New boost converter with continuous output current

Unlike buck converters, boost converters are rarely used for high-power conversion. The main reason is that a boost converter (Fig. 1a) does not perfectly match load R1: its output current I_out is 100% modulated, therefore an output filter capacitor C1 (and sometimes a large one) is required.

A goal of the invention is to find an effective solution for reduction of output voltage ripples and/or output capacitor value.

Fig. 1. Conventional boost converter (a) and invented boost converter operating in Continuous

Current Mode (CCM) (b)

The main idea of the invention (Fig. 1b) is to maintain an output current not while switch Q1 is OFF, like in conventional circuit, but during switch Q1 ON state too. For this purpose transformer T1 (as a rule with unity transformation coefficient) and diode D2 are embedded into the circuit. Besides an auxiliary diode D3 is added to demagnetize transformer T1 core.

As a result during the ON state of switch Q1 the energy, consumed from the primary source V1, is stored in inductor L1 and simultaneously the current, equal to the inductor L1 current, is delivered to the output though transformer T1 and diode D2, so the input current I_in from V1 is twice as large as the inductor L1 current. After switch Q1 ON-OFF transition the current through the transformer T1 secondary winding and diode D2 drops to zero, diode D2 closes, diode D3 opens, and the reverse voltage E is applied across the secondary winding of transformer T1. The sum of the input voltage E and output voltage U_R1 is applied to switch Q1. During OFF state of switch Q1 both input I_in and output I_out currents are equal to the inductor L1 current (like in the conventional boost converter).

Therefore, an output current flows across a load both in ON and OFF states of switch Q1. For unity T1 transformation coefficient the output current I_out is continuous and equal to the inductor L1 current. As a result, the invented boost converter is matched to a load as well as a buck converter.

The value of output capacitor C1 can be reduced many times (10-100) without increasing output voltage ripples across load R1 in comparison with the conventional boost converter.

Now we are looking for a partner who would be interested in sharing the further patenting of this invention. There are two possible bases for the cooperation:

- our company could sell the PCT Application, which implies a transfer of the patenting rights followed from Application WO 2006/019328 A1, published on 23 February 2006

- joint patenting, which involves sharing the costs and future benefits.

Some applications of the invented boost converter are:

a – battery powered electric vehicle with overdrive option,

b – output battery voltage stabilizer,

c – step-down – step-up converter with continuous output current and output voltage from 0 to 1.6V_in for industrial applications including arc power supply.

I look forward for cooperation in the future.
My Email: yikras@mail.ru

Best Regards,

Krass.