Design and application of a self-powered dual-stage circuit for piezoelectric energy harvesting system
Abstract : This paper describes the design and practical application of a dual-stage H-Bridge (DSHBR) circuit to reduce the rectification losses and mitigate ripples in piezoelectric energy harvesting. The proposed DSHBR circuit integrates both AC-DC and DC-DC conversion processes using bidirectional switches and a step-up DC-DC converter, which applies to both positive and negative half cycles. One additional feature is that it does not require external power to turn on the bidirectional switches (Vth < 0.3 V). Such feature facilitates active rectification at very low AC voltages (Vac < 0.5) generated by the piezoelectric device (PD). To validate the performance of the proposed circuit, a series of experimental tests were conducted. Firstly, the performance of circuit on rectifying the PD output was investigated using a shaker to generate high and low frequency excitations. Next, real-life testing was conducted with human arm motion as the source of excitation. Then, the ability of the entire system to charge solar batteries was investigated. The outcome shows that the DSHBR circuit prominently increased the rectified voltage and the output power while stabilising the DC voltage when compared with the conventional H-Bridge circuit.
? One of the most widely used power harvesting techniques for micro-power applications uses piezoelectric materials to convert any type of energy to electrical energy.
? The process of extracting unused energy from the ambient environment and converting it into a usable form of electrical energy is known as Energy Harvesting.
? Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices.
? The technique uses a mechanical stopper to broaden the operating frequency range by changing the damping and the stiffness of the system at impact.
? The design is simple, but it has energy losses due to mechanical impact and risks of mechanical impact fatigue.
? Some of the disadvantages associated with piezoelectric ceramics are: rigidity, brittleness, high density, lower voltage coefficient, physical limitation in producing small-sized piezoelectric ceramics, and lack of design flexibility.
• In this paper, a modified circuit and an improved analysis for the self powered SSHI (SP-SSHI) are proposed.
• The essence of the SP-SSHI technique proposed is the electronic breaker.
• Different energy harvesting techniques have been investigated for the purpose to broaden the energy sources, alleviate the dependence on batteries, and hopefully someday make all WSN devices self-powered.
? In their study, the performance of PD and single stage conditioning circuit has been analysed.
? The magnitude of extracted output power is a useful indicator of the performance of the proposed DSHBR circuit.
? An improvement in output power and efficiency was augmented in comparison with the FBR circuit.
? It includes a synchronous rectification process, which eliminates the need of diodes, minimises the size of the circuit and improves the overall efficiency.
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