Gate Driver Charge Pump Current Limiting in Hi-Z Mode
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Solution Overview
Problem
Conventional gate driver circuits for electric motors face issues with excessive power dissipation and temperature rise during the Hi-Z mode, leading to potential damage and fault triggering due to high current supply by the charge pump switch.
Innovation Solution
A mode-dependent current limiter is introduced in series with the charge pump switch, which receives a control signal to operate in either a low-impedance configuration for switching mode or a current-limiting configuration for Hi-Z mode, reducing the current supplied to the bootstrap capacitor and thereby limiting power dissipation and temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the charge pump switch supplies high current to the bootstrap capacitor during Hi-Z mode, then the gate driver circuit can respond quickly to mode transitions, but excessive power dissipation and temperature rise occur
Solution Approach 1:
The current limiter dynamically adjusts its impedance based on the operational mode. During switching mode, it operates in low-impedance configuration to allow high current flow for fast response. During Hi-Z mode, it switches to current-limiting configuration to reduce power dissipation. This dynamic adaptation resolves the contradiction between needing high current for fast response and limiting current to reduce energy loss.
Solution Approach 2:
The system changes the current parameter based on operational mode. A control signal switches the current limiter between two impedance states, thereby changing the current supplied to the bootstrap capacitor. This parameter change allows the system to optimize between fast response (high current) and energy efficiency (low current) depending on the operational requirements.
2Duration of action of moving object
If the charge pump switch supplies high current to the bootstrap capacitor, then the gate driver can charge the capacitor quickly, but temperature rise leads to potential damage and fault triggering
Solution Approach 1:
The current limiter provides dynamic current control by switching between low-impedance and current-limiting configurations. During charging phases requiring speed, it allows high current. During Hi-Z mode, it limits current to prevent excessive temperature rise. This dynamic behavior enables the system to achieve fast charging when needed while preventing thermal damage during idle periods.
3Productivity
If the current limiter operates in low-impedance configuration, then high current can flow for fast switching, but power dissipation increases during Hi-Z mode
Solution Approach 1:
The current limiter dynamically switches between low-impedance and current-limiting configurations based on a control signal. During switching operations, it operates in low-impedance mode to enable fast charging of the bootstrap capacitor. During Hi-Z mode, it transitions to current-limiting configuration to minimize power dissipation. This dynamic operation resolves the contradiction between productivity and energy loss.
Data Source
AI summary
A device includes a charge pump configured to provide a current to a bootstrap capacitor responsive to a charge pump switch being closed. The device also includes a current limiter coupled in series between the charge pump switch and the charge pump. The current limiter is configured to receive a control signal from a controller that indicates whether the device is to operate in a first mode or in a second mode; responsive to the control signal indicating the first mode, allow a first value of current to the charge pump switch; and, responsive to the control signal indicating the second mode, limit the current to the charge pump switch to a second value. The second value is less than the first value.