Gate Driver Discharge Control for DC-Link Shoot-Through Peaks
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Solution Overview
Problem
Existing driver circuits for high-voltage systems are not robust enough to handle high current peaks during shoot-through discharging of DC-Link capacitors, leading to potential device breakdowns and safety hazards due to uncontrolled current slopes and lack of soft shut-down procedures.
Innovation Solution
A driver circuit with a high-side and low-side switch configuration, driven by programmable and fixed voltage circuits, respectively, and control circuitry that manages the switches to clamp voltages and control the discharge process, ensuring a controlled shoot-through and soft turn-off to manage high current peaks and prevent device breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If shoot-through discharge technique is used to discharge DC-Link capacitor, then discharge speed is improved, but current peak exceeds safe operating area causing device breakdown
Solution Approach 1:
The patent implements dynamic control of the shoot-through discharge process by adjusting the discharge duration and current limits in real-time. The controller monitors system state and dynamically modifies discharge parameters to maintain current within safe operating areas while achieving rapid voltage reduction, resolving the contradiction between fast discharge and device safety.
Solution Approach 2:
The patent employs feedback control mechanisms where the controller continuously monitors discharge current and voltage levels, comparing them against predefined safe operating thresholds. Based on this feedback, the controller adjusts discharge switch timing and duration to prevent current peaks from exceeding device ratings, thereby enabling fast discharge without compromising reliability.
2Reliability
If additional discharge circuits are added to control current peaks, then device safety is improved, but system complexity and cost increase
Solution Approach 1:
The patent makes the existing inverter switches and control circuitry perform the additional function of controlled shoot-through discharge. By programming the existing power switches to operate in a controlled shoot-through mode and using the existing controller to manage the discharge timing and duration, the system achieves safe discharge without adding dedicated discharge circuits, thus maintaining simplicity while improving safety.
Solution Approach 2:
The patent enables the inverter system to discharge its own DC-Link capacitor using its existing components. The inverter's power switches and control circuitry are utilized to perform the discharge function, eliminating the need for external discharge circuits. This self-service approach reduces system complexity and cost while maintaining device safety through controlled operation.
3Reliability
If closed-loop control is used to limit current peak, then device safety is improved, but reaction delay occurs incompatible with current peak limitation
Solution Approach 1:
The patent implements preliminary action by pre-calculating and pre-setting the optimal discharge timing and duration based on system parameters before the discharge event occurs. The controller is pre-programmed with discharge control algorithms that determine switch timing in advance, eliminating the need for real-time closed-loop adjustments during the actual discharge, thus reducing reaction delay while maintaining current peak limitation.
Data Source
Figure 1
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Figure 4~5
AI summary
In a driver circuit (20), a high-side switch (21) is coupled to a first output pin (VO+) and a low-side switch (22) is coupled to a second output pin (VO-). The output pins (VO+, VO-) are couplable (RCHG, RDCHG) to a control terminal (GSP) of a power switch (SP) to provide thereto a control signal. A high-side drive circuit (31) supplied by a programmable voltage (VGSHOOT) drives the high-side switch. A low-side drive circuit (32) supplied by a fixed voltage (VDRIVE_LS) drives the low-side switch. A programmable voltage generator (50) receives a programming signal (V2LTO+VN_TH) and produces the programmable voltage (VGSHOOT) as a function thereof. Control circuitry (40, 60, 70, 80) coupled to the high-side (31) and low-side (32) drive circuits receives an input command signal (i_gate_cmd). In response to the input command signal (i_gate_cmd) indicating that a discharge action is initiated, the control circuitry asserts a drive signal (drv) to activate the high-side drive circuit (31), whereby the high-side switch (21) is turned on and the voltage at the first output pin (VO+) is clamped at the programmable voltage (VGSHOOT). In response to expiration of a time interval (TSHOOT,DLY), the control circuitry de-asserts the drive signal (drv) to activate the low-side drive circuit (32), whereby the low-side switch (22) is turned on and the second output pin (VO-) is tied to the second supply voltage node (VL). The control signal for the power switch (SP) is thus produced at the first and second output pins (VO+, VO-) of the driver circuit (20).