High Voltage Motor Control via Direct On-Off Commutation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control systems using pulse width modulation (PWM) for synchronous electric motors face high switching losses and lower controller efficiency due to heat dissipation issues, which can lead to device failure, and are limited by cost and component capabilities, especially in high-voltage applications.
Innovation Solution
A high-efficiency motor control system employing a direct on-off communication routine that combines a hybrid bootstrap and charge pump circuit with a high frequency oscillator to maintain indefinite on-time for high-side switches, reducing switching losses and improving efficiency across a wide range of loads and speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM switching is used to control motor speed and torque, then the motor can be controlled across a wide range of speeds, but switching losses increase and controller efficiency decreases
Solution Approach 1:
The patent extracts the high-frequency PWM switching function from the control system and replaces it with a direct on-off commutation routine that operates at much lower frequency. The motor control is achieved through direct switching of power phases without requiring high-frequency PWM modulation, thereby eliminating the associated switching losses while maintaining speed control capability through varying the on-off timing and sequence of the power switches.
Solution Approach 2:
The patent implements periodic commutation of the motor phases through a simplified on-off routine that cycles through the power switches in a predetermined sequence. This periodic switching achieves motor control by varying the duration and timing of each phase's on-state, replacing the need for high-frequency PWM while maintaining effective torque control through the sequential activation of motor windings.
2Ease of manufacture
If bootstrap technique is used to drive high-side switch gate, then the circuit is cost effective, but the switch on-time is limited due to rapid capacitor discharge
Solution Approach 1:
The patent eliminates the need for bootstrap capacitors by using a direct on-off commutation routine that maintains continuous control of the high-side switches through alternative voltage sourcing. The system achieves indefinite on-time capability by using the bus voltage directly and controlling the switch gates through a different mechanism that does not rely on capacitor charge storage, thereby removing the fundamental limitation of bootstrap-driven circuits.
Solution Approach 2:
The patent introduces an intermediary control mechanism that mediates between the control logic and the high-side switch gates, replacing the bootstrap capacitor as the voltage source. This intermediary system uses the bus voltage and control signals to directly establish the gate drive voltage, eliminating the need for energy storage capacitors and enabling continuous on-state operation without the discharge limitation inherent in bootstrap circuits.
3Stability of the object's composition
If high frequency PWM is used to recharge bootstrap capacitor, then the capacitor can be maintained, but power dissipation in switches increases significantly
Solution Approach 1:
The patent extracts the bootstrap capacitor and its associated high-frequency recharge circuitry from the system, replacing it with a direct voltage control mechanism. The high-side switch gates are driven directly from the bus voltage through control logic that establishes the appropriate gate drive levels without requiring intermediate energy storage and recharge cycles, thereby eliminating the source of excessive power dissipation.
Solution Approach 2:
The patent establishes the gate drive voltage for high-side switches in advance through direct connection to the bus voltage, rather than requiring continuous recharge during operation. The control system preliminarily sets up the voltage conditions needed for switch operation through the commutation routine, eliminating the need for high-frequency recharge actions and the associated energy losses.
4Strength
If charge pump circuit is used to produce voltage higher than bus voltage, then gate drive voltage can be achieved, but component limitations restrict it to low voltage applications
Solution Approach 1:
The patent changes the approach to gate drive voltage generation by eliminating the need for voltage multiplication entirely. Instead of using charge pump circuits that step up the voltage, the system directly utilizes the bus voltage to establish gate drive levels, adjusting the control parameters and switching sequences to achieve effective motor control without requiring gate voltages exceeding the bus voltage. This parameter change enables the system to operate across a wide voltage range from low to high voltage applications.
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 direct on-off communication routine enhances system efficiency, reduces heat dissipation, and provides a cost-effective, flexible, and robust motor control solution, outperforming PWM systems in terms of efficiency and reliability.
Implementation Method 1
A high-efficiency motor control system employing a direct on-off communication routine that combines a hybrid bootstrap and charge pump circuit with a high frequency oscillator
Implementation Method 2
combines a hybrid bootstrap and charge pump circuit with a high frequency oscillator to maintain indefinite on-time for high-side switches
Implementation Method 3
Modern semiconductor switches or transistors such as a MOSFET or insulated-gate bipolar transistors (IGBTs) are well suited components for high-efficiency controllers
Data Source
AI summary
A high-efficiency control system and method is presented. The system can feature a gate drive circuit, a floating charge pump and pump circuitry, and a bootstrap capacitor circuit having a floating ground. The floating charge pump features a ground electrically coupled to a load. The bootstrap circuit can feature a floating ground, with a floating voltage being carried across the bootstrap circuit and delivered to the gate drive circuit to produce an indefinite on-time for switching a high-side of a power supply to the load.