H-Bridge Push-Pull Excitation Circuit for Balanced Bipolar Drive
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Solution Overview
Problem
Conventional resolver excitation circuits produce bipolar signals with slightly different positive and negative amplitudes due to inverting and non-inverting amplifier characteristics, leading to complexity and reduced reliability, especially when square-wave excitation is required.
Innovation Solution
An H-bridge push-pull excitation circuit with push-pull amplifiers arranged in two legs and a compensation circuit to compensate for distortion caused by the inductive load of the excitation coil, converting a unipolar square wave signal to a bipolar square wave signal with equal positive and negative amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional excitation circuits use inverting and non-inverting amplifiers to produce bipolar signals, then the circuit can drive the excitation coil, but the positive and negative amplitudes become slightly different due to amplifier characteristics and tolerances
Solution Approach 1:
The circuit is divided into two separate legs (inverting and non-inverting) that are independently compensated. Each leg has its own compensation circuit that independently adjusts the amplitude of its output signal, allowing precise control over the bipolar signal amplitudes without requiring complex interaction between amplifiers.
Solution Approach 2:
The compensation circuits adjust the amplitude parameters of the bipolar signal by varying component values (such as resistors and capacitors) to equalize the positive and negative amplitudes. This parameter adjustment compensates for the inherent differences in amplifier characteristics and tolerances.
2Reliability
If conventional excitation circuits use multiple amplifiers and components to achieve bipolar signal output, then the signal can be generated, but the number of components increases decreasing reliability
Solution Approach 1:
The compensation functionality is merged into the existing amplifier legs by adding compensation circuits to each leg. This approach combines the signal generation and amplitude balancing functions within a unified structure, reducing the need for separate correction components and simplifying the overall circuit architecture.
3Power
If push-pull amplifiers are used with inductive load of excitation coil, then the circuit can drive the coil effectively, but distortion occurs in the output signal due to inductive loading
Solution Approach 1:
The compensation circuits are designed to preemptively counteract the distorting effect of the inductive load. By adjusting the amplitude and phase of the signals from each leg before they reach the excitation coil, the compensation circuits prevent distortion from occurring, ensuring clean bipolar square wave output despite the inductive loading conditions.
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 H-bridge push-pull excitation circuit reduces complexity and increases reliability by producing a bipolar output signal with balanced amplitudes, enhancing the performance of transformer-based measuring devices like resolvers and LVDTs.
Implementation Method 1
an H-bridge circuit to convert a unipolar square wave signal to a bipolar square wave signal
Implementation Method 2
drive the excitation coil to generate an alternating magnetic field
Implementation Method 3
compensate for any distortion in the bipolar square wave signal caused by the excitation coil as an inductive load on the H-bridge circuit
Data Source
AI summary
An excitation circuit is provided for a transformer-based measuring device that includes an excitation coil. The excitation circuit includes an H-bridge circuit and a compensation circuit. The H-bridge circuit is to convert a unipolar square wave signal to a bipolar square wave signal to drive the excitation coil. The H-bridge circuit includes push-pull amplifiers arranged in two legs. The compensation circuit is coupled between the two legs of the H-bridge circuits, and compensates for any distortion in the bipolar square wave signal caused by the excitation coil as an inductive load on the H-bridge circuit.