Embedded Bidirectional Buck-Boost Converter in Half Bridge Class-D Audio Amplifier for Suppressing Bus Voltage Pumping
Abstract : In this paper, a half-bridge class-D audio amplifier (HB-CDAA) system with embedded bidirectional buck-boost converter is proposed. The proposed HB-CDAA system consists of a front-end symmetric bipolar output converter, a bidirectional buck-boost converter and a HB-CDAA. With the help of the embedded bidirectional buck-boost converter, bus voltage pumping on the output of the front-end symmetric bipolar output converter of HB-CDAA can be suppressed. Thus, small ceramic capacitors can be used as bus capacitors to increase power density and to improve audio output quality. Furthermore, ZVS of the embedded bidirectional buck-boost converter can be achieved. The operating principle of the proposed circuit is analyzed and an experimental prototype is built. Experimental results show that ZVS of the embedded bidirectional buck-boost converter is realized, and bus voltage pumping is successfully suppressed with small bus capacitors.
? This can lead to a latch-up of the device in the ON state. The hazard of latch-up existed in the first generation IGBTs.
? The over-temperature function provides effective protection against overloads and cooling system failures. Tripping of the over-temperature protection is an indication of stressful operation. Repetitive tripping is an indication that the above symptoms exist.
? The output apart from the desired average voltage (dVg), also has superimposed alternating voltage at switching frequency. Real dc-to-dc converters are required to provide nearly constant dc output voltage.
? In order to achieve efficient operation, the low pass filter is realized by means of non-dissipative passive elements such as inductors and capacitors.
? Special techniques and methods have been developed to overcome this issue.
? However, when the continuous operation of a load is critical, the hold-up time has been extended by means of external additional devices—so-called hold-up time extension circuits (HTEC).
? In these high current applications, each low side device must have its own isolated control power supply in order to avoid ground loop noise problems.
? This problem set is to apply the simple steady state and transient thermal models to evaluate temperature rise, thermal resistance, temperature ripple, etc.
• Resonant transition converters were proposed more recently. They combine the low switching loss characteristics of the resonant converters and the low conduction loss and constant frequency characteristics of the PWM converters.
• In particular this invention relates to efficient turn-on and turn-off of power semiconductor switches in power supplies and converters. Several new circuit topologies are proposed incorporating this invention.
• The load being inductive, may be considered to be a constant current branch for the purpose of analysis.
• The switch voltage, current, switching energy loss and the v-i trajectory of the switch current and voltage on the vi plane in course of switching.
? The limitation of series-architectures is the size of the capacitor due to the limited voltage level of the DC bus. In addition, there is an obvious loss of efficiency because all the power consumed by the load passes through the HTEC.
? As a result, a new operational mode has been included in the decision-event approach and a linear voltage regulator has been replaced by a hysteresis controller, considerably improving the overall performance of the HTEC.
? A good choice for this value can be the minimum converter efficiency that always satisfies td .
? Converter efficiency as a function of the operation point of the converter can be experimentally determined by applying a test bench of controlled variation in the voltage of the capacitor and the load power.
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