Inverter Phase Switch Resistance Balancing for Current Waveform Control
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Solution Overview
Problem
Traditional motor control strategies using solid-state switches in inverters often result in imbalanced leg resistances, leading to inefficiencies in current waveform generation and control, particularly in AC motor drives for vehicles and industrial applications.
Innovation Solution
The use of high-side and low-side solid-state switches with different conducting-state resistance values, along with a shunt resistor in the low-side leg, to balance the resistances and improve current regulation, allowing for more precise control of the current waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical solid-state switches are used in high-side and low-side legs, then device simplicity and manufacturing consistency are improved, but leg resistance imbalance occurs leading to poor current waveform control
Solution Approach 1:
The patent applies local quality by assigning different resistance characteristics to specific locations in the circuit. The low-side solid-state switch is selected with a specific resistance value that complements the high-side switch resistance, creating locally optimized resistance balance in each leg while maintaining overall system performance.
Solution Approach 2:
The patent changes the resistance parameter of the solid-state switches by selecting devices with specific resistance values. The low-side switch is chosen to have a resistance that, when combined with its series resistor, balances the total leg resistance against the high-side leg, directly addressing the resistance imbalance problem.
2Manufacturing precision
If different resistance values are used for high-side and low-side solid-state switches, then current waveform control and thermal management are improved, but device complexity and selection requirements increase
Solution Approach 1:
The patent systematically changes the resistance parameters of the solid-state switches based on their position in the circuit. By calculating and selecting switches with specific resistance values for high-side and low-side legs, the patent achieves optimized current control and thermal performance while providing clear selection criteria.
Solution Approach 2:
The patent introduces series resistors as intermediary elements in the low-side leg to fine-tune the total resistance. These resistors act as mediators that allow precise adjustment of leg resistance to match the high-side leg, providing an additional degree of freedom for optimization.
3Measurement precision
If shunt resistors are added to balance leg resistances, then current regulation precision is improved, but device complexity and component count increase
Solution Approach 1:
The patent uses series resistors in the low-side leg as intermediary elements to balance the total resistance between high-side and low-side legs. These resistors provide precise current regulation by adjusting the resistance distribution, and they serve dual purposes of resistance balancing and current sensing.
Solution Approach 2:
The series resistors in the low-side leg serve multiple functions: they balance the leg resistance, provide current sensing capability, and allow for thermal management. This multi-functionality reduces the need for separate components and justifies their inclusion despite increasing component count.
Data Source
AI summary
One or more embodiments are provided for an inverter. The inverter includes a phase switch configured to supply AC power via an output terminal. The phase switch includes a high-side leg and a low-side leg. The high-side leg includes a high-side solid-state switch configured to selectively conduct current between a high-side conductor of a DC bus and the output terminal, and the low-side leg includes a low-side solid-state switch configured to selectively conduct current between the output terminal and a low-side conductor of the DC bus. The high-side solid-state switch has a first conducting-state resistance value, and the low-side solid-state switch has a second conducting-state resistance value different than the first conducting-state resistance value. A shunt resistor may be connected in series with a corresponding one of the high-side solid-state switch or the low-side solid-state switch, balancing the resistances of the high-side leg and the low-side leg.