Switch actuation measurement circuit for voltage converter
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Solution Overview
Problem
Existing voltage converter systems face challenges in accurately measuring and controlling the switching of switches in power factor correction circuits, particularly in high-frequency applications, leading to inefficiencies and potential damage due to delayed turn-on and turn-off times.
Innovation Solution
The implementation of a power factor correction circuit with a switch monitor circuit and a control module that generates control signals based on measured currents and switch states, transitioning the switch between open and closed states at frequencies of at least 50 Kilohertz, and includes a damping circuit to prevent oscillation and a clamp switch for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a power factor correction circuit operates at high switching frequencies (at least 50 kHz), then productivity and power conversion efficiency are improved, but measurement precision and control accuracy deteriorate due to difficulties in accurately measuring and controlling switch transitions at these frequencies
Solution Approach 1:
A dedicated switch monitor circuit is introduced as an intermediary component between the power switch and control module. This circuit includes voltage dividers that scale down the high-voltage switch node to measurable levels, and a comparator that accurately detects voltage transitions. This intermediary measurement system enables precise detection of switch transitions at high frequencies without directly burdening the control module, thus resolving the contradiction between high-speed operation and measurement accuracy.
Solution Approach 2:
The patent replaces direct high-voltage electrical measurement with a conditioned low-voltage signal measurement system. By using voltage dividers to scale down signals and a comparator to convert analog voltage transitions into digital logic levels, the system substitutes direct high-frequency voltage measurement with a processed signal measurement approach, enabling accurate detection at 50 kHz and above.
2Productivity
If the switch turn-on and turn-off times are reduced to improve response speed, then productivity is improved, but reliability deteriorates due to potential damage from insufficient transition time
Solution Approach 1:
The switch monitor circuit provides real-time feedback about the actual switch state to the control module. By continuously monitoring the voltage across the switch and comparing it against reference levels, the system receives immediate feedback on whether the switch has successfully transitioned. This feedback mechanism allows the control module to verify switch status and adjust timing parameters, ensuring sufficiently fast switching for productivity while maintaining adequate transition times for reliability.
Solution Approach 2:
The control module uses the switch monitor circuit to detect transition completion before initiating the next switching cycle. By waiting for confirmation that the previous switch transition is complete (as detected by the monitor circuit), the system ensures that each switch operation has sufficient time to complete safely, preventing overlapping transitions that could damage the switch while maintaining optimal switching frequency.
3Ease of manufacture
If a simple switch control system is used to reduce device complexity, then ease of manufacture is improved, but reliability deteriorates due to inability to accurately detect switch states and prevent oscillations
Solution Approach 1:
The monitoring function is segmented into dedicated, simple sub-circuits: voltage dividers for signal scaling and a comparator for threshold detection. Rather than using a complex integrated monitoring system, the patent divides the monitoring function into separate discrete components that are easier to manufacture and understand. Each segment performs a single function, making the overall system more reliable while maintaining manufacturing simplicity.
Solution Approach 2:
The patent changes the voltage parameters of the switch node signal by using voltage dividers to scale down the high-voltage switching waveform to a safe, measurable range. This parameter transformation allows standard, low-voltage comparator circuits to detect high-voltage switch states, enabling accurate monitoring without requiring complex high-voltage measurement components, thus maintaining ease of manufacture while improving reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient and precise control of switch states, reducing turn-on and turn-off delays, minimizing oscillations, and enhancing the overall performance and reliability of the voltage converter system by maintaining the switch in the closed state until the current exceeds a predetermined threshold.
Implementation Method 1
a first voltage divider configured to generate a fifth reference potential based on a sixth reference potential at the node; a second voltage divider configured to generate a seventh reference potential based on an eighth reference potential at the second terminal of the switch
Implementation Method 2
a comparator configured to generate the signal indicating whether the switch is in the open state or the closed state based on a comparison of the fifth reference potential and the seventh reference potential
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A drive includes an inverter power circuit that applies power to an electric motor of a compressor from a direct current (DC) voltage bus. A power factor correction (PFC) circuit outputs power to the DC voltage bus based on input alternating current (AC) power. The PFC circuit includes: (i) a switch having a first terminal, a second terminal, and a control terminal; (ii) a driver that switches the switch between open and closed states based on a control signal; (iii) an inductor that charges and discharges based on switching of the switch; and (iv) a circuit that outputs a signal indicating whether the switch is in the open state or the closed state based on a voltage across the first and second terminals of the switch.