*Matrix Converter for More Electric Aircraft DOI: http://dx.doi.org/10.5772/intechopen.81056*

*Aerospace Engineering*

following merits:

switching frequency.

**1.1 Green technology**

DC link converter or AC-DC-AC converter has been implemented at industries since 1902 because of its special features. For example, voltage source inverter has

The main demerits of AC-DC-AC converter or DC link converters are as follows: (1) they are not suitable for transients operations because voltage across the large capacitor or large inductor in the circuit cannot be instantly changed [2]; (2) bulky, more weight, and costly. These limitations are overcome by direct AC-AC converters such as cycloconverters and matrix converters [2, 3]. This chapter is about matrix converter [4, 5], and its application is especially for aerospace. The matrix converter is preferred for cycloconverter [6] because of no limitations with respect to obtaining output frequency. The reason is that cycloconverter is limited to offer

M. Venturini and A. Alesina invented the matrix converter technology in 1981 [4], and this paper described the fundamentals of matrix converter such as PWM to generate nine pulses with maximum voltage transfer ratio of 0.5 [4, 5]. The main advantages of MC are good sinusoidal input/output waveforms and inherent regeneration capability. The same authors improved the PWM algorithm to get 0.866 voltage transfer ratio with good sinusoidal output waveforms in 1986 [5]. After that, a lot of papers discussed different kinds of modulation schemes for MC [4, 5, 7]. The MC has severe problem with commutating bidirectional switches (BDS); but in 1992, four-step commutation [8, 9] was introduced. In 2001, Yaskawa Electric in Japan made 5.5-kW and 11-kW matrix converters, and now it is developing higher rating of matrix converters such as 22 kW and 45 kW [10] and selling for lift applications. Because of potential advantages of the Matrix Converter, this has been considered for commercial, industrial [11] and aerospace applications [12]. The MC is especially suitable for aerospace applications because of it capability to provide wide range of unrestricted output frequencies which is imposed by it

The aim of More Electric Aircraft (MEA) is to support green technology by replacing other powers usage of aircraft with electrical power usage.

1.Easy voltage supply control is possible for VSI.

output frequency of one-third of its input frequency.

2.Low harmonics content exist.

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**Figure 1.**

*AC-AC power converter topologies.*

The conventional aircraft requires mainly four powers such as electrical power, pneumatic power, hydraulic power, and mechanical power. The concept of MEA is to replace other powers with electrical power using green technologies. This chapter is focused on green technology for aerospace applications such as aircraft surface actuation control systems. The reason is that regenerative power from the MC drive causes stability problems at aircraft power supply. Overcoming this limitation of MC drive is vital. For example, the host drum drive motor (HDDM) regenerates power when the tanker aircraft (TA) refueling hose trails and winds at air. **Figure 2** shows circuit of the tanker aircraft with regeneration control circuit (RCC), which is used to dissipate regenerative power of MC drive using proposed methods.

The host drum drive system (HDDS), which is controlled by Refuelling Control Unit (RCU) and Aeronautical Radio Incorporated Commands (ARINC), controls refueling hose and has three units such as motor control unit (MCU), dump resistor pack (DRP), and two motors. The schematic circuit of HDDS of TA is depicted in **Figure 3**.

Regeneration occurs only whenever refueling hose winds and trails and this action is commanded by MCU with RCU. It means that the MCU supervises direction of motors based on input from RCU commands. Hence, HDDS must dissipate the regenerated power; otherwise, it can cause below mentioned problems:


The HDDS is using DC link converter, which is not favorable to transient operations of HDDS drive, and this system is bulky and more weight, which are not desirable characteristics for aircraft. The MC drive is proposed to address above problems. However, inherent regeneration capability of matrix converter limits itself being used for above application because bidirectional switches directly fed back to regenerated power to aircraft input power supply without requiring any additional power electronic components.

According to aerospace power quality specifications, this regeneration onto aircraft input power supply must be limited. For this reason, avoidance of regeneration is vital for aircraft surface actuation systems of aircraft. Hence, to avoid regeneration in the matrix converter drive, three novel methods are proposed:


To detect regeneration in MC drive, two novel techniques are proposed:

1.Power comparison (PC) technique

2.Input voltage reference (IVR) technique

Each and every method has its own regeneration control circuit (RCC). For example, RCC for BDS method consists of three bidirectional switches (BDS) in series with three resistors, and this setup is connected across small input filter of MC drive. The RCC for IPC method requires one conventional uncontrolled sixpulse rectifier and a unidirectional switch (UDS) in series with a resistor, and this

**Figure 2.** *Tanker aircraft with RCC.*

#### **Figure 3.**

setup is connected in between input power supply and small input filter of MC. SCC method does not require additional components, which means that no separate RCC is required to do the same action.

The simulation results prove that the matrix converter is a suitable alternative to conventional HDDS converter topologies. The BDS method is experimentally adopted to verify the proposed concept by laboratory prototype matrix converter, which is built at Smiths Aerospace laboratory (later called GE Aviation laboratory) in University of Nottingham. This MEA project strongly supports the green environment by adopting abovementioned green technologies to obtain reduced aircraft emissions.
