Current Balanced Push-Pull Inverter Circuit Topology
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Solution Overview
Problem
Conventional inverter circuits face issues such as high cost due to the need for multiple switching elements, increased size and price of components, and excessive surge voltages caused by leakage inductance in center tap push-pull types, and high electrical currents in half bridge types.
Innovation Solution
A current balanced push-pull inverter circuit using two semiconductor switching elements with an output transformer and voltage sources connected in a specific configuration, along with snubber and recovery circuits to achieve Zero Voltage Switching and Zero Current Switching operations, reducing losses and surge voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the full bridge type inverter circuit is used, then the inverter can operate with balanced voltage distribution, but the cost becomes high due to the need for four switching elements
Solution Approach 1:
The patent divides the single primary winding into two separate primary windings (first primary winding and second primary winding) connected in series. This segmentation allows each winding to be independently controlled by its own switching element, reducing the total number of switching elements needed while maintaining balanced voltage distribution across the transformer.
Solution Approach 2:
Instead of using four switching elements in a bridge configuration to achieve balanced operation, the patent inverts the approach by using two switching elements with series-connected primary windings. The voltage balance is achieved through the series connection configuration rather than through four independent switching paths.
2Device complexity
If the half bridge type inverter circuit is used, then only two switching elements are needed, but the electrical currents become twice as great causing size increase and high price of components
Solution Approach 1:
The patent segments the primary winding into two series-connected windings, which divides the current path. Each switching element handles only half of the total power transfer, reducing the current magnitude through each switching element and transformer winding compared to a half-bridge configuration where all current flows through single components.
Solution Approach 2:
The patent transitions from the half-bridge's parallel voltage source configuration to a series winding configuration. This dimensional change in circuit topology allows the same power transfer function to be achieved with reduced current stress on individual components by distributing the current load across series-connected elements.
3Device complexity
If the center tap push-pull type inverter circuit is used, then two switching elements are sufficient with moderate current values, but leakage inductance causes excessive surge voltage on switching elements
Solution Approach 1:
The patent removes the center tap connection from the transformer, eliminating the source of leakage inductance problems. By disconnecting the power supply from the center tap and instead using series-connected primary windings without a center tap, the harmful leakage inductance effect is extracted from the circuit, preventing surge voltage generation during switching transitions.
Solution Approach 2:
The patent converts the potential harm of leakage inductance into a benefit by eliminating the center tap configuration that causes the problem. The series winding configuration without center tap transforms what would have been a harmful leakage path into a controlled magnetic coupling path, where the leakage inductance no longer causes surge voltages but instead supports balanced current distribution.
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 allows for efficient operation with low current flow in switching elements, reduced surge voltages, and enhanced efficiency by utilizing snubber and recovery circuits, thereby minimizing heat losses and maintaining high efficiency.
Implementation Method 1
an output transformer which has a first primary winding P1 connected in series between a first switching element S1 and a second switching element S2, and which moreover has a secondary winding from which an output voltage is obtained
Data Source
AI summary
This inverter circuit includes first and second switching elements and an output transformer which has a first primary winding connected in series between the first switching element and the second switching element and a second primary winding for obtaining an output voltage. The inverter circuit also includes a first voltage source, a second voltage source, and a control unit. The first voltage source is connected between a first connection point at which the first primary winding is connected to the second switching element, and the first switching element, and applies a voltage to the first switching element via the first primary winding. And the second voltage source is connected between a second connection point at which the first primary winding is connected to the first switching element, and the second switching element, and applies a voltage to the second switching element via the first primary winding. The control unit alternately turns the first switching element and the second switching element ON and OFF. And this inverter circuit also may include first and second recovery snubber circuits for recovering electrical charge in snubber capacitors.