Bidirectional Totem-Pole Power Stage for Split-Phase Vehicle AC Output

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Solution Overview

Problem

Existing power conversion technologies lack a unified solution for bidirectional AC to DC and DC to AC conversions using the same hardware, particularly in vehicles where efficient energy management is crucial.

Innovation Solution

A power stage circuit utilizing a common neutral line connects multiple AC to DC and DC to AC circuits, enabling both AC to DC conversion for charging a battery pack and DC to AC conversion for powering vehicle outlets, using existing components for both directions of power flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate hardware is used for AC to DC and DC to AC conversions, then conversion functionality is achieved, but device complexity and cost increase

Engineering Contradiction:

Improvebidirectional conversion capabilityVSAvoidhardware complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The power stage circuit is designed to perform both AC to DC conversion (for battery charging) and DC to AC conversion (for powering outlets) using the same hardware components. The circuit topology and control strategy enable bidirectional power flow, eliminating the need for separate conversion circuits and reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the AC to DC rectifier circuit and DC to AC inverter circuit into a single unified power stage circuit. By merging these functions into one circuit with shared components (such as switches, diodes, and capacitors), the system achieves bidirectional conversion capability while minimizing hardware redundancy.

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If a common neutral line is used to connect multiple circuits, then component reuse is maximized, but electrical isolation and safety may be compromised

Engineering Contradiction:

Improvecircuit configuration simplicityVSAvoidelectrical isolation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The common neutral line serves as an intermediary connection that allows multiple AC to DC and DC to AC circuits to share a reference potential without direct galvanic isolation. The neutral line is properly grounded and referenced to ensure electrical safety while enabling component reuse across multiple conversion circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If bidirectional conversion is implemented, then energy management efficiency improves, but control complexity increases

Engineering Contradiction:

Improveenergy management efficiencyVSAvoidcontrol system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The control system dynamically adjusts the operation mode of the power stage circuit based on real-time power flow requirements. The controller can switch between AC to DC conversion mode (for charging), DC to AC conversion mode (for discharging), or bidirectional mode, optimizing energy management efficiency while adapting to different operating conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control strategy modifies switching parameters (such as PWM duty cycles, switching frequencies, and phase angles) to achieve optimal bidirectional power conversion. By dynamically changing these parameters based on load conditions and battery state of charge, the system maximizes energy efficiency without requiring complex additional hardware.

Inventive Principle:

Principle #35Parameter changes

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 allows for efficient bidirectional power conversion, supporting both onboard charging of vehicle batteries and providing AC power to vehicle outlets, while utilizing existing components to reduce complexity and cost.

Implementation Method 1

a power stage circuit configured to convert an alternating current (AC) input to a direct current (DC) output to charge a battery pack

Methodology Applied

Scientific EffectRectification:

Implementation Method 2

the power stage circuit may convert a DC input from the battery pack to an AC output at the load

Methodology Applied

Scientific EffectInversion:

Implementation Method 3

The power stage circuit may include a first totem pole circuit including a first switch and a second switch. The power stage circuit may further include a second totem pole circuit including a third switch and a fourth switch

Methodology Applied

Scientific EffectElectrical Switching:

Data Source

PatentUS12296711B2Bidirectional series connected totem pole for split phase DCAC

Publication Date: 2025.05.13 RIVIAN HOLDINGS LLC

AI summary

A power stage circuit with multiple bidirectional AC to DC circuits for bidirectional charging is modified to connect the power stage converters in series for DC to AC applications. The power stage circuit can covert a DC input from a DC power source of a vehicle to an AC output for a power outlet of the vehicle. The power stage circuit uses two lines with a 120 VAC at the power outlet. Using a common neutral line, the AC to DC circuits are connected together to form a split phase power output, and the 120 VAC lines are 180 degrees out of phase to create a 240 VAC source at the power outlet.