Drive Device Charge Pump Circuit for Short Dead Time
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Solution Overview
Problem
Conventional drive devices face challenges in suppressing transistor malfunctions during short dead times while maintaining a reduced circuit scale, as they cannot generate a negative power supply efficiently, leading to increased dead time and circuit complexity.
Innovation Solution
A drive device configuration that includes a power supply terminal, a grounding terminal, transistors, bootstrap circuits, stabilizing capacitors, and charge pump circuits to generate a negative power supply voltage from a positive power supply, allowing for PWM-controlled transistor operations and reducing circuit scale by omitting the power supply circuit for negative voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a bootstrap power supply is used to reduce circuit scale, then the circuit scale is reduced, but the inability to generate negative power supply increases dead time
Solution Approach 1:
The patent combines the negative power supply generation function with the existing bootstrap circuit by adding a charge pump circuit that uses the bootstrap capacitor's voltage to generate the negative power supply. This merging allows the circuit to maintain reduced scale while acquiring negative voltage generation capability, resolving the contradiction between circuit simplicity and functionality.
Solution Approach 2:
The charge pump circuit acts as an intermediary component that converts the positive voltage from the bootstrap capacitor into a negative power supply voltage. This intermediary mechanism enables the system to generate negative voltage without requiring a separate negative power supply circuit, thus reducing overall circuit scale while maintaining short dead time capability.
2Reliability
If dead time is increased to prevent transistor malfunction, then transistor malfunction is suppressed, but circuit efficiency decreases
Solution Approach 1:
The patent changes the voltage parameter by generating a negative power supply voltage that creates a sufficient voltage margin below the transistor threshold voltage. This parameter change allows the system to use very short dead time while still preventing transistor malfunction, as the negative voltage ensures the transistor remains firmly in the off state during the dead time period.
3Reliability
If a separate negative power supply circuit is added to generate negative voltage, then negative power supply is available, but circuit complexity increases
Solution Approach 1:
The bootstrap capacitor serves multiple functions: it provides the bootstrap voltage for the high-side transistor gate drive and simultaneously serves as the voltage source for the charge pump circuit to generate the negative power supply. This multi-functionality eliminates the need for separate negative power supply circuitry, maintaining circuit simplicity while achieving reliable negative voltage generation.
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 suppresses transistor malfunctions in short dead times by generating a negative power supply voltage, reducing circuit complexity and ensuring a margin between the threshold voltage and control signal, thus shortening dead time.
Implementation Method 1
a first charge pump circuit that applies the first negative power supply voltage to the first negative power supply wiring, by generating the first negative power supply voltage having a polarity opposite to that of the first positive power supply voltage
Implementation Method 2
a first bootstrap capacitor having one end connected to the cathode of the first bootstrap diode and the other end connected to the output terminal
Data Source
AI summary
A drive device includes a first gate driver circuit that controls operations of the first transistor by outputting a first control signal to a control terminal of the first transistor; a second gate driver circuit that controls operations of the second transistor so that the first transistor and the second transistor are turned on/off in a complementary manner, by outputting a second control signal to the control terminal of the second transistor; and a first charge pump circuit that applies the first negative power supply voltage to the first negative power supply wiring, by generating the first negative power supply voltage having a polarity opposite to that of the first positive power supply voltage with reference to a potential of the output terminal, based on the first control signal.