Balanced Transformer Drive for Low-Noise High-Voltage Switching
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Solution Overview
Problem
High-voltage power supply devices using semiconductor switching elements face issues with high-frequency noise superimposed on the output voltage, which can degrade mass resolution and accuracy in mass spectrometers, and increasing output capacitor capacitance to reduce noise prolongs polarity inversion time.
Innovation Solution
A high-voltage power supply device with a balanced output type high-frequency excitation unit and a stray capacitance distribution symmetric high-frequency transformer, which reduces common mode noise and allows for smaller output capacitors, enabling faster polarity switching and improved mass spectrometer performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the capacitance of the output capacitor is increased to reduce high-frequency noise, then the noise level decreases, but the polarity inversion time increases
Solution Approach 1:
A common mode choke is introduced as an intermediary component between the full-bridge circuit and the output capacitor. The choke acts as a filter that blocks high-frequency noise from reaching the output capacitor and the load, while allowing the output capacitor to maintain a smaller capacitance value for fast polarity inversion. This mediator resolves the contradiction by providing noise suppression without requiring a large capacitor.
2Device complexity
If a mechanical relay is used as a high-voltage switch, then the circuit is simple, but the switching speed is limited and reliability is reduced
Solution Approach 1:
The patent replaces the mechanical relay with a solid-state full-bridge circuit consisting of four switching elements (MOSFETs or IGBTs) and associated control circuits. This substitution eliminates mechanical wear, enables high-speed switching (microsecond or nanosecond range), and improves reliability while maintaining circuit functionality. The solid-state implementation achieves both simplicity and high performance.
3Loss of time
If the capacitance of the output capacitor is reduced for faster polarity switching, then the polarity inversion time decreases, but the high-frequency noise increases
Solution Approach 1:
The common mode choke serves as a mediator that allows the output capacitor to be reduced in size for fast switching while the choke compensates for the increased noise by filtering high-frequency components. The choke's inductance provides impedance to noise currents, enabling the system to achieve both fast polarity inversion and low noise levels with a smaller capacitor.
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
The solution effectively suppresses common mode noise, reduces the size and weight of the power supply, and shortens analysis time by allowing simultaneous switching between positive and negative ion measurement modes with improved mass resolution and accuracy.
Implementation Method 1
a high-frequency transformer (502) having a primary winding (502a) and a secondary winding (502b)
Data Source
AI summary
A high-voltage power supply device includes a voltage generation unit for outputting a DC high-voltage, a switching unit using a semiconductor switching element, the switching unit being configured to output an output voltage by the voltage generation unit to a voltage output terminal in a conduction state, a driver for driving a control terminal of the semiconductor switching element, and a controller for controlling the switching unit via the driver. The driver includes a high-frequency transformer provided with primary and secondary windings, a distribution of a stray capacitance per number of unit turns of the primary winding between the primary and secondary windings in an extension direction of the primary winding being symmetrical to a midpoint of the primary winding, a rectifier for rectifying an AC current induced in the secondary winding, and a balanced output type high-frequency excitation unit for exciting the primary winding differentially.