H-Bridge Load Simulation Circuit for High Voltage Blocking
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Solution Overview
Problem
Existing circuits for simulating electrical loads struggle with high power levels, leading to significant power losses and limitations in blocking voltages during switching operations due to the low dielectric strength of MOSFETs, which are inadequate for high-power applications like electric vehicle drives.
Innovation Solution
A circuit with an H-bridge configuration, utilizing a controllable voltage source and active inductance in a transverse bridge branch, allows for precise adjustment of current flow by a current-control unit, enabling the simulation of substantial loads at high voltages and power levels through direct or inductive coupling, and using a four-quadrant capable switchover device to manage voltage and prevent common-mode interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If MOSFETs are used as switches in the half-bridge circuit for simulating electrical loads, then high switching frequencies can be achieved, but the dielectric strength is insufficient for blocking high voltages during switching operations
Solution Approach 1:
The patent introduces an intermediary voltage division mechanism using capacitors C1 and C2 that split the high voltage into lower voltage segments. This allows MOSFETs to operate at high frequencies while the voltage division network handles the high voltage blocking requirement, effectively mediating between the conflicting requirements of high switching frequency and high voltage blocking capability.
Solution Approach 2:
The patent segments the high voltage blocking function across multiple components (capacitors C1, C2 and their series connection) rather than relying on a single MOSFET to block the entire high voltage. This segmentation allows each MOSFET to only block a portion of the total voltage, making high voltage operation feasible with standard MOSFETs while maintaining high switching frequencies.
2Power
If high power levels are converted in the circuit for simulating load, then substantial loads can be simulated, but significant power losses occur
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors the actual current flowing through the test circuit and compares it with the desired setpoint current. Based on this feedback, the control unit adjusts the switching duty cycle of the MOSFETs to minimize the difference between actual and setpoint currents, thereby optimizing power conversion efficiency and reducing power losses while maintaining the ability to simulate high power levels.
Solution Approach 2:
The patent employs dynamic pulse-width modulation (PWM) control that continuously adapts the switching duty cycle based on the instantaneous power requirements. This dynamic control allows the circuit to operate at optimal efficiency points across varying power levels, reducing unnecessary power losses while maintaining the capability to simulate substantial high power loads.
3Measurement precision
If the voltage at the output of the test circuit is measured metrologically and setpoint current is calculated using a mathematical model, then current control can be achieved, but the circuit complexity increases
Solution Approach 1:
The patent implements a control unit that performs multiple functions: it measures the output voltage, calculates the setpoint current based on mathematical models, generates PWM control signals, and monitors actual current. By consolidating these multiple functions into a single integrated control unit, the patent achieves precise voltage measurement and current control while minimizing the increase in overall circuit complexity through functional integration.
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 simulates electrical loads at high power levels with reduced power losses and improved voltage handling, enabling the simulation of substantial loads and dynamic control of currents, suitable for applications like electric vehicle drives.
Implementation Method 1
An inductance is active in the transverse bridge branch
Implementation Method 2
A controllable voltage source is connected in a transverse bridge branch between the terminal and the second internal connection point
Data Source
AI summary
A circuit for simulating an electrical load at a terminal of a test circuit having at least one first switch and at least one second switch includes a third switch connected to the first switch of the test circuit via a first external connection point. A fourth switch is connected to the second switch of the test circuit via a second external connection point. The first switch and the second switch are connected via a shared, first internal connection point to the terminal of the test circuit and the third switch and the fourth switch are connected via a shared, second internal connection point such that that the first switch, the second switch, the third switch and the fourth switch form an H-bridge circuit. A voltage source is configured to provide the first and second external connection points with a supply voltage. A controllable voltage source is connected in a transverse bridge branch between the terminal and the second internal connection point. An inductance is active in the transverse bridge branch. A current-control unit is operable on the controllable voltage source so as to adjust, to a predetermined setpoint current, an actual current flowing over the terminal of the test circuit and over the transverse bridge branch.