Motor Pre-Charging Circuit for Fast Start and Rush Current Suppression
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Solution Overview
Problem
Existing motor control apparatuses face delays in starting motor driving due to excessive rush currents and the need for current-limiting resistors, which prolong pre-charging times and delay motor start-up.
Innovation Solution
A motor control apparatus with a pre-charging circuit that starts charging from a DC power source before the control unit operates, using a relay circuit and a pre-charging circuit in parallel to complete charging before the control unit begins, thereby avoiding the reliance on current-limiting resistors and reducing start-up time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a current-limiting resistor is used in the pre-charging circuit, then the rush current to the charging circuit is suppressed, but the pre-charging time is prolonged and motor start-up is delayed
Solution Approach 1:
The control unit determines whether pre-charging is necessary before connecting the power source to the charging circuit. By performing this determination action in advance, the system avoids unnecessary pre-charging delays while still suppressing rush current when needed, thus resolving the contradiction between rush current suppression and pre-charging time reduction.
Solution Approach 2:
The system changes the operational parameters of the pre-charging circuit dynamically. Instead of always using the current-limiting resistor, the control unit adjusts the circuit configuration based on detected conditions (such as voltage levels or charging state), allowing the system to optimize between rush current suppression and pre-charging speed by changing the electrical parameters of the pre-charging path.
2Reliability
If the capacity of the charging circuit is increased to stabilize power-source voltage, then the power-source voltage stability is improved, but the pre-charging time is prolonged due to the larger capacity requiring more charging time
Solution Approach 1:
The control unit performs a determination of whether pre-charging is necessary before initiating the pre-charging process. This preliminary assessment allows the system to avoid unnecessary pre-charging of large-capacity charging circuits, thereby reducing pre-charging time delays while maintaining voltage stability when actually needed.
Solution Approach 2:
Instead of always performing full pre-charging of the large-capacity charging circuit, the system applies partial pre-charging only when necessary. The control unit determines the appropriate level of pre-charging action based on actual needs, avoiding excessive pre-charging time while ensuring sufficient voltage stability for motor operation.
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
This solution effectively suppresses steep rush currents, shortens the time from power source activation to pre-charging completion, and enables quick motor start-up without relying on current-limiting resistors, reducing delays and enhancing motor control efficiency.
Implementation Method 1
a pre-charging circuit that is provided in parallel with the relay circuit, that starts charging from the DC power source to the charging circuit
Data Source
AI summary
Provided is a motor control apparatus that suppresses a steep rush current to a charging circuit and that can quickly start driving of a motor without depending on a current-limiting resistor. The motor control apparatus according to the present disclosure includes an inverter for driving a motor, a charging circuit for supplying electric power to the inverter, a relay circuit for connecting a charging circuit and a power supply terminal, a control unit for controlling the inverter and the relay circuit, and a pre-charging circuit that is provided in parallel with the relay circuit, that starts charging from the power supply terminal to the charging circuit after a power switch for connecting an external power source with the power supply terminal is turned on, and that completes charging of the charging circuit before the control unit starts operation thereof.