High-Side Gate Clamp Circuit for Regenerative Overvoltage Control
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Solution Overview
Problem
Conventional motor driving devices fail to inhibit the increase in applied voltage to switching elements due to regenerative electric power, particularly when the main circuit is operating.
Innovation Solution
A motor driving device with a bridge circuit and a voltage detection circuit that includes a high-side switching element and a control circuit, which outputs a drive signal to inhibit the increase in voltage by putting the switching element into a conducting state when a predetermined threshold is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective circuit is provided to drive the low-side switching element as in conventional technique, then overvoltage protection is achieved when the relay is opened and motor is rotated by external force, but the increase in applied voltage to the switching element due to regenerative electric power cannot be inhibited when the main circuit is operating
Solution Approach 1:
The protective circuit dynamically adjusts its operation based on the state of the main circuit. When the main circuit is operating, the protective circuit remains inactive to allow normal motor control. When the main circuit is stopped and regenerative voltage occurs, the protective circuit activates to clamp the voltage. This dynamic state-dependent operation resolves the contradiction by adapting the protection mechanism to different operating conditions.
Solution Approach 2:
The invention changes the operational parameters of the protective circuit based on the main circuit state. By monitoring whether the main circuit is operating or stopped, the protective circuit adjusts its threshold and activation characteristics. This parameter change allows the system to achieve both normal motor control during operation and overvoltage protection during shutdown, resolving the adaptability issue.
2Object-affected harmful factors
If the low-side switching element is driven into conducting state to inhibit voltage increase, then overvoltage protection is achieved, but normal motor control is interfered with during main circuit operation
Solution Approach 1:
The protective circuit is designed to be dynamically controllable, switching between active and inactive states based on main circuit operation status. During normal motor control, the protective circuit is inactive, allowing full ease of operation. During shutdown with regenerative voltage, it becomes active to protect against overvoltage. This dynamic behavior resolves the contradiction between protection and operational ease.
Solution Approach 2:
The system incorporates feedback from the main circuit state to control the protective circuit. By detecting whether the main circuit is operating or stopped, the system provides feedback that determines whether the protective circuit should be active or inactive. This feedback mechanism ensures that protection is applied only when needed, avoiding interference with normal motor control while effectively protecting during shutdown conditions.
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 device effectively inhibits the increase in applied voltage to switching elements due to regenerative electric power, ensuring stable operation of the motor driving device.
Implementation Method 1
a voltage detection circuit that is connected between the control terminal of the high-side switching element and the ground, is put into a conducting state when a voltage between the control terminal of the high-side switching element and the ground reaches or exceeds a first predetermined value
Implementation Method 2
the high-side switching element includes a first terminal, a second terminal, and a control terminal, and has a function of making an electrical connection between the first terminal and the second terminal when a voltage greater than or equal to a predetermined threshold is applied between the first terminal and the control terminal
Implementation Method 3
a logic circuit that puts the driving switch into an open state regardless of the drive signal when the detection signal from the voltage detection circuit is put into the first state
Data Source
AI summary
A motor driving device includes: a series circuit of a Zener diode and a detection resistor, connected between a gate terminal and a ground of a first high-side transistor; a comparator that compares a voltage of the detection resistor with a reference voltage; a first driving transistor that short-circuits between the gate and source terminals of the first high-side transistor, using a detection signal output by the comparator; a control circuit; and an OR circuit that puts the first driving transistor into an open state regardless of a drive signal from the control circuit. The motor driving device puts the first high-side transistor into a conducting state when a power supply voltage increases and the gate terminal of the first high-side transistor reaches or exceeds a predetermined voltage, to inhibit an increase in the power supply voltage.