant high bus voltage, then peak power delivery is ensured, but system efficiency deteriorates at lighter loads due to sustained high voltage operation
Solution Approach 1:
The system implements dynamic voltage adjustment where the bus voltage setpoint is continuously modified based on load conditions. During peak loads, the voltage is maintained at high levels to ensure adequate power delivery. During light loads, the voltage is reduced to optimize efficiency. This dynamic behavior resolves the contradiction between peak power delivery capability and overall system efficiency.
Solution Approach 2:
The bus voltage parameter is changed from a fixed constant to a variable that responds to load conditions. By implementing variable voltage operation, the system achieves high efficiency at light loads while maintaining the capability to deliver peak power when needed, thus resolving the efficiency-power trade-off contradiction.
3Power
If the bus voltage is set high to support peak voltages on motor drive terminals, then sufficient power is available for motor drives during peak operation, but losses in the PFC subsystem increase at light load situations
Solution Approach 1:
The controller implements dynamic adjustment of the bus voltage setpoint based on actual load requirements. During peak operations, the voltage is maintained at levels sufficient to support motor drive terminal voltages. During light load situations, the voltage is reduced to minimize PFC subsystem losses. This dynamic response resolves the contradiction between power availability and PFC subsystem efficiency.
Solution Approach 2:
The bus voltage parameter is transformed from a fixed high value to a variable parameter that changes with load conditions. This allows the system to maintain adequate power availability during peak operation while reducing PFC subsystem losses during light load operation, effectively resolving the contradiction.
Data Source
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AI summary
A system includes an alternating current (AC) to direct current (DC) voltage convertor (110), a power factor correction (PFC) subsystem (115), and one or more motor drives. The AC to DC voltage converter (110) receives alternating current from an AC voltage source (105). The PFC subsystem (115) receives DC voltage from the AC to DC voltage convertor (110). The PFC subsystem (115) also outputs a corrected DC voltage corresponding to an output voltage setpoint. The PFC subsystem includes a controller (120) operable to dynamically adjust the output voltage setpoint. The one or more motor drives receive voltage via the PFC subsystem (115). The output voltage setpoint is determined based at least in part on estimating a load associated with the one or more motor drives configured to receive voltage via the PFC subsystem (115).