Power Converter Stability via Output Power Control
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Solution Overview
Problem
Power converters using power factor correctors face instability and excessive heating or destruction when the output is short-circuited or the output voltage is very low, due to the inverse proportional gain in the secondary current loop, leading to loss of control and potential damage.
Innovation Solution
A power converter design incorporating a multiplication circuit to compensate for the inverse output voltage term, using a secondary current loop with a current reading module, adder, current correction module, multiplier, and voltage reading module to stabilize the system and control output power independently of the output voltage, ensuring safe isolation of faulty consumers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a power factor corrector regulates its output current, then the output current can be controlled, but the system becomes unstable when output voltage is very low or short-circuited due to inverse proportional gain
Solution Approach 1:
The patent changes the control parameter from output current to output power. By controlling output power instead of output current directly, the inverse proportional gain issue is eliminated because power control does not create the same stability problems at low voltages. The transfer function becomes independent of output voltage, maintaining stability across all operating conditions including short-circuits.
2Measurement precision
If the output voltage is very low or short-circuited, then the inverse proportional gain causes loss of control, but increasing gain to maintain control causes excessive heating and potential destruction
Solution Approach 1:
The patent transitions from current control to power control methodology. This parameter change fundamentally alters the system behavior at low voltages, allowing stable control without requiring excessive gain that would cause heating. The power control approach inherently limits energy delivery even when voltage is low, preventing thermal damage.
Solution Approach 2:
The patent implements a feedback mechanism where output power is measured and used to regulate the control signal to the power structure. This closed-loop power feedback ensures that even under short-circuit conditions, the system can detect and control the actual power being delivered, preventing uncontrolled current increases that would lead to overheating.
3Reliability
If a consumer is short-circuited in an electrical network, then the faulty consumer must be isolated, but cutting the power supply interrupts power to other consumers
Solution Approach 1:
The patent enables isolation of the faulty consumer segment from the rest of the network while maintaining power supply to healthy segments. By implementing precise control and monitoring at the consumer level with power-based protection, the system can selectively disconnect only the problematic load without affecting other consumers connected to the same power supply.
Data Source
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AI summary
A power converter characterised in that it comprises a power structure (11) receiving, as input, an alternating voltage comprising at least one phase and supplying, as output, a direct voltage (Vs), the output power of said power structure (11) being regulated by a multiplier (15) receiving as input a current control signal (I_commande) and a signal proportional to the output voltage of the power structure (11), said current control signal (I_commande) being generated by a current correction module (14) receiving as input a signal proportional to the difference between the output current of the power structure (11) and a current setpoint signal (I_consigne). An electrical grid characterised in that it comprises such a power conversion circuit.