Inverter Charge Pump Discharge Circuit for Surge Voltage Protection
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Solution Overview
Problem
Surge voltage generated in parasitic inductance during switching operations in inverter circuits can cause the output voltage of charge pump circuits to exceed their withstand voltage, leading to a risk of malfunction.
Innovation Solution
A discharge circuit is configured between the high side charge pump voltage terminal and the battery pack output voltage terminal, utilizing a discharge element such as a Zener diode or resistor to absorb the surge voltage, thereby preventing voltage fluctuations and reducing the risk of malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discharge circuit is not provided, then the circuit structure is simpler, but the output voltage of the charge pump circuit may exceed the withstand voltage of circuit elements due to surge voltage
Solution Approach 1:
A discharge circuit is introduced as an intermediary component between the charge pump circuit output terminal and the power supply terminal. This discharge circuit acts as a mediator to safely dissipate surge voltage energy, preventing direct damage to the charge pump circuit and other sensitive components while maintaining overall system reliability.
Solution Approach 2:
The discharge circuit is designed to provide beforehand cushioning against surge voltage by offering a predetermined discharge path. This preventive measure ensures that when surge voltage occurs during switching operations, the energy is safely dissipated through the discharge circuit before it can exceed the withstand voltage of circuit elements.
2Reliability
If electrolytic capacitors are used to absorb surge, then the surge voltage can be absorbed, but the device size and cost increase
Solution Approach 1:
The discharge circuit employs a discharge element (such as a resistor or Zener diode) that is simpler, smaller, and more cost-effective than electrolytic capacitors. This discharge element is designed to handle surge events temporarily and can be replaced if needed, providing surge protection without the size and cost penalties of electrolytic capacitors.
Solution Approach 2:
The invention changes the approach from energy storage (capacitors) to energy dissipation (discharge circuit). By altering the fundamental parameter of surge handling from absorption to controlled discharge, the system achieves surge protection with smaller, cheaper components while maintaining reliability.
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 discharge circuit effectively consumes surge energy, maintaining a stable high side charge pump voltage, reducing the risk of circuit malfunctions, enhancing reliability, and eliminating the need for electrolytic capacitors, while allowing for component cost reduction and design flexibility.
Implementation Method 1
a discharge circuit between the output terminal of the charge pump circuit and a power supply terminal... a discharge element such as a Zener diode or resistor to absorb the surge voltage
Implementation Method 2
a discharge element such as a Zener diode or resistor to absorb the surge voltage, thereby preventing voltage fluctuations
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An electric device is provided which can reduce risk of malfunction. This electric device is provided with a motor (32), an inverter circuit (30) which has switching elements (S1-S6) and which drives the motor (32), and a charge pump circuit (22) which generates the drive voltage of the switching elements (S1-S6). A discharge circuit (a discharge resistor R and a capacitor C1) is provided between a power line to which a drive voltage (VM) of the motor (32) is supplied and an output terminal (a VGT terminal) of the charge pump circuit (22). Energy of the surge voltage (Vs) generated in a parasitic inductance (Ls) when the switching elements (S4-S6) are turned off is absorbed by the discharge circuit (the discharge resistor R and the capacitor C1).