Power conversion apparatus, refrigeration cycle apparatus, and air conditioner
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Solution Overview
Problem
Conventional power conversion apparatuses with diode bridgeless (DBL) rectifier circuits do not effectively account for the influence of motor-induced voltage on efficiency, particularly at higher speed rotation ranges where motor-induced voltage and current increase, leading to reduced efficiency.
Innovation Solution
A power conversion apparatus comprising a reactor, a DBL rectifier circuit with parallel-connected legs, a smoothing capacitor, an inverter, and a control unit that adjusts the operation of switching elements based on detected motor-induced voltage and direct-current voltage to optimize efficiency, allowing for switching between synchronous rectification and boosting operations to manage motor current and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If motor rotates at higher speed, then motor performance and output power are improved, but motor induced voltage and current increase causing efficiency to deteriorate
Solution Approach 1:
The patent employs a feedback control mechanism where the control unit continuously detects the motor induced voltage and uses this information to adjust the rectifier circuit operation. By monitoring the actual motor operating conditions and dynamically adjusting the rectification strategy, the system compensates for efficiency losses that occur at high speeds, allowing the motor to maintain both high output power and high efficiency across the full speed range
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 configuration enhances efficiency in the higher speed rotation range of the motor by dynamically controlling the rectification and boosting operations, thereby reducing energy losses and improving motor performance.
Implementation Method 1
a rectifier circuit to receive a power supply voltage outputted by an alternating-current power supply
Implementation Method 2
a smoothing capacitor to smooth an output voltage of the rectifier circuit
Implementation Method 3
an inverter to convert a direct-current voltage smoothed by the smoothing capacitor into a drive voltage for a motor
Implementation Method 4
an influence of a motor induced voltage on efficiency when a load is a motor
Data Source
AI summary
A power conversion apparatus includes: a reactor; a rectifier circuit that includes a first leg including switching elements connected in series and a second leg connected in parallel with the first leg, including switching elements connected in series; and a smoothing capacitor that smooths an output voltage of the rectifier circuit. The power conversion apparatus also includes an inverter that converts a direct-current voltage smoothed by the smoothing capacitor into a drive voltage for a motor and applies the drive voltage to the motor; a voltage detection unit that detects the direct-current voltage; and a control unit that controls operation of the rectifier circuit and the inverter. The control unit controls operations of the switching elements on the basis of an induced voltage induced in the motor and a detected value of the direct-current voltage.